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Old 11-07-2012, 06:08 AM   #1
TheRadBaron OP
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Location: Central Illinois
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Honda 350 scrambler with a mix of SL/CB/CL parts

I started this build thread over on www.hondatwins.net, but I thought that I'd bring it over here too.
Let me start this log with some history of this bike. It started out as an all-original '73 CB350G, purple in color. It was given to my dad in the early '90s by a friend of his. It had been sitting in a garage for 10 years or so before that, and I think it was a case of the old ran-when-parked story. My dad is into antique American bikes, but the Honda was free and it was in good shape, so he stuck it in his garage and it remained there until I got out of the Marines at the end of '06. I'd grown up riding '70s Japanese dirt bikes and I still had my old '75 Honda XL125 although it needed some freshening up. I started working on it that winter and I was enjoying myself so much that I asked my dad if I could have the old purple 350 to wrench on. He was happy to get it out of his garage. He also showed me a junkyard '72 CB350 he had that was a wreck but had some good parts on it.
I'd like to take this opportunity to apologize and express a bit of remorse for hacking up a nice, all-original, CB350. Not that CB350s are rare bikes, but now I know better and as a rule I leave the nice, original bikes as they are and only cut up and heavily modify already messed up machines. If I could go back and do it differently I would, but at the time I was younger and less cultured than I am now. I was a good mechanic, but I was used to working on big, American, V-8s and was new to small Japanese motorcycles. I really liked Japanese bikes, but at the time I didn't view them as historically significant. So again, I repent. Now is now, and what's done is done, though, so I won't dwell on it and I intend to turn this poor machine into a really enjoyable bike again.
So back in the winter of '06 I sat on a milk crate in my unheated Illinois garage and got the 350 running. In true Honda form, it didn't take much. The hydraulic disc front brake was totally yucked up and non-functional, so I just took it off and made a spool hub. Hell yeah! (Remember, I know better now). I took it for a test ride and it ran well so I decided to plate it and made plans to make it my main rider. I quickly realized that riding a purple motorcycle was a thing that I found unacceptable, so I swapped the faded, gold tank from the '72 onto it and took the purple side covers off. I liked the look of the bare air boxes, and I would later take the minimalist approach to the extreme. I rode the bike around all winter and spring like this, no front brake and all. After a few minivan-caused Fred Flinstone-style panic stops I decided that I should invest in a front brake. Luckily, the DLS drum from the '72 swapped right on.
After that, I gradually modified things and took things off, and did some engine work. After a friend of mine had a catastrophic cam tensioner failure on his 350 I installed the KA Performance teflon slipper cam chain tensioner and the Camellia cam chain that goes with it. I was having trouble with the stock carbs and decided that I wanted some Mikunis. I listened to the wrong people and put 32mm units on it which were much too large for the stock motor. I managed to get it tuned well enough that it ran nicely and was fun to ride, but it was kind of finnicky about the throttle and I knew that it wasn't running at its potential. I rode it like this for a few years and countless thousands of miles. Here's what it looked like for the last few years I was riding it.

Then in the winter of '09 I had an engine seizure while riding the 350 for the first time in a few months. I had recently fixed up a Yamaha XS650 that had replaced the CB as my main bike, so the CB wasn't getting ridden as much. I was going down the road at 65 or so and the engine just tightened up and locked solid. I was bummed but I had the 650 so I just got the bike home and put it in the corner. I recently started to really miss the old 350, though. It was my first street bike and the bike that I really cut my teeth on mechanically. I decided to pull the motor out and see what happened.
It turns out that it had lost oil flow to the top end and the cam had welded itself into the bearing blocks. It wasn't caused by a lack of maintenance as I always changed the oil and cleaned out the centrifugal slinger regularly. I had all the extra parts on hand to rebuild it so I set about doing it. I'm happy to report that the KA Performance cam tensioner showed no wear whatsoever after thousands of hard miles on the street. One of the first things that I did when I first got this bike was to remove the electric starter. I really hate electric starters. I refer to them as "femstarters". I've found it to be a very divisive subject over the years so I won't elaborate unless you guys really want to hear it. Anyway, I thought that this would be a good opportunity to rebuild the motor into a set of later SL350 engine cases that didn't have the electric starter provision. I was going to have to split the cases anyway to get the new cam chain on. I had a nice set of SL cases that I bought a few years ago at a swap meet. I knew that the crankshaft was different since the SL crank didn't have the starter clutch so I got a good SL350 crank, too. I had done some research and the people "in the know" told me that everything (CB350 parts) else would swap right into the SL cases, but the motor mounts were in different locations so I'd have to do some fabricating to get the SL cases into the CB frame. In hindsight, these were probably the same guys that told me that VM32 carbs were the only way to go. If I would have researched it to the point of looking up part numbers I could have learned that nearly every part in the bottom end was different between the two models. Almost nothing interchanges. I think the main reason for this is that the SL uses a primary kickstart while the CB kickstart goes through the clutch, and this difference caused everything to be build differently. This makes sense, though. Since the CB is designed to have an electric starter as it's main starter and the kicker as just an emergency backup, I guess Honda found it acceptable to design the kickstart mechanism so that the transmission had to be in neutral with the clutch engaged for the kicker to turn the motor. More than once I found myself stalled in traffic, frantically trying to find neutral so that I could kick the bike back to life. No fun. Since the SL's only starter was the kicker and it was designed as an off-road bike, it really needed the primary kickstart design that would allow it to be started in any gear with the clutch disengaged, or engaged and in neutral. At the time when I discovered all of this I was bummed out because it looked like the SL cases were going to be totally impractical and I really had grown fond of the idea. However, I was able to locate a complete SL bottom end for a good price. Now that I have all the parts, I really like the idea of having a primary kickstarter.
I got the motor all back together the other day. It's the complete SL bottom end with the complete CB top end. It has a new Camellia cam chain and all the damaged parts from the seizure have been replaced. Since I had it apart I got the cylinders honed and put new Honda factory rings on the pistons.
I had been thinking about what direction I wanted to take the bike in this time around. I had a few ideas, but I knew that I wanted to address some of the things that were holding the bike back now that I'm older and smarter and a better mechanic and tuner. First on my list was to change out the too-big carbs. I don't like the design of the stock Keihins at all, so I planned to just put some smaller Mikuni VMs on. Next was to get some decent exhaust on it. The little shorty pipes that I had were too loud and were such a poor design that I'm sure they were hurting performance over the stock mufflers. While gazing at the bike in the garage I decided the direction that I wanted to go. I'd always admired the SL350s, both the early ones and the later ones that were more dirt-oriented. I liked the look of the high front fender and the abbreviated seat in particular. I also really liked the high pipes that came on Honda CLs. So a high-fendered street scrambler with CL pipes and a single (or at least shorter) seat it would be.
I was able to address both big improvements that I wanted to make to the bike in one fell swoop when I realized that I had a set of really nice Mikuni VM28 carbs from a '72 Yamaha R5 that will work great with a bit of rejetting. Furthermore, I talked to a friend that's building a CB350 race bike and wanted some VM32s and happened to have a set of nice '71 CL350 pipes hanging in his shop. Bartering is great.
It turns out the the motor mount locations are in the same position after all. I had to clearance the frame on the right side of the bike where the rear of the motor mounts to clear a part of the engine case casting, but it was very slight.

The other thing that was necessary was to add a 6mm spacer on each side between the front motor mounts on the frame and the case. I used a stack of 3 washers on each side that worked out perfectly. Crude but effective. Here's the hybrid motor all bolted up in my CB frame.

I was having trouble finding a seat that I liked the look of. I tried a bunch of different seats on and hey were either too short so the rear fender and the loop of the frame over the fender looked awkward, or too long so they almost touched the tail light, or too wide so that they hung out of the frame rails and looked stupid, etc. I thought that I'd have to end up getting an early SL seat, but I wasn't able to find one for sale anywhere. Being a one (or maybe two) year part on a bike that I don't think many were sold, coupled with the abuse that seats get didn't have me feeling too optimistic about finding one. Well yesterday while I was looking around in a different building I came across an old Suzuki TS90 chassis with a good looking seat on it. I took it over to the 350 and it turns out that it looks good to my eye. The only problem is that it doesn't meet the fuel tank just right and looks a bit unprofessional there, but I can live with it. I really like the proportions and shape of the seat on the bike. It will take a bit of fabricating brackets and mounts, but it's actually a really close fit already. It will be getting a fresh seat cover at some point, but the foam and pan are in great shape.


Today I addressed the mounting of the high front fender. It would have been easy to use a universal plastic fender, but I really wanted to keep this bike looking late-'60s period correct. I have a '70 SL70 with a simple metal high fender that's painted the same color as the tank and I love the look of it. I took the fender bracket from the triple clamp of the same TS90 that I robbed the seat from and welded it to the bottom of the CB350 clamp.

I'll get it painted up and reinstalled soon. For the fender itself I'm using a stock front fender from a CB350 that I removed all the bracing from, shortened, and drilled to match the fender bracket. I mocked it up on the bike and I like the way it looks. I hope to blast the fender and get it painted tomorrow. I'll put up some more pictures when I get it on.
My heart is really set on having period correct on/off road tires on this bike when it's done, but I can't find any of the old universal trials tires for sale. They're the ones with the closely spaced, tall, square tread blocks that used to be on every dirt bike and are usually still on every dirt bike that's been neglected for a few decades. Cheng Shin used to make them and I liked them a lot, but I guess they don't make them anymore. Does anyone here know a source for these tires?
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Old 11-07-2012, 06:10 AM   #2
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I stayed up late last night looking around for suitable tires and it looks like Shinko has a model that will work. It's called the SR241 tire. They have the tread pattern I'm looking for and they're reasonably priced. It looks like I can get both front and rear tires for less than $100.
I just got back from using the parts washer and bead blaster at my dad's house. I'll be out to paint the stuff this afternoon. I ordered a set of Daystar fork boots that are designed for minibikes that I'm hoping will work and look right on this bike. Once I get them the front of the bike can go back together.
I got the front fender all set up and mocked up on the bike. I'm really liking the way the bike looks as it comes together. It's almost exactly the way it looked in my mind's eye. I think the tires will add a lot to the look, too.



I'm planning to rubber mount the front fender to the stay using some rubber washers. I think the fender would eventually start to crack from the vibration if it was mounted rigidly. I'm waiting for a few more parts to show up before I can wrap up the front end. The fork boots that I mentioned in the last post, ans also a set of '71 SL350 headlight ears that I nabbed last night. They're the black painted ones with the holes up and down their length. I always really liked the look of these and I think the pair that I got has just the right amount of rust speckling and faded paint to match the weathered look of the rest of the bike. Whether or not they'll fit without modifications remains to be seen. The '71 SL had the same 33mm forks that the CB has, but I don't know if the distance between the upper and lower triple clamps is the same. Even if they don't fit perfectly, I'm confident that I can modify them to work.
Man, I'm having a lot of fun picking all of my favorite pieces and putting them together to make the "perfect" 350. I guess that what modifying motorcycles is all about. It's just a lot cooler when it's not yet another hideous chopper with skulls and "tribal ghost flames" and stuff.
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Old 11-07-2012, 06:12 AM   #3
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I spent some time this evening sitting in my shop, smoking a cigar, drinking some single malt scotch, and gazing at the 350. A few things occurred to me. First was an "oh crap" moment when I looked that the front fender and thought that the exhaust pipes might hit it where they come out of the cylinder head. I mocked them up and everything has plenty of clearance. Whew.
Another thing that I realized is that I should have painted the lower triple clamp and fender stay flat or semi-gloss black instead of the gloss black that I used. It looks out of place because every other black part on the bike is low-gloss. The paint that was once glossy has been subdued over the years and all the parts that I've painted black in the past are low-gloss. It won't be a big deal at all to pull it back out and spray a low-gloss coat over it, as the front end has to come back apart anyway to put the fork boots on.

I find myself needing a few parts. I need a countershaft sprocket cover that the clutch release mechanism goes in. It turns out that the SL uses a different cover. I also need the rubber bushings that hold the headlight ears onto the forks from a '71 SL350. There's a total of four of them. It's a one year part because the '70 uses different ears and the '72 got 35mm forks. I could probably make the CB350 ones that I have work, but I'd rather have the correct bushings. Anyone have any of these parts? Thanks.

Here are the front and rear brake stays and the outer swingarm brackets that I've been working on. The front brake stay has just been painted. It was originally chrome, but the speed holes are stock. I drilled the rear brake stay so the holes match the layout and size of the holes in the front stay.
For the swingarm brackets I cut off the rear portions that sere used to mount the exhaust pipes and passenger pegs. I reshaped the brackets to match the contours on the frame where the brackets mount. I don't plan on using the pegs and I won't need the exhaust mounts since I'm using the high pipes. Although the bike won't be quite as spartan as it was before, I'm planning to keep it as minimalist as I can.

I'll be picking up the fork boots later on today and my SL350 headlight ears arrived and look like they'll work with minimal mods. I should have the front end done in a few days.
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Old 11-07-2012, 06:13 AM   #4
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Well, progress has been a bit slow since my last post but I'm still plugging along. I'm mainly being held up by the fork boots. The original set that I ordered were Daystar "83" Series which were listed as fitting "all mini/ATVs with 30-40mm upper tubes and up to 9" of travel". They fit the forks well but were too long for the CB350. They were already getting bunched up when the forks were fully extended and looked crummy. I have other dirt bikes that they'll fit, so it's not a total waste. I'd really like to run fork boots because I like the way they look, but also because my fork tubes are pitted and nasty looking above the travel areas and I want the ugliness to be hidden. More on the forks later. I looked through the offerings from Daystar and ordered a set of "245" Series which are listed for "All PW-50s and Y-Zingers". I believe that the PW50 has 27mm fork tubes and the travel is quite short. I'm hoping that the boots will stretch to fit over the 33mm CB forks and I think the length of the boots will be much more inline with the CB forks. Hopefully they'll be here this week and I can give them a shot.
The other thing that I did to the forks was to buy a can of chrome spray paint and paint over the rusted areas between the triple clamps. I'm embarrassed to say that I actually used "Tijuana chrome" spray paint. I never thought that I'd stoop that low on one of my bikes. The fork tubes will show through the SL350 headlight ears, though, and I don't have the budget for a set of replacement fork tubes. The good news is that the SL ears showed up and they'll work with some minor mods. It looks like the distance between the clamps on the SL is slightly greater than on the CB, but I'll be able to make them work. Once I get the fork boots and get the front end all the way together I'll post some pics and a description of what I did to make them fit.
Here's the swell 36-tooth, aluminum, 520 sprocket that I got from Todd Henning Racing.

I would have preferred a steel sprocket, but I didn't have any luck finding one. I really want to run a 520 chain so that I can use an o-ring chain, but the sprocket choices are really limited. I guess that you can use SL350 sprockets on a CB wheel if you swap out the 10mm CB sprocket studs with the 12mm SL studs. The problem is that I wanted to keep the gearing somewhat highway friendly and I couldn't find any SL rear sprockets with less than 40 teeth and I can't find any SL350 front sprockets with more that 16 teeth. The gearing will be right where I want it the the 16/36 combo using the THR rear sprocket. Hopefully the aluminum doesn't wear too quickly. Since I don't plan on putting mega-miles on this bike, it should probably last a few years at least. Now hopefully I don't have any sprocket alignment issues of other difficulties and I can consider the chain/sprocket part of the project done. I'll probably mock it up tomorrow.
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Old 11-07-2012, 06:14 AM   #5
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The plot thickens on the chain drive. The SL bottom end places the countershaft sprocket further outboard by 1/2" or more from where the CB bottom end had it. I'm hoping that a swap to a SL350 rear wheel will fix that, but the only way that it will is if the sprocket to centerline of the hub distance is greater than the CB350 wheel's. Would someone here be willing to take a measurement for me of the sprocket to hub centerline distance on a '71-'72 SL350 rear wheel? I measure from the inside face of the sprocket to the point midway between the right-hand and left-hand spokes on the hub. It seems likely to me that the SL wheel will fix it since I don't think that they would have offset the motor in the frame.
If the SL wheel won't fix it, I think that I'll be able to get the misalignment down to a pretty small amount by shimming the rear sprocket outward and shimming the front sprocket inward. I haven't taken any precise measurements, but it might work. I'd rather swap the wheel and have everything line up by design, though.
Does anyone have an SL350 rear wheel and brake assembly for sale? Thanks.
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Old 11-07-2012, 02:22 PM   #6
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Nevermind. Problem solved. I got all excited about this before I did a no-nonsense, everything bolted together, mockup. I can actually get the sprockets to align when I shim the front sprocket as far inboard as I can get it without causing the chain to rub, and when I shim the rear sprocket out as far as the circlip groove will let me. Cool. Problem solved.
For the record, though, if I were using a front sprocket that was any smaller than the 16t that I'm using I wouldn't be able to move the sprocket as far inboard as I did. A smaller diameter sprocket would probably move the chain down into the boss in the cases that holds the output shaft seal.
While sitting in my chair looking at the bike, another little detail that needed to be addressed occurred to me. I didn't like the way the front fender looked on the rear edge. I had just cut it straight across and left it like that, but the more I looked at it the more it bugged me. The front fender on my '70 SL100 was my inspiration for this fender so I took a look at it. The edges of it are cut are about a 45 degree angle and rounded off, so I duplicated that on the 350 fender. I think that I'll be a lot happier with it now and it won't bug me when I sit in my chair and gaze at the bike in the evenings.

The CL pipes that I have are a bit rusty and needed a bit of welding repair. Plus, I've always favored the look of flat black exhaust pipes on motorcycles. The problem is, hi-temp exhaust paint never really lasts and I've never wanted to pay the money to have my pipes ceramic coated. I have a buddy who works with a guy who does powdercoating on the side and I guess he has some hi-temp exhaust powercoat that's supposed to be great stuff. He's done some pipes for local shops and I guess the stuff really holds up. It's not too expensive (still waiting to hear from the guy), so I think that I'll give it a shot. I'm planning to have the complete set of pipes and mufflers coated flat black but leave the heat shields chrome.
I've been trying to save money lately since I'm between jobs at the moment (short term) and buy the parts that I need when I get back to work. However, I want to keep making forward progress on the bike and I'd hate to put things together now only to have to take them back apart when I buy the parts that I need. So rather than put the wheels on now and have to take them back off when I get the tires, I'm off to order them up now. Money is a renewable resource.
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Old 11-12-2012, 10:55 AM   #7
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Uh...back to the drawing board

I wish that they would have had a picture showing them to scale. I knew that PW50s and Tri-Zingers were small machines, but sheesh. It's like they're for Ken's dirt bike. Or like at the camping store where they have tiny models of tents and sleeping bags above the display. These must be Daystar's miniature fork boot models for display purposes.
I have a plan, though. I'm not quite ready to give up on the fork boots just yet. My tires are scheduled to arrive today, so hopefully I'll make a bunch of progress this evening.
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Old 11-12-2012, 10:56 AM   #8
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I've made some real progress over the last few days. The tires showed up so I got them mounted. On the subject of tires; for you guys who mount your own tires, I bought a can of Yamalube tire mounting lubricant and I'll never change a tire without it again. I've never tried any other tire mounting lube other than the dish soap that my dad uses (which totally sucks for mounting tires), but this Yamaha stuff is like magic. Seriously, try it out and you'll never go back.

So here are a few pictures of the bike mocked up as it is. The exhaust is just haphazardly stuck on it for the pictures. I got ahold of the guy who does the powdercoating so I'll be dropping the pipes off to him this week to get coated flat black.
Anyway, I got the fork boots figured out, too. I took the first pair that I got and shortened them by cutting the top bellow off that has the lip that gets zip-tied around the fork leg. Then I cut a few bellows out of the main section of the boots and tucked the top bellow into the first bellow of the shortened boot. The result is acceptable. The headlight is from a '76 Yamaha IT400. It uses a 6v bulb that I believe is the same bulb that antique Harleys use. It's sort of an odd design, but I'm almost sure that they make a 12v version. If for nothing else, the guys who do 12v conversions to their old Harleys would need them and there's a lot of aftermarket support there.
The SL350 headlight ears worked with just a bit of mods to the triple clamp setup. The SL ears are a bit taller than the distance between the upper and lower clamps. I could have cut down the ears a bit, but I wanted to avoid that. I used the proper rubber donuts on the bottom of the ears, but I just put a thick o-ring around the fork tubes at the top of the ears. I used a few machine bushings (basically precision washers) between the upper yoke and the nut that goes on top the the steering bearing. This gave me about 3/16 more distance between the yokes, which is what I needed. I just slid the fork tubes up a bit in the bottom yoke to get them even with the top. Yeah, it's going to change the steering geometry just a bit, but I also think the knobby tire is a bit taller than stock and that will make up the difference. The 520 chain is working out well now that I've got the sprockets aligned. It's an RK 520GXW, "XW-ring" chain. It's a high quality chain that should last quite a while. I love o-ring chains. They last forever and rarely need to be adjusted.

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Old 11-12-2012, 12:18 PM   #9
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Lookin' good, neat project.
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Old 11-12-2012, 05:31 PM   #10
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Quote:
Originally Posted by TheRadBaron View Post
I'd like to take this opportunity to apologize and express a bit of remorse for hacking up a nice, all-original, CB350. Not that CB350s are rare bikes, but now I know better and as a rule I leave the nice, original bikes as they are and only cut up and heavily modify already messed up machines. If I could go back and do it differently I would, but at the time I was younger and less cultured than I am now. I was a good mechanic, but I was used to working on big, American, V-8s and was new to small Japanese motorcycles. I really liked Japanese bikes, but at the time I didn't view them as historically significant. So again, I repent. Now is now, and what's done is done, though, so I won't dwell on it and I intend to turn this poor machine into a really enjoyable bike again.
I was thinking the exact same thing when I decided to not even look at a minty-fresh, low mile Honda several days ago. My first thought was that it'd be a great platform to have some fun with, but then it hit me...I'd actually feel bad for doing ANY modifications to it. Kinda defeats the purpose of having a project bike.

Have fun with yours!
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Old 11-14-2012, 09:33 AM   #11
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Man, at every turn I'm finding a new compatibility problem with the SL motor. The newest issue is with the rear brake pedal. The rear of the engine case near the point on the frame where the brake lever mounts is larger than on the CB cases, and there isn't room for the brake pedal. I was able to get it to work with some cutting/grinding/welding on the CB pedal, though. I had to grind off the front of the lever where the brake light switch went, and I cut off the top of the lever where the brake rod attached, flipped it around, and welded it together. I'll have to figure out where to hook the brake light switch up to, but that shouldn't be a big deal. Here are before and after pictures:


The foot pegs originally were tied together with a solid steel rod that goes under the belly of the bike. Years ago, when I was first stripping the bike of its unnecessary weight I cut this rod out and just had the two separate foot pegs. This turned out to be a flimsy setup, though. They were kind of flexy and the bolts were always coming loose. I thought about getting another set of pegs to put on the bike this time around, so I picked up an extra set from a buddy. Holding them in my hands, I still couldn't get over how heavy they were. One of the things that I love about this size bike is how lightweight and maneuverable they can be. Plus, the new pegs that I had were from an earlier CB350 and the location of the pegs was different. I settled on welding a piece of 1/2 steel tubing between my original pegs where the solid rod used to be. I think that this will be a good compromise between weight savings and strength. It will also be a good spot to mount the rear of a skid plate if I decide to build one. I'm thinking that I will.

I dropped the exhaust at the powdercoater the other day and I ordered the carb flanges for the cylinder head. The bike will soon have carbs and exhaust.
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Old 11-19-2012, 03:42 PM   #12
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I got the carbs on. They're Mikuni VM28s from a '72 Yamaha R5 (350cc 2-stroke twin). I originally had VM32s on it and they were way too big for the motor. Most people seem to use VM30s when they switch to Mikunis on their Honda 350s, but these are still too big for a stock motor. I just put a set of VM30s on a CB350 for a friend and they'll run pretty good, but I believe that a stock motor will run best with VM26s or 28s. I was planning to put 26s on, but I had this extra set of 28s that are in really good shape so I'm just using them.
I think one of the big reasons that people like the VM30s is that they'll fit into the stock carb flanges on the head and can be made to work with the factory battery box and air filters. The VM28s require a different (smaller) flange. Since the readily available aftermarket flanges don't have the angle built into them like the stock Honda ones do, I don't think the setup I'm using would work with the factory battery box and/or air filters.
For my purposes, though, it works great. The flanges are made by Mikuni and they're part# M-VM28-200K. They bolt right up to the Honda head without any modifications and the inner diameter is almost an exact match for the diameter of the intake runners in the head. Some very slight port matching would smooth things out, but I didn't worry about it since I won't be competing on this bike.
I'm using a mix of jets and brass that I had on hand that I think will put me in the ballpark. I'm using a 1750-8 needle jet, 5DP7 needle (clip in #3 position), 160 main, 32.5 pilot, with the screw 1.5 turns out. The needle jets that I'm using are the "bleed type" that are accepted to be better for 4-stroke applications than the more common primary type. Hopefully this will be close enough that I can work on fine tuning it once the bike's up and running.
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Old 11-19-2012, 04:07 PM   #13
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Alright. The bike is really starting to come into its final form. The more that I looked at that Suzuki seat the more unhappy I was with how the front of it met the tank. It just looked amateurish and wrong how the contour of the seat fit up against the tank so poorly. Just about the time that I was deciding that I couldn't live with it after all, what pops up on Ebay but a '70 SL350 seat. The cover was thrashed but the foam and pan looked to be in decent shape. I was prepared to pay a lot of money for it since they don't turn up for sale very often, but the auction gods were smiling on me and I got it for cheap. If anyone here is the other bidder that was smited by the auction gods, I apologize. It will take a bit of frame modification to make it work, but nothing serious. I mainly just have to cut off the rear loop that goes over the fender and weld it back on a few inches farther forward. I'll also need to mount the seat latch that goes behind the gas tank since my bike was originally a side-hinged seat and the SL350 seat is a rear-hinged.
I mocked it up on the bike and the fitment is much better than with the Suzuki seat. This one will look like it's designed to be on there. I actually prefer the slimmer look of the Suzuki seat to the taller profile of the SL seat, but I'm overall much happier with the SL seat.
I picked up the pipes from the powdercoater today and I'm very happy with the result. I have a bit of work to do before I can mount them up for good, but the mockup looks nice. The bike has taken on a much chunkier and more squat look than I had anticipated, but I don't dislike it at all. Based on the look of the bike, I've changed my plan to mount a small battery under the seat. I was originally going for a very "open" look behind the engine, but since the rest of the bike looks so dense I think that I'll just reuse the home made battery box that I had on the bike originally. It also serves as the lower mount for the rear fender so I won't have to fabricate something new there.
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Old 11-19-2012, 06:08 PM   #14
Kt-88
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I'm doing the opposite of you- pushing a cl350 motor into an sl350 frame. And man, there are all kinds of annoying differences!
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Old 11-19-2012, 06:26 PM   #15
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Yes indeed. I wonder which one of us has it worse as far as the complications go. Are you having to modify the forward engine mounts? I could shim mine since the points in the frame were wider than on the case, but in your case I imagine that you'd have to cut them off and re-weld them, or something similar. I bet the sprocket alignment will be a headache as well.
It's nice when an engine swap (or any other part swap) is a simple bolt-in, but it's also rewarding to identify the problems and solve them. You end up with something more special that way. Good luck with your swap.
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