Suzuki RM 400 Vintage Race Bike Build

Discussion in '2 smokers' started by Racer111v, Dec 22, 2013.

  1. Enginerd

    Enginerd n00b

    Joined:
    Mar 25, 2013
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    7
    The RM is looking good! I had an 80 RM400 that I sold 18 years ago to buy a KX500. I would love to have another one!
    #21
  2. Racer111v

    Racer111v Long timer

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    Things are progressing, but not a lot of pictures right now. Today was in the high 40's and sunny, so I went out side and did some frame work. I sprayed it with some engine degreaser. I cleaned up the area and tig welded it back together. I think I will do some gusseting in that area. My thinking is a piece of tubing split in half and welded on the lower tube. I thick most of the issue was the wipped out crank, missing engine mount bolts, and tin front mounts. But a little help down there won't hurt. I can see where they stick welded the area in front of the footpeg. I ground out the old weld and tig'd it. I think I will do a little gusseting around there too. I ground off the PE brake cable mount that was added to make that rear wheel work. I also ground off the side stand mount that doesn't belong on mx bike. While I had the welder running I ran a bead around steering races and they fell right out as expected. They make a kit to convert to taper roller steering head bearing that I am going with. I am going to test fit everything on the frame before I have it blasted/painted/powdercoated.

    I have a connecting rod on order, and I will have more info when it arrives. I did a bunch of glass beading on the head, cylinder, cases, and covers. The clutch cover has some pin holes that I think I will just "red epoxy" closed. The swing arm needs a little welding in the guard mounts. I glass beaded it, and will probably just aluminum paint it when it's all sorted out.

    The bottom end I got off EBAY finally showed up. It looks to be in great shape with a tight crank. I will never order any parts around Christmas again. Every one shipped out right away, and then the stuff gets lost for weeks in the USPS system. The rear wheel I ordered got completely lost and we have given up on it. The seller is reimbursing me, and I have already ordered another one.

    I will have another update when I have some pics.
    #22
  3. buls4evr

    buls4evr No Marks....

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    Some more thoughts for you 111. Use MotionPro clutch and front brake cables as they give you the full range of motion without stretch on those drum brakes and really release your clutch without drag. Stockers are small diameter and stretchy. The bike shakes quite a bit at higher revs and they tend to oval out the motor mount holes so check those against your bolts....and loctite everything.The frame materials were unfortunately pretty crappy steel back then, so any additional gussets are a plus. I will tell you they are fast when they are right. We used to use S&W shocks on the back of ours which were far superior to stockers. Not made for years though.... and you want Nitrogens back there anyway. Not sure if "period rules" allow rebound damping. If they do ,get a shock with comp/rebound.
    #23
  4. Racer111v

    Racer111v Long timer

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    Things are starting to show up. It's been a international web trip of education. At least some of the dis-assembly is over and some reconstruction is starting.


    Two packages like this showed up a few days ago. One is the cases/crank/transmission. The other is the cylinder/piston/ring.

    [​IMG]


    I straightened out the shift shaft at work with an arbor press and a surface plate. I installed it in the cases with a new seal. I shifted it through the gears to be sure it was located correct. It took a few attempts to get it right.

    The clutch from the original engine has a lot of indentations from the clutch plates. I bought a new file and flatened out the ridges. This will make the clutch lever pull a little easier. I used a new nut and lock plate, some locktite, and torqued the clutch hub in place. This nut was finger tight when I pulled the original engine apart.

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    I soaked the clutch plates in motor oil. I used the original steel plates and new oem fibers. The pressure plate bolts were locktited and torqued. This bike has an internal clutch adjustment. The PO added some washers that I removed and correctly adjusted the play. I sanded out the epoxy on the clutch cover and hit it with some black engine enamel. I pressed in a new kick starter seal and installed it with a oem gasket and some non-oem socket head cap screws. I have never been impressed with the fasteners that Suzuki used.

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    I installed a new sprocket, nut, and locking washer. I was going to install the rotor and ignition, but when they removed the rotor they deformed the threads a little on the crank. I'll borrow a die and thread file from work next week and clean it up.


    I ordered new front and rear spokes from Buchanan. I have a new Excel front rim and will order a rear next week. :clap



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    #24
  5. P 0 P E Y E

    P 0 P E Y E Bald rider

    Joined:
    Nov 13, 2008
    Oddometer:
    121
    Location:
    southern Connecticut U S A
    I had a RM 370 back in the early 80s.

    It was wounderful.

    Nice pics
    #25
  6. Racer111v

    Racer111v Long timer

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    It was a reasonably nice day out side, so I did a little work on the frame. I bought a piece of 1.5" ID x .065" wall tubing to reinforce the lower cross tube on the frame. The pictures didn't come out that well, but at least you can get an idea of what I did. I still think the cracking was from the loose and missing engine mount bolts, and the completely wiped out crank. This thing must have been trying to shake it's self to death.


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    I cut a slice out of the tubing with a cutoff blade in my angle grinder


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    I have received lots of parts, but seam to always be missing the part I need to get to the next step. I have received the front and rear spoke sets from Buchanans, but the rear wheel looks to good to take apart. I'll keep an eye out for a used rear hub to lace up and have a spare wheel.



    More to come........................




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    #26
  7. Racer111v

    Racer111v Long timer

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    I finally found the right wrist pin for the Wiseco piston. I emailed Wiseco because I couldn't find a catalog old enough to list the RM400 piston. They replied without any info other than a phone number of someone with discontinued Wiseco parts, and it was disconnected. :huh The correct pin ended up being part number S343.

    I got the top end together enough to get a deck height. I sent the info and the cylinder head out to RK Tek to have the chamber welded and reshaped.

    [​IMG]


    The connecting rod for engine #2 arrived from NZ. It looks well made and is made out of EN39B which is a lot tougher than the oem rod. I'll bring it to the shop soon and record all the dimensions.


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    The fenders , gripper safety seat foam and cover have arrived. I'll have more on that when the time comes. I also located some tank and side cover decals. I went with the 1980 style, I just like them better.

    My next panic was the fact that the swingarm parts I ordered were all to large.....:huh Turns out the swing arm isn't a PE250/400, it's a PE175...:cry

    So for the last two weeks I have been searching the world for an appropriate piece. But the good news is I have a 1979 rm400, and a 1980 rm400 on there way from Cali.

    I have also bought a couple sets of Fox Air Shox. I made some tools to take these apart. The 15.75" long are a little scarce, so I took a chance on a set of 15.5" long, hoping the seller had just mismeasured. When they arrived the did measure 15.5". I didn't think they made a set that long, so I was hoping for internal spacers. I was rewarded with a .25" spacer on the shaft. They have a little pitting on one shaft, so I am going to send it out to get it refinished. More on these later.


    :clap
    #27
  8. Racer111v

    Racer111v Long timer

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    Not much progress this week. One of the swingarms will be here Tuesday, the other one will be later in the week. I ordered controls, and throttle (Magura). I attempted to lace the front wheel last weekend, but the spokes were to short to do the original cross three pattern. I emailed Bucanans a couple times with no reply. I finally got a chance to call them and was initially told the spoke length was correct. Then with a little more investigating I was told that Suzuki started production with a cross two pattern, and after a few broken hubs changed to a cross three pattern. The increased spoke angle takes some load off the hub. They said the spokes would work with a X2 pattern, or they would send me the longer spokes for a X3 pattern. I said I would prefer the longer spokes, and was told they would get them right out for me.

    I am glad I got going on this project right away. In spite of the tough winter this year, I know spring will be here quickly. I'm going to need every minute of practice time , for both me and the bike.........








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    #28
  9. Racer111v

    Racer111v Long timer

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    The '80 swing arm arrived, and it's in excellent shape. After two weeks, and an email saying it will soon be on it's way, the second ('79) swing arm isn't here. I got a call yesterday saying it wasn't the correct swing arm and they have credited my card. I have fork springs,fork bushings, and fork oil on it's way. I already have a RaceTech emulator and hope to attack the forks next weekend.

    It was nice out for a few hours, so I did some tailgate work. I got a "safety seat" as they were call. The PO did a half-assed job installing a new seat cover. There was bits of the old cover and lots of rusty staples.

    [​IMG]

    The seat bracket was sheet metal screwed onto the base and had been welded a few times. I remember seeing racers loosing seats more than once in the 70's/80's. Many times it was from leaving the seat bolts loose or out after cleaning the air filter. But some times it was just the brackets breaking. The modern bikes are designed better as far as seat design. This bike takes a lot of load on the brackets and really needs another arched brace under the seat base. For now I'll just make sure the original set up will work. I made a plate with a couple 6mm nuts welded to it.

    [​IMG]

    This is the stock seat next to the new foam.

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    And now the finished seat

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    I did some work on the side plate brackets and some details on the frame. At this point the plan is to just spray bomb the frame and get it together and running. At some time this summer I will pull it back apart and have the frame blasted and professionally painted or powder coated. I did some machine work on the steering stem to fit the tapered roller bearings. I'll detail that a little more later. The X3 front spokes will be here the first of the week, so I hope to have that laced soon. I have new wheel bearing to install in it also.

    :1drink


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    #29
  10. Racer111v

    Racer111v Long timer

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    The spokes arrived and the front wheel is laced. It warmed up last Saturday so I got some paint on the frame. I'll admit to painting over some mud. :D


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    The "ALL BALLS" tapered steering head bearings are not a drop in install. They require the steering stem to be machined. Not a big deal but not something your going to do without access to a decent size lathe.

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    The lower tapered bearing needs to be pressed on to the steering stem. I made a small spacer to do this because the roller cage sit a little above the inner race. I used a bearing inductive heater to install the bearing about 80% of the way. Then I used an arbor press and this spacer, along with some bearing press tools to seat it.

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    I made a tool to install the races in the frame. The press fit is pretty mild, and you might get away with tapping them in with a soft hammer.

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    Installing the upper race.

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    Then the lower race.

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    I used a hand drill to open up the foot peg pivot hole for a set of stock DR-Z 400E foot pegs. These are a lot wider than the RM pegs. The aftermarket DR-Z pegs are available even wider.

    [​IMG]

    I needed a swing arm pivot bolt and nut, so I made one out of chromoly at work. They are 15mm which is a very unusual diameter.

    [​IMG]

    The spacers that came with the swing arm were in great shape, so they are going back in. Here's on compared to the later ones still available from Suzuki.

    [​IMG]

    I slipped the swing arm and one shock one to see how it will look.

    [​IMG]

    I picked up a rebuilt spare engine for a good price. I'll use this for a few rides to make sure it's sorted out. Nothing worse than thrashing to put in your spare engine, and find out it has an issue.

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    They are having a hard time welding the head I sent out, so I bought another one on Ebay. I hope to have that in there hands the first of next week. I have all the parts to do the forks. I should be able to start putting this thing together this weekend :clap



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    #30
  11. tkitna

    tkitna Long timer

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    Subscribed.

    Great project. My dad bought a cherry RM 370 off of some guy about 15 years ago. I remember the top end on that bike seemed limitless. Rev it till she melts kind of stuff. Awesome bike, but my dad didn't like it and sold it to some kid that destroyed it within a few months. :cry
    #31
  12. Racer111v

    Racer111v Long timer

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    I sent another head off to be modified. They haven't attempted to weld it yet, but they are not to confident in success. I have seen this before with welding other castings. Mercury (marine) does a lot of castings for other companies (HarleyDavidson is one). They use some Zinc in their mix, and I think that is what causes some of the issues.

    * UPDATE * They were never able to weld the head, and will put it on there list of unweldable heads

    The spare engine I bought complete had the engine mount faces all messed up. I straightened them out as best as I could with a grinder. I'll true them up in the mill when I can spare the time and the engine. I added some shims to replace the removed material. I'm guessing it was run with this top mount loose or missing.


    [​IMG]

    I spent a few hours rebuilding this set of Fox Airshox. They we in good shape, but old. The seals and o-rings were dried and cracking. I completely disassembled and cleaned them. The seals, bladders, and oil was replaced. I had to make some tools, but these shocks are made to be rebuilt. I was on a mission, so I didn't take any pictures, but I have another set to rebuild. I will try to add it to this later.

    [​IMG]

    I need to make some spacers to mount the air box properly. They must of had twenty assorted nuts bolts and washers to mount it in two places.

    I got the forks apart and they are in great shape. I have new oem seals and wipers going in, RaceTech springs and emulators also. More on that tomorrow.

    [​IMG]
    #32
  13. Racer111v

    Racer111v Long timer

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    Another nice day, so I got a few more things done. They were leaking, but were about half full of fresh oil. They came apart fairly easy. I had to heat up the legs with a propane torch to get the seals out. I had bought new bushings, but they are staying in the plastic wrap. I cleaned everything up with brake-clean and rinsed out with the garden hose. The damping rods need two more holes added to each of them for the RaceTech emulators.

    [​IMG]

    Where the seals seated in the lower legs had some white corrosion. I took some sand paper and cleaned it up. I heated the legs up with a propane torch again to install the new seals. I installed the seals and circlips, but when I went to install the wipers, they were loose in the legs. I had to do some dumpster diving to find the old ones. There were rings that I assumed were part of the wipers. Wrong.........

    [​IMG]

    Make sure the damping rod bolts easily screw in to the damping rods. They use a lot of loctite on them. Treat these bolts like your life depends on them. To me, these are the two most important bolts on the bike. I torqued them to 35# with lots of blue loctite..........

    One of my first race bikes I bought was a '74 Bultaco Pursang 360. I bought it from one of my mentors and he installed extended damping rods that were popular at the time before he sold it to me. At my first race, I pulled the front end up in second gear off the start. I passed the front wheel, with the lower legs attached to it seconds before the tubes stuck into the dirt. The following cart wheel, so I heard, was pretty spectacular. There was no medical crew at the track, but one of my friends/racer is a ski patrol. He did what he could while we waited for the ambulance. This was my first experience with some nice opiates. I remember being totally fascinated by the fabric on the back of the front seats in my parents car. I think I stared at it for an hour on the trip back home from the hospital. Fortunately it was only some cuts and a broken collar bone. I remember seeing the x-ray and there was a gap of about a quarter of an inch between the bones. The doctor told me if you put to pieces of collar bone in a room they will eventually heal together. The bolts at the end of the damping rods had loosened up.

    This is the bike after I repaired it and I healed up.........................

    [​IMG]

    I setup the new springs with the original pre-load and 15wt at 7.25" from the top. It is a starting point.

    [​IMG]
    #33
  14. Racer111v

    Racer111v Long timer

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    The air box I bought was a little rough. It had been melted by the pipe a little, and I had to cut it a little to clear the Fox Airs. I cut the opening some to make it easier to change filters. I cut out the melted area and gave the pipe more clearance. I pop riveted a piece of number plate in and added some heat shield material. I pop riveted a piece of aluminum to strengthen the box a little. It looks like plenty of room now.

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    Although the pipe looked trick unpainted, I remember what it takes to maintain that look. Paint isn't the best solution, but it will do for now.

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    Here's the pipe and air box final install.

    [​IMG]
    #34
  15. chamber66

    chamber66 Adventurer

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    I'm really enjoying this thread. I'm doing something similar, and about as far along as you. though i'm having a lot of trouble trying to find an airbaox.
    Mines a 400 engine and swingarm in a 370 frame.
    keep up the good work

    [​IMG]
    #35
  16. Racer111v

    Racer111v Long timer

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    #36
  17. chamber66

    chamber66 Adventurer

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    #37
  18. chamber66

    chamber66 Adventurer

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    Racer111v are there any updates to your build?
    #38
  19. Racer111v

    Racer111v Long timer

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    Summer came and I had to move on to prepping my other bikes. I could see that this wasn't going to happen in time for this season. I'll pick it back up now that fall is here and I have some time again. :D
    #39
  20. Kevin K

    Kevin K Adventurer

    Joined:
    Jul 20, 2008
    Oddometer:
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    You are doing a really nice job. Im sure you know this judging by the quality of your work but incase you dont, be sure to make some type of guard to keep the chain from rubbing against the chrome shaft of the Fox Shox. They look new themselves.
    The 79/80 400s are pretty rare. I'd love to own one of those.
    I remember on my 79 125 for some reason the side plate bolts would vibrate loose all the time and I'd have to use loc Tite .
    I think it would look good on the 250 or 400 to mount the smaller 125 tank. It's not like any vintage moto is more than 10 or 15 minutes long.
    #40