Vintage Dirt Racing on a 350 Honda Twin

Discussion in 'Racing' started by LC Garage, Jun 16, 2011.

  1. LC Garage

    LC Garage On Any Sunday

    Joined:
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    774
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    Finally got around to weighing the bike, using two old school bathroom scales. Just as it rolled off the track, it weighed a svelte 297 lbs. (give or take a few pounds either way). The target weight for next spring is 280. :D
    #81
  2. oregoncoast

    oregoncoast Racing Like a Noob

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    May 15, 2007
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    Duh!
    :loco


    Why can't you just accept her as she is. She is big-boned, she's never going to be an Elsinore. You know what guys did back in the day to lesson the weight of their SL350? They bought an XL350 as soon as they could :1drink



    :wink:
    #82
  3. LC Garage

    LC Garage On Any Sunday

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    OC, you know I prefer "my girls" to have a little meat on their bones, not some hyper skinny little twig like an Elsinore! Besides, the twin gives me a challenge to make it competitive and will be all the more satisfying if and when I ever win a race on it. Right now I have the best of all worlds, if I do poorly it is the bikes fault and if I do well I get the credit! :evil

    #83
  4. darmst6829

    darmst6829 Been here awhile

    Joined:
    Jul 25, 2006
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    379
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    Redmond WA

    Hi LC Garage,

    Make sure and take the survey on the AHRMA NW web site.

    Thanks,

    Dave
    #84
  5. LC Garage

    LC Garage On Any Sunday

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    Dave,

    I'm having trouble navigating the new AHRMA website, do you have a link to the survey?

    Thanks!

    Rick

    #85
  6. LC Garage

    LC Garage On Any Sunday

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    Brought home a new addition to the Barn Fresh stable today. Bought an SL100 for my daughter to vintage race. Fairly clean with some nice pieces, but the wiring looks like it was done by Edward Scissor-Hands!

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    It is supposed to have a fresh bore, but does not run due to electrical issues. The goal is to have the bike ready for next summer, my daughter will ride & race when on leave from the Air Force. Stay tuned for updates! :D
    #86
  7. darmst6829

    darmst6829 Been here awhile

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    Redmond WA
    #87
  8. LC Garage

    LC Garage On Any Sunday

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    Have been working on the SL100 as time allows, trying to decipher the wiring and finally realized the reason the prior owner and his friends could not get the bike wired or running. It had an AC coil instead of the correct DC coil. It had been at a small shop for a fresh bore and piston and the owner went out of business, returning the bike in non running condition with an assortment of parts and evidently gave them the wrong coil. :cry I ordered the correct coil, put it on, and the wiring began to fall in place and it now has spark. The carb is in pretty rough shape, had a broken drain screw lodged in the bowl so I tried a bowl from the SL350 carbs and it was a perfect fit. Put some fuel in it and it runs (although a little rough) but at least now I have a starting point. :clap My daughter has also spent a few hours rubbing and scrubbing the many years of accumulated grime off of it and it is starting to look a little better.

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    On the SL350 front, I have a pair of new 30mm Mikunis coming from OC and found a 1974 Yamaha rear wheel that fits and will give lighter unsprung weight, have many other ideas and am getting excited to tear the bike down and get started on a thorough overhaul for both reduced weight, more power and a little cleaner appearance. Stay tuned. :D
    #88
  9. oregoncoast

    oregoncoast Racing Like a Noob

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    Duh!
    Gotta have more power!!! :wink:
    #89
  10. Foot dragger

    Foot dragger singletracker

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    Location:
    chico,just below rag dump(nor-cal)
    Did Brownell help out with that bike?
    #90
  11. LC Garage

    LC Garage On Any Sunday

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    Have been working on my daughters SL100, trying to get the now running motorcycle to perform properly. Even though it starts fairly easily, it doesn't want to run past mid throttle and runs very rich, with a light inversion of fuel coming back out of the carb throat. I went back into the carb several times, cleaning and adjusting, especially the float level as well as checking the needle (center position) and nothing changed. I also went through and tightened the head bolts (they were loose), adjusted the cam chain, valves and reset the timing again. Checked compression, 110 psi and although a little low it is supposed to have a new bore so the low number may be due to rings not being seated yet. Still ran the same, so then I took off the exhaust thinking it might be plugged, but other than being much louder, no change in how it ran. :eek1

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    At this point I decided to order a new float, needle & seat, 105 main jet (it had a 110 in it and looked like it may have been drilled??) carb gasket kit, petcock gaskets, all screws and nuts that were stripped, rounded or otherwise boogered up, and a few other items like new chain, tank mounts, battery strap, etc. While waiting for these parts to arrive, I have fixed or repaired a few other items such as the missing footpeg bolts, continued to sort out the wiring (almost done, really just need to trim and loom everything now) and then last night I decided to put a number plate on it as my daughter has decided on her vintage racing number, #9. She chose this number based on her varsity soccer team number, but I explained to her how the old AMA National Numbers used to work and how this number had always been Gary Nixon's and what an icon he has always been and also how he just recently passed. This number has a lot of meaning for us older riders and I hope it will someday have similar meaning for her. :D

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    As far as the SL350, my next step is to have two sets of 2 into 1 exhausts made, one for my bike and one for Paul's (Oregon Coast) SL350. In a couple of weeks I have one whole weekend with nothing planned, that is when I will completely dismantle my SL350 and get a serious start on the winter rebuild. :clap
    #91
  12. never2old4fun

    never2old4fun Been here awhile

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    Jul 2, 2007
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    491
    Location:
    Joliet, Illinois
    Oh yes, a SL 100 was my first what I called a real motorcycle. I have many fond memories of riding the track in the subdivition in New Lenox, Ill. where I had grown up. Also the farmers fields near the old homestead, too. Lots of fun.:D
    #92
  13. Czechsix

    Czechsix Slower than you....

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    SoCal San Diego Suckage
    Just an FYI, maybe it'll help some of you scrambler types....ad just popped up on San Diego CL
    http://sandiego.craigslist.org/ssd/mcy/2622563334.html

    Truckload Honda Scrambler - Super Hawk Parts - $1 (Spring Valley)



    I'm not the seller, have no idea who it is, have no connection, etc etc call my lawyer blah blah blah welcome to california
    #93
  14. kimber45

    kimber45 I'm over it.

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    Clay,MI
    :lurk

    #94
  15. LC Garage

    LC Garage On Any Sunday

    Joined:
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    Last night my daughter and I worked on her SL100 and even though we are making great progress, the bike still does not run right. We now have a fully and carefully rebuilt carburetor (new float, needle & seat, 105 mainjet, gaskets & seals, etc), and also installed the chain and finished hooking up the charging system (which does not appear to be working either, arghh).

    Rebuilt Carb

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    Rebuilt carb on bike (with fresh gaskets and o-ring)

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    Adjusting new chain (I had her grind the sideplate off and help cut chain, she also did the whole adjustment with dad "advising" her

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    So I am a little stumped with this thing. The carb now seems to be working really well, not seeing any sloppy fuel or misting, but the engine still will not rev out past about 1/3 throttle, it acts like it is being held back like the timing is off. I have double checked cam timing and believe it is right on, it almost acts like the advance mechanism is working backward, retarding the iginition instead of advancing it. Does not backfire out the intake or exhaust, which leads me to believe the cam timing is right. I don't normally put a timing light on these small bikes, but think I'm going to give it a try to find out exactly where the timing is and what happens as we rev it up. It just feels like I have missed something altogether. Please bear in mind the bike was re-bored and assembled by someone else, so it makes me wonder what might have been missed internally? It does not smoke and seems to have reasonable compression (110 psi), but is slightly on the low side. Any ideas anyone??
    #95
  16. snowhawk jockey

    snowhawk jockey Slack Jaw Gaper

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    The slide needle/nozzle in those carbs is also a wearing part. I had an old 70's "barn fresh" xr 80 and the needle had vibrated in the nozzle for sooooo long(decades of changing water on the back 40 and barn yard hot laps) that the needle/nozzle were worn thin allowing much more gas than the motor could use. Replaced the needle and nozzle and it would cleanly rev out again. Another snag with that bike was that the edge of the exhaust valve seat had been eroded and wouldn't allow a good seal resulting in low compression allowing it to fall on its face, when the throttle was opened too quickly.

    Great thread, which has me eyeing the classifieds for that canary yellow cl66 type, I passed up so long ago... Might have to pick up that CL175, that keeps turning up on the local craigslist, as a tide me over!
    #96
  17. drdubb

    drdubb OFWG

    Joined:
    Dec 13, 2009
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    472
    Location:
    Raleigh, North Carolina
    I've been reading OC's and your threads with great enthusiasm. Is that a K1 or K2 SL350? Can you give me the low down on the MR forks/wheel? I'm picking up a K1 tomorrow. I had a new one as a teen. I want to upgrade the suspension to be acceptable on TAT style riding. I won't be doing any racing, but the trials stuff is intriguing. Thanks for any assistance.
    #97
  18. LC Garage

    LC Garage On Any Sunday

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    Snowhawk, I think you pin-pointed at least 50% of the problem. Today we installed a new condensor and points (genuine Honda) and were especially careful to gap and time properly. Also went thru petcock and completely cleaned and checked, disassembled the fuel cap and cleaned and replaced gasket, as well as subsituting all the worn out, stripped and boogered up screws. However, did not get charging system working as rectifier still has not arrived. Arghhh!

    Ran bike and with all changes ran about the same. Since charging system isn't working, decided to try running bike while on charger. and what do you know, it showed a noticeable improvement in top end. So now it idles great, has a bad sag or burble in mid range and will rev out to some degree while on battery charger. Since the needle mostly controls the midrange, I pulled it out and looked at it under a magnifying glass. It does show some wear and without knowing how worn the nozzle is I'm just going to order them both and replace.

    Today I also replaced the brake pedal spring and tightened a few more miscellaneous nuts and bolts. It always amazes me how pieces of machinery can be used until there is so little left functioning properly and yet they somehow continue to function, then when you are working to resurrect, there are layer upon layer of problems. It does keep it interesting and a challenge.

    Good luck with whatever bike you decide on, do you ever go to any races? The reason I ask, is that AHRMA has an event in Crooked River called Steel Stampede, missed it this year but am hoping to make it in 2012, maybe I will see you there?


    #98
  19. LC Garage

    LC Garage On Any Sunday

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    Dale, welcome to the 350 twin club. I believe our particular bikes are K2's because they have the 35 mm triple trees, which is what allows the bolt on of the early CR/MT components. I am mostly riding MX with mine while OC is tackling just about ever discipline you can imagine. While our approaches may differ, we both have a great respect for the fine engineering that created this enduring classic. Good luck and don't hesitate to share your discoveries or ask questions.


    #99
  20. LC Garage

    LC Garage On Any Sunday

    Joined:
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    So today was a long day in the shop, but got lots done and am pretty happy with the progress. Besides working on the daughters SL100 (see above), I also spent some time mocking up the exhaust system on my bike and also partially dismantled another parts bike. For relaxation I took an afternoon break and mowed the lawn!

    While mocking up the exhaust I installed the skid plate off of OC's SL350 onto my bike, so that if what I end up building is also suitable for his bike, we will know it is a fit.

    I was unable to take pictures as the wife and her girlfriends are in Astoria taking the basic rider training course, and have the camera to document their hi-jinx. Tomorrow I plan to finish stripping both parts bikes and will get a few pics of the exhaust project.