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1973tr6

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  1. Agree on the gearing. 1976 Mod 183. I went down 1 tooth on the front to 11 (a 10 is too small) and up to a 52 (from 46) in the rear for an 18.9% reduction. Made a significant difference. I had to modify the lock washer on the front sprocket as the original was too large and didn't allow the chain to seat correctly. Ratio Calculator: www.sprocketcalculator.com
  2. Sherpated, No I never got the OKO sorted. It is puzzling because the earlier issues I had with the carb, continually overflowing when the motor was warmed up, despite setting and re setting the float many times, were solved by replacing the float needle. The bike was running well one trial and then the next it was fine to start but quickly deteriorated, sounding like it was running too lean, then nothing... no start, no run. I cleaned and fiddled about with the F&%$^@ for weeks and finally gave in. Put on the Mikuni and voila.... not looked back since. The OKO is now in a box gathering dust.
  3. 1973tr6

    Old Bultaco

    Grind out the cracks with a dremel or similar, hollow out the crack area to make a slight concave using sanding discs, lay in suitable glass mat to cover the crack and thoroughly apply resin, making sure there are no air bubbles, repeat as needed. When you are hollowing out, make sure you go past the end of the crack otherwise it will start again. Fill with bondo and re profile.Plan B wold be to try using some low viscosity epoxy (check out the boat fibreglassing sites) https://www.youtube.com/watch?v=eggAzL9oQxg
  4. A couple of good suggestions there, thanks. I'll contact Talon and also take a look at the modified Yam idea... I'm up for a challenge too (and have access to a lathe !)
  5. I am trying to gear down my' 76 model 183. The current sprockets are 11T front and 46T rear. I'd like to lay my hands on a 10T (or even better a 9T) front from somewhere but they seem to be unobtainable. I could go larger on the rear but to get anything over a 4% reduction I wold have to get a custom sprocket made and increase the diameter which I don't really want to do. A 10T front will give me just over 9%, a 10T/48T will give me almost 13%. Any suggestions ?
  6. My parts book tells me that it is the same for 350 models 159, 183 and 191 and also for 250 models 158, 182, 190. The Bultaco part number is 23.12.007, crank stop. Part 4 on the pdf attached. I only have the manual for 5 speed models 1967 and on. Hope this helps. Nov 14th.pdf
  7. Sounds to me like the kick starter pawl is not clearing the ratchet properly. If moving the kickstart forward on the spline doesn't work, then the fix is probably inside the gearbox. Take a look at the exploded diagram attached, Parts 2,4 and 10. Item 4, the crank stop may be adjustable from inside the ignition cover but I don't know for sure as it is so long since I pulled one of these engines apart. Part 13, the ratchet stop or a broken return spring (part 3) could also be the culprit. Nov 14th.pdf
  8. Thanks for all the advice, It is a Taiwanese, not Chinese carb complete with markings on the jets. I have stripped, blown, poked, immersed in solvent and WD40'd the carb until I am sick of it. It now knows its own way off the bike- I just stand there and whistle and it teleports from the bike to the workbench ;-) I have ordered a Mikuni today having finally given up. It is such a simple thing but so frustrating. What jets have users found work the best ? I am 500 ft above sea level.
  9. Suggestions please; The bike was running well when it was last used, I went into the garage to run it for a while and it starts OK but there is now a large flat spot when coming off idle. The motor stops firing and "bogs down", coming back the life about about 1/3 throttle. Opening the throttle very slowly helps a little, a little choke helps a little. I have had issues with the carb from day 1, overflowing every trial after about an hour but I had got that sorted . Here's what I have done: Emailed the OKO guys and they said look for an air leak. Stripped and cleaned the carb, blowing out all passages / jets etc. Checked the carb for air leaks Checked the rubber connector for cracks (it was new with the carb last fall) checked the inlet manifold to cylinder joint integrity. Checked the spark Replaced the main crank seals 6 months ago Things to check Cylinder base seal ? Replace the main seals again? Dump the OKO and fit a MIkuni ? Reset the float level (for about the 100th time?) The puzzle it that it was fine, nothing had changed and now it's not.
  10. That brings back memories.. I was HMCC club sec in the early 80"s and ran the Hillsborough Trophy Trial (as it was then) for few times along with Donald Brown who was clerk of the course until emigrating. Only rode the Kwai a couple of times as course closer but it was tough. (I only ever aspired to Novice). My avatar is from the HMCC Novice & Veteran trial at Hollowmeadows, can't remember the year but I had hair !. I was riding a demo Fantic from Jeff Hall. I see from recent results that Dave Thorpe, Keith Hobson and Dave Knaggs (Haggis) are still riding.
  11. I didn't want to cut and weld on the stock exhaust if I could help it. Maybe I could get a banana exhaust with the single outlet and keep the clubfoot stock ??? Lineaway, what do the guys with stock clubfoot exhausts do in your area ?
  12. Just found out that spark arrestors are going to be mandatory soon here, Anyone any ideas about how to fit something like this to a clubfoot rear box ?
  13. 1973tr6

    Rear Shocks

    Looking to replace the rear shocks (13.5" or 340mm) on my 350 Sherpa. Any suggestions in North America ? I spoke to Bultaco UK and they said that air freight was an issue with gas filled shocks.
  14. New (exchange) coil on its way--- and I have invested in a magnetic parts tray !
  15. I have a spark again, traced the wires and there were cracks in the insulation in a number of places so something was grounding out. I have taken out the lighting coil but will still get a new ignition one if only to eliminate the electrical tape that is now covering all the wire!
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