I’ve got a Yamaha RD250 1977 model and that has twin points,I keep saying I’ll convert it to electronics.
When I look at the prices of some classic bikes especially on eBay I think there’s getting quite a few chancers out there.
Very nice job fella can remember rebuilding one that belonged to an old girlfriend when i was in my twenties...great little bikes.
Hi I have just got a cub with the Mikuni carb have you any tips on starting up from cold. IE. choke lever up or down ? throttle open or shut , choke off as soon as she fires or do you have to let it warm up. not had one of these little beauties since the sixty's, any advise would be most help full. also anyone know where I can get a rack to fit @ and mirrors handle bars or bar ends ? many thanks james
Hi James On my Mikuni carb the choke was on when the lever was down, a little throttle as you kick it over and leave the choke on for a bit until it warms and will run without it. I put a bar end mirror on mine because I couldn't find a decent looking clamp on one and as far as a rack is concerned either ebay or Greystone Enterprises may have something.
Jim I have just picked up a 1967 Cub that has been converted (not very well) to trials with a Mikuni carb. Bugger to start. Have tried lifting and lowering the main needle, which helped a little, but may require different jets. No idea which model of Mikuni carb mine is, as didn't have any info when I bought the bike and cannot see anything on the carb to indicate the model.....anyone who might be able to suggest a model from the pics of this? Any info welcomed. Jim - will be interested to hear how you get on with yours. Cheers Dan
Dan Have a look in the catalogue. Yours will be in the round single slide section page 20. It'll have the part numbers of jets etc. I'm assuming you've checked timing, spark and all that stuff as well. http://www.mikunipower.com/Catalog/MikuniCarburetorCatalog2012.pdf Good luck with all that stuff . Mind you, looks like the AA could help. Do you have a satchel for all that wood when you go out?
Iron Great help and info. Thank you! Regarding my makeshift paddock stand, I am looking for a nice set of "trials" paniers that might fit!!!
Hi, nice looking bike. The blue line on this AFR/dyno chart is from where I completely re-jetted a larger Mikuni VM carb from scratch to fit an RE 350 Bullet (there was no data anywhere to use as a guide) so it's quite possible to get excellent results (with time, patience and money) Before you can diagnose any problem you need to accurately mark the throttle grip/handlebar clamp body so you can pinpoint where any problem is by looking at the throttle position as you ride. This means idle screw out so the slide sits on its underside and marking things just as it begins to move (NB handlebars straight ahead) and for fully open seeing the point the underside just clears the throat. - not when the grip is against the stop. If you get spluttering at 1/5 open, the oft overlooked needle jet holder will be the problem despite the tuning guides pictorials showing otherwise. Three long stroke engines with VM carb problems I've owned were all improved with bigger jet holders. http://www.mikuni.com/pdf/vmmanual.pdf this guide should be helpful. I found using the 'closing the throttle from fully open' method for determining the correct main jet size quicker (cheaper) and just as accurate. When I put the bike on the Dyno I was advised that the main jet would benefit from going up one size if I intended to run the bike flat out for any length of time! I left the carb as I'd tuned it .
Thanks a lot Kinjane. Another great link. Will have a play and update on progress. Greatly appreciated.
After a few months of being bone idle, I have finally started to rip into the Tiger Cub. I would like to get the engine stripped down and rebuilt, as it has a couple of minor leaks, but this is probably a step too far for me. Does anyone therefore know of anybody good in the north west (UK) area that might take this on? Any info greatly appreciated. Thanks Dan
Hi Dan, If you are prepared to look towards Birmingham for an engine rebuild I would suggest Chris at Meriden Off Road. www.meridenoffroad.co.uk
Hi Samsgrandad Brum might be a bit far for what need. Thanks anyway. I have just spoken to Glynn at GT Tuning in Oldham who is going to strip and rebuild for £150, plus parts. He generally specialises in 500 Jap and Westlake speedway bikes and engines tuning. He was highly recommended by another bike mechanic as a top mechanic and engine tuner. Will let you know how I get on. Cheers Dan
