Rabbit_Fighter
Member
- Mar 10, 2009
- 6
- 0
I was wondering if anyone who has jetted a few older single 4 strokes might enlighten me here? I bought it off ebay and have replaced, head bearings, clutch, fork seals, rectifier,,......just about everything that wears out. I'm not even sure if the TM flat slide was standard on this bike. The only manual available is in german, but I can read the part that says the original was a VM 38 Mikuni, which is a round slide.
Good motor though and pulls hard at everything above idle. I have set the valve clearances and fitted new needle and seat and have set the float bowl height. This carby has an airscrew below and in front of the carby. I've done the tune up method of warm up the bike,turn up the idle and listen to the point the idle is at its highest and use that as a means of setting the mixture. I'm finding that in order to stop it back firing on decell (lean?), I'm needing this air screw out about 2 and a half turns out which I understand is too many.
The only problem is it's damn hard to start cold. And rolling on from idle. Warm starting is one kick. Hesitation is most noticed if I go to top gear, or exit turns in high gear, and do a from just above idle roll on that big singles usually like. Once revs pick up it's strong. Seems to idle higher the warmer it gets.
I have a #25 Pilot fitted and have ordered a #22.5 and a #27.5. Fact is I'm not sure if I'm rich or lean. If it was a problem in the high rpm I could do a plug cut and see the condition. Will reading plugs from a vehicle at idle tell me anything if the problem is with the slow speed circuit? I would appreciate any comments from those with more knowledge than me of Mikuni TM 38 with accel pump on big 4 strokes.
Thanks
RF
Good motor though and pulls hard at everything above idle. I have set the valve clearances and fitted new needle and seat and have set the float bowl height. This carby has an airscrew below and in front of the carby. I've done the tune up method of warm up the bike,turn up the idle and listen to the point the idle is at its highest and use that as a means of setting the mixture. I'm finding that in order to stop it back firing on decell (lean?), I'm needing this air screw out about 2 and a half turns out which I understand is too many.
The only problem is it's damn hard to start cold. And rolling on from idle. Warm starting is one kick. Hesitation is most noticed if I go to top gear, or exit turns in high gear, and do a from just above idle roll on that big singles usually like. Once revs pick up it's strong. Seems to idle higher the warmer it gets.
I have a #25 Pilot fitted and have ordered a #22.5 and a #27.5. Fact is I'm not sure if I'm rich or lean. If it was a problem in the high rpm I could do a plug cut and see the condition. Will reading plugs from a vehicle at idle tell me anything if the problem is with the slow speed circuit? I would appreciate any comments from those with more knowledge than me of Mikuni TM 38 with accel pump on big 4 strokes.
Thanks
RF