I just finished the 350 rebuild a few weeks ago and took it out for a spin for 15 miles and decided the jetting was too far out.
I adjusted to 147 50 bottom clip starts fine, however the down pipe started glowing and therefore running lean. I checked my timing thinking it may be slightly off and it looks like the chains stretched slightly. At tdc I cant get the cams to line up 100% initially i thought they both were equally but slightly out, however now i have more room around it the inlet cam looks slightly further out.
I have had the Yamaha cam chain in for less than 6 months and doubt I've been further than 1500 miles. Has anyone else had this problem? I doubt it's anything like the tensioner. I'm surprised its stretched so soon but I'm sure it has, rather annoying that I'll have to buy another.
When the cams are level the marking on the rotor side are far off, see attached.
-- Edited by dlee22 on Sunday 17th of November 2019 12:05:18 PM
Darn it, number 3 is not playing it easy!
Confusingly, I hear header can also glow if too rich from fuel still burning in the header, or if timing is out.
If you move the chain by 1 tooth is it out by the same amount in the opposite direction?
What colour is your plug?
I cant remember if I'm honest, I got it very close though. Maybe being so slightly out is still okay? We are working to a tolerance in an old engine? I could be too hopeful there.
Well it was lean then I adjusted and, run it around with the bottom needle position, 147,50 as I think I read(and lost) a thread on here with dialogue about 1 and 2s jetting, this was similar to Steve's I believe.
I also double checked the valves and they were on the low side for the inlet, probably not helping. I adjusted them and with the above jetting it was way to rich and stutter when I rode half a miles max. So way too rich, as the plug said.
I adjusted the needle to the centre but its still to rich. Based on putting my hand near the exhaust, I'll take it for a mini ride. So far the 142 50 middle pulled the best, thinking about it the inlet valves were just below spec, letting less fuel in so that could explain why it was lean.... think I've went full circle here
If you put it in tdc what are the cams doing? photo please, never seen it done the way you have done it before (lining up the cams and then looking at the tdc mark)
You say the chain has stretched, I would be surprised after such a few miles.
I went to replace the stem seals on the 350 top help with the excess oil burn on the 350 and found the third OEM cam chain I have had since the first 350 batch has stretched again. This bike has done barely any miles since the last chain and hasn't been out since July 2021.
I checked it at tdc on the single marking and the RHS of each cam sprocket was higher. The tensioned Chain had a bit too much movement for my liking and when I slackened tension I was able to easily pull the chains off with one hand and not removing the cams
Last weekend I fitted a cam chain to Brians old 325 and things were much much tighter. I really don't know why mine is eating cam chains?
Any ideas are welcome, we are meant to be going to South America on
Them October 2022.
