No start hot
 

Hello folks, 1st post here and really excited to be part of this group. I bought an 88 XT600 in September and have enjoyed the few rides I have been able to go on. I've gotten good at starting it on the 1st kick cold. If not on the 1st kick, the second or third will always get it running. But if I ride it for 15 minutes and shut it off, there is no restarting until it cools off. What blows my mind is this: When it won't start, it has a nice strong blue spark, but even if I use the cold start valve, the spark plug will come out dry. This is while my fuel level is about a mm below the top of the bowl. I have had my YDIS carbs apart 2x now. The 2nd time I spent a few hours getting familiar with how they're different from conventional motorcycle carbs and I can't account for how it's not getting fuel to the plug. I have set my valves and the auto decomp lever free play. Here's one weird thing it's doing: When it's cold, I have to get the piston just past TDC compression to be able to kick it, but when it does the no-start thing, I can kick and kick and kick without paying attention to what stroke I'm on. This feels to me like gas has washed the oil out of the rings, but it seems like it would get on the spark plug too, right? I know I should have tested compression by now, but I have not. Sorry for the long post, thanks for reading, and any comment would be appreciated!

hi
since i don't have any experience with kick-only xts, will tell just couple basic stuff.
did you had this problems since the beginning of owning that bike or it appeared later, maybe after something?
guess cold start valve = choke.
according to manual, fuel level must be set by adjusting the float height when upside down.
generally, ydis is pretty intricate setup - two very different carbs sharing one bowl.
don't know whether you've already read or not, here's some threads (probably not all) on more or less similar issue, worth checking before more experienced members will give actual suggestions:
https://www.horizonsunlimited.com/hu...nt-start-65544
https://www.horizonsunlimited.com/hu...-34l-hot-24304
https://www.horizonsunlimited.com/hu...ard-cold-50986
https://www.horizonsunlimited.com/hu...starting-66461
good luck and hope you'll manage enjoying that bike for a long time.

Thanks for responding and for those links. I read through all of them and got a few ideas for things to check after work this evening. When I got the bike, it only ran with the cold start valve pulled. That was why I took the carbs apart the 1st time. They were clean inside. When I put them back on I was able to adjust the idle fuel mixture and idle speed screw to where I had a nice smooth idle with the choke off. Then I replaced the steering head bearings. The next time I rode it, I went to the gas station and filled her up and had to push it back home (right at 2 miles). Anyway, I think I'll do a compression test on it next.

Disconect the decomp wire and see how it is hot turning on kick, i always had problem kicking it to start if it stopped, waited 10sc and it was ok. In traffic and offroad i hated the kickstarter and never again on any bike! Its for mopeds and mx...Worst part is people talking about weight issue regarding starter motor on xt, its just funny..

Yeah, since XT600s are such lightweight machines! I'm ok with a kick start only bike, even a 600, as long as there's a good chance I can get it going. Not really ok with pushing one home though. The 1st thing I did when I noticed how it was easier to kick when hot was to put the max amount of slack in the decomp cable. When that didn't make it harder to kick through, I completely removed the cable, which also didn't help. So I put it back together and set the freeplay. Thanks for the suggestion though! I guess I'll take that cable back off to do a compression test when I get a free minute.

if you "loose compression" when bike is hot, sounds to me like valve lash set too tight.


in the name of science, would try to set the lash bigger than spec and see if it brings back compression also when warm,


go for 0.25mm both in and ex just to test if it makes a difference, leave decompressor off to make sure its not interfering, report test result...



you didnt say how many miles on that bike, valve guide/seat wear might be an issue.....