Problem solved..!

After cleaning everything out yesterday and turning the washer for the coasting enricher around everything works..!

It starts great cold
Has nice throttle response when warm
and doesn't pop and bang.

I took it for a ride along a country road, it had a small issue at 80km/h when accellerating.

After that I took it through central Copenhagen. Classic city traffic and redlights. No issues.
But, it stalled for me at a red light. And then it was really hard to start.


Conclusion
I believe that all this is many small thing adding up to a bike that wouldn't run.
But I do believe that all this has been an carb issue, and truly fuel related.
I think the bike was starving from fuel all along.
I am even considering to remove the small filter within the carb itself.

Anyway, thank you all for your help..!!!

You are Awesome

If it starts good cold but not hot it is usually rich , not lean.THUMPTHUMP

You can plug the Air Cut off valve entirely... It's not strictly necessary.


But yeah. Older bikes can be a consortium of problems. Glad you're on the way to full motorcycle health :thumbup1:

My bike has been doing something similar. It's an '03 xt600e and on deceleration it pops and cracks like no other. I thought this could be from clogged jets ect., but cleaned and checked and they were spotless. When I checked over my carb, gasket #17 (5Y1-14536-00) was missing from the previous owner. (In the bowl there is a shaft that fills up from the bottom and has a tube that reaches the bottom.This tube goes into this shaft from the carb side of things and is located near the pilot jet. That gasket which sits right there. ALSO what is this for?????) Also the Rich \ lean screw was out 4.75 turns, which normally its 2.5 give or take. I have an aftermarket CRD pipe on it. ( I think that's the name. I wrapped it after I burnt myself) Anyway, I turned it to 3.5 turns out (little richer for pipe comp)and am running the #130 main jet (main carb) , and the #46 pilot jet, living 1 mile from the ocean but at times traveling to the mountains. SO, now it runs better but still pops back through the carb at times and is real poppy on decel... could this be caused by the same valve? Valve clearances are all good also. I checked those all. This carb pop at idle is driving me to drink!!!! jeigerbeerjeigerbeer:funmeterno:

If you are turning the screw on the main carb underneath and towards the front of the carb, this is a FUEL screw, not AIR screw. Further out is righer. Air screws are on the inlet side of the carb, fuel on the outlet side.

Hope this helps.

That popping on decel is from a lean condition. You should have the next size bigger pilot jet if your at 4.5 turns out with the fuel mixture screw. I believe #48 pilot is the biggest available with #46 as the "normal" one. If you have an adjustable needle in the primary carb maybe the clip should be moved down one groove (needle will be raised up for a richer mixture). Otherwise a washer can be added under the clip if not adjustable.

An air leak up at the head on the exhaust pipe will also cause a backfire, but usually just one or 2 big bangs, a steady crackle and popping as the motor slows down is from being lean. The coasting enrichment setup should also be checked for proper operation.

I dont know about 4,5 turns out. If i dont remember all wrong mine is 2,2-3 out with bigger size jet and never have any problems, sparkplug looks fine.

Thanks I will have to rip out the carb and do this with the needle. Ya the guy before me was kind of an idiot, so i think Im fixing his problems. The thing I cant understand is that when I bought the crazy thing it was running better and now its running like garbage. When it back fires under idle it kills itself. *** I did let it sit for 4 months while I was in the states *** But i drained the carbs (during that time) and have cleaned the jets ect. IS there something I missed while cleaning it? BTW been wrenching for 8 years so I'm not a newbie. Just trying to track down ghosts.

Check the enrisher valve on the side of the left carb for any cracks in the diaphragm, along with the spring and plunger there and working. Also make sure you have the o-ring around that pipe you were talking about in the bowl where it seal to the bottom of carb. There should also be an o-ring and small washer on the mixture screw to watch out for falling out if you had that out.

Check check and check.... Man alive still. Does this bike come normally with exhaust gaskets? :nono: (haha) There wernt any on it when I took off the exhaust. (thanks to the previous guy!) So I bought 2 close to the size i needed and put them in... Uff. Seemed to get worse, now the "puffing" back firing sound is now also a leak pop. So looks like EBay is in order to get the gaskets.

Someone told me that the Yamaha 660 Raptor had timing chain tensionr problems. This being said... xt600 and Raptor 660 are almost the same low end. Could it be the same cheap plastic tensionr going bad, causing all of these back firing "puffing" sounds and not wanting to run proper?? Uff....:funmeterno:

Xt600 Misfires, then cuts out... Help Needed
 

Is this thread still active? I'm trying to tune the carbs on my 1989 xt600 and I'm not sure what the stock main jet size is. Can someone please enlighten me?

Thanks!

Pk


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I think my stock ones are 120 main left carb, 125 right carb,
#46 pilot and 2 turns out on the mixture screw.

My 86 came with 130 in the left and 125 in the right. TTs had 135 in both. THUMPTHUMP