1999 beartracker will only idle. stalls under load
 

so. i just bought the thing. it ran completely fine. changed the diff oil a few times while running it around the yard in between. all good.

changed the engine oil and i could barely get it to start. wont start or run with the choke, cold or hot.
so choke off, i can get it started - it will idle. but if you touch the throttle it just dies. no sputter or anything. just straight dies like you hit the kill switch. occasionally it will actually run completely fine, it will idle and rev up no problem, but only in neutral. if you put it in gear and try to go it basically dies instantly. occasionally it will sputter along but will die within 10 feet.

so what ive tried:
- ive completely cleaned the carb, its the original mikuni. probably about 5 times now. all the jets and needle are the stock sizes, everythings clean. sprayed carb cleaner and compressed air in everything. the diaphram is fine.
so just in case, bought one of those chinese knock off carbs on amazon. same problem. just incase i took that one all apart and everything seemed to be in order. so im thinking with the amount ive gone thru the carb, and the same result with both of them. im thinking its not the carbs. tried with and without an airfilter and a new airfilter. no change. but it doesnt really run at all without the filter. i think that makes sense because the needle isnt even adjustable, so the air fuel mix is setup from factory. i double checked the mixture screw is 2 turns out as per the service manual. tried other turns out or in but no difference there.

- replaced the carb intake manifold. and double checked the rubbers from the air box. snorkle isnt plugged. it runs the same with the airbox cover off or on.
- put in a new spark plug. no change. (it has spark with either plug)
- changed the spark plug coil, no change.
- cleaned every electrical connection i could find, no change.
- its definitely getting fuel from the tank
- checked the timing. its lined up right. looks like someone replaced the timing chain recently too.
- checked compression

at this point im guessing its gotta be ignition related if both carbs do the exact same thing?
so ive got a new cdi, stator and pickup coming. thats the only other thing i can think of to try.

curious if anyone has any other thoughts?

I once had a Honda 300 with those symptoms and, like you, changed the carb with no improvement, so assumed it must be electrical and changed the CDI, instant cure. However, when you fit a new CDI, always check the earth to it is sound and that the battery voltage does not exceed 15v with the engine running, otherwise your new CDI could go the same way as the old one.

Well. Update. New stator and pickup coils in.. same problem.

​​​​​​CDI comes tomorrow, crossing fingers

New cdi. Same problem.. I dunno now

Come to think of it I did have an Eiger that did this, wouldn't run above idle at all though and didn't die, just wouldn't rev.. It had stood outside for a couple of years awaiting an engine rebuild. Got that done and found this problem. I re-did everything, assuming it was something I got wrong on the rebuild. It was only when showing someone else the problem, he was stood behind it and said "I can't feel any exhaust gas" I realised it was a plugged exhaust, took the silencer off and it ran fine.

Is there any update about the situation?

Check compression and charging system voltage regulator

So it ended up being the carb. Couldn't get the stock mikuni working well at all. But the Chinese one did do better so i decided to work with it. I had to take the white plastic piece on the jet needle and double it up on the Chinese carb, to get the needle high enough. Also had to use the main jet and pilot jet from the mikuni and now it runs perfectly.

I don't know what changed exactly from it running perfect to all of a sudden not and having to raise the jet needle so high but I'm not complaining now. It's crazy how restricted the run tho. Just taking the air box lid off and it won't run at all. Id imagine getting some better airflow with bigger jets would wake this thing up a ton
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Thank you so much for the solution.

I am new here and have some questions to ask, can I ask those?