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  #11  
Old 15-06-2018
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2 Stroke Troubleshooting

It's a good thing that 2t's are easy to troubleshoot. I once had a WR250Z give me the run around with similar symptoms. The bloody magnets inside the rotor had moved. Good luck with your project
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  #12  
Old 15-06-2018
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Changed carb and it seems better . Running cleaner sooner. Its a newer mikuni so not a good fit . Shorter and longer.
I think it must be carb but not sure what might be causing an issue . I will keep playing. Thanks for the help.

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  #13  
Old 17-06-2018
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Quote:
Originally Posted by LAPPER View Post
Changed carb and it seems better . Running cleaner sooner. Its a newer mikuni so not a good fit . Shorter and longer.
I think it must be carb but not sure what might be causing an issue . I will keep playing. Thanks for the help.
It could be the fuel needle/seat not opening fully. Dress the square edges on the corner of the needles' ribs with a points file, turn the needle 1/2 turn and retest. Check float height and fuel inflow before assembly.

Also eyeball the seat and make sure there's no rubber residues from the needle-hat blocking the seat.
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  #14  
Old 17-06-2018
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I would be checking the crank seal, possibly drawing gear box oil into the cylinder.
Milky gear box oil is head gasket isn't it nutty?
Worth checking if the head bolts were loose.

I wouldn't lean the carb out to much, especially if it was running in that set up for a while with the previous owner.

Probably somthing has worn out to change the running condition so much.

Crank seal, head gasket, slide/needle then electric gremlins.

Any oil in the coolent?
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  #15  
Old 18-06-2018
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Quote:
Originally Posted by Nutty View Post
It could be the fuel needle/seat not opening fully. Dress the square edges on the corner of the needles' ribs with a points file, turn the needle 1/2 turn and retest. Check float height and fuel inflow before assembly.

Also eyeball the seat and make sure there's no rubber residues from the needle-hat blocking the seat.
Thanks . I tried swapping the oring around needle seat . I can try a different float needle. I lowered the float height . Im going to check air holes in bell housing


Quote:
Originally Posted by Danh124 View Post
I would be checking the crank seal, possibly drawing gear box oil into the cylinder.
Milky gear box oil is head gasket isn't it nutty?
Worth checking if the head bolts were loose.

I wouldn't lean the carb out to much, especially if it was running in that set up for a while with the previous owner.

Probably somthing has worn out to change the running condition so much.

Crank seal, head gasket, slide/needle then electric gremlins.

Any oil in the coolent?
I took it out to the bush and its running well with a newer Mikuni - was actually way too lean on a richer pilot than other carb .
Newer carb is almost 10mm shorter in body (front to rear) so need to make an adapter plate front or rear

Id like to get older carb running at least .

As soon as I put it on its like it hits a rev limiter at 2/3 throttle

It did have loose head bolts when I got it . Coolant was dripping out through head bolts.
Coolant cant get into the gearbox from the cylinder on a 2 stroke. My guess is the repair on water pump wasnt too good .
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  #16  
Old 19-06-2018
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Its still not right . About to give up but found this just now

I took mine apart to clean the varnish out of the carburetor. Re-assembled and installed. Would not rev off of idle. Struggled with the main jet, thinking that was the issue. NOT. Found it to be the brass sleeve that surrounds the main needle (slide needle). The brass sleeve was not lined up correctly. It MUST be lined up with a small pin at the bottom of the casting. Once I got that lined up correctly, runs great! Fuel was not being pulled through the main jet since the fuel port on the slide-sleeve was improperly aligned.


Not sure what part of sleeve needs to be aligned with pin but will check later
This sounds promising - previous owners may have pulled this sleeve out . I pulled it out but wasn't aware of alignment requirement .
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  #17  
Old 25-06-2018
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Changed float needle, float height , turned the float needle seat to be as per other carb ( it has holes which I am not sure if they need to line with slots in housing ) , adjusted needle height . Running good now .
Just need to get jetting sorted now but its not far off
Not 100 % on exact cause but it was definitely very rich in that 1/2 to 3/4 throttle range.
Thanks
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