craps out at top end

[radrob]

i got 120 miles on my bike so far. ir is running stronger and smoother than it was to start with.
my only problum is that at top speed (24 mph) it runs very poorly. If i back off the throttle just a bit it smooths out and runs alot better. I havent adjusted my needle in the carb yet. Is that what you would try. If so witch way shouls i go its in the middle right now.
rob

[Pablo]

Tell us more. Stock spark plug? Change it.

Stock exhaust and no gasket port matching? Check it out. Big power robbers.

I don't think the needle will make much difference at top end, but try one notch each way and see what happens.

Is the intake track well sealed, no leaks?

Check your new plug after several hot hard runs. How does it look?

You may consider the main jet is typically a bit rich. .70mm or so. .65mm is a bit better.

What is your rear sprocket size?

[radrob]

i am running a b5hs ngk plug. I switched out the plug wire . 44 tooth sprocket. ( i have a 40 tooth on order) put silicone sealer on the carb to intake connection.
it runs good 20 to 22 mph i was hoping for a little more top speed!

[Pablo]

What does your plug look like after a hot hard run?

Have you tightened your head nuts lately?

Also at the very least match the exhaust gasket and exhaust flange to the exhaust port outlet.

[ibcnya]

Originally Posted by radrob

i am running a b5hs ngk plug. I switched out the plug wire . 44 tooth sprocket. ( i have a 40 tooth on order) put silicone sealer on the carb to intake connection.
it runs good 20 to 22 mph i was hoping for a little more top speed!

Change your jet in the carb....even with a #65 I still ran rich and 4stroke all the time. Your engine is simply taking in more fuel and not enough air. If you can get more air into it, example and intake or change the jet out itll run better. Your plug should be gapped at .018" and .022" any more than that is gonna affect top end speed, not that youre gonna get much top end with a 44T.

[Bikeguy Joe]

Does it sputter when you have it wide open, (too rich) or seem to surge and feel weaker? (too lean)

What fuel to oil mix are you running? Go to at least 24:1 or even 32:1.

[radrob]

the plug is dark around the outside and light brown in the middle.
I had my gap at 25 i will reduce it.
what is the torque on the head bolts.
it kind uf sputters at top speed

[Pablo]

Hmm...fuel ratio seems OK by your description.

Torque depends on your stud size. 6mm (10mm wrench) 10-12 ft-lbs. or 8mm (13 or 14mm wrench) 14-16 ft-lbs. Please don't blame me if the stupid acorn nuts strip.

[Cabinfever1977]

even with a 44t a 26" bike will do up to 30mph.

[JD-StukNchaoS]

"c" clip moved to the 1st notch(furthest from point of needle) will decrease wot flutter.,.,good luck