Up against a wall

Chaz

Well-Known Member
Jun 3, 2012
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48
Vancouver, British Columbia
I have an older pk80 with over 1000 miles on it. Moderately ported. Free flow exhaust, and NT speed carb with stock jet. The needle clip is in the leanest slot. I drilled a bunch of holes in the air filter cover so I believe it is breathing ok for the intake. Plug colour is okay if anything a bit on the rich side. 26 inch wheels with the 44 tooth. Upgraded plug wire and socket with ngk b6

I have been having trouble getting the rpm past a wall. Sorry, no tach reading. I'm getting some 4 stroking in low to mid rpms/speed. As I reach about 25 mph it sort of feels like bogging or is it 4 stroking? I'm not sure. The fuel flow seems adequate.

When the rain stops I will test again but it seems like the bike would rev up to higher rpm if I turn off the gas at the tank and burn off the gas in the carb bowl.

In the summer I was able to rev up to reach 30 plus mph and, as a side note, the engine actually smooths out at higher rpm

I suspect I will have to jet smaller but looking for confirmation of this.

Does anyone know what my problem is?

thanks, Chaz
 
Last edited:

crassius

Well-Known Member
Sep 30, 2012
4,032
156
63
USA
usually, first thing to do is check for oil residue around gasket and seals, then check float level, also check that mounts are tight
 

crassius

Well-Known Member
Sep 30, 2012
4,032
156
63
USA
I just started testing on my new pk80 kits and find the longer stroke does smooth out at higher revs (pulls hills better at low speed tho) - did you try loosening your muffler to see if that helps?
 

curtisfox

Well-Known Member
Dec 29, 2008
5,184
1,597
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minesota
if I turn off the gas at the tank and burn off the gas in the carb bowl.
Good sign that it is running to rich, as it runs out of gas it leans and revs higher. Take the air cleaner of and see how it runs. Like Crassius said do some testing before changing jet..........Curt