New engine

LewieBike

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May 21, 2014
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698
No, no special gearing. Just the standard sprocket. I adjusted the carb today, revs much higher (sounds normal) but after it heats up it needs to cool again before it will rev high. Every time I ride it this gets better, today it held 20 mph without my pedal assist. Maybe it just needs more miles?
These engines need an extensive break-in period using a fairly rich fuel oil mix of about 25:1, for a couple hundred miles. At least that's how I broke in my 48cc, and it's now coming into it's own. Initially it would be hard pressed to make near 20 mph when new, but it also had a big gasket restriction in the intake manifold to cylinder connection. That problem was easily fixed with a home-made manila folder gasket and a couple 3/16" holes drilled through the exhaust muffler cap pipe internal section. You shouldn't need to pedal assist at all on level ground with no wind.

That your engine is overheating when taking long runs is a concern, I'd be checking the carb to manifold joint for the O-ring or at least buy a new one if the stock one is creased or damaged.
 


Eddie2Stroke

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Joined
Oct 31, 2019
Messages
51
66cc kit can make 45mph tops, on stock parts that's the max I've gotten. But you do require port work, I did and even drilled the hole on the cap of exhaust for low end, and drilled two holes on the black carb filter. I also had mag wheels with a 36t, on triple tree suspension forks with disc brakes(160mm)
 

Bozeman55

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Oct 7, 2019
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17
So I messed around with the carb the other day, took off the air filter and it ripped! Up to 35 no problem. Getting a performance filter soon, not sure why the stock one was so ridiculously restrictive
 

Eddie2Stroke

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Oct 31, 2019
Messages
51
So I messed around with the carb the other day, took off the air filter and it ripped! Up to 35 no problem. Getting a performance filter soon, not sure why the stock one was so ridiculously restrictive
For now I'd cut out the black/red filter part to allow more airflow, or clean your filter. I just drill holes on it, but an exacto knife might make a better precise cut that allows more air.
 
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Purple Haze

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Joined
Aug 21, 2011
Messages
409
So I messed around with the carb the other day, took off the air filter and it ripped! Up to 35 no problem. Getting a performance filter soon, not sure why the stock one was so ridiculously restrictive
Y
So I messed around with the carb the other day, took off the air filter and it ripped! Up to 35 no problem. Getting a performance filter soon, not sure why the stock one was so ridiculously restrictive
I think these engines were deliberately designed to be restricted. The more you dig into them, you'll find lots of places to open them up for better breathing without spending much money.
 

danlandberg

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Joined
Apr 25, 2009
Messages
574
I have been having idle problems with my PK80. I cleaned the carb, changed the intake manifold to a billet shorty and added a performance air filter.
Still it won't idle. Thinking I'm going to have to change the needle clip to a a lower notch to get Moore fuel to air mixture.
 

Purple Haze

Active Member
Joined
Aug 21, 2011
Messages
409
I have been having idle problems with my PK80. I cleaned the carb, changed the intake manifold to a billet shorty and added a performance air filter.
Still it won't idle. Thinking I'm going to have to change the needle clip to a a lower notch to get Moore fuel to air mixture.
My experience is that they are too rich from the factory. Try putting the clip in the top notch. Also, try a mid #60s jet, always seems to make em more responsive.
 

danlandberg

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Joined
Apr 25, 2009
Messages
574
Thanks. The engine idled worst with the new air filter. Also, if I turned the idle screw in to open the slide to increase the idle it would not speed up. If I turned it out the idle would increase, but only if I was giving it a little throttle to keep it running. That is why I'm thinking I'm getting to much air to fuel. I have to ride with the choke slightly on to get to top speed and the sweet spot.
 

Eddie2Stroke

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Joined
Oct 31, 2019
Messages
51
Possible air leak in the intake that connects to the carb..I used an O-ring inside the Carb to help it not get air leaks. I got one from home Depot for like a buck or two for a bunch of them.
 
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