PK-80 cold start ups

Charged-Reacter

Charged-Reacter

New Member
I purchased my first mountian bike and it was a cheap Roadmaster alunimin made frame
6-speed and a pk-80 engine. To start up you stand up to peddle and bump your butt on the seat
and it takes right off. A very easy start up.
The other pk-80 is on a steel frame 7- speed bicycle. To start this one up - you have to
peddle your legs off. A very hard start up. Does anybody know why these start ups are different?
 
brnotIt could be because the steel frame is heavier than the aluminum one, or you might just need a new spark plug, I would advice opening up the engine to see if theres any problem, if you have a list of the parts, check each part to see if its all working.

A quick tip: Use BLUE Loctite on essential threads, it makes sure they are in there tight, and will allow for repairs

Best of luck, ride hard, Mojoman.
 
about the only tune up you can do to one of these is the spark plug I think. I would experiment with choke setting each one starts a little differently. Also the tickler thing puts more gas in on some models than others. In other words they don't all start exactly the same I have heard. One of the reasons I went electric.
 
I have a pk-80 on a bike I built at the end of the summer (Firebird, Silverbear's Worksman Cruiser is what the thread is called) and it is a nice motor. I didn't have a chance to ride it much as I got involved in other builds, but I did notice it was cold blooded. It took a good bit of choke to get going when a couple other two strokes didn't require any. It may be that as it breaks in that will change. I hope so as it is a powerful little motor. Other than the hard starting I think it's a winner. If you learn anything, pass it along. I wonder if the iridium plug would make a difference.
SB
 
The PK-80 engine on the steel frame bike did not have the clutch
arm adjusted right. Noticed that when bicycle was running and idleing
with clutch handle pulled in and raising back wheel off the ground, the
tire would spin. Corrected that and cold start-ups got easier.
 
It's most probably the fuel float arm. When mine was overflowing, it would start right up, when I bent it a bit, it sputtered to life. I changed the engine to another bike, on a lower angle and now I gotta prime it a fair bit, and even then it takes a bit to start (should prob bend em back).
 
CHANGE the carburetor you will get a much smoother running engine and easier starts
the cns performance carb works very well also the delorto and chinese knock off delorto work well also the cns carb comes with a handle bar mounted choke.I am running a cns carb with a uno foam motorcycle filter....no restriction
and works very well

I am building a 66cc boost ported cly engine with walbro carb and reed valve
hope it boosts hp.
 
I am having a similar issue, but I believe mine is more fuel related. The clutch is adjusted properly, no issues there. Mine is a HARD cold start, but once she fires up, runs strong as I could hope for. I'm going to go over my fuel set up this weekend, and post any findings as to why mine became such a hard start when it's cold.
 
Well, I did it.
I pulled the fuel shut off valve, and found that the guy before me reassembled it wrong, this was letting fuel over fill the bowl, and flood the carb. My filter was dripping wet, and the cap for the cable and slide assembly was stripped and not holding everything together very well.
So....... rebuild the shut off valve so when I turn it off,, it actually stops fuel flow. Dried out the filter, cleaned out some gunk at the bottom of the bowl. Then I replaced the slide assembly cap with a spare out of my parts box.
Re assembled everything, filled it with my new mixture of 32:1,,,, and she fired right up. Just like my other bike. Ride down the driveway to the street, pop the clutch, and Was on my way.
I really felt that it was a fuel problem,, and after the things I found, thats what it was, a flooded carb.

Hope this helps someone out in the future.
Have fun, and keep safe.
 
For the peanut gallery 1) throw that junk motor kit carburetor as far as you can
2)find cns race carb,delorto,delorto knock-off or mikuni 3)install .....problem solved other carbs may work well but these are the ones I have tried
my stock engines run smooth at idle all the way to max rpm's.If you don't have the scratch for a new carb try burnishing main jet with a torch cleaner..never use a drill bit to open up a jet it leaves tool marks that will mess up fuel flow especialy on carbs with main jet needle valves
a very small burr on main jet can cause a world of performance problems Don't try to oversize the jet just clean and burnish.These engines are very touchy in high altitude if you live or ride way up high use lower octane fuel (81octane) or downsize main jet as you have less atmospheric pressure meaning less oxygenleading to a rich fuel/air mixture.
 
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My PK 80 starts up kinda good, just habe to find the right choke posision, but it takes a long time to warm up so I can go fast, it takes twice as long as the SkyHawk, but runs good when its warm or shouls I say hot. Oh why I messed with the bowl clip to lean it out some. Cause Im going to put the ezpansion chamber on after almost over brakin, anyway the expansion chamber makes it jerk alot, but if you lean it out a tad by the float it helps the jerking less.flg.usflg
 
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