Motor starts, will not idle, and shakes

G

gokart25

Member
I have a brand new PK80 motor, and it will start, but I have to keep hitting the throttle to keep it running, then when I ride down the driveway (while it's running) and let the clutch out the thing shakes bad at full throttle, then if I back off a little it's better but still there...any thoughts??
 
How is the engine mounted? Did you put rubber between the engine and the frame?

Tom
 
I have those kw machine mounts, direct to the frame, no rubber.
I got it to idle, but it's still not right. (bent tongs down, and put 68 jet)
It has a long delay, twist the throttle and it takes a long time to spool up.
When i put the choke on it does not kill it right away.
 
Start looking for an air (vacuum) leak. The choke should kill the engine quickly. If it doesn't that's a good indication that the engine is getting air from somplace it shouldn't be. Carburetor to intake manifold and the intake manifold gasket to the cylinder is where to look first. If all is good there check the crankshaft seal behind the magneto rotor (magnet).

Tom
 
it has to be an air leak somewhere???? Help.
I'm 98 percent it is not between the air filter and the cylinder. (RTV)
If it's an air leak in the magneto area, how do you seal this area?
I took the side cover off and it's clean in there.
I got it running and put the propane gas next to the 3 wires going in, and it died 3 times in a row? coincidence?
 
gokart25 said:
it has to be an air leak somewhere???? Help.
I'm 98 percent it is not between the air filter and the cylinder. (RTV)
If it's an air leak in the magneto area, how do you seal this area?
I took the side cover off and it's clean in there.
I got it running and put the propane gas next to the 3 wires going in, and it died 3 times in a row? coincidence?
Click to expand...

Sounds like a crank seal to me. Pull the rotor and replace the seal. I'd do them all while you're at it...
 
yes I can get it to idle, and it idles ok. at first I had to have the idle screw all the way in, but now it's about 1.5 out. As I get rolling it's real boggy, and no power (my other bike is great).
Then when I put the choke on it takes about 15 seconds to kill the motor.
 
Here's an idea for you to check.

Make sure your magneto rotor in indexed correctly. It should look like this when the piston is at TDC, with the rotor keyway at 1 o:clock.

picture.php
 
yeah it's like yours. I just checked it. At first I thought it was off, by moving the back wheel to TDC..It looked like my picture. then I put it in your position, and looked at the piston and it was TDC.

I have a sloppy video, I will try to upload it.
 

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Honestly from the sound, it doesn't seem like anything is wrong compared to the sounds I get out of my motors.
 
ok I was able to get out an ride it today. I want to thank everyone that help post on this topic...Thanks.
It's not perfect, but it's better.
It's really slow starting off, shakes a bit, and acts like it is missing, but once it gets going, I'll bet that I'm going 25mph+.
What temp should the head be? (I bought one of those temp guns)
Do they make a 9 tooth front gear?
 
gokart25 said:
ok I was able to get out an ride it today. I want to thank everyone that help post on this topic...Thanks.
It's not perfect, but it's better.
It's really slow starting off, shakes a bit, and acts like it is missing, but once it gets going, I'll bet that I'm going 25mph+.
What temp should the head be? (I bought one of those temp guns)
Do they make a 9 tooth front gear?
Click to expand...

You do realize it's not going to run well till it the motor warms up? It takes a few miles in the winter.
 
Thanks to everyone that posted on my problems!!
I'm finally rolling, and it's much better.
Here is a list of things I did, from all the suggestions..
cleaned up intake, exhaust and transfer ports with dremel.
filed down the crank shaft key (offset), to advance the timing, it didn't take much, but this was the biggest/noticeable difference.
trimmed the piston skirt on intake side.

I have been taking my laser temp gun with me on my rides to check the head and header temps.
 
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