Bike engine skipping, not as powerful

[ShiFuBill]

Hi, I'm having some trouble with my bike. It was running fine, but I noticed there was an oil leak. The muffler wasn't on well and oil was leaking out. It didn't fit quite right because the muffler was against the frame. I cut
a piece of cardboard (very thin) in the shape of the piece that is fitted between the muffler and the engine and fitted the cardboard between this piece and the engine. This fixed the lead, however there is another problem that may or may not be related.
When I'm running engine, it runs smoothly for a while, but then feels like it pulls back every few seconds. Like it's missing, or skipping or something.
Also, it seems like it isn't getting as much power as it used to. I'm not sure because I didn't run it for a while, but seems like it's just not going as fast as it had been. I'm not sure if the fix I mentioned above has anything to do with it, it doesn't seem that that would do anything, but I thought I'd mention it.
Another issue is that I also added a new tension piece (that piece that adds tention to the chain from the engine). Could it be that it has too much/little tension?
I've adjusted the carbourator adjustment screw and the air intake lever, but I'm not sure if I'm helping it.
Also, since I added the cardboard piece it seems to be running quieter. I don't know if that's a symptom or a benefit.
Any ideas?

Thanks!!!

 

[arceeguy]

Sounds like the engine may be running a little too rich. As things warm up from winter to spring/summer, the jet needle may need to be adjusted. In this case, raise the clip a notch to lower the jet needle and lean the mixture a little.

 

[ShiFuBill]

Interesting. What's the jet needle and what's the clip? And how do I adjust them?

 

[arceeguy]

clicky clicky and go approx half way down.

 

[ShiFuBill]

Well, there was nothing about a jet needle or a clip, but I think you meet the part that regulates how much fuel enters the chamber. As I understand it, turning the throttle makes more fuel go in, so if it needs to be more lean wouldn't you just not turn the throttle as much, and wouldn't that make it even less powerful?

 

[gerichardson]

Too much Too little chain tension

ShiFulBill,

Your chain should have some play. Roll your bike a bit and take a ruler to measure the movement. An inch or so is okay. That's what I have.
The chain shouldn't be tight with no play. Check the forum for more specifics on the best adjustments.

Ride on!

 

[arceeguy]

Well, there was nothing about a jet needle or a clip, but I think you meet the part that regulates how much fuel enters the chamber. As I understand it, turning the throttle makes more fuel go in, so if it needs to be more lean wouldn't you just not turn the throttle as much, and wouldn't that make it even less powerful?

Whoops sorry - go to the point where it says that "All Skyhawk GT kits come with throttle cable pre attached". The photos of the carb slide assembly are there. The jet needle is the brass needle that moves up and down with the slide. There is a circlip that adjusts the level of the needle.

 

[ShiFuBill]

Once again, I think that this just regulates how much fuel is coming into the chamber. I can understand how this would affect it when the engine was idling, but not how it runs.

 

[ShiFuBill]

There is another thing I forgot to mention. It doesn't start as quickly as it used to. It seems to pull without firing for a second before it begins to start. It feels like it's dragging or something.

 

[arceeguy]

Once again, I think that this just regulates how much fuel is coming into the chamber. I can understand how this would affect it when the engine was idling, but not how it runs.

The jet needle controls idle mixture to about 3/4 throttle, that's when the main jet comes into play. Some folks have posted that their engines run too lean with the stock main jet and some post that they run too rich. It all depends on your operating conditions and the phase of the moon when your carb was manufactured. Is your engine "skipping" at part throttle or at full throttle?