Lazy engine

So, like many people recently posting, I also picked up one the the cheapo kstar kits, and have been having some trouble getting my engine to behave properly. My setup is as follows

- 14mm bing bored out to 16.5

- 80 jet

- second from top of needle

- intake made from ped's original exhaust header approximating 18mm in inner diameter

- kstar kit w/ kstar high compression head

- Proma country exhaust

- timing is about halfway between fully advanced and retarded

I think I've included all the essentials; bike is hardwired, and am running about 40:1 non-synthetic.

The problem is that it doesn't seem to like slowing down/coasting. It idles fine, and accelerates well, but once I'm up to speed (and am not running WOT yet as the kit is two days old) it seems to four stroke, or for that matter, simply not fire. As I'm cruising at 25 or 30 and ease off the throttle, all I hear is the whirr of the engine, and an occasional pop.... pop.... pop...

Furthermore, as I decelerate when approaching a stop, I can kind of hear the engine stall and I must give it a lil gas to keep it going, but once I'm at a full stop and have given it a few bursts of fuel to recover from the previously mentioned stalling, it idles fine.

This deceleration occurs on a more rapid scale when going around corners as one would expect; slow down for a turn, and it almost stalls out completely unless I throttle into the turn.

I've tried both upjetting to 84 (which resulted in barely being able to start the engine) as well as down-jetting to 76 (which did not hurt, but did not seem to help, and I don't want to run too lean with the new kit).

Any suggestions for what might be causing this are greatly appreciated. Thank you.

Re: Lazy engine

Oh yeah, fully port-matched as well.

Re: Lazy engine

When you are at WOT are you four stroking like crazy?

Re: Lazy engine

oh...i just re-read your post and saw that you are not running it at wot yet. Duh.

Re: Lazy engine

And even then, it's when I'm decelerating that it's the biggest problem. When running at top speed ('top' being as fast as I'm willing to take it yet) it runs... okay... four strokes a little bit, but only when the engine isn't under load (going down a slight decline, tail wind, etc).

It seems like if I were to lock up my back brake a bit so the engine always has to work a bit more, it would be fine :-P

Re: Lazy engine

lean or rich. whats your plug look like?

Re: Lazy engine

halfway between fully advanced and fully retarded is not a real timing setting. depending on how new or worn the points are, that could mean anything. I suggest setting your timing correctly, then go from there.

Re: Lazy engine

90 % of all carb problems are electrical.

Re: Lazy engine


Well, points and timing are nicely adjusted, everything is thoroughly grounded and despite trying a range of jets and needle settings, I still can't shake the behavior initially described.

Would such behavior be caused by simply having too small of a carb? It's a 14mm bing bored out to 16.5, with a matching intake.

Re: Lazy engine

Well, I found the very obvious reason; I must have spaced when putting my needle in, and had it all the way up; yeah, whoops! All the way down, it runs much better!

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account