Tri-z cutting out-help

[Tri-Z Pilot]

It's gotten a little colder out around here, and the other night, my tri-z started acting up. It ran really good, till you got up around 1/2tofull throttle (not exactly sure at what throttle opening), but when you went past it, the engine would die out, unless you took it back under half throttle,then it runs really good. If you gradually increased the throttle, it would keep running, but it would still cut out at some point. My question is, is this happening because it's running lean, or is it running rich from the colder air hitting the radiators? Off idle, it smoke like a mother till it remotley warms up,(but that is probably normal), the only mod is a k&n airfilter(in the stock airbox), and the previous owner said that the main jet was upped a couple sizes,could it be too rich, or lean, how can I tell? I cant do a plug chop (no kill switch).

[J.D.]

Sounds to me like possibly rich. Just reach down and pull the plug wire off the spark plug! Be a man, you can do it :shock: 8)

[Tri-Z Pilot]

Hmm, didnt think about that, might sting a little though,lol! I think the bike might be running on half choke, (the choke knob is pulled way out of the carb, even at the bottom position, shouldnt it sit flush on the carb?

[J.D.]

For a stock carb? Nope. I'll tryo to get some detailed pics. You can see bout 2 inches of the line when the choke is fully down. When you pull it up, it comes up about 1/2 an inch or so.

[Tri-Z Pilot]

Hmmm, I thought it sat flush, oh well, guess I was wrong.

[twgranger]

Mine did that with the weather being cold. It was running LEAN!

[TimSr]

Pull the choke, and see if it will rev out. If it does, you probably have your thermostat out or its stuck open which is how they usually fail, and its not heating up to operating temperature. Another indication will be a plug that looks like its running very rich. If this is the case, you can block one or both radiators if necessary in very cold temperatures.

[Tri-Z Pilot]

That doesnt make any sense to me timsr. If I pull the choke on, and it revs out, that would mean I was running lean right, and if my thermostat is nonexsistant or stuck open, it would be running rich, right? If the bike is not up to operating temp, it would be rich and the choke wouldnt help,so if I pull the choke on, and it revs out, I should expect the bike to be running lean correct? I could be wrong, but correct me if I am.

[TimSr]

Your thinking too hard and getting way too technical. Forget lean and rich. Think about how a bike should act when its cold and choked, or cold and not choked. When you start a cold bike with the choke on, you can rev it right up while its cold. If you shut the choke off immediately and try to rev it, it bogs as soon as the throttle is opened up about halfway. When it eventually warms up, you can crack the throttle all the way open. If it never warms up, or it cools back down as soon as air flows through the radiator, your back to bogging at half throttle. If your bogging at half throttle because your engine is cold, and you choke it, you can rev it right up. Also if you pull your plug it will probably be black. If you get this response, it is a temperature problem, and not a carburetion problem. Its also pretty common on TriZ's.

If on the other hand, when you choke it, it begins running like a hot motor with the choke on, it could be a carburetion problem. I just happen to have seen the other scenario a lot more often.

[Tri-Z Pilot]

Thanx timsr, I never thought about it that way, I will see how it is acting tommorrow, and if it starts cutting out, I will try running it on half choke and see what happens.

[Tri-Z Pilot]

OK, this is what happened today, I tried running it with the choke on, and it kept stalling out, but with the choke off, I could revv it the whole way out in first gear with no problems, but when I tried it in second, it started to cut out a little at full throttle, and at third it started to cut out even more, and so on, so is it the colder air on my radiators, should I try blocking one off?

[Tri-Z Pilot]

Tommorrow I am going to block one of the radiators, is there anything I should be careful about or pay attention to? Will the bike start to loose power if it is overheating? I just dont want to melt a piston.

[TimSr]

OK, this is what happened today, I tried running it with the choke on, and it kept stalling out, but with the choke off, I could revv it the whole way out in first gear with no problems, but when I tried it in second, it started to cut out a little at full throttle, and at third it started to cut out even more, and so on, so is it the colder air on my radiators, should I try blocking one off?

When you flip the choke on, will it die if you keep the throttle on and try to rev it out? If you can keep it running with the throttle on, and it revs all the way out, it is a temperature problem. If the choke kills the motor, regardless of throttle position, it is not a temperature problem.

Also, when it "cuts out" does it bog like you would see with no fule, or does it spit and sputter like youd see with electrical problems?

[Tri-Z Pilot]

No, it will bog down, like it isnt getting fuel, I was just riding it, and I didnt take it out off first gear, I was in the yard playin, blowin donuts and what not for a while, and then I would wind it out down my road every now and then, and it seems to run fine now, I must have not givin it a chance to warm up good enough the other times,(I wasnt rippin it as hard).