Hello all-

I just got my CBR900rr powered race car running and did a test day yesterday. Ran great and had good power. A bit of popping under deceleration.

The setup uses a very open exhaust and filter. Main jet is a 160 (!) and that seems to be good up top. I have heard that the lean idle mixture that causes the decel. popping could also make the engine run hot. Even with a pretty large radiator and fan always on, it tended to overheat during a 20 minute track session. I realize this could be caused by a lot of issues though.

Opinions on jetting and engine temps?

Thanks

 

Wow that is a pretty technical question. I honestly have no idea.

My bike was already jetted by the last owner(s) and I have no issues with it running hot.

I think the bike has a stock radiator too.

 

Those popping should be from the exhaust sucking back some amount of air when you close your throttle. Does it overheat when the bike is idling? Does the gauge hit the red or just above the center?

 

Thanks for the replies. Just to clarify. The engine is not in a bike. It's in a lightweight race car. I realize this is a bike forum but this is where people know about these engines.

The temp gauge reads very near the red during race pace lapping. Runs totally cool at all other times. Plugs look good. Light tan in color.
Engine runs well though. Good power though out the rev range.

 

This is interesting. You are running a modified car engine that is installed in your bike. What is the displacement of the engine anyway? From what you had described the engine is overheating or the whole coolant system is not working up to the mark only when the bike is in very fast pace. Since you are having a different radiator, I will suggest you do a service on it first. What about all the water hoses? What about the pump? Does the pump has the enough power or capacity to pull off enough coolant to distribute to the engine and radiator when the bike is running fast?
This can be really tricky when you have a modded engine like this.

 

Dinez, perhaps a picture will help. Engine is now a 900 though.

Thanks.

[IMG]local://upfiles/27284/CBE3438E6EDD44F8B98346A83079D18B.jpg[/IMG]

 

Looks like your radiator is at the wrong spot. Probably you dont have enough cold air going in it because of the emplacement. Should be at the front or somewhere where the air can go freely into it.