I recently installed my IMS 440 kit and so far, so good.
BUT, recently I have noticed a sound under wide open throttle that SOUNDS LIKE a piston slapping noise. I think the noise goes away after the engine is fully warm. (20 mins of riding) The valves are adjusted properly. I did my idea of a proper break in. (took it very easy on motor, and gradually increased to more aggresive throttle over time)
Bike runs super super strong, and the sound makes no affect on power.
Any ideas?

-Matt

 

Mine does that too. I guess if its not normal I'll have to do an autopsy on it later. The honda dealership said it sounded fine though. I think it might be my over critical mind playing games.

 

I tighened my skidplate (full length) and it solved my sounds....

 

I thought of something. Detonation. Ping. Knock.

Clues: Only at WOT, At higher RPM's. Using 92 octane, but from cheap gas station.
10.3:1 piston. Im adding some octane booster tomorrow and will see if that does it.
I know from the top end rebuild that the valves have lots of carbon buildup on them.
This would only contribute to the problem from added compression from carbon, and hot spots on carbon causing pre-detonation.

 

Most of the octane boosters available suck. When they say it raises the rating by 1 point, that means 93 becomes 93.1 Woooo.

Many paint stores have Toluene @ about $5.00 a gallon. Tolune is 114 octane, check out these sites for more info: http://www.faqs.org/faqs/autos/gasoline-faq/
http://patriot.net/~jonroq/Tech/octane2.html

Mixing race fuel works well also.

 

Could easily be detonation. My previous 416 had the 10.3/1 (10.6?) JE and had detonation with pump gas. I had to run race gas.

 

MattFisher is right, octane booster is a huge rip off. It sounds like detonation to me. Since your in Arizona and the temps are higher it will only compound your problem. One way to test for detonation is to put it in high gear and travel up a steep grade at a fairly low rpm, then hold it at WOT. You should be able to detect the pinging from detonation/preignition. You can mix race gas with 93 octane to help the problem. Im not familiar with hondas so I don't know if your timing is adjustable, but if it is you can take some timing out of it(retard) by a few degrees, this usually helps. Good luck.

 

Try running lead additive to your gas.I read that FST's Mickey
Dunlop uses this to decrease head temperature in his 400EXs.

 

Mr350X, you could try the octane booster. Using that will help you determine if that's the problem. Other than the experiment, I wouldn't run it unless you are using Klotz's.

Go to your airport and get some AV gas. You will have to tune your carb to run it, but it works wonders. 106 octane, and very steady from one batch to the next.

 

Although avgas does have a higher octane, it's actually not the best choice for performance. It's formulated for cold temps, and steady state rpm's. Your throttle response will suffer if you use enough to really affect the octane rating of the poo pump gas.

Get a magnifying glass and look at your plug right after you hear the noise. If you see little ***** on there- that's aluminum from your piston- you have a detonation problem.

Lead additive certainly raises the octane, but it's very hard to get anything that really has much in it, the EPA has seen to that. And truthfully, Tetraethel lead is really nasty ****. VERY hazardous to your health. From the research I've done, Toulene and Xylene are the best additives (Toulene is a major component in gasoline anyway), and then race fuel is even better. Not just because of the octane, but the burn properties are excellent for making power. Fast burning, yet detonation resistant. Mixing avgas (not straight) seems to be an answer for some folks, but many airports aren't allowing just anybody to fill er' up for various reasons.

You might want to pull the head back off and get rid of the carbon. Check for scuffing on the piston while you're in there. If you have an ignition advance key, go back to the stocker. Check your coil, a poor ignition can wreck havoc. Go to 1 heat range cooler plug. If all else fails, stuff a thicker base gasket in there. Keep the head gasket thin.