my 03 eiger (footshift) sounds like a diesel pickup when i shift up, slow down and fuel back up or on a hard pull. it only does it when it gets warmed up, cold it sounds great. i've changed plugs, used high octain
gas and even had the valves adjusted, nothing helped. i can let it cool for just five minutes and it sounds good until it heats back up.

any and all help (please) will be appreciated.

 

haha that's cool deisels sound awesome!

 

You'll be less impressed with the cool sound when your piston develops a grape size hole in the crown and your bottom end and main bearings are contaminated with aluminum junk. Your bike is pre-igniting. Sometimes called 'dieseling' this is very harmful. Take out the spark plug and see if it has grayish deposits or flecks on it. That's aluminum. Piston aluminum. Either you need to upgrade your gas octane and/or richen up your main jet. Have you performed some hop-up lately? Anything you do to hop up the motor makes it draw proportionately more air and this air needs it's proportion more gasoline mist in it. Run too lean and you run hot and preignite (and don't get the power you could, as well)

 

i checked the plug, looks o.k. i use 93 octane fuel, no mods just stock except for the ngk iridium plug. what size jet would you recomend (i' ll order one today) one more thing i forgot to mention, after i fuel up the engine and get it wound tight the noise stops until i slow down and fuel the throttle up again.
thanks, keep the info. coming.

 

I'm going with a 135mm same as aksafari...aksafari's thread on Eiger main jet change

 

I know this sounds basic, but do you have enough oil in the crankcase? Is it the correct viscosity? Any additives?

 

yes, the oil level is full and it is up to specs.
i called my dealer and he said to adjust the clip to richen the fuel, any thoughts on this and is it easy done, never removed or worked on a carb before.

 

Heres an article on doing it on a motorcycle. Its not exactly what you need to do, but close enough.jetting
They write about shimming the needle, which you wont do, you need to just move the 'e' clip, towards the needle end. This will make the needle ride higher, in the needle jet, and make things richer. Go one notch at a time, and see how it runs.
Another thing you could try, Which is quick and easy to do, and will let you know if going richer will help or not, is to put a piece of duct tape, over the snorkel( air intake for carb), and cover the hole, about 30%. This will reduce the air coming in, and make the fuel mixture rich enough, for you to see if going richer will be the answer or not.

 

uhhh... no clip on the CVK32 carb in the Eiger. Either a shim, or my recommendation, which is to go to a 134/135 jet.
never actually heard 'detonation' or 'preignition' called dieseling... dieseling in a gas engine is when you shut off the ignition, but it continues to run LIKE A DIESEL engine, chugging away for a small amount of time on merely the fuel alone W/O spark. This is not due to timing (obviously), but can be caused by high idle or unburned fuel from a rich mixture.

EDIT: I was mixing my stupid thoughts in the above paragraph. It was pointed out, thank God, before too many people noticed it. duh

Mine makes that sound, 'valve clatter', when I lug it out. BUT, lugging is about the worst thing you can do to your engine, so DON'T DO IT!! I try not to, but it's hard not to sometimes. My ATC70 made that sound sometimes, my ATC200 made that sound, too. Go out to your car or truck (if it's a manual), put it in 3rd gear and drive around a parking lot at 10mph. You'll hear that noise. It's when the fuel/air ignites, but the piston can't move down quickly enough, so the shock wave slams into the top of the piston, making that sound from all the slack in your bearings, or in your whatever being taken out suddenly. NOT GOOD, whatever you call it.
I'm more inclined to believe that high RPM is MUCH better on your engine than low RPM. Rotating parts were made to rotate. Let them!

 

Raising the needle will richen up the middle or intermediate throttle settings but won't do much at full throttle, where you are likely experiencing the pre-ignition. In fact I'll bet you can make it stop pre-igniting by backing off on the throttle to the intermediate range.
At full throttle the cylinder pressure is greatest. That and a hot motor and lean mix makes it pre-ignite. The air is wide open and the needle is high enough in the tube that it's not having an effect on the fuel metering. The gasoline hole is only so big. To make it richer at full throttle you have to have a bigger gashole.