Plinking noise.....

[TrxTex]

I just put in a cam (450/451), 11:1 wiseco piston, and the rev box.... I broke it in as said.

Onto the noise.....

Every once in a while when I start up it makes a plinking noise...just one plink....and you never here again. Until...you bog it down on a hill in the wrong gear or something. When it bogs it also makes the plinking noise. I have come to the conclusion that it only does it at very very low rpm. I plan on putting the stock rev box back in to see if it does the same thing. I hear that they change the ignition curve....if its not that then I have no idea. Other than that it runs like a bat outta **** compared to stock. I have had it apart checking the cam, springs, rockers, but I find nothing out of the ordinary.

Anyone having the same noises? It sounds like it comes from the cam area.

[phatswinn]

i think that after putting a 11:1 piston in you need to run race gas, i dont know though but im 99% percent shur

[Leo]

Are you sure it's not predetonating (pinging?)..

I just put an 10.5:1 JE piston, and XR cam in mine.. 4 or 5 times while out riding saturday I heard it start to ping just a bit during low rpm / high load conditions.. I'm hoping it was just the gas I was running (92) I'm going to try a tank of 94 next, along with playing with my jetting a bit... It was only in the 50's so I think I might wind up running a 50/50 mix of 94/race gas during the summer..

Leo

Check to make sure your timing chain is good and tight, my 200s three-wheeler made a pinging sound just before the chain broke because it was to loose.

[TrxTex]

I guess mine was doing it during high load conditions also. I sure hope it isnt the timing chain slipping. I put it back on how it was. It sure seemed to be tight. I pulled on it when I had it part last... I also turned the motor over about 20-30 times with the plug in and out. It all seemed to work just fine.

It runs awesome at all other times...... I dont think it would be the gas because it would make the noise all the time.....wouldnt it? I sounds like the cam slapping the rocker arms or something...

I just dont know....any other ideas????

Let me know how the gas turns out Leo or if the sound continues.

[NVR2L8]

My JE piston 416 engine did the same thing after the upgrade about a year ago. I thought it was predetonating at first, but after the mechanic who did my rebuild took a look at it, he called it "piston chatter" and said it wasn't anything to worry about. Not altogether satisfied with that answer, I asked another mototcycle/ATV mechanic to take my quad for a ride, and he agreed and called it "piston shake". He explained that under load the piston is slightly vibrating (or whatever you want to call it) and that's what's causing the noise. I'm not really happy with it doing this, but it runs well and really only does it when riding really hard at the dunes.

Not fool proof but give this a try.

After first getting going in 1st shift to 2nd or 3rd and give half throttle. With the engine luggin due to the higher gear any pinging from preignition etc will be very prevelant. at this point the pinging will or should be more obvious and increase if you hammer it, but will go away as the rpm increases since you not be putting as large a load on the engine.

If your finding anything like this then you will need to up the octane as the fuel mix is ignighting before it should due to the increase in compression. This is also the cheapest way to test it.

You should think of this as a good thing (if it is what is happening) as you have done a good job increasing the compression and therefore the power. I think you will be even happier with the power with the correct fuel.

Try the mix recomended above first as it will save you a few $$ and if the octane is too high it will not help performance.


Good Luck

[TrxTex]

You hit the nail on the head. It only does it in that situation. I was cruising along with my wife on the back and I decided to mess with her and goose it. Turns out i was in 3rd gear going fairly slow and it ping pretty bad for a second but when it rapped up it sounded normal. The plink it makes when starting is what I question now.... Could it be the same thing? Sounds the same.

Im sure I can find some race gas here in Amarillo and mix 50/50 with premium.

Thanks for the info...I will test it out this saturday.

Sounds like the pings have it:D

Try the mix and let us know how it goes.

[NVR2L8]

Well, I ran a 50/50 mix of Chevron 92 octane and 111 leaded race gas (effective octane of 101), and my engine still pinged a little after it got really hot at the dunes, and/or when lugging it and then trying to accelerate. Having said that, I think I can rule out the possibility of the pinging resulting from running too low of an octane rated gas. In my situation I honestly think I have a little piston chatter... At any rate, I can tell you from a year's riding experience on a 416cc motor with an XR400 cam and 39mm FCR carb, and I can tell you that this type of motor, while still have tons of bottom end power, it doesn't like to be lugged around and really prefers to be revved.

[TrxTex]

Well...no more pings...

I bought some 112 race gas and mixed 50/50 and its working great.

Oh.....I raced a buddy of mine today who used to outrun me by a hair....well...it wasnt even close. I beat him by 10 bike lengths now!!!! I would suggest going higher compression and getting the cam to anyone....best $$$$ Ive spent in a while. :D

Thanks for the info....