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Strange sound under power

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Hi, when I turn on the gas in the midrange, there's a strange sound coming from the engine. Low range no sound, high revs also not. It sounds a bit like a exhaust gasket not working properly. After checking torque, it's not very likely that this is it. Anyone 2cents left?

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I use 95 octane now, could use 98, does anyone have a example of the sound of pinging?

my first guess was a exhaust gasket or maybe the headgasket. The last one is new and consists of more layers aluminium. Maybe i should retorque this..experience anyone?

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If a motorcycle shop were to fix your engine and torque the bolts they don't as far as I know ask you to come back in

so they can re-torque the bolts again.

 

Pingings hard to describe,,My XL600 used to do it a bit ..I'd describe it as a sort of cracking noise under load in higher gears. If you

ease off the throttle at the tinny/cracking noise it stops,,More throttle generally makes it worse and you get no increase in speed

of the vehicle with the throttle applied..Bike just sort of holds back...

Edited by Horri
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I use 95 octane now, could use 98, does anyone have a example of the sound of pinging?

my first guess was a exhaust gasket or maybe the headgasket. The last one is new and consists of more layers aluminium. Maybe i should retorque this..experience anyone?

I doubt it is detonation in these machines unless you have done some significant mods to the engine. I would look elsewhere..I run 87 octane , run the hell out of it with no detonation.. Edited by dochawken

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I doubt it is detonation in these machines unless you have done some significant mods to the engine. I would look elsewhere..I run 87 octane , run the hell out of it with no detonation..

87 octane in the USA might or might not be the same a 95 in The Netherlands.  It's not measured the same way.

 

Still, mine is happy with the lowest octane using the stock piston.

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Looks like my sound, so I'll try 98 octane and hope it'll be gone

lol...jet fuel! Why do you run 95 octane?

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Even if there is a 4 point differential, at 95 oct in the Netherlands your running our 91 oct...I still doubt it is your issue..

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They use a higher pump octane number than the US or Canada...4-5 points..these bikes could run cow on piss for crissake. I would recommend loading the engine in 5th gear, if you do not hear it, doubtful it is detonation.

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They use a higher pump octane number than the US or Canada...4-5 points..these bikes could run on cow piss for crissake. I would recommend loading the engine in 5th gear, if you do not hear it, doubtful it is detonation.

They use a higher pump octane number than the US or Canada...4-5 points..these bikes could run on cow piss for crissake. I would recommend loading the engine in 5th gear, if you do not hear it, doubtful it is detonation.

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The noise he describes sounds like detonation. There isnt enough information to be sure. If he trys the better quality fuel and the noise improves we will have the answer.

correct....but doubtful. Unless he is running unbelievably lean and it overheats the engine.

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Guys,,before you break boilers on octane ratings read page 2 there..last post,,,then skip back to page one where Okay73 says he's

running a 152 main..miles too small imho..Dunno what's what with the gas mileage ,,that's not good for a 600..

 

http://www.thumpertalk.com/topic/1067970-follow-up-on-issues/page-2

 

Even when I had the stock carb on my current bike which has the 100mm XL bore I ran 165/65,,Needle one slot down from blunt.

Possibly a bit rich at that but ok should have at least a 158 main if he's running that bigger bore..

 

What main and pilot do you have in the carb now okay???,,Forget that,,I have the answer..

152/60.

Edited by Horri

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Guys,,before you break boilers on octane ratings read page 2 there..last post,,,then skip back to page one where Okay73 says he's

running a 152 main..miles too small imho..Dunno what's what with the gas mileage ,,that's not good for a 600..

http://www.thumpertalk.com/topic/1067970-follow-up-on-issues/page-2

Even when I had the stock carb on my current bike which has the 100mm XL bore I ran 165/65,,Needle one slot down from blunt.

Possibly a bit rich at that but ok should have at least a 158 main if he's running that bigger bore..

What main and pilot do you have in the carb now okay???,,Forget that,,I have the answer..

152/60.

I agree Horri..but even my stock setup never detonated, it just couldn't get out of it's own way. I think as you say, it is far too lean...but we don't know. My experience with my pig demonstrated the extreme durability of the power plant when the AFR is correct.

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So what you are saying, is pinging is related to the jet size and I'll have to change my main jet (and possibly my slow as well)

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So what you are saying, is pinging is related to the jet size and I'll have to change my main jet (and possibly my slow as well)

If it is stock, it is too lean. Look at your plug. When jetted properly it will pull like a red mule. Rarely would octane be an issue with these machines. Why pay for more expensive fuel? Just jet it properly, make simple mods to your airbox and your probably good to go. 4 strokes.com has a nice pictorial on Dave's mods for the carb and air box..I would recommend you replace the carb screws with stainless steel allen head, I think M4 is the correct size. Add a free flow air filter...you will be the envy of the dirt rocket community when you get it correct.:p Edited by dochawken

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I noticed all manor of odd noises that disappeared as soon as I replaced the stock carb with a TM flatslide on the 07 I'm currently working with.

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I noticed all manor of odd noises that disappeared as soon as I replaced the stock carb with a TM flatslide on the 07 I'm currently working with.

but I think the most cost effective solution is to give it the proper AFR...then I think he will be happy.

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