A buddy of mine wanted me to post this and ask if anyone has any ideas on this. His 650 (with 1200 miles) has developed a rather loud knock from the motor. Oil is fine and initially thought the valves were out of spec. Took it to the dealer, they adjusted his valves and the knock persisted. He took it back and they told him it was a....aahhemmm....'CARBON KNOCK'. They told him to take it home and ride it, let them know if anything happens. Higher octane gas hasn't helped, and neither has fuel additives.

He just told me the other day that he is now loosing anti-freeze (about 1/2 to 3/4 of the reservoir on a 30 mile ride). He checked the oil, no sign of anti-freeze in the oil, no blue/black exhaust smoke. Anyone have any clue? Head gasket?

He's got the extended warranty so if something happens it's going right back to the dealer...on them hopefully. If something does happen, I want to be with him when he goes back. I've argued w/ this same dealer about everything you could think of. When they see me come in, you can see it on their faces and they all try to hide. They hate it when you can tell them about things on the 650 that they have no clue about. Or try to keep your stock parts (like shims after I had the clutch adjusted, or the tires on my buddies when he bought aftermarket tires the day he bought the 650 and they tried to keep the stockers).

One of these days, and I'm serious, I'm gonna walk in there like Michael Douglas in that movie "FALLING DOWN", I joked about it before...but enough is enough.

So any ideas?

 

I,m not positive ,but you may have bent a rod, the reason I say this is if you have a seeping head gasket you could have hyrdo locked the engine(while it sat over night), then when you hit the key to start it the next day it would have struggled but then pushed through, but it would have tried to compress coolant, VERY BAD. its pretty rare to see it on a quad , but its not impossable. after you run it for a while , pull your spark plugs and see if they are wet after sitting. plus with the plugs out, turn the engine over and see if coolant comes out the plug holes.

 

Some 650's had a tendency to lose coolant from several different locations - hoses/connectors/thermostat housings, etc. The knock is likely coming from a little wear in the primary clutch.

 

It's a blown heaD GASKET.

bEST WAY TO TELL IS PULL YOUR RADIATOR CAP AND START THE QUAD. yOU WILL PROBABLY (oops sory) find it having air bubles or foaming.

It may show a good compression but some times it takes the quad to warm up before the compression bypasses the head gaskets.

Most times the engine rune hotter and the plugs show the cylinder with the problrem. But deffinately a head gasket is gone. Do a compression check cold and hot, you'll find it rite there.

 

I don't think the two problems are related. Like Novakaw said the coolant problem is probably just from a loose hose clamp. The most comon ones are of course the hardest ones to get at. The hoses that meet at the junction which is allso where your rad cap is are the clamps that are usually loose. A teltale sign that on or more of them are leaking is some dampness on the top left side of the front cyl. But don't only look at that as somtimes it runs down your rad hoses and evaporates before it can reach a spot to drip off. You might have to remove some of the fender skirting to get at a couple of them but I'd almost bet thats what your problem is. As for the noise I'd have to say it's the drive clutch clacking because its a little on the loose side. It's pretty easy to check that, all you got to do is pop the clutch off and fire it up.

 

wasn't there a weak weld on the radiator? might be a place to check

 

Yea thats rite, the fan mount on some of the 650s broke although I havn't seen any like this it is another possibility.

 

Thanks for info guys...there hasn't been any leaks noticed. No dripping or puddles or anything that we can tell. The knock is definately not from the clutch, it's from the engine...definately. I know the clutch knock...we took the shims out of his clutch already and tightened up the belt. That worked very well...had the clutch knock before and after tightening the belt it was fine.

Don't think the bike has ever been hydro locked before, but could be a possibility I guess. I'd think it was a blown head gasket, but where the hell is the anti-freeze going if it's not in the oil or on the floor and the bike isn't smoking?

...I don't know...

 

Dang!!

I just posted this big long itelligent sounding answer and pushed the wrong buttin and lost it all!!

Parker

The clutch you adjusted is not the one the noise comes from. Unless you have a puller to take it off you should get your dealer to pop it off for you just for a quick check. Also with the loose hose clamp problem, sometimes it evaporates while running down the hoses before it has a chance to drip on the ground. I still think it would be worth you while to check the hose clamps. I'm a lazy little toot so I usualy start with the easy things to check first when a problem arises. With as bullet proof as these engines are I'd almoste bet you it's somthing simple.

 

I'll have him check it out this weekend...still puzzled...