Sup fellow thumpers;

So, to follow up on my plug fouling problem that I have been battling against with CO Powersports, I come to find out on Friday that they finally did a leak down test on my cylinder, and found a "bubble" in my head gasket causing a leak. I'll spare you all my thoughts on this. :) This kind of a problem is rather new to me, so can this possibly be the cause of part of, or all of my fouling problems to date?? Can this cause excessive where on other engine parts, or cause other problems in the engine?? I'm definately going to have them check the valves while they are replacing the gasket. Retribution will be paid for these 3 months of hell once this finally gets taken care of.

Thanks to all for your help and input.


A leaky head gasget? I'm surprised that you didn't notice this problem earlier in the form of missing coolant, milky oil and/or burning coolant smell out the exhaust. Could a leaky head gasget cause plug fouling? I suppose so, but I have never see it. From what I have seen, typically a leaky head gasget will result in either coolant blowing out the radiator overflow, or coolant getting into the cylinder which will disolve all of the carbon deposits and leave everything shiny and new looking.

Can a leaky head gasget cause other problems? Definitely, usually heat related (from loosing coolant) or lubrication related (from coolant in the oil). It can also burn the cylinder or head where it leaks if the leak is bad enough, but typically you will notice the problem much before this happens. If you weren't loosing a noticable amount of coolant then I doubt that this was causing you any problems. Are you by chance paying for the new head gasget and labor?

Thumpalot, what's Shaken;

Nope, not paying for this. You better believe everything needed to make this bike run is on the shops tab. Ok, this seem awful fishy to me to. I check my coolant level everytime I change my oil, the level has never changed, nor do I have any thing burning. My patience wears thin. :)


Is this a new 2001, or did you buy used from the shop. I know your problem is not jetting but I think sirthumpalot is right-this doesn't sound right.

What's up Mike;

This of corse is Dodger here in boulder. You betch'a I bought this new from CO Powersports Hopefully I'm supposed to have my bike back by the end of the week. They had to order a frig'n head gasket for my bike. They didn't like the idea when I told them to take one off of the floor. Story from the shop is that the leak in the head gasket wasn't to one of the liquid passages (Coolant, or oil) but to another cavity in the head. We'll see, they seem to be pretty positive that the leak is going to be the cause of my "lean fouling." I'd like to hook up and ride here soon, see if we can get Eric from the shop out also. If my problem still isn't fixed after this, I may take you up on the CDI swap. I'd appreciate the help.


Dodger, your not alone. My dealer(Santa Fe Motor Sports) seems to be taking the hard route to a simple fix(changing out the cdi!)I've explained how I've swapped cdi's with a buddy(firejake69) and proved without a doubt that the cdi was causing the plug to foul.SF Motor Sports claims they've spoken to Yamaha-ha and they know of this problem BUT they don't want them to replace the cdi, they want them to do some other testing....acc. pump,throt. position sensor,etc. blah blah blah.

Yo lou;

A CDI swap is definately next. Hopefully Mike O. here is boulder will still be willing to help me out. CO Powersports told me today that it isn't a head gasket problem, and that they have tested the coil, which spec's out fine. And have checked the CDI twice. Bull S#@t. Either this particular bike is really really F'd up, or the shop is trying to hide something else. I've gotten on the nerves of their president so bad that he has authorized a buy back on the bike. I'm going to ride it out for a little longer, after 3 months I'm still hoping for a viable solution. I guess I'll take them up on the loaner they offere today so I can get a little saddle time. This sucks!!!


I've had head gaskets blow(not on a YZF) without showing through the coolant or oil. If the problem is away from the coolant and/or oil passages, the two won't transfer.


I could try and help you out Thursday afternoon at Berthoud, or on the weekend. Let me know.

[This message has been edited by mikeolichney (edited 08-20-2001).]

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