Author Topic: head gasket ? (Read 2876 times)

dirtyd · « **on:** November 21, 2014, 07:02:20 PM »

I'm going to ask here since there are so many knowledgeable people here and cant get a reply on the Tecate site (theres like 4 people on there). I'm going over a motor I have that is a standard bore (67.4mm). I have a new head gasket that is for a big bore (73mm). When I took off the head I noticed that it had the same 73mm gasket on it already. Is it ok to run a motor like this where the ID of the gasket is sitting back a couple mm from the actual bore?

MANIAK · « **Reply #1 on:** November 21, 2014, 07:46:34 PM »

From your measurements, it is more than a couple of millimeters. It is actually 5.6 mm. That is a substantial amount. I can think of a couple things here. One is that you are losing compression because you are increasing the size of the combustion chamber. The other is that you are decreasing the sealing surface of the gasket which can lead to premature failure.

Are you having trouble finding the correct gasket? If you can't find a gasket for a Tecate, look one up for a KX250 of the same vintage. I believe that Kawasaki used the same engine in the trike and quad as they did in the bike. I've owned all three of the above mentioned toys and had a three apart but it was soo long ago that I don't remember what I used for head gaskets. If my memory serves me right I think I used a gasket from a YZ that was thinner in order to bump up the compression.

You'd be surprised at how many of the different manufacturer's gasket bolt patterns are the same.

If you have a motorcycle junk yard near by, I would consult someone there or find an old school motorcycle shop.

dirtyd · « **Reply #2 on:** November 21, 2014, 07:59:12 PM »

I'm just being cheap. I was going to part this quad but decided to get it rideable. The motor was rebuilt before i got it and by looking at the piston it was. I only pulled it apart because i found all kinds of crud in the cooling system. Looks like Bars leak was used in it. I had to dig out all kinds of crap from the water jackets. Anyways figured since i had a new gasket and one like it was used.

Yes its 5.6 overall but its 2.8 as you go around

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MANIAK · « **Reply #3 on:** November 21, 2014, 08:17:03 PM »

How was the compression? If it still had decent compression, you might be OK.

The bars leak worries me a little. It is possible that there wasn't enough sealing surface and it was building compression in the cooling system they may have used a crap ton of bars leak to stop the leak.

dirtyd · « **Reply #4 on:** November 21, 2014, 09:03:50 PM »

Had great compression. The radiator was trashed and had holes in it, so thinking that was why the bars leak.

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Pro-Fab · « **Reply #5 on:** November 24, 2014, 01:30:24 AM »

Any detonation will chinger up the outer edges of the compression chamber really easily. Also it can creat more heat with the friction area created by the crevice between the head and cylinder. I would buy a new OEM head gasket.