CR Gaskets

[Iliketogofast]

What year CR Head gasket do I use to get more compression?

[BKex]

1989 cr250, ive got one on my R

[Tom TRX250R]

Another option instead of the CR gasket is to use the stock TRX gasket and split it into the three pieces. You can use each of the outer pieces. It is the same thickness as the CR gasket and you get two for the price of one.

[Iliketogofast]

So I can take mine apart and split it right now? I also need to know if I can still run Premium pump.

[Tom TRX250R]

Yeah the way you seperate them is to take a drill a bit smaller than the rivets and just be REALLY careful not damage the gasket. Drill out the rivet then you will have two gaskets. I don't know what octane gas you'll have to run depending on how high your compression is. After doing the gasket mod, put a compression tester on it and test the compression. That will tell you where you need to go if you have to run race gas or premium.

[Antony250R]

You are better off to use a stock 250r head
gasket and get the head milled down. I ran a cr gasket and it leaked coolant.

[hondardr4life]

How much of a difference in compression does it really make? My head is shaved for more compression, and I mean it has a ton shaved off of it. But I am running a stock head gasket. I don't think that Hetricks would have sent me a stock oen if thats not what I should use, but still, it makes me wonder.

[matt250r21]

When I used a CR250 head gasket I had to spray it with Copper coat to get the gasket to seal. You can find it at an auto parts store. Its like gasket in a spray can, kinda cool, but o-ring head gaskets are way cooler.

[Iliketogofast]

I was going to have the head milled when I sent it in to bore it but I decided against. How much did it cost?

[Tom TRX250R]

Milling the head is a better option IMO, my buddy has his stock head milled by Dave Moore for $40. I believe he had it milled 40 thousandths.

[Iliketogofast]

Okay, I got the gasket out and there aren't any rivets on it. There is a cardboard type piece on top of a piece that I think is made of really flimsy metal. Around the inside diameter of the gasket there is a metal ring. It doesn't look to me like it can be split.

Is this a CR gasket? Since the guy who bored my topend put it back together for me, I'm thinking maybe he put one in?

[CHAR250R]

1985 ATC250R head gasket. Duncan Racing recommends it, and I've been using it for years. ;)

[Tom TRX250R]

The ATC 250R gasket is in between thickness of the CR and TRX250R. With CR being the thinnest, then ATC, then TRX the thickest. Your best bet would be to go with the stock TRX gasket split. For the TRX gasket its not really rivets as it is little rings that hold the three pieces together. I know it doesn't look like it will split apart but use a drill a hair smaller than the outer diameter of the metal ring. Once you start drilling it they litterally just fall off. Use one of the outer pieces and save the other outer gasket for a spare. If your not sure if your gasket is a stock TRX gasket its not a bad idea to start with a new one.

[Iliketogofast]

There are no metal rings. The only part that I am absolutely positive is metal is the inside diameter of the gasket, which is a metal ring type thing.

This metal ring is the same size as the sleeve, it borders the sleeve. I'm pretty sure it would have to be taken off for this to work... I don't think it's a stock gasket(It is probably aftermarket designed for the 250R). I don't have pics.

I think I'm going to have the head milled a little (About .010) and use an '85 ATC gasket.

[Iliketogofast]

Here is exactly what it looks like. It looks to me that the ring in the center will hold everything together when I try to split it. Am I trying to get this ring off?

[novaracr70]

looks like a cometic cant split that

[Iliketogofast]

That's what I thought. So, should I order an ATC gasket or order a TRX one and split it? Is the TRX mod one likely to lead or blow?

[novaracr70]

well you could do either gasket and get the same. If you order the trx you have 2 gaskets the top and bottom. I personally run the cometic just have my head chamberd. I kick over at 210 . but it took a lot of work to do my head right . My brother runs the trx split he went from 180psi cometic to all most 205psi

[Iliketogofast]

Is the base gasket thinner as well? I am seeing that it would be almost as cheap to buy an entire topend gasket set for an ATC than it would to buy just the head gasket for a TRX.

[Tom TRX250R]

That isn't a stock TRX gasket. You would be the best off if you would send your stock head in to be milled 40 thousandths over and then just use the stock TRX gasket. That will bump up your compression considerably. Or if your wanting to go the cheap route you could simply use the TRX gasket split, one of the outer pieces and spray the copper gasket sealer on it to ensure it doesn't leak.

[Iliketogofast]

Is the milling safe on the piston? How do I know it isn't going to have clearance issues?

[SuperChris]

Here is the best way for you to build cheap horsepower. Put a piece of 65 thousandths thick solder on top of your piston in the same direction as the wristpin (with the head off), tape it down or it may fall in the transfers and require a complete teardown. Put the head back on with one side of a modified TRX gasket and slowly turn the motor over past TDC. This will squish the solder so it's gonna be a little hard to turn over. Take it apart and measure on the outer edge of both sides of the solder with a set of good calipers, if you don't have a set, take it to a machine shop and they'll tell you what it measures. Average out the squish(thickness of the solder) by adding the two values and dividing them my 2. If they are more than 35, you can run that motor. If they are less, cut the head to fit. Ideal squish is 35 thousandths and the best way to get that is to take your cylinder off, remove the studs and have it decked however much you need to get 35 thou.