Finally got around to running a squish band test on the 02 ZR 800 EFI. Motor cold, all 4 points come out to 0.080. Been thinking about whacking that down a bit.

Also ran a compression test. Cold and dry it was 122 mag, 122 pto. Added a bit of oil and it was 130 mag, 124 pto. I sort of expected this as I had to replace a piston and rings on the pto side early last season. Might replace both this season just for consistancly and assurity.

Looking to open up dialogue on the results.

Why are you checking compression cold?? Is the motor not in running condition?

That's what I could do with the time I had. I have done a lot of reading on testing compression and some reputable people have used the cold method the way I did. Tested cold and dry, then add about 1oz of oil to the cylinders, give it a couple pulls and test cold again. When I have time to pull the sled out of the garage and warm it up I will test warm.

I've always used cold compression testing when I do compression tests. Most of what I've read says that is perfectly fine, and even preferred, for checking cranking compression. I believe you also get a slightly higher reading on the cold test than on a hot test, but either method should be perfectly fine as you are really checking relativity, not absolute readings.

ZRrrr, have you been able to find reliable info on optimum and minimum safe squish for the 800 engine? I expect you can cut the head slightly and still run regular fuel, a little more and be safe on premium, but what do you want and how do you want to use the sled? When I was doing my porting I spoke to John at Race Logic about head cutting. He told me that it would only enhance the impact of he porting and make the engine perform even better. The primary difficulty I think you will have is EFI and getting more fuel, if you need it.

Hey 94 great to see you here. Nice work on the car...looks like a fun project.

Yeah, I found the spec for the 02 800. Cats minimum squish for the 02 800 is 0.062. I have measured several times over and always come up at about 0.0785. Can easily take off 0.010 if not a bit more. I'm already running 91 octane due to the pipe so not worried about that. Good thing it's not my daily sled. I'll keep the Crossfire running 87 for everyday trail riding. I could probably get away with running 87 in the ZR being we are at 2000 feet and usually ride between 2000 and 5000.

ZR runs rich right from the get go. I have been running an Injector Perfector for a couple seasons now so still have room to "jet up" if need be. Wash and plugs have always been good. Last year I tried running it leaner, just for kicks, with wash and plugs still reading fine, but found it did not perform as well as it had being just ever so slightly richer. So I have the fuel setup fine with lots of room to add if need be.

Going to put it on the dyno this fall when air temps cool down.

In case you are interested, the 1993-2001 580 motor has a squish spec of between 0.057 - 0.079. That's a huge spread!!

That is a huge spread! Hugh, on A-Chat told me that they used to cut their 580 heads to .072 and that would really wake them up and run fine on regular fuel. I like the idea of staying with 87 and I like how the sled runs with that Race Logic porting, so one of these days I'll have to measure the squish and see where I'm at. The thing that makes this so attractive is I know I'll get better fuel consumption as well as more power. What's not to like?

When my car gets done you may see it around Edmonton this fall if I get there to visit my brother and other relatives.

If your coming to Edmonton let me know. Would like to see the car and shoot the chit.