Squish on my motor- Need Advice

[nightrider05]

I have read through a bunch of the threads and know on stock motors to run around .040 for squish. However I have also read that it can vary depending on your motor setup.

So basically im looking for some good info on what to run on my current motor setup.

701 62t/61x..Riva ported cylinders, Blowsion style head. Compression is currently reading 200 but may be a bit exaggerated since I used some oil when assembling the motor.

Current squish is at roughly .032-.035

Is that runable or do I need to install a thicker base gasket?

Also on base gaskets...is it ok to double up to get the correct thickness..or do you need to order just one gasket the correct thickness? When I got this ski, it has two base gaskets installed.

 

[jetski9010]

I am not an expert but that squish seems too close. Are you going to be running race gas? Your going to want your squish more around .045-.050

 

[nightrider05]

I am not an expert but that squish seems too close. Are you going to be running race gas? Your going to want your squish more around .045-.050

If the compression stays up around 200 or even any where close for that matter I will have no option but to run race gas.

I guess if I just ordered a thicker base gasket that would take care of most of my problems. That would lower compression, and get my squish in line. I have a metal base gasket that I believe is around .020"

If I installed that though my squish would be around .050...Guess I may have to go ahead and tear the thing back down. However I still don't know if doubling up base gaskets is a safe thing to do or not.

 

[Mark44]

I would order a thicker base gasket and run .045 with one gasket. Who ported the motor, remember you are changing port timing so check with the builder. I don't believe you would have any issues out of running two gaskets other than one being real thin.

Mark44

 

[nightrider05]

I would order a thicker base gasket and run .045 with one gasket. Who ported the motor, remember you are changing port timing so check with the builder. I don't believe you would have any issues out of running two gaskets other than one being real thin.

Mark44

It has Riva etched in the side..however when I gave the numbers to Riva they didn't recognize them..So as of right now..I simply have no clue.

I didn't personally have the work done..it was already like this when I got it.

This other base gasket I have is pretty thick...Im hoping its not too thick because then the squish will be excessive and I will have to screw around with it all again.

 

[#ZERO]

Run it.... you'll be fine with that squish on a smaller displacement engine using 93 octane or higher pump gas.

Just double check your cylinder height and see if it's close to 119mm tall; if its any shorter I'd machine the domes or use a thicker base gasket.

 

[nightrider05]

Run it.... you'll be fine with that squish on a smaller displacement engine using 93 octane or higher pump gas.

Just double check your cylinder height and see if it's close to 119mm tall; if its any shorter I'd machine the domes or use a thicker base gasket.

Too late. Pulled it apart.

So the gasket I put in from Jetmaniac looks to be about .015" thickness..of course it has already been squished down once so im assuming it was probably .02 before being squished.

The other gasket I have is roughly .035-.04"

I was reading the gauge wrong earlier...the squish is actually .020" currently.

So im thinking I will just put the thick gasket in with it and be done with it all. That is how it was setup before and they said it ripped. Im thinking it will put my squish around .055" roughly by the time that gasket is smashed down. Its above the sought after .045, but better than the tight squish(I guess?)..This will also lower my compression back down

 

[Waternut]

Honestly... If the other base gasket is that thick, I'd just run that one only. I'm sure it will compress down but even then you'd be looking at around 0.040"-0.050" of total squish. I'll say it again, I'm no engine builder but that would just make sense to me.

 

[SUPERJET-113]

So the gasket I put in from Jetmaniac looks to be about .015" thickness..of course it has already been squished down once so im assuming it was probably .02 before being squished.

Chris(Jetmaniac) and I get our gaskets from the same source. The Yam regular base gasket we get is .024" - .025".

 

[nightrider05]

Chris(Jetmaniac) and I get our gaskets from the same source. The Yam regular base gasket we get is .024" - .025".

Interesting.

I am using a cheapazz dial caliper so there is a good chance my readings are off.

I put both gaskets back in for now. Going to see where that puts my squish and then use these numbers to figure up which correct base gasket I need.

However, at this point if it is close and runs good..im leaving it the way it is for a while.

 

[750SX]

It has Riva etched in the side..however when I gave the numbers to Riva they didn't recognize them..So as of right now..I simply have no clue.

I didn't personally have the work done..it was already like this when I got it.

This other base gasket I have is pretty thick...Im hoping its not too thick because then the squish will be excessive and I will have to screw around with it all again.

I too have a mystery Riva 61x cylinder. Supposedly my numbers don't match any of theirs. The bore is at 82.5mm and I am running 35cc ada domes. My squish is at .033. If your cylinder is anything like mine you are going to really like it! I'd say keep that squish and get some larger cc domes to lower your compression. My compression is 175-180 with the 35's.

Good luck!

 

[nightrider05]

I too have a mystery Riva 61x cylinder. Supposedly my numbers don't match any of theirs. The bore is at 82.5mm and I am running 35cc ada domes. My squish is at .033. If your cylinder is anything like mine you are going to really like it! I'd say keep that squish and get some larger cc domes to lower your compression. My compression is 175-180 with the 35's.

Good luck!

That is really good to hear.

I found out my head has 31cc domes in it...so on a non ported motor it would be pushing around 215psi.

I am going to order 35cc domes and then redo all the squish. Probably going to just start out with the oem base gasket and I believe that should put me in the right area on squish.

One thing is for sure...I can replace a top end in no time at all now if needed. I have had my cylinders off and on 2 times already now in the past day.