Hi. I'm trying to find the stock squish on the above bike. I have a book for the 2010 Evo book but that gives a measurement for the top of the piston to the cylinder. This doesn't seem right for my bike as it would give my 4.5mm squish. Thanks for any help.

Probably lost in translation. Huge difference to the top of the head vs the cylinder.

Standard factory recommendations seem to be 1 to 1.5mm

This might be a dumb question but why bother? Are you trying to change engine characteristics? Is this a complete rebuild?

22 hours ago, dan williams said:

This might be a dumb question but why bother? Are you trying to change engine characteristics? Is this a complete rebuild?

you would bother if you want the best engine performance, 

I didn't think it was important until I set the clearance correctly on a 175 Yamaha , and found a noticeable improvement in power , plus it stopped pinging ( which had been a problem previously }

Pinging is just jetting and/or fuel issues. All the rev 3`s ran great with a little attention. Squish was not an issue unless at high elevation. 

On 10/21/2019 at 5:38 PM, dan williams said:

This might be a dumb question but why bother? Are you trying to change engine characteristics? Is this a complete rebuild?

He has measured his squish at 4.5mm. He should definitely bother

Thanks guys. I gave up on the top of piston to top of cylinder measurement. A face book user thinks that measurement was for a flat piston while mine is dome shaped. 

Once I stopped trying to change gaskets, to chase that measurement. I installed everything stock and measured squish at 1.8mm. As I'd just spent the night researching squish. This seems like a safe distance to start with. Most of the research I did, stated that Between 1 at 2mm would be your tuning zone.

Under 1 would be dangerous as my piston expand up 0.7mm when hot.

It's a shame beta don't have a book measurement to remove any confusion.

 

This was a new bike to me that blew after 4 hours, following a full rebuild by the previous owner. 

I'm just trying to make sure everything is back to stock so this doesn't happen again

3 hours ago, Crazymac680 said:

Thanks guys. I gave up on the top of piston to top of cylinder measurement. A face book user thinks that measurement was for a flat piston while mine is dome shaped. 

Once I stopped trying to change gaskets, to chase that measurement. I installed everything stock and measured squish at 1.8mm. As I'd just spent the night researching squish. This seems like a safe distance to start with. Most of the research I did, stated that Between 1 at 2mm would be your tuning zone.

Under 1 would be dangerous as my piston expand up 0.7mm when hot.

It's a shame beta don't have a book measurement to remove any confusion.

 

Beta don't even have a book measurement for ignition timing, so are unlikely to see squish as an important piece of information.

Edited October 24, 20196 yr by 2stroke4stroke

 From the sounds of it, I would be more concerned about the water pump and fan. Was it a full rebuild with mains, seals, and rod?

The water pump had loads of in and out play. Impeller was very worn. I replaced the bearing, seal, impeller and gasket. The in and out play is gone now.

Thanks