Compression Help!

SurfCrazed

SurfCrazed

Location
Southern Virginia
i just tryed to measure the squinch with some solder and it looked to me like the solder wasnt getting mashed at all or maybe i did it wrong.. i put the solder against the cyl wall then brought the piston TDC and got nothing.. tryed this about 15 times with no results!! :banghead: :banghead: is there another way to measure this?
 
SurfCrazed

SurfCrazed

Location
Southern Virginia
ill be going by autozone to buy a new one tomorrow if they are open. Also i took the motor to work to have guys at the shop take a look at it.. and ended up firing it off! started after couple cranks!!! but had to stop due to a leaking carb. Checked the pressure again and was still at 90 psi!:banghead: :banghead: find out tomorrow if its the guage
 
Speedfreak

Speedfreak

Location
So. IL
How thick is the solder. If you bent it in a "J" and put it through the spark plug hole up aginst the cylinder wall and it wasn't smashed at all then that would be why you have no compression. or rather LOW. You either need to figure out if that head has been cut on or what it is but there should be some mash. I have a 550 here that the customer was complaining that he had low compression it is about 105 with an aftermarket head and his squish is about .150 so he needs to have the head recut with his current motor setup. that would be the cheapest if running it without a headgasket doesn't work. (have heard that it works on 550's)
 
SurfCrazed

SurfCrazed

Location
Southern Virginia
The solder I bought is .062". The head is stock never been touched along with the deck of the cylinder! the metal rings around the domes on the gasket are about .050" thick and ring end gap is .016" I forgot to measure how far the piston comes to the top of the cylinder!
 
Speedfreak

Speedfreak

Location
So. IL
I think my solder is 1/8 of an inch so that might be why your solder didn't squash. That all sounds right. I would just send that head off to have it recut and tell them what you have then they will cut that thing to make 180 psi.. that would be a great bottom end improvement also.
 
SUPERTUNE

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
Speedfreak said:
How thick is the solder. If you bent it in a "J" and put it through the spark plug hole up aginst the cylinder wall and it wasn't smashed at all then that would be why you have no compression. or rather LOW. You either need to figure out if that head has been cut on or what it is but there should be some mash. I have a 550 here that the customer was complaining that he had low compression it is about 105 with an aftermarket head and his squish is about .150 so he needs to have the head recut with his current motor setup. that would be the cheapest if running it without a headgasket doesn't work. (have heard that it works on 550's)
Click to expand...

What!
You can never run a watercooled 2 stroke without a head gasket for any relibility! Maybe with the best sealer you can buy and just for 1 speed run (3 mins) for testing, MAYBE!
Glad to hear that you FINALLY got a gage to measure correct compression! Now watch your water pissers that they don't spit and steam after many hours of use with aftermarket headgasket as their not as good as the OEM Yamaha one.
 
SkiDaddy

SkiDaddy

Just Havin' Fun!
Location
Orange City, FL
I don't think it would work on a twin (too much surface area), but the old air cooled Husqvarna dirt bikes came from the factory w/NO head gasket - the heads were lapped to the cylinders. Of course, they needed to be re-lapped every now & then....:rolleyes:
 
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