Super Jet Lowering compression

[Little Trumps Super Jet]

I talk to the guy i bought it from. He said it has Pro X pistons 1.50 over stock bore. He said he didnt think the domes were reshaped and they looked factory. And that it would be ok to put on another head or a mod head as long as its not super milled. He said it didnt have much decking either just a little bit.

 

[Nuklear6]

Going to be very hard to determine how much was decked off with out removing the cylinder and measuring the total height. I would just put either of the stock heads on with a new stock gasket and check the squish. There is a good description of how to check squish earlier in the tread, they did however leave out one VERY important part. You must have the solder perfectly over top of and parallel to the wrist pin. If you do not check it in this way you will get incorrect measurements. The piston will rock and give you a lesser measurement then true. Any .001 increment caliper will work fine. (just dont forget to "0" it first)


ps: dont forget to torque head before checking squish clearance

 

[DEXTER]

I think one of the worst things of the internet is that the attaining of knowledge is not respected. Too many times I see things on forums like this where something is believed to be so simple that by just asking questions and getting answers that the issue is that simple. Squish is not that simple at least to those who have an idea of it. I think the issue should be taken to a performance shop and pay for an experts opinion. Let them measure it and take responsibility, ie; $$$$. If your wrong on setting up the squish on the engine what could happen? Be smart, let a pro do it. I don’t mean sound harsh, but be smart, pay a little now vs. a lot latter

 

[ajmps1]

out of curiosity so that you dont look like a troll, post pictures. everyone on a forum, myself included, are best compared to as 5th graders at best. we can read but thats lame. i will bet money that the majority of the people who actually clicked on the thread only skimmed your post, scoffed, scrolled for pics, scoffed again and left

 

[kevbo]

I talk to the guy i bought it from. He said it has Pro X pistons 1.50 over stock bore. He said he didnt think the domes were reshaped and they looked factory. And that it would be ok to put on another head or a mod head as long as its not super milled. He said it didnt have much decking either just a little bit.

Bolt on a stock head and see what you have. Lower compression will soften throttle response so low pitched impellers/bored nozzles are necessary.

 

[Little Trumps Super Jet]

I just got home to do all this. Problem. The guy called and told me he's unsure if it's a 701 head he gave me, I'm looking at and can't see any engravings or markings, how do you tell?

Il try and Post more pics next time, my phone doesn't really let me.

 

[SN760]

I would check it with the head that is on there first. It only takes a couple minutes to do.
You should be able to spin the engine over by rotating the coupler off PTO side of the engine. There is a plastic guard that covers the midshaft and engine couplers that you will have to remove.

Definitely check the squish band with the head that came on the ski and keep this number for your records. As stated above - Do Not - throw another head on and assume that you have enough clearance - good way to destroy your motor real quick.
If you don't want to mess with this then double up on your head gaskets ( as mentioned above) using the head that came on the motor - check your compression and go ride. It's possible it may drop your compression a bit lower than ideal but this is a quick and easy fix that you can do without the need to check piston to head clearance.