Looks like this sled has had a "Poor Man's" porting job...thin the head gasket + raise the cylinders slightly. With todays fuel + as a safety net I think I would put the 152.5 mains in.
Bob
Bob
sleddineinar
VIP Member
sideshowBob said:
2x what he said.
me three with todays poor fuel and agree with the statements above about poor mans port job. A real mans port job will yield tons of more results....
will it be alright if i just put new gaskets on or do you think i need to thin them out?
You can put it back together as the factory had originally did, BUT, it would not hurt to check the cylinder head squish distance before you install the new headgaskets, as tbis could save you a headache after your "rebuild". Use your old peeled headgaskets(I know they're missing a layer) and use a piece of solder as stated above then measure the thickness and your new head gasket will gain you the thickness that was removed.
Example if your reading is .035 with the old headgaskets then the new gasket should yield you somewhere in the .045.050" range.(Or whatever the thickness of the gasket that was removed). If the distance is a little bigger than that you are just that much safer.
Example if your reading is .035 with the old headgaskets then the new gasket should yield you somewhere in the .045.050" range.(Or whatever the thickness of the gasket that was removed). If the distance is a little bigger than that you are just that much safer.
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I did measure the thickness of the old gaskets, the head and cylinder gaskets were peeled, and they measured .6 mm and the exhaust gasket was 1.0 mm. If they are the same thickness then ill be adding about .8 mm overall to the cylinders. I bought a wiseco top end kit, so I'm assuming their gaskets measure out the same but ill measure them when I get it. Got any advice got when I put the cylinders and new pistons in ? I'm not too sure about how much ring end gap I should have, or play between piston and cylinder as these are forged pistons and rings
So if you had 2 sets of base gaskets on @ .6mm each then the space between the case and jug was technically 1.2mm and if you remove .6mm you are back to .6mm gap(so to speak). and this would make your jug and head gap .6 mm tighter.
*** Ok - I have a set of BRAND NEW Yamaha head gaskets at my computer desk and I measure them at .030' or about .75mm thick measured at the rivet that holds the layers together.
So it appears that the thought may have been to remove a layer of head gasket to make up for the space gained by adding a second base gasket... So you may be okay, and the previous owner may not have had the cylinderheads decked or material removed. BUT, it would still be wise to check the squish distance, as to tight of a squish band will cause detonation, and this will wreck or blow a motor and wreak havoc on all of the engine internals.
Wiseco should be able to answer the ring end gap questions and also the cylinder to piston gap. All I know is that when I used to run modified jet skis it was a fairily loose gap to accomodate piston swell. Also when you put your motor together dont for get to lubricate the pistons and cylinder walls with 2 cycle oil so that you dont assemble a dry motor.
*** Ok - I have a set of BRAND NEW Yamaha head gaskets at my computer desk and I measure them at .030' or about .75mm thick measured at the rivet that holds the layers together.
So it appears that the thought may have been to remove a layer of head gasket to make up for the space gained by adding a second base gasket... So you may be okay, and the previous owner may not have had the cylinderheads decked or material removed. BUT, it would still be wise to check the squish distance, as to tight of a squish band will cause detonation, and this will wreck or blow a motor and wreak havoc on all of the engine internals.
Wiseco should be able to answer the ring end gap questions and also the cylinder to piston gap. All I know is that when I used to run modified jet skis it was a fairily loose gap to accomodate piston swell. Also when you put your motor together dont for get to lubricate the pistons and cylinder walls with 2 cycle oil so that you dont assemble a dry motor.
I meant to correct myself on the double base gasket too. I didn't realize that they had more than 1 layer riveted together as stock, so it looks like its a stock gasket with just the middle metal layer removed as to increase the compression I think. The jets were only 147.5 so I'm thinking previous owner took out the metal layer from top and base to increase compression to accommodate the smaller jets. Do I do the squish test with the new pistons? Do I have to torque the nuts down and everything first? The way I see it is that the new gasket will be the stock thickness therefore elongating the cylinder
As a rule of thumb the smaller the compression area or higher compression ratio, the jetting will need to be bumped to a larger size as when you compress the gasses being burned into a smaller area and when ignited they generate more heat and this can overheat the piston tops causing internal engine damage. I have no Idea why the previous owner removed material from the base gasket, UNLESS it was similar to what you state, to help raise the compression ratio to gain performance. Still needs to be jetted bigger though.Plucan said:
Yes do the squish check with the new pistons as they are going to be the ones that you are going to use.
Ok so the jetting was most likely wrong from the beginning which led to over heating. The gaskets were in pretty rough shape too though. But I will do that squish test. What size solder should I use ? I'm going to be putting in 152.5 from bobs advice previously. Does anyone know what kinds performance ill be looking at having wiseco piston and rings and bender triples?
if you can find .060" solder that should work.
No real gains using Wisecos.... You will probably notice a gain being properly tuned and jetted and that will make all the difference in the world.
No real gains using Wisecos.... You will probably notice a gain being properly tuned and jetted and that will make all the difference in the world.
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