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What should the compression be on a stock 98 mach z?

mine is 125-90 -125

Looks like i have issues
 

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skinny said:
What should the compression be on a stock 98 mach z?

mine is 125-90 -125

Looks like i have issues
[snapback]298269[/snapback]​
125 is way to low and 90 is out of the question.
145-150 is normal.
Make sure you have a GOOD gauge with NO rubber hose.
 

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When checking your compression your biggest concern is the deviation between the cylinders. I am not sure what the maximum deviation should be, but I would guess around 5%. 155 psi seems a little high to me for trail riding on pump gas, one bad tank on the trail somewhere and you could lean it out and blow it up. If I had to guess I would say anywhere between 120 & 150 psi is acceptable for 91 octane fuel. With that said; you will definetly feel a difference on the lake between 120 and 150 psi.
 

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qshag said:
When checking your compression your biggest concern is the deviation between the cylinders. I am not sure what the maximum deviation should be, but I would guess around 5%. 155 psi seems a little high to me for trail riding on pump gas, one bad tank on the trail somewhere and you could lean it out and blow it up. If I had to guess I would say anywhere between 120 & 150 psi is acceptable for 91 octane fuel. With that said; you will definetly feel a difference on the lake between 120 and 150 psi.
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mine was reading 120 before and 155 after my friends z also has 150-155 on a different gauge i run super if you know how to check your plugs and jet your carbs the chances of leaning out and blowing your engine are slim unless something else goes wrong right now i have a 99 f3 800 crank shop pipes crank shop lake race clutch kit lifted base and cut head with 320 jets and its running great
 

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jamesfIII800 said:
qshag said:
right now i have a 99 f3 800 crank shop pipes crank shop lake race clutch kit lifted base and cut head with 320 jets and its running great
[snapback]303739[/snapback]​
That sounds like very small main jets to me, for that setup.

I run 360 mains, and there only safe to around 5*F.
 

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mtrsprt said:
jamesfIII800 said:
qshag said:
right now i have a 99 f3 800 crank shop pipes crank shop lake race clutch kit lifted base and cut head with 320 jets and its running great
[snapback]303739[/snapback]​
That sounds like very small main jets to me, for that setup.

I run 360 mains, and there only safe to around 5*F.
[snapback]304838[/snapback]​
i know they are small my friend has 350s in his with the same setup but 320s are doing good for me not too lean not too rich thats something i cant figure out
 

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I personnally would install a pyrometer if I wanted to run 155 psi warm on pump gas. You can monitor your exhaust gas temp and jet it accordingly. You will also know pretty quick if you have some bad fuel because your exhaust gas temp will rise. After all, the sled season is way too short to be waiting for parts.
 

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machzilla98 said:
i have a 1998 mach z i cant seem to keep pistong in. why i do not know? could it be eletrical or carbs? get back to me
[snapback]339370[/snapback]​
98 s had a problem with the harness under your motor they short out and you will have no tach or lights but i never seen pistons go because of it is it stock?
 

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it is all stock. the middel piston whent on it this time last time it was the meg. all stok but gearing. do u know where i can get a jug for it sh&%ty or a good one?
 

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machzilla98 said:
i have a 1998 mach z i cant seem to keep pistong in. why i do not know? could it be eletrical or carbs? get back to me
[snapback]339370[/snapback]​
I had a 98 Z also and the first 3 years I put 6 stator plates 2 modules and a motor at 1250miles due to a stator going bad. Check the ohms of your stator make sure the coils are ohm'n good. for starters. The harness under the motor is a factory recall. The update should be done by the dealer for no charge!!!
 

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skinny said:
how can you find out if recalls were completed on a sled???
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Dealers keep a record of completed updates, i am sure you can call any dealer,give them the serial number.They keep records so as to stop you from getting multiple free updates.
 
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