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Discussion Starter #1
Can anybody tell me what kind of cranking psi a 97 formula III should have.My brother bought this one new and its been a dog its whole life.We are only getting a reading in the mid 90 lb range which seems low to me but its the first triple we have had any experience with.
 

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A cold engine should give a 135 to 145 psi. a hot engine 125-135psi.
If you are trying to diagnois a engine problem or just checking engine condition a clyinder leal down test is the best way by far.
At least double check your readings with another comp. tester.
 

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Discussion Starter #3
All of our twins 3 670s,3 583s and 1 500 all are in the 135-150 range only the triple is so low.Unfortunately we didn't check it when it was new to use as a reference.My brother had the top end redone and it promptly blew the crank bearings the first weekend out.He said it was working better than ever but they also did a little clutching work as well.He took it back and had a new crank put in and after it was all back together we thought we should check the compression.It was barely any higher than it was before.Still under a 100lbs.This thing has nikasil cylinders so they just replaced the pistons and I'm wondering if the cylinders are worn out of spec.
 

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Find another gauge! If you really are running 90's you got a big problem!
You should be @ 145-150 cold and 125-130 hot. I have had 583-670-700 triple and 800 triple and they all have read in this range.
 

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Ditto, if it runs good suspect the guage, I have two guages, they read 15lbs apart....90 lbs though, is that in all cylinders? it almost has to be the guage.
 

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Discussion Starter #6
Checked all of the above mentioned sleds with the same gauge.Also double checked the F-III with two gauges.One read high 90s the other read low 90s.Why would the compression read higher on a cold engine? I thought they had to be warmed up to get everything expanded and a good piston seal.
 

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Pour 1/2 ounce of oil down one cylinder and check it again. If its way up, then you definitely have a problem. Oil will seal things up for a few cranks, and you will see the comp go up dramatically if thats your problem.

On my 700 tripple, I'm about 130 across all three cylinders with my gauge. Cold, it drops into the 120 area when hot.

FishHog
 
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