compression.

(RIP) pastyman

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Got given a compression tester for my birthday recently and put it to the test the other day . Ive been trying to get my 100 to run smoothly for a while and having done the full carb refurb, including new cables it was still a bit "off". I thested the compressions and found the right hand side was a bit down so checked the valve clearances again and found the inlet a bit tight. all now sorted with the same compression on both sides. My question now is , what should the readings be, any ideas.
 
They vary depending how many miles and how well the engine is looked after.
But so long as they're not too low, and they're both about the same don't worry about it.
 
Don't forget, it isn't a big job to change the piston rings..the bores are nicosil lined and don't wear. Good time to check the heads when doing this as well...but as Sir Steptoe says, if they are similar and she isn't blowing blue smoke, don't worry :)
 
Thanks for all of that.. I've got off me bum and had a good look in Haines. They give ,over 131psi is good . Between 109 and 131 is normal and below 109 is poor.
Checked mine again, plugs out and throttle opened wide and I got over 140 so I recon thats in the "bloody good " bracket:thumb2
 


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