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What causes an ENGINE TO HAVE HIGH COMPRESSION?

35K views 12 replies 10 participants last post by  Vinish 
#1 ·
Anyone know what can cause higher than normal engine compression?
 
#4 ·
I've never heard of it but extreme carbon build up could make the combustion chamber smaller, I suppose... Usually a cylinder will loose compression from this due to leaky valves/rings.
 
#6 ·
+1 try another gauge to rule out defective tool.

I'd check first with a second gauge, it should never be double. Higher compression readings are caused by carbon deposits that are stuck to the top of the pistons.
 
#7 ·
Let's see...Double compression would be somewhere in the area of 18:1 (just a guess as I don't know what the actual CR is for an 1800)...That would be too high for premium pump gas (limits there are about 14:1 max), and you would have so much detonation going on that you would've already burned holes in both pistons...I'd be checking to make sure that gage is accurate...:hmm2:
 
#8 ·
i think the manual specified 95psi per cylinder, but i have heard of people with up to 120 psi per cylinder. The only explanation for this problem,
carbon buildup in the combustion area. Maybe try some Lucas fuel additive to clean the injectors and carbon buildup. Good luck! O~by the way, What were your compression readings!!!!
 
#11 ·
Well, I hate having to drag information out of someone that is asking for help... Now, what is "double" We have no way of knowing what double means unless we know what the low number is. If one cylinder is 4 then double that is 8 and both of those would SUCK. So, give us the front and rear readings and maybe we can answer the question. But, just for the sake of an answer, a exhaust valve could be stuck and raising the compression or like one mentioned, carbom build-up. A worn cam would also give you a higher reading. But if neither cylinder is at spec (remember, you gave us no numbers) it could be worn rings and compression is leaking. Bottom line is we need more info.
 
#13 ·
rarpen,

Welcome to the VTX Cafe. It is a good idea to look at the age of threads to which you respond. Prior to your post, the last time this thread was active was 2011. Posting in such an old thread does not violate any rules. However, it is likely a waste of your time as the original poster has probably figured things out by now.
 
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