84' 250r HIGH compression

[Matrix]

I looked throughout my manual and know that my compression is much higher than it should be. About 190psi and it should be 142-165psi with a service limit of 128psi. As far as I know my cylinder is stock. I know that if everything is stock then I definitely have carbon build up. I know it is also running rich, fouling plugs once a month I would say. I run HP2 with 93 octane and have stock jetting I think with a DG expansion chamber and UNI filter. Should I take my ATC to the Honda shop and get it cleaned up, or, run something like sea foam through it, wait before you flip because I have heard that maybe I shouldn't but I have heard as many people say its okay. Just a couple days ago I had the infamous "Death Rev" and it scared the :Trailpro: :Trailpro: :Trailpro: :Trailpro: out of me. I later found out that it just ran out of gas (it happens) and in the midst of all this I had so many thoughts of getting it rebuilt etc...

So, what should I do about my high compression.

[fabiodriven]

There is absolutely no way you would have enough carbon buildup to cause that much of a spike in compression. Somebody's been inside of that motor and possibly miffed something.

[falloutboy]

Just be aware of any pinging/pre-detonation. You may need to run a 50/50 blend of pump/race gas to bring up your octane rating...

[82 250r]

Try another gauge. Go to autozone and rent a free compression tester and test it again to be sure.
It's hard to believe a 28 year old cylinder is giving that much compression.

Pull your choke and WOT when testing :)

[Matrix]

Try another gauge. Go to autozone and rent a free compression tester and test it again to be sure.
It's hard to believe a 28 year old cylinder is giving that much compression.

Pull your choke and WOT when testing :)

Oh, I didn't pull the choke on it. I'll give that a shot. And I'll try another tester. I just bought a pro grade tester from advanced. It was $42 and is really nice. I keep kicking until the gauge stops rising right?

[Matrix]

UPDATE: I called the guy who I bought this off of (couldn't find his number last night) and asked him about the piston. He said he thinks he remembers the guy who he bought it off of bored out the cylinder possibly .010 over and put new rings and what not on it because the cylinder was losing compression. Now I just need to work on my poor jetting.

Thanks for the answers guys.

[Yamaha_Rules69]

Boring the cylinder and installing a new piston will not increase the compression much at all, maybe a few psi if your lucky. There is no high compression piston on this 2 stroke. The way compression is increased is by modifying the head, which is shaving the head, or removing material to make the combustion chamber inside the head smaller. You could do a squish test (do a search, there are several) and see what you get, to be sure the head work is safe, and not a hack job. You can always get the combustion chamber re-cut, to correct the compression, or install a stock head. I hope this helps...

[Matrix]

Thanks. I'll look into it sometime. Now that I hear all this I am somewhat nervous about the compression. It's been like this for a year though so it can't be to bad or maybe its slowly deteriorating it..