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[Big_Ooomp]

Hey yal first post so here goes. Im purchasing a non running 94 as soon as i get back to tn from vegas. The seller tells me that one of the cyl is only getting 25 psi of compression while the other is gettin 200 now im not sure proper psi for these engines but im thinkin bent valve or blown piston but he doesnt mention suspicious noises while cranking. So after that long winded tidbit heres the question could it be just the head warpage these engines seem to adore causing the lost compression? I figure it would drop compression but that much? Or do yall suppose ill crack the case and cry?  I plan to tear the bike to bare bones when i get it so work im not afraid of lol its the wife if i have to tell her the new bike needs a new engine lol

[FloridaEX500]

Sounds just like the way my wife would act. "Look at that piece of junk you bought home for two hundred dollars". Yeah look at it now woman! Worth about $2200 now.

About the engine- why don't you just plan (budget) on replacing the engine then if you find some miracle cure for the compression problem, then you'll be way ahead of the game?

I take it you didn't do so well in Vegas?

[FOG]

Before you  go tearing it apart  Re check COmpression. Do it a second time with oil in the cylinders.  Pour 2 oz of oil in each cyl crank it a few times with the plugs out then check again.  The oil will seal rings and gasket leaks but not valvea or broken pistons.  Givea a bit more info to work with.

FOG

[dad]

... and with the throttle plates wide open! That might be all that's "wrong", an improperly performed compression check. At least all that's wrong with the compression.

Folks can have a miss that's caused by a carb or electric problem, hook up a sync tool and go at the carb balance screws thinking it's a carb sync problem, get them whacked WAY out, then do a compression check without opening the butterflies, and..... no surprise, two GROSSLY different compression readings.

The cylinders don't get a full slug of air through the butterflies at idle position. And the compression indicates the multiplication of what the cylinder started with. If less than 100%, it reads less than what it's capable of. And it can be fairly dramatic even with an engine that seems to be running decent, and will be dramatically different if the carbs are grossly out of sync. Hope that helps.

[triple88a]

pull the carb when testing is simpler ^ 

[Georg3]

Before you  go tearing it apart  Re check COmpression. Do it a second time with oil in the cylinders.  Pour 2 oz of oil in each cyl crank it a few times with the plugs out then check again.  The oil will seal rings and gasket leaks but not valvea or broken pistons.  Givea a bit more info to work with.

FOG

Now is this to diagnose the problem or is this a bit of a solution?

Honest question.

[FOG]

It's Dianogstic,  The oil will not seal a bad valve, or a holed piston,  but it will seal the rings and gasket leak for a short time. So say your 25 lb, cylinder jumps up to 150 Ods are you have a bad ring or scored cylinder.
A leak down test is a good tool as well. you can listen at the ports to Hear the leakage.

FOG

[Pogo]

Before you  go tearing it apart  Re check COmpression. Do it a second time with oil in the cylinders.  Pour 2 oz of oil in each cyl crank it a few times with the plugs out then check again.  The oil will seal rings and gasket leaks but not valvea or broken pistons.  Givea a bit more info to work with.

FOG

Damn that's a useful technique (the oil bit).

[Big_Ooomp]

Thanks a bunch fellas it sucks that i havent even got the bike in possesion yet. To really get into the diagnostics. And i know going by words alone can lead to trouble guess im stewing here in tiny motel waiting for some ninny to ship in my tranny so i can head home

[FloridaEX500]

Plan on the worst, hope for the best. You'll be allright, its just an ex. Its just a bunch of cheap parts.

[dragknee]

buy bike cheaply
buy engine cheaply
assemble
ride

[smith.p.sean]

+1.  You can find an ex engine for 500 bucks or less if you are motivated to do so. 

[dragknee]

i see them going for between 2-300 all the time on ebay.