81 suzuki gs450 has two cylinders in one head and two seperate exhaust pipes. Theres a serious crack on one sides pipe before that pipes muffler. That cylinders compression test reading was around 125. The other sides compression is at around 175.

So the question i have is this. Could that cracked exhaust pipe be causing a low compression test reading? The crack is severe and before the muffler.

Thanks for any and all help and have a great day!!

No. Even on the good side, there'll barely be any pressure inside the exhaust without the engine running. And even when it is, it won't be a lot.

Perhaps the crack has lead to a burnt/sticking/dirty valve. Perhaps your head gasket is blown and caused it to run lean, overheating the exhaust pipe and causing the crack. Perhaps the rings are sticking for whatever reason...tried adding a bit of oil in to the cylinder to see if it made a difference to the compression?

[This message has been edited by Stubby79 (edited 09-01-2011).]

No havent tried anything yet. Was a local bike shop that did the compression test. I asked them to clean the carbs and they never did after the compression test results, says its not worth it if theres low compression. Shop guy then goes on to tell me that "he doesnt work on motors"... what the heck? Then he noticed the fiero in the driveway and started to ask about it and so forth. What kinda motorcycle shop doesnt work on motors?? Think we need to find another shop. Same guy told a neighbor to just junk his bike that its not worth fixing. His bike was running fine till the starter went.

Off to find new motorcycle mechanic or a good clymers manual! Should we try some miracle oil or wth ever its called?

Got the antique plates and its all legit just needs to be ridden. think its sat for way too long and thats causing problems

No, low compression meands bad rings, bad gasket, worn cylinder walls, valve leak, or cracked head or block.

odometer has 5879 miles on it and its been sitting for years and years. The mechanic says when they pulled the plug and looked inside of the right cylinder there was surface rust visible inside. Not good news i know. The other cylinder looked great. Maybe I'm gonna have to rip it apart and see. My biggest concern with that is finding gaskets, but then cant I just use RTV with no paper gaskets?

This should be very interesting!

wet or dry test?

if they didn'y do both then they re just looking to screw you for more money or are just incompitant.

steve

quote Originally posted by fierowitch: wet or dry test? if they didn'y do both then they re just looking to screw you for more money or are just incompitant. steve

Fierowitch could you explain further? Or anyone else for that matter? Can explain the difference between a wet and a dry compression test?

quote Originally posted by weloveour86se: Fierowitch could you explain further? Or anyone else for that matter? Can explain the difference between a wet and a dry compression test?

dry test is when you just plug the tester in and run the test,
wet test you put a squirt or two of oil in the cylinder then run the test.
if the test is higher for the wet test you have bad rings or need to rebore the cylinder

old school rules
just noticed you live in maine to, we are in farmington
steve

[This message has been edited by fierowitch (edited 09-01-2011).]

quote Originally posted by fierowitch: dry test is when you just plug the tester in and run the test, wet test you put a squirt or two of oil in the cylinder then run the test. if the test is higher for the wet test you have bad rings or need to rebore the cylinder old school rules just noticed you live in maine to, we are in farmington steve

Great help TY very much. Guess I'm going to buy a compression tester tomorrow and do as you have said and find out. Either way tho I'm prolly gonna have to pull it apart unless theres some kinda magic stuff I can put in there.

We live in Old Orchard Beach. There are a few members here from Maine. Hey!, I just had the best idea...

...Why not take a run to OOB in your fiero and lets have a coffee or soda or beer or milk sometime and lets kick some tires? lol

edit; typo

[This message has been edited by weloveour86se (edited 09-02-2011).]