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Banshee Low Compression in one cylinder 90psi


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#1 patoke

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Posted 01 February 2008 - 09:39 PM

Hello,

I just picked up a used banshee and I had the compression tested at the Yamaha dealership. It has 130psi in one cylinder and 90psi in the other. Can I ride it this way or will the large diference between the two cylinders cause it to blow up? I want to go to the dunes tomorrow so I don't have time to put a new top end into it. What do you guys think is the problem?

Thanks,

Pat

#2 gentner8

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Posted 01 February 2008 - 09:42 PM

Hello,

I just picked up a used banshee and I had the compression tested at the Yamaha dealership. It has 130psi in one cylinder and 90psi in the other. Can I ride it this way or will the large diference between the two cylinders cause it to blow up? I want to go to the dunes tomorrow so I don't have time to put a new top end into it. What do you guys think is the problem?

Thanks,

Pat



sounds like that one side is already blown. why take the chance of running it and possibly causing more problems and more money?

I think I would buy a tester from sears and check it myself to make sure the dealership isnt trying to make a quick buck on me though.

Edited by gentner8, 01 February 2008 - 09:43 PM.


#3 patoke

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Posted 01 February 2008 - 09:55 PM

sounds like that one side is already blown. why take the chance of running it and possibly causing more problems and more money?

I think I would buy a tester from sears and check it myself to make sure the dealership isnt trying to make a quick buck on me though.


At the risk of being flamed here, How do I check the compression? I know I need to buy a compression tester, but then what? What do I need to do to fix the banshee if it is truly at 90psi? Sorry for all the basic questions.

#4 spike

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Posted 01 February 2008 - 11:36 PM

you remove a plug pull the wire off the other one, screw the compression tester in the hole and crank the bike with the throtle wide open until the reading on the gage stop climbing.
If your really at 90 PSI your due for a top end Its blown up in my book...

#5 TexasBansheeMan

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Posted 01 February 2008 - 11:44 PM

Buy a good book on your bike, Get some tools and get into her. Its easy, AS LONG AS YOU HAVE THE RIGH STUFF.

#6 gentner8

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Posted 02 February 2008 - 05:36 PM

At the risk of being flamed here, How do I check the compression? I know I need to buy a compression tester, but then what? What do I need to do to fix the banshee if it is truly at 90psi? Sorry for all the basic questions.



A top end job is pretty simple if you are mechanically inclined (at least on a 2 stroke anyway) You need to pull the cylinders and check the bore size before you order any parts. Find out the current size of the pistons in it and go up 1 size if there are no visible problems with the bore. I wouldnt pay the dealer to do anything if I didnt have to. You should be able to do the job for half the cost by doing it yourself, or better. If you look on ebay, there is a guy that will let you send your jugs to him, he will bore them and set you up with the proper pistons, rings, gaskets etc. That would take the guess work out of it for you. I think it was around $250 or so for the service and he had good feedback. PM me if you want more details on it. Dont sweat it, embrace this time as upgrade time since you are going to have it apart anyway.

BTW the testers at sears are resonably priced, so look into it before jumping into a tear down. I was convinced that I was going to need a rebuild, and the compression test proved me wrong. Glad I bought it.

#7 C&B

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Posted 02 February 2008 - 05:51 PM

A top end job is pretty simple if you are mechanically inclined (at least on a 2 stroke anyway) You need to pull the cylinders and check the bore size before you order any parts. Find out the current size of the pistons in it and go up 1 size if there are no visible problems with the bore. I wouldnt pay the dealer to do anything if I didnt have to. You should be able to do the job for half the cost by doing it yourself, or better. If you look on ebay, there is a guy that will let you send your jugs to him, he will bore them and set you up with the proper pistons, rings, gaskets etc. That would take the guess work out of it for you. I think it was around $250 or so for the service and he had good feedback. PM me if you want more details on it. Dont sweat it, embrace this time as upgrade time since you are going to have it apart anyway.

BTW the testers at sears are resonably priced, so look into it before jumping into a tear down. I was convinced that I was going to need a rebuild, and the compression test proved me wrong. Glad I bought it.

If the comp test is like you say, then definetly rebuild. The rings r prolly shot in the left side, and you now have piston slap. The rings arent making the piston run true up and down and it slaps the cyl wall eventually breaking the skirt on the piston. That is a major re-build. Do yourself a favor tear it down before hand.