Compression test/Best piston kit

[registered user]

namura are made in taiwan. if you want to spend your cash on that garbage then go ahead

[wreck]

Ok.... little update. I did another compression test with a different gauge. Here are the results. Driver side was at 110 psi and other side was about 61psi....the next step now is to start tearing it apart and figure out what size pistons I need. I just wonder why the one side is so much lower than the other...I guess I will find out when I take it apart.

[sheerider11]

Ok.... little update. I did another compression test with a different gauge. Here are the results. Driver side was at 110 psi and other side was about 61psi....the next step now is to start tearing it apart and figure out what size pistons I need. I just wonder why the one side is so much lower than the other...I guess I will find out when I take it apart.

You have to get it measured. You can't just slam a new piston in it. You might have a oval bore or need a hone. I'd say a fresh bore is needed

[vulvafan537240]

Id take the jugs to your machine shop to see what bore they will clean up at, then order them and take them to the machine shop so they can measure them and bore the jugs to the pistons exact size.

[04_blu_shee]

Put weisco Pro-Lites in it they hold together and if jetted right will last. This is my 4th season on my top end compression is the same as after I put a few heat cycles on the pistons my .02

[slktrik]

Im sure that I did it correctly....the compression test kit is from harbor freight...I know...its brand new....took both spark plugs out screwed in the portion of the gauge to spark plug hole...wide open throttle and kicked it over about 5 times or more. The bike definately still runs....or should it not run with that low of compression. And I will for sure buy the Wiseco since they really arent too much more than the Namura ones. I will also try another gauge to just double check my results. Thanks for the replies.

 

 

Saw this post and thought I would add to it for other people needing info. The harbor freight gauge was probably the issue to a point. if it showed differance between both jugs i am sure that is part of the motor problem but I also wanted to check compression on mine and bought a new harbor frieght gauge due to misplacing my other. I found 70psi per jug. OUCH!!! Found my original gauge and was relieved when it showed 155psi per side. Well the harbor junk is going back!

[bad 350 shee]

go with wiseco iv benn on the same pistons for 4 years and have put a ton of hours on them.. i put new rings in every season and im still at 155.. the same as when they were put in

[wreck]

I know that I am taking the bike apart this weekend and need to the cylinders measured to see which pistons I need. Question...I was wondering if milling the head with stock carbs and rejetting and news pistons will give me any horse power gains. Also thinking about the Vitos kit that adds more hp....any suggestions would be great.

[WINDYCITYJOHN400]

I'd say to hone the cylinders or bore them for a fresh surface, then put the vito's pistons in and save up for a cool head from Noss. Then jet that baby fat and go rip it.

[shanYE west]

if it were me.. and it was a stockish bike. I'd put cast pistons in. Pro-X, ART or WSM. I've never seen a wiseco go 10+ yrs like I have cast.. Proper bore setup is critical for either type piston.

[wreck]

It is pretty much stock....I was looking at those WSM on ebay, seems like a good price...comes with all the gaskets, wrist pins for a good deal....just wondering...like you said...forged or cast?