im changing the seal for all front and back cylinder cuz there a leak of oil. bike with 42000 miles on it. when taking the front cylinder out i saw 2 small crack in the chamber. im just taking the front out not the rear yet. since the belt for the rear kinda hard to remove. what should i do with the 2 crack... get a new one to replace or?????? plus the piston rod is shaking side to side. when i pull it follow the piston rod up and down like the piston movement then there no shaking to it. sorry my english is not so good. i try to add a picture but it didnt work. please help!!!
thanks

A picture would be very helpful... You need to upload it on a website of your choice then add the link here so it can be accessible.

As for the movement "side-to side" that is normal... it looks weird but the important thing is that there is no movement "up and down".

if it`s not too big you can attach a picture to your post

I'm Asian. And I still learning english. Anyway here is the link hope it work
https://m.facebook.com/photo.php?fbid=1 ... 7&__tn__=E

If I need to replace it. I wonder if 906 cylinder will fit 907??

Thanks

Yes, 906 & 907ie cylinders are the same. (same part numbers. You find all parts catalogues in the downloads)

Is the crack that bad?

I can`t really make it out on the picture. Is that the horizontal line in 1 o`clock position? (in the grey stripe)

Yeh that the one. And one next to it at 12 o'clock. I just ordered new sylinder jug. Used on ebay for 906. Hope it work out good

the 906 cylinder jug and piston come today. compare to the old one they are not the same. everyhing else fit to the engine and the valve head is fine. but the piston on the 907 is bigger then the one 906 that i bought will not fit in the hole. jug and piston on 906 smaller. and the design piston of my bike is diff then the one i bought. so i seach on ebay for the 907 sylinder jug and piston they all seen to look like the one 906 i bought. i think the old onwer of my 907 did change new piston and make the jug hole slightly bigger. since i already bought the part. im thinking im just gonna install it, it fit fine. is it ok to have 2 diff piston front and rear on the engine??? rear bigger front smaller.

that is strange because the 906 piston is #12220021A which was superseded by #12220081A which is the number of the 907ie piston & 900SS/Monster. Makes me wonder if the cylinder was bored larger to fit a bigger piston and the crack came from the cylinder walls being too thin or if a 944cc kit was installed.
The original pistons are 92mm the ones of a ST2 are 94mm. Did you measure your old and new one?
Don`t install different size cylinders/pistons.

Can you post a picture of the pistons?

I just search for 944cc kit and it show up the piston that I had on my bike. I will send a link of a pic later. So what should I do now. Get a another rear oem to match with the front.?

Drop Jaffa a pm. He may still have a complete set of 907 barrels, pistons, gudgon's, rings etc. See topic:

viewtopic.php?f=4&t=6518

Postage may be a killer, but it can't hurt to ask.

Cheers.

Nick.