vitos piston

[willd]

tore my shee down and cant find part numbers on these vito's pistons only 0.50 on top need to figure size out so i can order wiseco's

[Jeremy_bell_banshee99]

64.50mm or .020 over bud

[willd]

Thanks for the help. Would you happen to know what jets to run with toomey t5s

[Chip M]

Mine had a .75 stamped on the tops when I bought it. After checking the size with a mic I found out it meant .75 mm over stock. Mine checked out at 64.75 mm. That would make yours 64.5 mm assuming you are talking about a stock cylinder. You really need to put a micrometer or at least a set of dial calipers on your pistons to make sure you know what you have. I guess since you are changing them, the pistons are no good so I would be sure to check the bore size (or take it to someone who has the proper measuring equipment) to be certain the bore is within spec of size and roundness before putting the money in a nice set of pistons and rings only to put them in a bad bore. Good luck.

[Chip M]

Thanks for the help. Would you happen to know what jets to run with toomey t5s

 

Without more info on your mods I do not think you can get an exact answer for that question. Too many variables. I have only bolt on mods and I first tried 300 mains with the stock pilot jets (25's) and have now changed to 27.5 pilots. Much better but I am still in the process of tuning. read as much as you can in the jetting forum on this site. Also this link helps me out quite a bit. Banshee Jetting FAQ

[willd]

Thanks for the help man

[slothman]

I am in the same boat. Best thing to do, as mentioned, is to take it to a reputable machine shop so they can mic it and tell you the current bore size.

 

If the jug walls are "clean enough" you might get away with just a hone and get the 64.5 Wiseco prolite pistons. If the machine shop recommends a bore, you would go the next size up. So take it to a shop, or send it to one of the forum vendors (such as F.A.S.T) and they will take care of you.

 

For the jet size, every motor is going to be different. This is mainly do to factors such as elevation, outside temperature, and engine mods like air intakes or exhaust pipes. Elevation plays a huge factor, because the higher up you are, the LESS fuel you need (meaning smaller jets).

 

There is a thread on this forum where people have posted their current setup with elevation, mods, and jet sizes. You can find someone that lives around the same elevation as you do, and try those jet numbers. But basically it's trial and error. There is a test called "the plug chop" which will tell you if you are running lean or rich. It is definitely better to run rich versus lean. A lean motor will cause detonation, which will fry your pistons fairly quickly. For this reason ALWAYS run premium 91 octane.

 

I would recommend buying a few jet sizes, ranging from 280-310 for the main jets, and 27.5 on the pilot. Start rich with the larger jets, and work your way down.

 

Hopefully this helps you out a little, keep reading this forum, and you will learn very quickly (as I have) ! Also- be sure to DL the service manual - just do a search in the search bar and you will find it !