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jetstar two cylinder bores

A

Anonymous-0

Well-known Member
Looks like I'll have to do some work on the cylinders of my 206 gas. How far can we bore them to clean them up. Can we go all the way to .125 over and use 302 pistons et al. Also what is considered the most reliable source for engine parts. Thanks jack.
 
You can go to .125 over but to use U302 pistons, you will have to swap the rods to U302 one also as they are different length. The piston pins sit higher in the pistons on a U302. M&W used to make .125 over pistons for the 206 engines. .125 over pistons may still be available from Welters, Everetts, Charlie Biler or others.
 
I recently had a 445 that I overhauled. I found a set of NOS; M-M factory 3 7/8 overbore at an old M-M dealer. Moline offered an overbore of 1/4" on a 206. Yes they are thin; yes, if the cylinders has rust pits on the coolant side they may go thru; (mine did; had to improvise but it is still going strong). What I am saying is: If you can find the pistons; it is possible to go .125 or more.
 
A good used set of U302 pistons & rods, and new rings are an economical way to repower the old 206.
 
In a side note, Ford 172 pistons make great MM 220 overbore pistons. Std 172 is a 3.9 bore and just over a 2" compression height, similar to the original.
 
To go to .125 overbore do you need to switch to a 220 carb and intake? Or will the stock 206 stuff work? Also are the rings for the m&w pistons available anywhere?
 
One thing nobody else said: You may be able to sleeve your 206 bores and then re-use the old pistons and rods.

I don't know what it cost now, but I am thinking the last time (2003?) it was $48 for the first cylinder and $35 for all the others.

The last time I bought pistons for a 206 they were $125 each.

Last thing: I put a 445 carburtor on my 302 and it seemed to work with no problems I never worked it hard. The correct carburetor has a right much larger bore in it, however.
 
Thankyou gentlemen for the data. We now have a better idea of what is possible. What is the wrist pin to top of piston dimension for the 206g and for the 220g engines? jack
 
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