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China Big Bore 660 build

Rich Fife

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I'm slowly acquiring the parts for this build.
The case was an ebay China case, $40... the tank was a farmertec $38... the 56mm cylinder and piston are from Farmertec, $42.

Yes.... I know that piecing a saw together, especially a china saw isn't the smartest or most cost effective route.

The cylinder plating looks good buuuuut, There is a catch... or two. The lower x-fers are super small and the uppers are a bit large for my liking... lastly the FT piston when at TDC is free porting approximately. 015"... sooo needless to say, that *s-word isn't going to work. Luckily I found a good used 661 piston in my box. Comparing the AM piston and the OEM 661 piston... the 661 piston is approximately .100" taller from the pin to the crown and the skirt is well below the floor of the exhaust... tomorrow I'll get detailed numbers and weights.
The crank seems decent... I gave away my good used oem 660 crank so the China crank will have to do.
I have SKF crank bearings and OEM crank seals that I'll be using.
I have a new oem 660 carb, I machined a velocity stack and I have an UNI filter to boot. I'm certain that I have an intake boot and an oem coil.
Items to purchase... suspension, full wrap, flywheel, clutch items, chain adjuster, chain brake parts, dogs, starter assembly, clutch cover and the list continues... 🤔 this might be the most expensive China 660 build. 😆
 

Powerstroke Cowboy

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A 660 big bore cylinder/piston showed up today for a build I'm working on. My piston free ports just a little as well with the piston up against the squish band. Not going to be able to cut much out of the squish on this cylinder unless I aquire a different piston.

The transfer leave a lot to be desired from the bottom to the top. The air flow looks like it's a free for all. But, it was less than 30 on fleabay for the whole setup. It's going to need addressed with epoxy and grinding.

I'll be following this build and looking forward to the 661 piston specs.
 
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maulhead

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A 660 big bore cylinder/piston shawed today for a build I'm working on. My piston free ports just a little as well with the piston up against the squish band. Not going to be able to cut much out of the squish on this cylinder unless I aquire a different piston.

The transfer leave a lot to be desired from the bottom to the top. The air flow looks like it's a free for all. But, it was less than 30 on fleabay for the whole setup. It's going to need addressed with epoxy and grinding.

I'll be following this build and looking forward to the .661 piston specs.

Kinda strange.
 

thedude74

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A 660 big bore cylinder/piston showed up today for a build I'm working on. My piston free ports just a little as well with the piston up against the squish band. Not going to be able to cut much out of the squish on this cylinder unless I aquire a different piston.

The transfer leave a lot to be desired from the bottom to the top. The air flow looks like it's a free for all. But, it was less than 30 on fleabay for the whole setup. It's going to need addressed with epoxy and grinding.

I'll be following this build and looking forward to the 661 piston specs.


How about a 395xp or 2100 husky piston? 🤔
 

Rich Fife

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A 660 big bore cylinder/piston showed up today for a build I'm working on. My piston free ports just a little as well with the piston up against the squish band. Not going to be able to cut much out of the squish on this cylinder unless I aquire a different piston.
Yeah man, look Into either a Saw salvage 661 piston from the Dukes or a 056 Magnum piston... from what I've read the 056 magnum has longer skirts... I think I'm going to order a Dukes 056 magnum and compare it to the oem 661 piston. I'll post the numbers later today.
The transfer leave a lot to be desired from the bottom to the top. The air flow looks like it's a free for all. But, it was less than 30 on fleabay for the whole setup. It's going to need addressed with epoxy and grinding.
The lowers look as if they were designed for an 044 and then the extra thick base creates a larger separation/distance for the charge...
Pics to come after work.
I'll be following this build and looking forward to the 661 piston specs.
Yessir, I'll get those specs after work.
 

Rich Fife

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Thanks!

Pardon my ignorance, where's compression distance measured from? Is it from center of wrist pin to top of piston?
For saws, I measure from the top of the wrist pin bore to the top of the crown...

For our dirt race motors, I measure the CH from the center of the wrist pin to the top of the crown (Compression Height).
 
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Rich Fife

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*s-word, it looks like the 056 magnum piston has a 13mm wrist pin as well... 👎
 
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