China Big Bore 660 build

[Powerstroke Cowboy]

661 won't work. Too tall and it Freeports worse.
Onto the 056 magnum and 395xp.

I can make the 661 work. It's just a matter if I can get the components around the cylinder to work. The 660 cylinder I have is not going to be used on a 40mm stroke saw, but a 38mm. I have plenty of room for the extra compression height of the 661, without cutting into the squish band and taking about 1mm off the cylinders base. Now going with the 660 big bore piston I'd have to take around 6.5mm off the cylinders base.

Ideally I'd like it if the 660 BB piston had a 2mm longer skirt.



I can see why in your case it would not work since your useing the 660 platform. You would have more that just a Freeport problem. The piston at bdc would be sticking up in the exhaust port by close to 6mm. That in itself would not be exceptable.

I still may end up using the 660 BB piston so I can lower the cylinder and have the exhaust port close to the same as the factory location, as well as the intake would line up a lot better with the factory carb location.

Time will tell.

 

[Rich Fife]

I can make the 661 work. It's just a matter if I can get the components around the cylinder to work. The 660 cylinder I have is not going to be used on a 40mm stroke saw, but a 38mm. I have plenty of room for the extra compression height of the 661, without cutting into the squish band and taking about 1mm off the cylinders base. Now going with the 660 big bore piston I'd have to take around 6.5mm off the cylinders base.

Ideally I'd like it if the 660 BB piston had a 2mm longer skirt.



I can see why in your case it would not work since your useing the 660 platform. You would have more that just a Freeport problem. The piston at bdc would be sticking up in the exhaust port by close to 6mm. That in itself would not be exceptable.

I still may end up using the 660 BB piston so I can lower the cylinder and have the exhaust port close to the same as the factory location, as well as the intake would line up a lot better with the factory carb location.

Time will tell.

Yeah man... I figured fawk-it, time to cut this one up.
Your build sounds interesting!

 

[Rich Fife]

Cutting the cylinder.

 

[Powerstroke Cowboy]

Yeah man... I figured fawk-it, time to cut this one up.
Your build sounds interesting!

How do you plan to deal with the exhaust port timing? Or are you just going to run with the 97 degree?

Well see how interesting it is. It'll be interesting if it works good. But just unique if it doesn't. LOL

 

[Rich Fife]

How do you plan to deal with the exhaust port timing? Or are you just going to run with the 97 degree?

Well see how interesting it is. It'll be interesting if it works good. But just unique if it doesn't. LOL

It's gonna take some work... I have a couple pistons coming. I'll know more once they come in. Lol

 

[Rich Fife]

If I can't find anything... I'll bore the cylinder and toss in a melling sleeve.

 

[Mastermind]

I'm looking at the 395xp piston. Waiting to see what the specs are.

Big bore 066 with 395 piston. Carb was running dry the last cut....

 

[Rich Fife]

Big bore 066 with 395 piston. Carb was running dry the last cut....

I Like It!

 

[Mastermind]

I Like It!

I chit canned that top end in favor of a 54mm oem one.

 

[Rich Fife]

I chit canned that top end in favor of a 54mm oem one.

I seen you mentioned that before...
this 56mm cylinder is bottom of the barrel quality... lol. I have an OEM cylinder... but, I don't want to use it on a China saw. Idk, I guess if push comes to shove I might as well...

 

[Mastermind]

I seen you mentioned that before...
this 56mm cylinder is bottom of the barrel quality... lol. I have an OEM cylinder... but, I don't want to use it on a China saw. Idk, I guess if push comes to shove I might as well...

I've yet to see one that was very good. With the 395 slug, it can be made to work pretty well.

 

[Rich Fife]

I've yet to see one that was very good. With the 395 slug, it can be made to work pretty well.

Right. Time will tell with this junk.

 

[Powerstroke Cowboy]

Big bore 066 with 395 piston. Carb was running dry the last cut....

It runs good. It's crazy to think it's even better oem. But it's the truth.

I wish (yea I know) somebody made a 56mm version of the 288xp piston.

 

[Powerstroke Cowboy]

I

If I can't find anything... I'll bore the cylinder and toss in a melling sleeve.

Id like to see you toss it in....... LOL

at that point you could put the ports where and how you want them.

 

[Rich Fife]

I
Id like to see you toss it in....... LOL

at that point you could put the ports where and how you want them.

That's exactly my thoughts

 

[Powerstroke Cowboy]

That's exactly my thoughts

Do it! I want to watch! You could even make it into a quad port.

 

[drf256]

You know that all the 56mm 660 big bores freeport, right?

They purposely make the pistons skirts shorter for the 56mm piston the clear the case. That’s why. If you look, the bottom of that slug won’t go below the deck surface at BDC.

 

[Rich Fife]

You know that all the 56mm 660 big bores freeport, right?

They purposely make the pistons skirts shorter for the 56mm piston the clear the case. That’s why. If you look, the bottom of that slug won’t go below the deck surface at BDC.

Yeah, the case will be bored and the sides will be tapered kinda like a husky case.

I don't like free porting. That's part of their issue.

 

[Rich Fife]

Do it! I want to watch! You could even make it into a quad port.

If I do go that route I'll show how I do it. I cheat though, I use a HAAS and rough out the ports...

 

[srcarr52]

Cutting the cylinder.

I usually chop through the camber with a drop bandsaw, then finish with a boring bar so I can create a good ID to reference the head. Having to create a head that centers up off an OD on the cylinder sucks to make any changes to.