General Ignorance Question (Stihl Engines)

[ImpulseRocket]

I was under the impression the yd100 rod still leaves the stroke just shy of what it should be.. I know the geometry is totally different from saw to cg cranks and another thing I found out was if you mill the cylinder down to get stihls squish specs you end up going like 1mm too much and at tdc the exhaust port is slightly open below the piston skirt.. something about using the rod from a Husqvarna 760 cut saw.. good luck finding just the rod.. crank assembly is around $350-400.. I'm hard pass on that one.. but if you find someone with a few of them laying around, I needs one.. but as far as port timing goes.. idk.. Im pretty sure it would probably need some finessing to get it dialed in properly.. lol. Properly.. if that word even belongs in the same category as chinasaw.. but, if I'm not mistaken, I think it's the ms260 or 290.. there's no rod swap needed and the 48mm bike motor piston will work with a 1mm spacer to lift the cylinder.. again, Im just going by what I halfway threw together out of curiosity with a trash cylinder I had laying around. Ended up buying the ms660 54mm kit instead of the 48..

Everything you said is more or less correct. Despite these shortcomings, the 460 cylinder still works amazingly well. It's a case of "nearly perfect" compared to other options which were even more involved.

That is why the Phantom cylinder was made. It corrects the main issues, such as the exhaust port, and gives a bolt on solution so that no machine work is required. The only real change made outside of port position corrections to work on the yd bottom end was the size and shape of the intake port, converting it to flange for the 40mm intakes, and making it smaller at the flange to - I presume - reduce the power output a little bit.

I own a 460 saw and have a cylinder left over from a rebuild. If you place them side by side you can see the changes that were made, but also just how nearly identical they are.

 

[jaybird6638]

Those are Big Bore MS660 cylinders with a 56mm bore. In order to fit them to a standard bottom end they need a decent amount of work. The case halves need to be opened up to clear the 56mm piston. The original stud holes need to be filled in and the deck re-drilled for the new bolt pattern. Often the deck of the case halves and/or the cylinder need to be milled down to set the correct compression height/squish gap as well as port timing.

The transfers on the case need to be filled in when using an MS380, 460, or 660 cylinder.

Then there is the issue with the wrist pin bearing. Most of the stihl saws use a 12mm wrist pin while the CG bottom ends run a 10mm pin, so most often people run bronze bushings to run the smaller wrist pin. There are YD/LD100 bottom ends that run a 12mm pin, as well as the 110cc engine. The YD100 rods can and have also been opened up to the 15.8-16mm ID in order to run the larger wrist pin needle bearings.

The YD100 bottom ends have enough space to run up to a 54mm piston without clearance issues and the 110cc engines can run the 56mm piston with no clearance issues.

None of this work is overly complicated, but it is a lot of tedious work to get it right. Small details like ensuring the cylinder is centered before marking your holes to drill and tap.

This is actually one reason the Phantom 85 engine was created. It gives you the chance to have what is essentially an MS460 Saw cylinder on a YD100 case with none of the work mentioned above. Unfortunately, that doesn't mean you won't be doing a bunch of work anyway to get a good engine, but the work you do have to do is much simpler. I love my Phantom, but I had to rebuild it and rework it to get it to a point where it isn't a time bomb (hopefully).

is there a way i can put the 56mm 660 on the phantom my phantom blew up

 

[DieselTech]

is there a way i can put the 56mm 660 on the phantom my phantom blew up

It might take some machining to do it. I'm not sure thou. I want to build a ms660 china girl but havent got around to do it.

 

[cdeuce1988]

Those are Big Bore MS660 cylinders with a 56mm bore. In order to fit them to a standard bottom end they need a decent amount of work. The case halves need to be opened up to clear the 56mm piston. The original stud holes need to be filled in and the deck re-drilled for the new bolt pattern. Often the deck of the case halves and/or the cylinder need to be milled down to set the correct compression height/squish gap as well as port timing.

The transfers on the case need to be filled in when using an MS380, 460, or 660 cylinder.

Then there is the issue with the wrist pin bearing. Most of the stihl saws use a 12mm wrist pin while the CG bottom ends run a 10mm pin, so most often people run bronze bushings to run the smaller wrist pin. There are YD/LD100 bottom ends that run a 12mm pin, as well as the 110cc engine. The YD100 rods can and have also been opened up to the 15.8-16mm ID in order to run the larger wrist pin needle bearings.

The YD100 bottom ends have enough space to run up to a 54mm piston without clearance issues and the 110cc engines can run the 56mm piston with no clearance issues.

None of this work is overly complicated, but it is a lot of tedious work to get it right. Small details like ensuring the cylinder is centered before marking your holes to drill and tap.

This is actually one reason the Phantom 85 engine was created. It gives you the chance to have what is essentially an MS460 Saw cylinder on a YD100 case with none of the work mentioned above. Unfortunately, that doesn't mean you won't be doing a bunch of work anyway to get a good engine, but the work you do have to do is much simpler. I love my Phantom, but I had to rebuild it and rework it to get it to a point where it isn't a time bomb (hopefully).

Yeah you'll need a zmn100 connecting which takes a 12mm wristpin needle bearing.

 

[ImpulseRocket]

Yeah you'll need a zmn100 connecting which takes a 12mm wristpin needle bearing.

You would need way more than the rod.

 

[ImpulseRocket]

is there a way i can put the 56mm 660 on the phantom my phantom blew up

Same way it would need.to.be done with any other motor. Case half flanges for the jug need to be filled and drilled for the 660 pattern. The case or jug flange surface needs to be machined down to set correct port timing and squish gap, and a filler/adapter plate to block the transfers in the case halves or the transfers need to be filled in. The case would also need to be bored a little to fit the 56mm piston. On the plus side, the Phantom rod already takes a 12mm wrist pin, so it has that going for it.

The '110' engines are actually a better starting platform. They also use a 12mm wrist pin, but the case halves are a bit bigger to accomodate a larger bore. They can fit the 56mm piston with no machining as the case is bored to 58.5mm and the flange surface for the jug is bigger. The transfers still need to be filled or blocked and the flanges filled, drilled, and machined for squish and timing.

The 110 case halves also have a bit more "meat" on their bones, which in the world of chinesium means more strength

 

[DAMIEN1307]

The 110 case halves also have a bit more "meat" on their bones, which in the world of chinesium means more strength

Love it...lol.

 

[DAMIEN1307]

Same way it would need.to.be done with any other motor. Case half flanges for the jug need to be filled and drilled for the 660 pattern. The case or jug flange surface needs to be machined down to set correct port timing and squish gap, and a filler/adapter plate to block the transfers in the case halves or the transfers need to be filled in. The case would also need to be bored a little to fit the 56mm piston. On the plus side, the Phantom rod already takes a 12mm wrist pin, so it has that going for it.

The '110' engines are actually a better starting platform. They also use a 12mm wrist pin, but the case halves are a bit bigger to accomodate a larger bore. They can fit the 56mm piston with no machining as the case is bored to 58.5mm and the flange surface for the jug is bigger. The transfers still need to be filled or blocked and the flanges filled, drilled, and machined for squish and timing.

The 110 case halves also have a bit more "meat" on their bones, which in the world of chinesium means more strength

A hell of alot of work for little gain when the Phantom 85 suffices quite well over trying to modify an MS 660 cylinder jug and piston assembly to an existing P-85 "100" bottom end.

 

[ImpulseRocket]

A hell of alot of work for little gain when the Phantom 85 suffices quite well over trying to modify an MS 660 cylinder jug and piston assembly to an existing P-85 "100" bottom end.

I actually disagree. The MS660 has a 40mm stroke, same as the yd100 bottom end (should have at least). Paired with a 56mm big bore cylinder that makes for a 98.5cc engine that could easily push 8 to 10hp as a piston port setup with basic port cleanup and put out torque to make even a P85 jealous. If your goal was an engine that could pull the fattest of butts up a hill, the 660 would be the way to go.

 

[DAMIEN1307]

I actually disagree. The MS660 has a 40mm stroke, same as the yd100 bottom end (should have at least). Paired with a 56mm big bore cylinder that makes for a 98.5cc engine that could easily push 8 to 10hp as a piston port setup with basic port cleanup and put out torque to make even a P85 jealous. If your goal was an engine that could pull the fattest of butts up a hill, the 660 would be the way to go.

WOW...I think it would be a suicide machine to have that much power on a mere bicycle frame if it actually puts out that much power.

It still seems to be an awful amount of work to do it though, I didn't realise it would be THAT powerful as an end result...lol.