440 hybrid

[Ronie]

Not really a build thread, just going to post the progress on my build.

So far I've painted the cases and dyed the ugly plastics black. Put the crank in, repainted the front of the case because the oven heat gave the gray a yellow tent. Did the muffler mod and fitted the cylinder to the case.

 

[Ronie]

I've also started on the cylinder and cut .025 from the band and .020 off the base, squish is .022. My plan is to leave the exhaust low and more blow down than most do to start with and If I don't like it I'll go back in and change it, looking for good torque. The pic of the port timing is after I cut the base and how I want it to end up.

Just want to add that's it's a Stihl branded jug.

 

[Ronie]

Finished the cylinder up.

 

[Ronie]

Flywheel cut down to clear the cylinder and I stripped out one of the cylinder bolt holes so I tapped it to m6.

 

[slackinoff]

That looks great Ronie!

 

[Ronie]

That looks great Ronie!

Thanks

 

[huskihl]

Looks good, Ron. Your numbers should make for a nice even-keeled torque curve

 

[Ronie]

Looks good, Ron. Your numbers should make for a nice even-keeled torque curve

Thanks Kevin

 

[Bjorn]

Hello. Are you going to use the original piston, or a 272 piston? The 272 piston is higher and singel ring. Very nice for making a pop up piston.

 

[Ronie]

Hello. Are you going to use the original piston, or a 272 piston? The 272 piston is higher and singel ring. Very nice for making a pop up piston.

I'm going to use a 440 piston, I cut .025 from the band. I would have cut more but I don't want the compression to high. My right elbow and shoulder are shot and I starting saws with my left arm at the moment.

 

[Bjorn]

I'm going to use a 440 piston, I cut .025 from the band. I would have cut more but I don't want the compression to high. My right elbow and shoulder are shot and I starting saws with my left arm at the moment.

Decomp? 440 piston?

 

[Ronie]

Decomp? 440 piston?

I meant a 460 piston, I'm going to put a decomp in it.

 

[Ronie]

I've been doing some thinking about the transfers and had decided to angle them so that the exhaust side opens first instead of the intake side like it came from the factory. I figured I'd cut them flat and then mark a couple of degrees higher, then cut from the intake side up to the mark on the exhaust side. After cutting them flat, I thought that they are starting to get big and I didn't want them any bigger than they need to be so I'm just going to leave them flat.

I also was looking at how flat the exhaust roof is a put and larger bevel on it.

New numbers are,

EX 104
TR 124
IN 78

 

[Ronie]

I took .025 of the flywheel key and got the cylinder on this afternoon, it free ports a little, maybe .010, but I think it will ok with that. I didn't take any off the floor so it must have been close to start with.

 

[Wonkydonkey]

Although it probably wont matter with that little bit of free porting if you need a bit more squish clearance, a little gasket made from a soda can or something would sort both out

 

[Ronie]

Although it probably wont matter with that little bit of free porting if you need a bit more squish clearance, a little gasket made from a soda can or something would sort both out

I'm going to leave it and see how it does, squish is .022 so I'm good there.

 

[Ronie]

Didn't get much done today , I put the seals in and vac tested it, opened up the hole and extended the deflector on the back half of the muffler, I'm out of flat black so I put some gloss on it.

 

[Ronie]

I picked up some VHT header paint so I stripped that gloss paint off the muffler and repainted it this morning. I also drilled a few holes in the outside spike and painted both spikes, tomorrow I'll put it in the oven and bake the muffler and spikes.

 

[slackinoff]

I like the non glossy muffler paint better as well. Looks great.

 

[Ronie]

I like the non glossy muffler paint better as well. Looks great.

Thanks, I like the flat black better too. Once I bake it on, I'll take some scotch brite to it and it won't look so chalky.