Project "low buck 346"

[Stihlbro]

Picked up a aftermarket cylinder to inspect.

 

[Stihlbro]

Was able to pick up a 353 bottomed end with some horse trading in the bac ground. Mocked it up to degree the cylinder. If I remember correctly the exhaust was 106 ish, transfers 127 ish, intake was 75 to 76 ish. Ports shapes, especially the transfer were less than desirable. No problem cause I was going to use one of them rotating thingies and Change them.

 

[Stihlbro]

Kinda went off the deep end and wanted to do a 2 piece head. Made a fixture to mount the cylinder, cut the bulk off with a sawzaw and trued the top up with the lathe. The ability to make your own combustion chamber, squish band, spark plug placement has my interest. My thoughts are a work saw with a 2 piece head fitted under the covers with no cutting.

 

[Stihlbro]

Pictures are huge here lately so I will leave themas a thumbnail for now. Once the head is off and a degree wheel is mounted, it is super easy to measure port timing. No guessing thru a spark plug hole or using a ring to get exact openings. Two things here is I need to consider are type of head, and I'll call it a inny or a outy. This cylinder I was able to leave enough cylinder wall above the the top of piston at top dead center to make a head to fit inside the cylinder. I can control squish by the depth of head into cylinder. Secondly is you can lower top of cylinder and make a head that does not go into cylinder.

 

[Stihlbro]

I am no machinist, self taught and I have contacts that have been a tremendous help.
Started off with a 3 and 1/2 inch round aluminum stock. I'm wanting to make a head with a hemispheric chamber and the squishband at 1/2 of the bore width.

 

[Stihlbro]

Total time from mocking up cylinder, the current picture of spark plug installed, and top cover in place is about 6 hours. It's a lot of measure 10 times and cut once. So far I am close but no where near done. Head is too thick for cover, plug fits right. Getting the holes for mounting is hard for me. I cut a step In the top of the head and used a base gasket to center and mark holes. I found 4 carb bolts off a husky 181/281 that will work lengthy wise. Threads are 4mm and length is 90 mm. The muffler bolt for these saws is close. The 281 were all shiney and knurled on the ends and I thought it would look cool.

 

[Stihlbro]

Made a boo boo on the head but yet still fixable. Raising transfers, removing the blemishes. The material in this cylinder is not of oem. I'm alittle concerned at the moment. The top of cylinder did not turn out right. I tried different cutting bits, changed speeds, different lubricants. Doing the transfers, it was loading the tooling up and I had one nugget that jerked out and took some plating with it.

 

[Stihlbro]

Few more pictures, intake done.

 

[Stihlbro]

Exhaust and view of combustion chamber.

 

[Stihlbro]

Here we are. All mounted up. A top cover will clear. Porting done. Ready to fire up. I ordered a top cover and waiting on it.

 

[Mastermind]

Excellent thread Joey.

 

[Stihlbro]

Thanks. I used a 350 parts to the 353 crankcase. I'm in it for about less than $50 at the moment. But had trouble......

 

[Brush Ape]

 

[Stihlbro]

Top cover is in. Looks like the fit is a go. Ordered new buckles, man those are pricey.

 

[Mastermind]

Too cool.

What was the trouble?

 

[Stihlbro]

I've had it up and running and went thru a couple of heat cycles. Checking ring and cylinder. Actually thought it was time to chain it up. Well............

 

[Mastermind]

That's not a big deal. Use a better clip, slick it up, and go again.

 

[Stihlbro]

Ive read to be leary of the aftermarket circlips. And have been putting a drop of loctite and have not had a problem.

I was able to save the cylinder, use oem clips. Not real comfortable on how they fit but I'm certain the pin won't come out.

 

[Mastermind]

Did you look at the pics in the Hyway cylinder thread I posted?

 

[Stihlbro]

Here is my current piston wash. It looks like my Pto side transfers are lazy. Hmmm??????