4Cycle Chainsaw

[eyolf]

I was never impressed with the old XT500's. maybe 3 more hp than a stock Honda XL350.

I used to take stock 'XL350, send the cranks to Powroll in Oregon to be stroked 3mm, bore them 8mm and sleeve back down to 6mm overbore, Jahns domed piston for 14:1 comp, and cammed up to about .510 lift at the valve, 315/308 duration, advanced 1-2 deg. This engine would eat Yam XT500''s for breakfast, and the old BSA 441 never stood a chance in the 1/2 liter class at 1/2 mile oval dirt track racing.

Made an interesting street bike ...throttle roll on at 60mph would embarass a Kawasaki Z1 to about 100 mph, but you really didn't dare rev past about 10000, or she'd literally grenade.

 

[bwalker]

EXACTLY what the dirtbike guys thought about the thumper Yamahas

I still think the yzf is a boat anchor. More weight and complexity and the same amount of HP. BTW the YZF only won 1 championship and that was during the development year when it was exempted from weight and cc rules. Everybody has jumped on the four cycle band wagon because they are easier for a beginner to ride and thats whta the factories are pushing. As for two strokes going away. Its not going to happen. Do a patent search and see for your self what the ope companies are doing.

 

[sedanman]

Ben, I wish you lived closer to me, I'd put one of the p.o.s. 4-mix trimmers in your hands and take a picture of the astonished look on you face when you experienced TORQUE for the first time. Maybe 4 cycle won't totally replace 2 cycle but there will be more of them in the future and you may be selling them short before giving them a chance. I stand by staement, when they build a 4-mix chainsaw, I'll be the first one on my block to own one.

 

[bwalker]

I'd put one of the p.o.s. 4-mix trimmers in your hands

I already demoed one and then bought a stihl fs 250. I had hoped the four mix had the power for my needs by virtue of a four cycle torque, but it just didnt cut it. The fs 250 on the other hand is simply outstanding. Like other stihl trimmers it is heavy, but its power is secodn to none.

 

[NevadaWalrus]

Comparing the 40.2 CC 250 to the 31.4 CC 110 4Mix isn't exactly square. That's almost a 1/3 displacement larger engine, it should have more power.

 

[bwalker]

OK, it felt like a fs 85 with more lowend and a little less top.

 

[max2cam]

Originally posted by eyolf
I was never impressed with the old XT500's. maybe 3 more hp than a stock Honda XL350.

I used to take stock 'XL350, send the cranks to Powroll in Oregon to be stroked 3mm, bore them 8mm and sleeve back down to 6mm overbore, Jahns domed piston for 14:1 comp, and cammed up to about .510 lift at the valve, 315/308 duration, advanced 1-2 deg. This engine would eat Yam XT500''s for breakfast, and the old BSA 441 never stood a chance in the 1/2 liter class at 1/2 mile oval dirt track racing.

Made an interesting street bike ...throttle roll on at 60mph would embarass a Kawasaki Z1 to about 100 mph, but you really didn't dare rev past about 10000, or she'd literally grenade.

That sounds like a great bike you built from the XL350. Hondas are good bikes. My first motorcycle was a 1967 Honda CL160. I thought that was a trail bike when I got it! When I was 17 I rode that thing from Wis. to the West Coast back to the East Coast and then back home. Longest motorcycle trip I ever made.

My XT500 is stock with a big dent in the gas tank. Painted flat black and duck boat green. I'm not into racing so it suits me fine. But any of the bigger dirt bikes would. For some reason I always like that machine -- long before I had one. It sure pulls and I can ride it anywhere. Vibrates quite a bit on the highway though, but it's street legal. 500cc (30.50) is a nice traditional size for a single, but so is 350cc (21ci). The Brits had lots of cool singles in the 1920s; fast little OHV and OHC jobs. Then Harley built one too. Their 21ci OHV was a cool little bike. Good for about 65 mph. Wide open valve springs. Led to better things in 1936.

As to 4-stroke chainsaws, can't say that I'm crazy for all the little extra parts necessary. Would we see little cam chains and stuff like that? One thing I like about the modern 2-stroke chainsaw engine is its simplicity. I had my 024 apart last years and had it on my lap while working on it. There was just a couple pieces in the whole top end. Fixing it was simple. Although a 4-stroke may not have "stuck" a piston like that.

Guns, Lore, Harleys...
http://www.atthecreation.com/

 

[eyolf]

Great post, Max2Cam. I actually built a few of those Honda's...I was working part-timr for a body and fender shop, the guy also would build choppers if you asked nice, and loved to race flat-trackers. I didn't even know he was into the racing thing when I started, but he saw my personal bike and asked a few questions.

He thought he would challenge and embarass me pretty good with his BSA flattracker, and I'll admit he could outride me with no trouble at all, but it was a lot harder than he thought to get away from me...he got way ahead on the corners, but I darn near caught him again on the straights.

So,...we modified an old flattracker frame to take a Honda Engine (dang chain comes out of the wrong side of a BSA...LOL) Whether it was legal or not that first year, he cleaned up with Honda. The next year several guys had 'em, but mid-summer the series promoter sold out to another guy who had a lot tighter rules for his tracks...end of the game.

Now there are no races for the old British bikes in my area.