Considering port work on Stihl 362

[HolmenTree]

My brother Dennis here ran a 7 pin on his Mac 101, he was getting times in the low 4 second range in 3 cuts with cold start included.
His saw has a 34mm carb and the pipe has a inverted stinger.
Look at them chips fly.

[Mad Professor]

ya and its turning about 2500 rpms less in the cut than it should be once under load and listen to how the motor sounds . Its producing a ton of heat because your making it lug . You go ahead and run your 8 pin, I will stay with 7 pin, I have seen guys run 9 or 10 pin gears on saws , they thought it was faster but on video it was not  

Did ya look at the video?  The saw has a tach on board and it's doing 11,500 in the cut.

So you want to spin a 034S at 14,000 rpm?   kaboom!!!

[Mad Professor]

My brother Dennis here ran a 7 pin on his Mac 101, he was getting times in the low 4 second range in 3 cuts with cold start included.
His saw has a 34mm carb and the pipe has a inverted stinger.
Look at them chips fly.

(Image hidden from quote, click to view.)

But how did he finish the cuts, after the chamber hit the cant?

[Mad Professor]

ya and its turning about 2500 rpms less in the cut than it should be once under load and listen to how the motor sounds . Its producing a ton of heat because your making it lug . You go ahead and run your 8 pin, I will stay with 7 pin, I have seen guys run 9 or 10 pin gears on saws , they thought it was faster but on video it was not  

Yea, sometimes ya need a 7-pin.
And those 034/036 don't have any torque either........

[HolmenTree]

But how did he finish the cuts, after the chamber hit the cant?

Seriously!!

[ehp]

its not turning 11500 in the cut when your leaning on it , Im talking the fastest way threw the block not making a video of a saw screaming doing nothing in the cut , Hell Man, over half the 0-81cc methanol /nitro stock appearing  saws are running a 8 pin so your going to tell me a saw of 60cc or less on pump gas is going to cut faster running a 8 pin and next time put the saw in some real wood, not that paper soft stuff , that's about like cutting white pine

[HolmenTree]

Well said Ed.

[HolmenTree]

But how did he finish the cuts, after the chamber hit the cant?

Those Mac pipes are offset away from the power head to allow clearance from the log.
Here's two pictures from 1982 at The  Pas, Manitoba Canada during their winter festival.
In the  first pic is me with my 090 and my 2 brothers Dennis and Cliff in the back with their Mac 101's. All three of us were timber fallers at the time.
The guy with the red hat cutting with the 3rd Mac 101 is Jack Quinn a skiddder operator from the area. His cutting skills shows as he cut into a line on the log and was disqualified.
Last picture is brother Dennis winning it.


 

[ehp]

who built the 090, I know Marcel sent a couple 090's out that way

[HolmenTree]

who built the 090, I know Marcel sent a couple 090's out that way

Ed,  I built it myself. Madsens  built the pipe did the cylinder.
I fitted a 100cc kart reed valve manifold on it and put boost ports on the piston skirt. Then installed the 34mm Mikuni alky carb. This was my very first hotsaw build. Trouble was I was running a 11 pin sprocket on it and never won many races.
As last picture shows at the time our competition was a 400cc Husqvarna dirt bike saw built by Husky dealer Jim Hayes from White Fox, Saskatchewan.


 

 

 

[ehp]

ya that pipe could use a lot of help on the 090, first real racesaw I ever built was a 090 , the faster I made it the more money it cost in parts , got to the point I think a top fuel dragster was more dependable . first real problem is the crank with the flywheel sitting out so far away from the crank bearings and case is sure a weak link, it would break a crank as fast as it came out of the wood , took new crank and machined it to take a 064 flywheel in close to case and bearing , put new 064 coil in saw. crank breaking was fixed so switch to methanol with 20% nitro . Got saw to handle that but then the clutch would not handle the power and once I got that fixed I could not get clutch to stop slipping on the crank . Sure was a learning curve but helped me figure out how to solve problems . It was pretty fast but just never knew when trouble would show up so parked it and went with 3120

[HolmenTree]

Madsens admitted the pipe was built for a Jonsereds 111 so didn't charge me for it. Still worked ok for size of wood I was running it in.
I had more plans for the 090 like a cut off head and epoxied transfer covers.
I did run it without the flywheel fan plate and got rid of the clutch. Made it direct drive with a 11 T spur sprocket and machined hub screwed onto the crank. Saved quite a but of weight and better spoolup off a cold start into the wood.

My next project was my last with the Yamaha YZ bike engine. Had alot of fun building and running  it over the last 30 plus years. Still a tough little little engine.

[ehp]

i was running a 13 tooth at the end at a rpm the 090 was never meant to see

[HolmenTree]

Ed did you ever see anyone put a full circle crank in a 090?
It seemed everyone in the upper level of competition back in the 1980's was running a stock appearing saw with those crankshafts.

[ehp]

ran I seen lots of full circle cranks , not really a fan of them . They tighten the crankcase up but you end up not being able to move much air inside engine compared to full race porting with a stroked crank . But the full circle crank sure makes building a carb a lot easier to run on methanol/nitro  , mainly cause it doesnot move as much air so no need for lots of fuel , The limiting factor is the amount of fuel a carb can move and how much torque/power can stuff like the crank take before it breaks , On gas you donot have this problem but on methanol/nitro you do have this problem

[ehp]

On crankcase volume , there is a lot of things that go into this area and a lot more than a lot of people think goes into this , crankcase volume is very important on how much power a motor can produce . A stroked 3120 that is 60 mm bore by 46mm stroke has a ratio on 1.47 to 1 , the perfect ratio is 1.20 to 1 but to have that you would need to build a new crankcase with larger volume . Now on gas you could supply enough fuel to feed the motor at that ratio but on methanol/nitro that would most likely never be done , If motor was ported and piped to any kind of a race saw you just could not get enough fuel to it with a single carb which rules state we must use . The difference in hp is about double using a 1.20 ratio crankcase over the 1.47 . Main reason for double hp is cause the 1.20 crankcase  can move double the air volume and to make power you got to move air . You cannot compare a chainsaw engine to say a snowmobile engine. Most chainsaw motors are built with the bore/stroke ratio being totally backwards to a snowmobile engine so if you do the crankcase volume ratio on a snowmobile engine its a lot closer to the 1.20 ratio .

[EZTundra77]

Yep my 395XP came from the factory with a 7 pin 3/8" rim sprocket for good reason.

Work saw with a round filed chisel chain no matter what cc 7 pin is the best.
Race chisel bit chain thinned out, cutter square filed half ways back, .015 lowered depth gauges you can get by with a 8 pin fine in smaller logs with a work saw.
But round filed chisel chain sucks the power out of todays high revving work saws.

Race saws....I once had a Stihl 090 I raced that was ported etc on a tune pipe. Madsens from the PNW saw pictures of my small logs we cut in our contests. They said you need a 11 pin sprocket on the 090, I believed them and got beat by the Mac 101's race after race.
Then I found out they were running 7 and 8 pin sprockets on the Macs, I put a 7 on the 090 and was then beating them or keeping up to them.

My 40 horse YZ125 bike saw I run a 11 pin sprocket. Works good for big and smaller wood.

My buddy gave me a bunch of spare parts including 8 pin sprockets for my smaller 036 pro, my 362 CM, my 462 CM , and my 661.  I could swap them easily.  But everything Ive seen shows a loss or torque.  If I was running a 20" bar on the 661 or a 16" bar on the 462 -having massive torque to spare- I might run an 8 tooth.  But in my real world, those 8 pin sprockets will stay in the tool chest.