Author Topic: HolmenTree Bikesaw Resurrection  (Read 1532 times)

0 Members and 1 Guest are viewing this topic.

Offline HolmenTree

  • Nitro Hotsaw
  • *******
  • Posts: 1378
  • Karma: 195
  • Location: Manitoba Canada
HolmenTree Bikesaw Resurrection
« on: December 29, 2016, 11:19:41 pm »
Well here we go. :)
I pulled my old relic from out of the attic, a 1982 Yamaha YZ125J bike saw I built 33 years in my garden shed when I was a young 25 year old timber faller.

Thanks to inspiration from saw restorer Ken Steeves  I've decided it's time to completely redesign and rebuild the old YZ125. Which as a matter of fact put out more horse power then all the other factory 125's during that era. Only trouble was ...left hand drive.
As I go through this rebuild project thread I'll show pics and explain how I originally built it right hand drive through inspiration from former Hot saw legend Gary Walrath with his Yamaha 292 Thunder Jet snowmobile engine saw . But our saws were different.... the chain turned backwards.   :o
Threw rooster tail chips like crazy on the down cuts and pulled in nice on the up cuts. But was a handful to hang onto ;D
I rebuilt it to left hand drive and worked well for me over the years with our central region 10"10"- 12"12" three cuts all down modified events.

But since retiring from competing for 25 years and since only sponsoring and running my own little yearly saw cutting competitions. I want to take one last stab at it and for fun get out the Hytest axes, Mercier bow saw and crosscut along with the YZ and maybe a quick little 272XP.


Making a living with a saw since age 16.

Share on Facebook Share on Twitter

Like Like x 1 Love Love x 1 View List

Offline HolmenTree

  • Nitro Hotsaw
  • *******
  • Posts: 1378
  • Karma: 195
  • Location: Manitoba Canada
Re: HolmenTree Bikesaw Resurrection
« Reply #1 on: December 30, 2016, 12:39:34 am »
Now you're probably wondering why I didn't build a 250 moto cross engine saw.
Well way back in 1983 my intention was to compete exclusively in the Canadian PNW.  Canlog rules out there maintained 140cc maximum displacement for hot saw.
So I went 125 ...with over 30 horsepower factory they were competition for the Kart saws.

So here I am wanting to redesign my Yamaha 125 with massive weight reduction and compactness. Already the powerhead only weighs 32 lbs with lots of room to get it into the 20's.
So with my plans to go right hand drive I had several decisions....rotate cylinder and piston and ignition then run engine backwards, or....rotate crank and ignition, or....Lay engine on back with carb up to right hand drive and run engine rotation backwards with ignition reversed 180 degree .

Well I concluded after pulling the rewind housing and the starter cup off the rotor. Why not run the drive sprocket off the rotor.
From looking at the Jack Stewart/Sven Johnson 250 CanAm Rotax bike saw rebuild that Ken Steeves did...the drive sprocket was driving off a single long shaft held to the crank with 8 small screws.
 This shaft held the ignition, clutch, rim sprocket  and rewind starter. And that powerfull saw won Hayward, Wisconsin 7 years in a row. 8) Best time 8.03 seconds in 3 cuts of 20" pine with cold start.

So as my pics show with the starter cup removed what I'll  do is re-thread the rotor puller threads in the rotor to left hand thread.
Build a 2 piece shaft with both pieces left hand thread. The piece threaded into the rotor will be locked with a internal nut on the crank. Supported by a sealed bearing and seal in a aluminum side cover sealing the ignition. The 2nd piece external shaft will left hand thread into the base shaft with a standard 7 spline welded to it, holding the 11-13 tooth Danzco rim sprocket. With a washer and C clip on the end. Different size rims can be easily swapped for different wood.
B/C will still be very close to crankcase centerline.

A new aluminium rewind rope spool will be mounted on the left side crank end replacing the old 11 tooth spur sprocket.
Left hand rewind rope position will be a natural fit for a quick cold start as the saw is lifted and started at the same time.



Making a living with a saw since age 16.
Informative Informative x 1 Love Love x 1 View List

Offline adam32

  • Piped Saw
  • *****
  • Posts: 429
  • Karma: 46
Re: HolmenTree Bikesaw Resurrection
« Reply #2 on: December 30, 2016, 10:36:28 am »
Ken Steeves did an awesome job on the Rotax! I sold that saw to him. Great guy too!

I'll be watching this thread, should be really cool!!!
Like Like x 2 View List

Offline HolmenTree

  • Nitro Hotsaw
  • *******
  • Posts: 1378
  • Karma: 195
  • Location: Manitoba Canada
Re: HolmenTree Bikesaw Resurrection
« Reply #3 on: December 30, 2016, 10:58:41 am »
Thanks Adam.
 Yes I meant to mention you owned that "original Rotax hotsaw" . Very cool engine with the dual HR's on a rotary valve. With a little redesign that saw could still be competitive today.
Making a living with a saw since age 16.
Like Like x 2 View List

Offline adam32

  • Piped Saw
  • *****
  • Posts: 429
  • Karma: 46
Re: HolmenTree Bikesaw Resurrection
« Reply #4 on: December 30, 2016, 11:49:51 am »
Thanks Adam.
 Yes I meant to mention you owned that "original Rotax hotsaw" . Very cool engine with the dual HR's on a rotary valve. With a little redesign that saw could still be competitive today.

I agree.

 I thought it was 330cc? I never measured it though.

Offline aclarke

  • Nitro Hotsaw
  • *******
  • Posts: 1676
  • Karma: 172
Re: HolmenTree Bikesaw Resurrection
« Reply #5 on: December 30, 2016, 05:44:39 pm »
Super cool, really like the lightweight bar!
How does the big tillotson (HR/HD?) work?

Adam

Offline HolmenTree

  • Nitro Hotsaw
  • *******
  • Posts: 1378
  • Karma: 195
  • Location: Manitoba Canada
Re: HolmenTree Bikesaw Resurrection
« Reply #6 on: December 30, 2016, 10:19:18 pm »
Super cool, really like the lightweight bar!
How does the big tillotson (HR/HD?) work?

Adam
Big Tillotson HD 42 mm works really good Adam. It's got H and L screws which makes it super easy to tune. Very reliable carb, there's a return line that cycles unused fuel back to the fuel tank.
I had a smaller 34mm HR on it when I originally built the saw with the engine laying horizontal with the chain cutting backwards on right hand drive.

Here's some pics of the original setup. Plus some pics of Gary Walrath's world record time setter 292 Yamaha Thunder Jet hotsaw back in 1984 in Estacada, Oregon. Also cuts backwards while throwing wood chip rooster tails 70 feet.


Making a living with a saw since age 16.
Like Like x 1 View List

Offline sharkey

  • Piped Saw
  • *****
  • Posts: 367
  • Karma: 37
Re: HolmenTree Bikesaw Resurrection
« Reply #7 on: December 30, 2016, 10:23:55 pm »
Really cool project!  I kike that Newspaper clipping too. 

Offline HolmenTree

  • Nitro Hotsaw
  • *******
  • Posts: 1378
  • Karma: 195
  • Location: Manitoba Canada
Re: HolmenTree Bikesaw Resurrection
« Reply #8 on: December 30, 2016, 10:43:48 pm »
Really cool project!  I kike that Newspaper clipping too. 
I remember that event like it was yesterday.  Thompson Manitoba Winter Festival. We qualified outdoors Saturday the day before when it was around 40 below .
Sunday afternoon we did the finals inside a hockey rink with 2000 people jammed to the rafters cheering us on. Rick McIvor ran a 600 Polaris Indy snowmobile engine saw with triple tune pipes..
 We made lots of noise in there lol.
Making a living with a saw since age 16.

Offline HolmenTree

  • Nitro Hotsaw
  • *******
  • Posts: 1378
  • Karma: 195
  • Location: Manitoba Canada
Re: HolmenTree Bikesaw Resurrection
« Reply #9 on: December 30, 2016, 10:52:34 pm »
I made some noise with my ole 090 before the YZ. Had it setup on alcohol with a nice 34mm Mikuni alky kart carb. Direct drive with no clutch, fan wheel and oil tank.

090 couldn't beat my older brother Dennis's Mac 101 kart saw though. The Mac also ran a 34mm but on gas.
Making a living with a saw since age 16.
Like Like x 1 View List

 

Related Topics

  Subject / Started by Replies Last post
14 Replies
1017 Views
Last post August 06, 2020, 08:42:03 am
by Cut4fun
3 Replies
423 Views
Last post April 12, 2012, 06:17:11 pm
by EHP
2 Replies
281 Views
Last post April 06, 2013, 10:31:16 am
by EHP
1 Replies
260 Views
Last post April 23, 2013, 08:31:21 pm
by Cut4fun
12 Replies
554 Views
Last post March 10, 2014, 11:50:48 pm
by stihls066
6 Replies
135 Views
Last post April 04, 2014, 03:36:29 pm
by Vance in AK
0 Replies
202 Views
Last post February 14, 2014, 03:12:32 pm
by SDB777
8 Replies
245 Views
Last post January 16, 2016, 08:15:28 pm
by jmester
4 Replies
64 Views
Last post June 01, 2019, 12:35:38 pm
by Al Smith
0 Replies
36 Views
Last post March 19, 2021, 12:03:57 pm
by Cut4fun .