HolmenTree bikesaw projects.

[HolmenTree]

Little update here. My welder did a beautiful job welding up the YZ125 and cr250r fuel tanks with built in chain oil tank.
He used mig on the exterior and tig on the interior oil tank . These tanks are solid !
Now I can get the carbon fiber sideplates with bar pads all done up.
I'll have to do the project on the rainy off days as I'm  back into the start of my tree service season.


 

 

 

[realzed]

See you are officially 'snowless' Willard - but maybe it is not a good thing to say that too loudly though just yet - eh?  
I made the mistake here and said that and we got 6" of the crap a week back a couple of days later..
Not bad weather now - but lots of stuff to get done with before our second season starts here (Bug Season) which I think will 'kick off' later this week!
Ever hear from your engineer friend from last years' accident?  Got wondering how he made out..
Randy

[HolmenTree]

Randy, yes spring or maybe it's  summer now has finally sprung. It's calling for rain later in the week which will get the tree buds opening and get some much needed greenery.

No.I haven't heard from Chris since his train derailment accident, besides being one of his customers at his dealership we weren't all that close.
He sold his gas station and car wash and his wife and grandson are still running the Stihl dealership.
Yep really good people.

[HolmenTree]

remember vibration is your real enemy so make sure you have as close to zero as you can get . the more the saw vibrates the harder it is to keep the chain on it . If your using .080 gauge chain you can buy bars from Oregon that fit up to 18 tooth , the one harvester  runs a 17 or 18 tooth gear

i run a ctl harvester. i like sthil  chain doesn't break as often as others. sthil makes 2 one is heavier. oregon 18x cuts as good but weights less if that matters to you. the new 19x i was told takes a lot of hp. i have not tried it. a oregon speed max xl bar comes in lots of different widths and taper towards the sprocket. all 404  80 rakers at .050  

I like the look of the 19X. Alot heavier then the 18X and cuts faster from reports.
Speed max XL bar and 16- 18 T sprocket looks like a good setup.

Oregon doesn't recommend the 19X on spur sprockets , they say rim sprocket only.
What do you guys think?

[olcowhand]

Willard,
Until I started reading your posts, I didn't know the difference between a Spur Sprocket and a Rim Sprocket.... I personally think there's less "lash" in the Rim Sprocket over time. The Chain wears grooves in the Spur type.
For your application, I have no expertise or opinion, but I trust yours... I'm just following because you've got a cool build going.
Steve

[HolmenTree]

Thanks Steve, I got plans for the 1992 066 too.
The spur sprocket is actually preferred turning the chain on these high powered hot saws.
I've always had one on my 37 year old Yamaha and I never threw a chain.

Now I'm thinking why Oregon recommends the rim sprocket on the new heavy fast cutting 19X harvester chain is dangers of chain shot.

This heavy 65 hp rated chain running with a 16-18 tooth sprocket would be putting out some major chain speed .
The result of breakage from a derail when the spurs teeth grap onto the chain can cause some serious damage. Especially when pieces of chain are flying everywhere.
We all know how little happens when we derail a chain on our chainsaws with a rim sprocket.
But the spurs if properly tensioned  are easier on the chain and derail less then a rim.

[HolmenTree]

I can't find any information from the Stihl websites on harvester bars and chain.
Nothing pulls up on a google search.

[HolmenTree]

Still pecking away at the projects. 
Limited time as my tree service season is full on.


 

[snowstorm]

I use sthil.404 harvester chain. As far as I know it's still made. Only bought one of there harvester bars. That was enough. It was made in Brazil. No give to it and it broke. The best bar is painted blue. Lggesund forest. One tuff bar

[HolmenTree]

I use sthil.404 harvester chain. As far as I know it's still made. Only bought one of there harvester bars. That was enough. It was made in Brazil. No give to it and it broke. The best bar is painted blue. Lggesund forest. One tuff bar

snowstorm,  this must be for a processor you're running not a hand held hotsaw....or you'd have arms big enough to rip trees out of the ground breaking that bar :D

[Tacotodd]

I know that I'm still looking forward to more of this thread. I'm looking forward to it every time I log on. I guess my wants are small, but I bet that you all would like to see how it comes out as well. Yes, I mean EVERYONE, including you, Willard.

[HolmenTree]

Yes Tacotodd I'm pumped :D
Going from a 125cc bikesaw to a 250cc model is new uncharted territory for me. Will definitely keep the rakers higher on this one.

[Air Lad]

So I'll try  both saws with the Mikuni SBN 38mm jetski gas carb. Then if it works out for both, the next new SBN 38 I'll buy will "probably" be a alky carb.
Not sure yet which motor will get the alky carb and the other running race gas.


 

 

Crikey... My old RM250B had a 36mm Mikuni . Come to think of it my 900 Ducati had 2 x 40 mm Delorto's ,that's 40mm each 450cc cylinder( actually the 900 Duc was 864cc, but still?). Enjoying seeing your project/s unfold 

[HolmenTree]

So I'll try  both saws with the Mikuni SBN 38mm jetski gas carb. Then if it works out for both, the next new SBN 38 I'll buy will "probably" be a alky carb.
Not sure yet which motor will get the alky carb and the other running race gas.


 

 

Crikey... My old RM250B had a 36mm Mikuni . Come to think of it my 900 Ducati had 2 x 40 mm Delorto's ,that's 40mm each 450cc cylinder( actually the 900 Duc was 864cc, but still?). Enjoying seeing your project/s unfold  

Moto cross engines with reed valve intakes from about 1981 and newer have huge intake and port flow.
My YZ125 was handling no problem a 40mm + snowmobile carb.
These 125 mx motors have port flow with much higher rpm capabilities to match the larger 250cc engines.
I'm thinking running the same size 38 SBN on both 125 and 250 hotsaws.
But there is one other similar carb in 38 and 40mm that the Honda cr250r may get.
I've decided Alcohol fuel is no longer in my plans. Definitely will not run it now.

[HolmenTree]

@Evanguy
How is your 1984 CR250R hotsaw project progressing?
I have a photo here of a rough mock up of my 1983 CR250R project.
I found a CR250R 2003/04 FMF Fatty pipe from Royal Distributing (@ehp) hometown area. They blew them out on sale for $259 ($170USD). Can't go wrong with that!
Also bought 3 harvester .080" bars out of Alberta for $100 each. 22" 25" 28". The "22 was back ordered and coming to my door this week.
Harvester chain coming out of Quebec.

Now to get the fuel / oil tank moved 2" rearward and bolted in. Modify the pipe and get it mounted.


 

 

[joe_indi]

Willard, I am on a couple of bike groups especially the 2 Strokes of the early 80s. It would really be something to see your Yamaha powered saw in action.
Would it be possible for you to upload a clip to YouTube and post a link.

Please! smiley_biggrin01

[HolmenTree]

Joe,
I will have videos to post in a month or 2.
I have no videos of the YZ125 cutting when last filmed over 30 years ago. My brother has some on VCR tape that could be transferred to digital DVD. But he lives half way across the country.

The 1980's motorcycle 2 strokes were very strong and simple to work on.
My 1983 Honda CR250 design is the last year with a cast iron sleeve and no exhaust power valve.
1984 Honda introduced aluminum cylinder bores plated with Nikisel and the complicated power valve in the exhaust port.

In 1997 Mr Honda admitted the transition to Nikisel in 1984 was for cost savings and faster factory production runs. But cast iron lined aluminum cylinders were more superior in lubricancy,  better compression capabilities and more rigid durability for maximum power.

[ehp]

you sure that pipe is going to work on the 250, totally different engine design , 2002 to 2007 cr engines are different than the test 

[ehp]

your pipe is for a crankcase with reed block mounted in it, your motor has that on the cylinder , port timing is different as well

[HolmenTree]

No problems Ed. This is a Fmf 2003-2004 CR250R pipe.
The 2003 CR250R has stock 188-189°exhaust with 129-130° transfer porting same as what my 1983 CR250R will be ported to.
Plus same bore stroke,. Same identical exhaust transfer cylinder port design and sizes. Case reed versus my cylinder reed makes little or no difference .

I'm cutting the header pipe to fit my horizontal engine. Plus it will be adjustable for length for tuning.Same with an adjustable stinger.
It will take some adjusting and testing but will all work out.

[HolmenTree]

Just to add...

Ideally a handmade cone pipe  custom built to a custom built blue printed engine is the ultimate way to go...but if no dyno testing is done the custom pipe may mean nothing even if the computer program says it should work that way.

My wife and I have August long weekend 2021 booked for Squamish,B.C. Logger Sports. If there is one next year??

[HolmenTree]

Great practice and testing b/c for the CR250R bikesaw!

[HolmenTree]

My tree service isn't allowing any free time in the workshop tinkering with the hotsaw projects. 
So found a hour last night to clamp a bar/chain onto the Honda for motivation.  :D


 

[lxskllr]

What's the difference between a "practice" bar and a "production" bar in a race scenario? What's the practice bar lacking?

[SpaceBus]

Wow, lots of great reading to do!