Willard's vintage Hotsaw Builds

[Willard]

Looking good! How did your dust collection go?

Dust collection went good, I got my other shop vac from the car garage working too.
Next I'll be working with the bench top belt sander and dremel to finish the rear handle and fabricate the fuel tanks.
Call me fussy but I looking at weld on 1/4"or 5/16" aluminum bungs and aluminum fittings for the fuel line, oil line and vents on the tanks. Braided hoses?

 

[Willard]

I read to run methonal bigger fittings/hoses the better.

 

[Bigmac]

Yes methonal burns a half the air fuel ratio as gas, so twice the fuel is used!
This is on of the methonal conversion carbs I did

 

[Willard]

Looks good!
The YZ125 on the bike originally had a 5/16" fuel line gravity fed which is pretty big.
On the saw which is not gravity fed hopefully 5/16" won't be too big for the 38mm super BN alky carb to pump the fuel up about 6" elevation with a 10" long or so fuel line.
There will be a return line back to the tank also

 

[Billy Currie]

@Bigmac OMG, I didn't know someone else had done something similar. I guess it's more common than I thought. I added another nozzle, wide open, no adjustment to it,w a 3/16" copper alloy brake line ran externally. Only an adjustment for the main nozzle.

 

[Bigmac]

@Bigmac OMG, I didn't know someone else had done something similar. I guess it's more common than I thought. I added another nozzle, wide open, no adjustment to it,w a 3/16" copper alloy brake line ran externally. Only an adjustment for the main nozzle.

View attachment 213076
View attachment 213077

That’s cool! And super sneaky!

 

[Willard]

Not much to report.
I'm at the start of my fuel tank build will have pics later today.

While taking a break yesterday I watched a 3 minute video from Bubba out of Arkansas on the importance of crankshaft journal to main bearings interference fit.
Then I came to realize my used crank I bought has the problem with slip fit. Darn money out the window!

But watching this video this morning a guy from Norway says slip fit is good !
I guess I lucked out with the crank.

 

[Bigmac]

There is a fine line with the slip fit, if is is slightly beyond slip the crank will walk and cause an air leak.not good, I will run a tight slip on one side but not both, the thing he is not considering is if the crank can move side to side it will rub the case and loose power and potentially get particles of case material going threw your motor. I think Honda intended for the pto side to be a tight slip fit, I have had many new crankshafts the the pto side was looser, and intended to add in assembly, pull the crank on the ignition side and then the pto side can be slid on with a small amount of heat to the bearing. Another thing to note, is where you get your bearings, 0n Honda’s I only use Oem bearings in a Honda package(also cr500 8 ball) in the trx. Honda gets the best quality, if you get an aftermarket, even koyo, it’s not the same, been through it a few times with aftermarket koyo’s being sloppy, and oem koyo fit tight, just an FYI

 

[Willard]

Thanks Nathan.
Mind you the bearings I tried on the crank are old ones still in the used matched cases I bought. They appear to be OEM but not 8 ball

Doesn't Loctite make a bearing mount that might help?

 

[Bigmac]

I wouldn’t worry about it until you get new bearings, do a test fit and see how they go onto your crankshaft if they don’t want to slide on your good, if they want to come on and off easily I would look at a new crankshaft, you could use the green Loctite this design for slip fit use, I Haven’t used it, but I hear it’s great, but the bearing will also be permanently on there, not quite, but I hear it’s strong stuff!
It’s pretty common for old bearings to be loose,If you inspect your crank drills and the bearing surfaces look super shiny it may have spun the bearings on the journal and the crank is no longer good, but I doubt that’s the case

 

[Willard]

Took some pictures both sides
Caliper says both journals at main bearing areas are 28.06mm approximately.
I can feel a small ridge with my finger nail on the mag side where it steps down to the seal surface. Which is good, better then opposite
It's a snug slip fit and the bearing won't fall off even after tapping the crank ends onto a spruce 2x4
New bearings when I get them in will solve the mystery.

 

[Bigmac]

Took some pictures both sides
Caliper says both journals at main bearing areas are 28.06mm approximately.
I can feel a small ridge with my finger nail on the mag side where it steps down to the seal surface. Which is good, better then opposite
It's a snug slip fit and the bearing won't fall off even after tapping the crank ends onto a spruce 2x4
New bearings when I get them in will solve the mystery.
View attachment 213376 View attachment 213377

That looks good, the black-is ignition side is great, small movement but not spinning, the pto side looks normal too, if it was spinning it would be super shiny. New bearings and you should be golden!
If you buy aftermarket bearings for a CR 500 and they will sometimes come at seven ball, bearings the OEM bearings are eight ball, and as I said before the OEM bearings are a different grade than the ones you bye from aftermarket suppliers, The TRX bearings came at seven ball originally, I believe even most of the newer CR 250s came eight ball, but replacements were usually the TRX style seven ball, I’m not sure what bearing deck dimensions your motor has but if you can get OEM 500 bearings to fit I would

 

[Willard]

The first year 1984 air cooled CR500 has the same 91009 HCO 003 (63/28) main bearings as my '83 CR250R.
Then from 1985 to 2001 the liquid cooled CR500 takes a 91008 KAE 731 bearings.
When I rebuild my crank I'll be setting it up with the ProX rod and bearings kit which fits the CR250R from 1983 to 2001

Also heard the Pro X bearings are from the same Japan plant where the old CR250 OEM parts were made.

 

[Bigmac]

I personally would not run the pro X crank bearings get OEM cr500 crank bearings, they are the same Dimensions as your 250, the 250 and 500 bearings are interchangeable as well dimensionally, I think the designation is seven ball versus eight ball on the part numbers, I’m guessing physical dimensions are the same for the 84 CR 500, they just didn’t have the eight ball yet. I have ran lots of crank bearings, Koyo Is the original manufacture of the bearings, And yes other manufacturers sell them in their name, they will still be Marked koyo,90% of them Are not the same quality as Honda bearings, they are seconds as to quality in my opinion. I have taken a pro X crank bearing marked koyo and had it fall off of brand new crankshaft, never had an OEM Honda do that, still Marked koyo and the same part number. I will never run anything but oem Honda ever again, Unless I have no choice!

 

[Willard]

Thanks for the info. I'll go for the 8 ball CR500 bearings.
I can get OEM Honda bearings and parts through the US and Japanese warehouses from Mega Zip.

 

[Willard]

Nathan, I checked the OEM part #'s for main bearings 91008-KAE 731 they fit all CR250R and CR500 from 1985 to 2007.
So I guess it doesn't matter whether they're for either 250 or 500.
Just from a quick measurement through the crankcase the main bearing inner race is approximately 3/4" wide and they are 63/28mm diameter

 

[Bigmac]

Cool, all of the newer cr250’s I have always ordered the 500 ones to be safe! They aren’t cheep, but the quality is there!

 

[Willard]

Got both saw's fuel tanks with built in oil tanks ready for tig welding. Will weld on the side plates later this week when the weld on bungs with fittings come in.

CR250R has 17oz fuel capacity.
6oz oil.
YZ125 has 14oz fuel capacity.
5oz oil.
Only one major problem, I can't weld the cap bungs underneath the top of the tanks for a 5/16" lower profile.
So it's back to the drawing board with new 6061 2"×2"×1/8" channel and 6061 2"×1/8" flat rectangle.

 

[Willard]

I gotta say I really like the looks of my 1983 Honda CR250R cylinder.

 

[Willard]

Then the next year in 1984 Honda introduced their first CR250R with a power valve.
Butt ugly like a huge tumor on someone's face.