Re-doing my chainsaw hybrid the right way!

[Sloppyslopster]

Are you talking about this thread? I originally thought he was using bushing in his con rod, but I messaged him privately about it and he explained what he was doing and yes, that would work. However he had trouble even finding those bushings because of how thin walked they are.

372xp Big Bore w/ Tillotson carb (a true 80cc)

Hyway 372xp big bore cylinder which would be for a Husqvarna 372xp chainsaw (52mm x 38mm). The crank bought by Don Butler initially claimed to be balanced to 52%, turned out to be only 35%. To rectify this, I bored out the original holes and drilled them deeper, achieving 50% balance. The...

motoredbikes.com

I edited my reply before with the post I'm talking about. But I can read through this too maybe.

This might be the worst part yet with this build lol. I thought drilling the holes was going to be a nightmare but jeez cranks for these are a pain.

So my option right now are:

By a 38mm long rod crank

1. Either bore the small hole to 16mm
2. Swap rods in the 38mm crank
3. Use bushing in the 38mm crank

Leaning more towards drilling the hole to 16mm. Swapping rods will just cost too much over time with truing and the bushings seem to suck overall. I think my current crank has that lol, it's an af80 that fits the 16mm bearing and weirdly the hole is offset.

I contacted a seller on ebay who's selling a crank with a long rod on it, just waiting to hear back to see if its a 38mm

 

[Gordy]

Actually you know what I could do to make my life easier. I saw a post on here were a guy just uses a stock 38mm crank and puts copper bushing inside the piston to make it use a 10mm pin. Funny enough you were first reply lol: https://motoredbikes.com/threads/how-to-run-a-12mm-piston-on-a-10mm-pin-crank-w-photos.64685/


I'll also keep looking around to see if I can find a 38mm crank with a long rod.

That's the same fellow I talked with. He's got a good idea. Why not order the bushings he has a link to on that thread.

 

[Sloppyslopster]

That's the same fellow I talked with. He's got a good idea. Why not order the bushings he has a link to on that thread.

That was my original intention yeah. I rather just go off of someone elses work and not waste more money lol.

 

[Sloppyslopster]

Ok probably gonna buy this crank. It’s got a long rod on it and the rating is 3.7 solely because a guy didn’t like it was a long rod 38mm crank. Perfect for me lol.

Edit I bought this one; https://www.ebay.com/itm/1956178243...n:1&_trksid=p2380424.m570.l5997&ul_noapp=true

 

[Chainlube]

Adaptor plate? Like they do on minarellis? Saws don't need them that's why I cut need holes in the case. Only things I have to do is sand the case's bore out by like 2mm, tap new threads which will be M7, then bore out the ms660s bolt holes to 7mm or 9/32'', and also modify the piston because apparently the slot where the piston sink onto the rod to line up with it is just barely too small to fit the bearing. But a small amount of shaving it all it will take. Looks like less than a mm on each side.

Edit: just found out you have to cut the 660 jug in order for it to actually fit. So I'm not going that route.

What covers up the big gaping hole?

 

[Gordy]

What covers up the big gaping hole?
View attachment 216448

JBL weld. Put some blue painters tape inside the case to keep it from getting everywhere in the case, and JB weld it.

 

[Chainlube]

JBL weld. Put some blue painters tape inside the case to keep it from getting everywhere in the case, and JB weld it.

NO! A plate will cover the hole and help adjust the squish.

 

[Sloppyslopster]

NO! A plate will cover the hole and help adjust the squish.

No Gordy is right you’re supposed to use jbweld to fill the holes. Marine weld specifically. People sometimes make copper gaskets which can fix squish too. Just using a plate will cause fuel to build up and leak out.

 

[Gordy]

No Gordy is right you’re supposed to use jbweld to fill the holes. Marine weld specifically. People sometimes make copper gaskets which can fix squish too. Just using a plate will cause fuel to build up and leak out.

A plate will also leave more.case volume and harm performance.

 

[Sloppyslopster]

Hey I know this is a random question, but does anyone know if the newer yd100s come as a 38mm stroke like the CDH ones? This doesn't really apply to my current project, but I have a really interesting idea I might try out after this is done that could be really good for others.