Hybrid clonesaw 365 with a 390 topend - aka the "86'r from youtube"

[jacktheripper]

Any more updates?

 

[Jake Dykstra]

Its all for fun (and learning) for sure but I'm wondering with all the work your doing if the weight will get close to factory 390 weight?

 

[Ketchup]

It’s lighter and smaller. Just the smaller tanks means a lot less weight. You do have to fill it more often…

 

[Jake Dykstra]

It’s lighter and smaller. Just the smaller tanks means a lot less weight. You do have to fill it more often…

Yeah I get it. Im just curious with bigger p&c and crank what it actually ends up weighing.
Dry weight?
Wet weight?
Does it save 1lb? Maybe 1.5lbs?
Certainly the wet weight will be less due to less fluid capacity. But that poses a downside as well.
Guess what im thinking is could I trim 1lb off the 390 and get the benefit of more stroke?
West coast guy here...we need the stroke! Lol

 

[davidwyby]

Take the V6 out of a truck and put a big block in. Negligible. I’m sure the weight is closer to the small saw weight than the big saw weight.

 

[Ketchup]

Mine is all torn apart in a box under my bench. I think it ingested a piece of exhaust gasket. I put a lot of work into that piston and haven’t wanted to bother again. I could weigh the jugs and cranks with some effort. My guess is the 372 is still well under 15lbs with the 57mm jug and 37mm crank. So 1.5 lbs is a rough guess. Add liquids and that will be higher. I liked the smaller frame size for handling as well. She was thirsty though.

 

[Outback]

What was your piston process?

 

[Jake Dykstra]

Mine is all torn apart in a box under my bench. I think it ingested a piece of exhaust gasket. I put a lot of work into that piston and haven’t wanted to bother again. I could weigh the jugs and cranks with some effort. My guess is the 372 is still well under 15lbs with the 57mm jug and 37mm crank. So 1.5 lbs is a rough guess. Add liquids and that will be higher. I liked the smaller frame size for handling as well. She was thirsty though.

Ah shoot. That sucks. I had a 353 that I put lots of time into as well. It ripped for a 50cc saw. Lost a Cclip and wasted the piston and jug. I feel your pain. Still sitting in a box. Im still in mourning so I haven't put the 346 jug that I bought for it on yet. Lol

 

[Ketchup]

What was your piston process?

I took a lot of weight off. Cut the crown, slabbed the sides, cut windows, ground out a lot from inside.
That piston had the original long skirts before Hyway realized they were hitting the case. They’re all much shorter now, which kind of means you have to epoxy.

 

[upstateamish]

Hey hey, it's been a minute. Sorry for leaving everyone hanging. . . I got pulled away on to some vehicle projects and then life got in the way and haven't signed in here for a bit.

Any more updates?

Yes and No. No real chances to run the saw* (it's not here at the moment) but also with the other irons in the fire, haven't had a chance to run any saws.

However, I've got a buddy I grew up with who's got his own machiniest company with cnc capabilities. https://dumpybunny.bigcartel.com/ He typically specailizes in VW swap / Car realted stuff but if you check out his products he's also got dual port mufflers and bucking spikes for sale.

Anyway, I've floated the idea with him to see if he'd be willing / able to make up a jig to do some case modifications that would more easily allow the top end & crank swap. (e.g. clearancing the case halves, maybe bore out bearing pockets, etc.) Idle curiosity but would be fun to be able to make something less artisen and more plug and play.

*I'd sent him my 3rd prototype so he has an idea of the final product and see what I'm looking to do. But, as he's also got lots of irons in the fire, this week he was finally able to fire it up and run it. More to come on this as I keep that ball rolling and I find out what the cost will be.

Its all for fun (and learning) for sure but I'm wondering with all the work your doing if the weight will get close to factory 390 weight?

I'll work on getting you a rough weight of the second prototype I have (it'll be 'roughly' similar to the 3rd)

I don't have a 390 so can't give you a direct comparison, but probably what @Ketchup has said

It’s lighter and smaller. Just the smaller tanks means a lot less weight. You do have to fill it more often…

 

[Jake Dykstra]

My 390 pho weights 19.6 lbs topped off.

 

[upstateamish]

My 390 pho weights 19.6 lbs topped off.

prototype 2 (pho with a 572 clutch cover, half wrap handle) weighs - 16.6lbs topped off with gas/oil

 

[Jake Dykstra]

prototype 2 (pho with a 572 clutch cover, half wrap handle) weighs - 16.6lbs topped off with gas/oil
View attachment 474649

That would be worth the work!

 

[Ketchup]

It’s a ported 94.4cc saw that weighs 16.6lbs. Nothing else comes close to that.

 

[davidwyby]

It’s a ported 94.4cc saw that weighs 16.6lbs. Nothing else comes close to that.

I thought 86?

I think I want one. But autotune.

 

[Outback]

I think the 94.4 quoted is a 390xp crank and 57mm big bore top end on the 372xp case.

Just adapting the 390cyl gives you 85.5cc.

I'm thinking of going the other way. The 385 cylinder should have more piston options and yields 82.45cc on the 372xp crank. Then just giver the cut and port with a custom 383xp sticker.

 

[Ketchup]

I think the 94.4 quoted is a 390xp crank and 57mm big bore top end on the 372xp case.

Just adapting the 390cyl gives you 85.5cc.

I'm thinking of going the other way. The 385 cylinder should have more piston options and yields 82.45cc on the 372xp crank. Then just giver the cut and port with a custom 383xp sticker.

You get more piston options and that may solve the wrist pin difficulties, but you only gain 12cc instead of 24.

At that point you’re really not far from 500i/ 681 capabilities and similar weight. Less squeeze for less juice.

I think it’s worth doing though. Interested to hear what piston you go with and what that does to the numbers.

 

[Ketchup]

I thought 86?

I think I want one. But autotune.

592 jug on a 572?

 

[Jake Dykstra]

592 jug on a 572?

Thats exactly whats on my bench next. 592 should be here next week!
I was thinking of starting with a 585 if I can't get enough weight off the 592 piston.