Time to get familiar with Dolkitas... picked up a 6401 today.

Isn't that an argument for getting the OEM jug if you aren't going to modify it?

 

My vote is big bore kit... or sell it to me for $30 and have a 100% ROI !!

 

Great read here, sorry no suggestions but hedge is saying you can port a 79cc OEM, (effectively by good builders) whereas the AF 84cc not so much....I think anyways.

 

Yes and no...
If cost is a factor, then good, solid, bolt on power is available from an 84cc BB kit... It will run fine, and be cheap...
The best scenario, where price is not an option, is the 79cc OEM jug...
Performance equal to the BB kit, with mod potential... But more $$$.
BB kit don't mean more hp... Just means different power... More torque, not necessarily more speed...
Less$ though...

 

I'll probably let those options marinate for a day or two. Regardless, I'll need to grab a new impulse line, base gasket and may as well get a wrist pin bearing and some OEM retaining rings just to be sure. In the meantime I can try cleaning up the cylinder and rinse the crankcase out in case there are unseen particles of something or other hiding in there.

Does anyone have clever suggestions for removing the thicker globs of aluminum from the cylinder bore? I've used Mastermind's mild abrasive method once on lighter deposits, but I'm hesitant to go flapping big pieces of flexible abrasive at such small targets. It's tempting to lay a fresh utility knife blade in there and see if I can't slice 'em off sideways. The plating has to be harder than utility blade steel if it tolerates constant friction with the piston ring... right?

 

Sanding will get it. The lining is hard to grind through with sanding wheels

 

What's this base gasket talk? I'm sure Hedgerow knows the factory squish on your options and can talk you out of a gasket.

 

I think I even already have the appropriate sealant, but I haven't ever tried measuring squish, or done any other sort of mod. I've never had a chance to even try a non-stock saw, so I don't really know what I'm missing.

Right you were. I've sanded out the aluminum transfer, and underneath it I did find some minor scuffs in the plating - the sort of marks I can only see under very bright light, and can't feel at all. I scraped the little lump of aluminum off of the piston ring too, and then used the piston to push the ring down the bore, examining the fit at various points. I have a little LED reading light with its head on a long flexible stalk, so I put that light inside the cylinder on the far side of the ring. Towards the bottom end of the cylinder the ring springs out a little into the transfer ports and pulls away from the bore a bit so I can see a sliver of light between the ring and bore, but the slightly scuffed area doesn't pass any more light than the unscuffed areas. Above the transfer ports the ring fits as close to perfectly as I can see - no light at all comes through. Tonight I'll use a Mastermind-style arrangement to run a square of Scotchbrite through it just to finish the cleanup. I'll post photographs in the morning.

 

I figured it would clean up. Motoseal is what I use.

 

Yup, I have a tube of the same from when I rebuilt my 350.

 

For the curious, here's the intake side of the cleaned up cylinder in the merciless glare of my LED reading light, with the contrast amped up to make the detail stand out. I didn't bother with an exhaust-side pic because it cleaned up perfectly.

I'm not sure what to make of this sort of broad scuffing, but if there's a smoking gun here I can't see it.

 

If you can't feel anything with a finger nail then it's probably just discoloring.

 

It's a little more than discoloration, but not much. I can't feel anything with a fingernail, but there are 2 or 3 spots where I can feel a bit of a catch or roughness by dragging the corner of a steel ruler across. The whole intake port is only half an inch high, so we're talking about a line that's maybe a quarter of an inch long, and a rough patch that's about an eighth of an inch across.

 

Unless you have any intention of keeping this saw, and as good as the jug cleaned up, I'd be very tempted to put in a new piston and send it down the road for a nice profit. Heck, even if you do plan on keeping it, I would run with that jug for a while...you could always sell it later if you wanted to go big bore down the road.

 

Yes, it would be easy to make money with this one, and I realize this cylinder is pretty darn good whether I keep the saw or sell it. I suppose the main reason I'm thinking of upping the displacement is to make it easier to rationalize keeping it. Restored to stock, keeping it would make no sense because it's capabilities are too similar to other saws I already have.

 

From what I can see, Meteor doesn't make one, and even the OEM pistons are unavailable except as part of a whole top end kit. All I'm seeing is cheaper aftermarket stuff. Anyhow, I suspect you're just trying to get me to make it a 6400 so I'll have no need for it and put it up for sale.