Clone 660 piston problem

[2kworth]

So I built my clone about 15 tanks ago. It started giving me some issues starting hot after tank fills while milling. Checked all the normal problem areas after it got bad enough that it wouldn’t idle. Found that it’s blowing an excessive amount of fuel out the carb at WOT. I suspect that I should have beveled the intake port a little before putting the saw together by look of my piston. Wanted some opinions to make sure I correct the issue. Cylinder looks good other than the bottom of the intake port’s a little sharp.

I could clean up the intake port and add a new piston.
Attempt to do a woods port, and add a new piston.
Or buy a new P&C.

 

[Wonkydonkey]

Idk if it’s a good way to go, but if it were me, and. If it ran good, I’d just get a cheapo piston and get bevelling the ports, if it ran cr@p then a little timing and porting. And still a cheapo piston.

It really depends if you have the time but if hl supply has a deal on mmws 660 p&c then that’s the way I,d go.
Your mileage may vary

Maybe worth posting a pic of the intake of the jug

 

[2kworth]

Cleaning it up was my thought too. My saw ran great. I had to chase the tune around some but that makes sense given the premature wear. My kit came from HLS and was labeled with cross performance parts not farmertec. I’ve read conflicting information on if they are the same.
Reading the reviews on hls for the mmws P&C some state that the intake needed to be cleaned up. Any idea if this is the cylinder that was supplied with the kit?

I will do my best to bevel and clean up the port, while putting in a new piston. Before and after pics for a double check from some experts.

 

[Wonkydonkey]

I,m guessing you’ve read those rice burner builds sub forum threads. Iirc there was a bit of ring damage and a few other things, and peeps were saying to bevel /smooth the edges

It’s a lot of reading but worth it IMO

Cheers

 

[bottlefed]

Just built my first 066 (however mine was direct from Farmertec) and on mine if you placed the piston in the bore and applied light pressure with a finger to the skirt it would flat catch the skirt on the edge of the port. I rounded the port floor slightly (it was dead parallel to the piston skirt) and also chamfered the edge significantly. After doing this you could apply all the pressure you wanted and there was no catching. I am sure mine would have chewed the skirt if I had not.
Hopefully its just the picture and my poor eyes but the big end rod bearing looks like it may be discolored, hopefully this is not the case and the only damage is the piston skirt.

 

[2kworth]

I've cleaned up the port and dropped in a new piston. Got 2 tanks through it and all seems well. Next test is to put it back on the mill and see how long it lasts!!

 

[bottlefed]

Happy milling!

 

[AlfA01]

What mix are you running. Milling is hard on saws, and their parts. I would imagine that running 32:1 mix ratio would help a bit with wear and keeping components (bearings especially) cool during long durations of cutting. A well lubed component is a happy component.

IIRC, most folks run a variety of pistons, but almost all choose Caber rings for AM stuff. They seem to wear better and last longer than other ring manufacturers in the AM world. Port cleanup is a good idea, especially on AM jugs.

Happy milling and welcome to OPE.

Cheers,
Dan

 

[67L36Driver]

Just built my first 066 (however mine was direct from Farmertec) and on mine if you placed the piston in the bore and applied light pressure with a finger to the skirt it would flat catch the skirt on the edge of the port. I rounded the port floor slightly (it was dead parallel to the piston skirt) and also chamfered the edge significantly. After doing this you could apply all the pressure you wanted and there was no catching. I am sure mine would have chewed the skirt if I had not.
Hopefully its just the picture and my poor eyes but the big end rod bearing looks like it may be discolored, hopefully this is not the case and the only damage is the piston skirt.

+1 on the rod big end.