Porting a ms260

[t4driller]

I'm probably gonna have to wait til Friday to get videos. Wife's car broke down. Spent all ev
ening working on it. I did fire it up again and try to get it dialed in a little better. Spools up real quick and revs out nice. Very snappy. And it sounds nasty.

 

[drf256]

You didn't catch a ring, so all is good.

 

[t4driller]

finally got a video to upload. Here is how it turned out. 18 inch bar .325 oregon chain. Less then 1 tank threw it.

 

[drf256]

Looks great!!

 

[smokey7]

finally got a video to upload. Here is how it turned out. 18 inch bar .325 oregon chain. Less then 1 tank threw it.

Sounds a little lean on the low side. Maybe just a very small amount lean on the hi jet. Very very close. Idle comes a little slow for me. Great job.

 

[Canadian farm boy]

Very nice. Good job!

 

[paragonbuilder]

She's cutting nice! That'll put a smile on your face!!!


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[t4driller]

I'm pretty happy with the way it turned out. The only thing I was thinking about doing was going back in and raising the transfers a little. After reading many of Drf225 build threads, seems like it needs the blow down lowered a little. Also wanted to say thanks for everyone's help. Especially drf225. [emoji2] [emoji2]

 

[t4driller]

Sounds a little lean on the low side. Maybe just a very small amount lean on the hi jet. Very very close. Idle comes a little slow for me. Great job.

Idle does come down a little slow. What would cause that? I'm still trying to get it fined tuned. Haven't had much of a chance to run it though. [emoji20] Kids keep me pretty busy.

 

[smokey7]

Open low screw a 1/8-1/4 turn
Listen for idle to gain or drop. Adjust idle screw accordingly. I'd start there. Good runner. Good job

 

[huskihl]

Yep. That idling high is from added heat from several long cuts in a row. Drf's and mine both do it also due to the heat from added compression. Open your H jet about an hour on the clock and see if it's better. An hour out on the L jet help also

 

[drf256]

I'm pretty happy with the way it turned out. The only thing I was thinking about doing was going back in and raising the transfers a little. After reading many of Drf225 build threads, seems like it needs the blow down lowered a little. Also wanted to say thanks for everyone's help. Especially drf225. [emoji2] [emoji2]

Remember, the enemy of success is perfection.

You're much more likely to make it run worse by raising the transfers. The factory does a great job casting the openings in the uppers. There's a lot more going on there than meets the eye.

 

[paragonbuilder]

If you are dead set on ruining a good thing, like the rest of us! Lol!
Mark out on the piston where the transfers are and file the piston what you want to raise the transfers. Try the saw. Then you will know if the saw likes the added transfer duration. If not pop a new piston in there and you are back where you were.
If it runs stronger you can study those transfers before grinding and try to match what the factory did.


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[t4driller]

That's the thing. Try to make it faster and stronger til you start to go backwards. I agree I should just leave it where it's at and put some run time on it to see its full potential. I'm really happy with the way it turned out.

 

[merc_man]

Thank you for the sound advice. That bottom ring end gap is close. I was still up in the air about running a single ring, but now I'm pretty sure I will just run one. I'll get the jug bolted back on in a little bit and ch3ck timing again. How is it for longevity running a single ring?

How much compression will you loose by going with one ring.

 

[cus_deluxe]

Not enough to worry about

 

[qurotro]

So... I've seen some builders flatten the piston top. Why?

 

[huskihl]

So... I've seen some builders flatten the piston top. Why?

Couple reasons. It’s more difficult to cut the squish band on an angle to match it, and by the time we cut the squish and base enough to get the exhaust down where we like it they have too much compression so we cut the dome off to get the compression back down