61-272 hybrid build

[kfd518]

Have parts on the way, new oem cylinder and piston going in it. I am toying with the idea of grinding in finger and boost ports. I still want to be able to use it for work but want it to be a surprise to folks in sheep’s 61 clothing still including orange 61 top cover and keeping 61 decal. I have an HS 254a carb on hand but it was said that I need to make sure I put a carb that will flow plenty on it.

Questions,
is this a decent idea for the build?

What carb should I use if not the HS254a?

 

[CJ Brown]

Off the top of my head I think the HS-228 is the 272xp carb.

 

[cus_deluxe]

Off the top of my head I think the HS-228 is the 272xp carb.

hs260, 228 was 281/288. ur welcome

 

[CJ Brown]

hs260, 228 was 281/288. ur welcome

Well there ya go - thx Custer!

 

[Adirondackstihl]

 

[Stump Shot]

 

[kfd518]

You hinting something Steve? @Stump Shot

 

[Stump Shot]

You hinting something Steve? @Stump Shot

Maybe...

 

[kfd518]

Some pics I forgot to post earlier split, cleaned and ready to be put back together. Was waiting on most of my parts got bored and polished the cases a bit after I cleaned them due to the degreased dull look that was left after cleaning

Well HS 260 A carb on the way. Crank case together with new bearings seals and oil pump O ring. My idiot but broke my ring though grrrrr new piston ring on it’s way

Squish .022
Exh 157*
Tx 119*
Intake 142*
Blow down 19*

Going to widen exhaust, intake already matches the block.


Old green gasket wouldn’t come off of the block. Carb cleaner wouldn't take it off for nothing. Used a full chisel cutter guided by the molded in seal ring to clean it out. Who would have thought that would be a use for saw chain lol

 

[kfd518]

Decided I’m not going to go all wild and crazy with this as I planned originally since my ports already match what my goal was. Compression might not be STELLAR but won’t be bad by any means .

 

[jakethesnake]

Decided I’m not going to go all wild and crazy with this as I planned originally since my ports already match what my goal was. Compression might not be STELLAR but won’t be bad by any means .

They run really well stock

 

[kfd518]

Well I noticed something this morning that I didn’t catch yesterday not happy about it either. Not happy that it’s there and not happy I didn’t catch it before I put the grinder to it.



They are below the plating so I know it’s not from me, no that is not a pecker track under the transfer either just the lighting.

 

[Mkinslow]

Well I noticed something this morning that I didn’t catch yesterday not happy about it either. Not happy that it’s there and not happy I didn’t catch it before I put the grinder to it.
View attachment 176438

View attachment 176439
They are below the playing so I know it’s not from me, no that is not a pecker track under the transfer either just the lighting.

Wouldn't worry about it. RUN THE SNOT OUT OF IT BUD

Sent from my SM-G892A using Tapatalk

 

[kfd518]

Just figure an OEM cylinder...... and if you look at the lower transfer right below it in the unmarked photo you can see a divot right in line w it in the tx divider. It is what it is though.

 

[kfd518]

Well she is all back together. Thanks to @Stump Shot, for helping me out with an HS260A carb. My wife got a kick out of the carb having been off of a saw from Atlanta Ga as she grew up right down the road. I widened the exhaust and blended the lower transfers to get rid of the lip then sanded the casting marks out on intake and exhaust. Took out the casting flash in the piston windows.
Had to lengthen the plug wire since for some reason it wouldn’t fit up to the plug on the new cylinder. Still have the clapped out 20” that it came with on it, that and husky version of vanguard chain. Have a johnsered labeled Tsumura 20” in 3/8” .063 on its way for it and plenty of Stihl RSL to make a loop or two for it.
Top cover is about 3/32” proud without sucking it down with the screws. Wanting to leave it as a 61 cover though to keep it under wraps.

Edited to add. Timing advanced 6*

 

[kfd518]

Well here’s the first cut, got to 9300 pushing on it. Maintained 10000-10100 without leaning on it. Will see how it does when I get new bar and can put decent chain on it.

 

[kfd518]

Had some fun this morning, modified a cheap bar to put on it. Little 16” 3/8. Loop of archer Full comp full chisel converted to square ground.


Four stroking to 14,300 holding 10,700 in the cut without leaning and still holding 10,000-10,200 leaning on it. Standing on it it dropped to 9,300

Of course though I had to have me helper along this morning as well fixing his saw too.

 

[kfd518]

So ended up with Oregon 20” on it the Tsumura was a hard nose and I didn’t realize it. Going to keep it for a stumping bar. Newer oem c spring clutch as well. Pulling pretty nicely so far. Got about 2 tanks through it so far. It will be gone back into at some time but with no lathe not much point right this moment.

 

[kfd518]

Well, this thing started giving me fits yesterday, I used a cheap Chinese ring when I put it back together, wasn’t happy w it in my mind. I took it apart and put the replacement ring I had ordered for the one I broke in it. Well it started hesitating on return to idle when I put it back together.
Seemed as though I could get it back down to idle by manually pulling throttle down. But no binding could be found with throttle linkage or carb return separate or together.

Reset base tune 3/4 L, 1 H ,same crap.

Thinking maybe I had messed the gasket up when I pulled it apart I cut a new base gasket and used Honda bond to ensure there were no leaks there. Back together fired up, same thing! Check intake tract bolts, all tight!

P&V steady as a rock.

Hmmmm refine my google search words. Found a thread where @blsnelling had advised L might be lean.. also the same found on a 2 stroke bike site... well once again retuned.

1 L, 1 H fiddled with idle speed screw got high end back up 4 stroking. BAM back in business.

Don’t know why I thought 3/4 L was correct when I rechecked settings the first time.
Back to running well though.

Don’t know if I messed up the L screw in my fiddling since I pulled cylinder carb and muff all in one piece. Thought I was careful to set everything down so it would be disturbed.

 

[blsnelling]

Those are nothing more than initial settings, to get you in the ballpark. You have to actually tune the saw based on how it runs.