61 vs 272xp intake block and carb

[Oldtoolsnewproblems]

when i was rebuilding my 266 I got a too-good-to-pass up deal on a 52mm piston/cyl kit for a 272, which I was told is a bolt-in upgrade. BUt when i opened up the saw the old cylinder was in perfect shape so i just re-ringed theold piston and its running a top now. Fastforward 2 years, now I have a 61 that makes about 35psi on crankover, so I think I have a use for the 272 kit. However the intake bolt pattern is different, so I wanted to make sure that if I bought a 272 intake that I can use one of my old carbs. looks like I have a spare HS224 carb, which was the bigger of the factory 266se carbs, so if that fits the 272xp intake then I'll be a happy camper. otherwise I guess I have to buy a carb as well.

 

[Karrl]

A tillotsen 224 will fit on a 268 intake which I’m pretty sure is the same as a 272 intake. You’ll have to cut a small hole in the cover for the spark plug to fit with the taller cylinder. Ironhorse on yt has a few videos where he talks about converting and the differences in that chassis of saw.

 

[Woodslasher]

A 61, 66, 266, or 268 carb will bolt right on to a 272 cylinder. Carb bolt spacing tends to be pretty universal in some senses. For classes, such as 60-80cc, or models, like Tillotson HS*** carbs, the spacing tends to be the same.

 

[drf255]

I’ve personally done the conversion.

You need the 272 intake tract, but your smaller 266 carb will work.

The spark plug is at a different angle on the 272 jug, so the boot will rub on the top cover but the cover will still fit. Also, if you have the metal brake handle, the decomp valve won’t work and has to be plugged.

 

[Oldtoolsnewproblems]

Fantastic! At first I thought nothing would fit because my dumb brain had convinced me the carb bolts go thru the intake into the cylinder. Now that I see they're seperate I'll be following your tips. Modifying the cover is nbd, I'll make a pop up to keep dust out. I have two or three metal brakes, fingers crossed I have a plastic one but I'm also ok with ditching the decomp. One less thing to break. Are they really needed, or just nice to have?

 

[drf255]

Yeah, it’s strange. The 266 intake block is bolted to the jug, then the carb and elbow bolt to that. The 272 is more traditional long bolts through entire intake assembly from elbow to jug.

The top cover will fit without any modding, it did for me. The boot will just rub a bit.

Decomp valves are nice but usually not needed in 70cc or under stock saws.

 

[huskihl]

You’ll need the m4 272 carb bolts and insulating sleeves also.