Husqvarna 61 Blacktop - upgrade to 50mm piston

[Marty Lawrence]

Thanks for all your infomation. It seems some of you say the carb & bolts & block will work on a 50mm piston. then others are saying I need to get replacements.
Interestingly I do notice some sellers are selling carbs that say they will fit a 61, 266,268 & 272. Which made me think the original 61 carb would work.
I guess the easiest solution would be a quality P&C kit that matches the original (48mm) and hope I see more power than the cheap P&C.

Out of curiosity what should I see if I do a compression test? How much PSI would be good? I do have an old tester that should give me some indication.
Also how can I easily do a vacuum test without buying extra equipment that I may never use again?

 

[singinwoodwackr]

Thanks for all your infomation. It seems some of you say the carb & bolts & block will work on a 50mm piston. then others are saying I need to get replacements.
Interestingly I do notice some sellers are selling carbs that say they will fit a 61, 266,268 & 272. Which made me think the original 61 carb would work.
I guess the easiest solution would be a quality P&C kit that matches the original (48mm) and hope I see more power than the cheap P&C.

Out of curiosity what should I see if I do a compression test? How much PSI would be good? I do have an old tester that should give me some indication.
Also how can I easily do a vacuum test without buying extra equipment that I may never use again?

You will never see more power with a cheap top end, sorry. A stock 48mm will blow a cheap, Chinese 50 out of the water, period.
I frankly couldn’t care less what some site says about fitment when I have all the parts in front of me showing otherwise. But, do whatever…

 

[Bob Hedgecutter]

Thanks for all your infomation. It seems some of you say the carb & bolts & block will work on a 50mm piston. then others are saying I need to get replacements.
Interestingly I do notice some sellers are selling carbs that say they will fit a 61, 266,268 & 272. Which made me think the original 61 carb would work.
I guess the easiest solution would be a quality P&C kit that matches the original (48mm) and hope I see more power than the cheap P&C.

Out of curiosity what should I see if I do a compression test? How much PSI would be good? I do have an old tester that should give me some indication.
Also how can I easily do a vacuum test without buying extra equipment that I may never use again?

You can do it properly, or you can do it half arsed - mostly you seem to be hinting at the latter. but hey, your saw your choice.
You can use whatever carb you want- but you will need specific blocks and bolts to suit specific cylinder.
Odds are you have a SCA or Repco compression tester- automotive model and it will not give a true reading of a small engine cylinder- but if by some miracle it does read true- anything over 120 psi be good to go.
Go back to SCA or Repco and get a cheap brake bleeder kit- it can be used for pressure and vacuum testing- but you will need to make a spark plug adapter to be able to test easily.

 

[Marty Lawrence]

You can do it properly, or you can do it half arsed - mostly you seem to be hinting at the latter. but hey, your saw your choice.
You can use whatever carb you want- but you will need specific blocks and bolts to suit specific cylinder.
Odds are you have a SCA or Repco compression tester- automotive model and it will not give a true reading of a small engine cylinder- but if by some miracle it does read true- anything over 120 psi be good to go.
Go back to SCA or Repco and get a cheap brake bleeder kit- it can be used for pressure and vacuum testing- but you will need to make a spark plug adapter to be able to test easily.

Thanks, Yep its an old tester for an old car. Might work I'll give it a go.
I have a vacuum pump, or do you think it would be too much vacuum over a brake bleeder?

I dont know why you think I'm being half arsed about it though. i came on here to learn more. I do want a quality P&C. I am pretty sure thats what my questions are about.
I now figure that I would be better just sticking with original sizes so I dont have to modify other stuff. My trouble is the quality brands are hard to find here in Australia, which is why I asked about that Tacsum brand. Am I being half arsed asking these questions?

 

[Gord404]

the trouble with a lot of am cylinders is all about squish and port timing etc- if not close to being correct loss of power

 

[ChillyB]

Thanks, Yep its an old tester for an old car. Might work I'll give it a go.
I have a vacuum pump, or do you think it would be too much vacuum over a brake bleeder?

I dont know why you think I'm being half arsed about it though. i came on here to learn more. I do want a quality P&C. I am pretty sure thats what my questions are about.
I now figure that I would be better just sticking with original sizes so I dont have to modify other stuff. My trouble is the quality brands are hard to find here in Australia, which is why I asked about that Tacsum brand. Am I being half arsed asking these questions?

I suspect the long-timers here have answered enough questions and given the same advice so often that they've lost most of their patience. So while it may be a new question for you it sounds differently to them. I suppose safest bet is to just ask them to tell you what to do and don't question anything. You won't learn much but they won't get their blood pressure out of range. Same story on many forums.


Welcome aboard. I'm a come-and-go learner. My interests wander among old Jeeps, tractors, firearms, chainsaws, and small scale homesteading. So I come for a while then I'm onto a different thing. Once current project saw is done I'll wander away for another few years I suppose.

 

[NSEric]

According to these guys I half arsed the 61 I redid with a 52mm cylinder while using the 61's carb/intake.
Trouble is the saw runs great with way more power than a 61 ever had. It is faster than a 365 x torque by a fair bit but it's not supposed to run with that carb or intake lol.

 

[Marty Lawrence]

According to these guys I half arsed the 61 I redid with a 52mm cylinder while using the 61's carb/intake.
Trouble is the saw runs great with way more power than a 61 ever had. It is faster than a 365 x torque by a fair bit but it's not supposed to run with that carb or intake lol.

Hey thats interesting to hear. Did you need to change bolts or re-tap threads? What about top cover. Did you need to cut it?
Is yours a black top?

 

[Jethro 2t sniffer]

Is the 61 intake the same as 162 closed port cylinder? Never really looked

Pretty much I see it if going cheap am cylinder you'd be mad to go any smaller than 52mm.

The other option is ask around look on ebay ring up a wrecker for a good used oem whatever size closed port cylinder you like.

Have a search up but intake won't be a drama if going to a 272 style cylinder.

Pretty sure the top cover will fit.

Don't worry about the grumpy old buggers. They are good basterds

If you spend 20 bucks on the wong cylinder it will run like a wong 20 buck cylinder will. If you spend the extra you'll get a mean chainsaw that will cut like a beast for a long long time

 

[Gord404]

It seems the newer tops will fit- did one about 6 months ago -272- if not the china ones are cheap and amazingly enough they fit- not too many parts they make you dont have to alter somehow- never seem to get it right on- I dont buy much from them

 

[NSEric]

Hey thats interesting to hear. Did you need to change bolts or re-tap threads? What about top cover. Did you need to cut it?
Is yours a black top?

I used the 272 intake bolts and sourced 6mm muffler bolts. The old white top ones need a hole for the spark plug boot to poke out of the cover, all the other 61's will clear a 272 cylinder, the only clearance issue is the different angle of the spark plug.
The kit I bought came with a 272 intake block, bolts and carb but the intake didnt line up well and the carb wouldnt hold a tune so I put the 61 carb/intake on it. I did port the cylinder, it was good number and squish wise out of the box tho, I just went wider and added some intake timing.