MCCULLOCH The official McCulloch thread

[heimannm]

I will make the final organization once I get through sorting all of the parts and hardware, I suspect there will be more 12-24 fasteners turn up in the other totes of hardware. I did a little digging last week and was able to find the OEM 110717 10-32x3/4 hex head screws used to hold the muffler cover on the SP125 for Bob Framke.







Mark

 

[Al Smith]

I've got fasteners by the tonnage problem is they are scattered to the four winds .It's never if but rather where . Then on a rare situation you might find an odd ball such as the special splined headed rod bolts used on the SP 125 .Because of the space and fit condition nothing else will work .Of which I made do by cutting the head diameter down on a high quality grade 8 socket head cap screw made by Hollow Chrome but leaving a flange just like OEM .Some times you have to do what you have to do ..

 

[edju1958]

I have had a few 10 series that have been the smaller 10-24 bolts. Most are the larger 12-24 threads. The 10-10 that I put a nos engine in got me as the original engine was 10-24 and the new engine was 12-24. Ended up pulling the threads out of the new cylinder with the smaller bolts.

If I wouldn't have been able to find the smaller bolt (10-24),my next thought would've been to drill the bosses out & re-tap them to a 12-24.

 

[Scott Kelsey]

I am looking for some opinions here. When I went to look at this saw Sunday I knew it did not fire. I have not had a chance to work on it, but have been doing some thinking. Here are the details. I purchased it from the fellow who got it from the original owner in on trade not long ago. He did a carburetor kit, and I believe he said a clean on the ignition. It has 135lbs of compression which I know is low, but I believe it should still fire. Thoughts on that? He said it pops off but won't go which i witnessed. When he tried to start it for me it seemed as if it was flooding out because it has fuel leaking from what looked like the muffler. The saw has good spark in my opinion. I initially thought it may be out of time, but I truthfully do not know if this saw has points or electronic ignition. With regards to the compression I thought it may have bad seals. I also know it may be rings, etc. Where would you start?

 

[Steve]

I am looking for some opinions here. When I went to look at this saw Sunday I knew it did not fire. I have not had a chance to work on it, but have been doing some thinking. Here are the details. I purchased it from the fellow who got it from the original owner in on trade not long ago. He did a carburetor kit, and I believe he said a clean on the ignition. It has 135lbs of compression which I know is low, but I believe it should still fire. Thoughts on that? He said it pops off but won't go which i witnessed. When he tried to start it for me it seemed as if it was flooding out because it has fuel leaking from what looked like the muffler. The saw has good spark in my opinion. I initially thought it may be out of time, but I truthfully do not know if this saw has points or electronic ignition. With regards to the compression I thought it may have bad seals. I also know it may be rings, etc. I am looking for your guys input and thoughts. Where would you start?

1. Reliable spark

2. Vac/pressure check it

3. Go through carb. The flooding and fuel out the exhaust is usually a inlet needle not sealing. Check the intake side of the piston with the carb off for scoring. If you put it at tdc you can also see some of the exhaust side.

135 psi is enough for the saw to run with some balls. My 850 has that and runs reasonably well.

 

[Maintenance Chief]

I am looking for some opinions here. When I went to look at this saw Sunday I knew it did not fire. I have not had a chance to work on it, but have been doing some thinking. Here are the details. I purchased it from the fellow who got it from the original owner in on trade not long ago. He did a carburetor kit, and I believe he said a clean on the ignition. It has 135lbs of compression which I know is low, but I believe it should still fire. Thoughts on that? He said it pops off but won't go which i witnessed. When he tried to start it for me it seemed as if it was flooding out because it has fuel leaking from what looked like the muffler. The saw has good spark in my opinion. I initially thought it may be out of time, but I truthfully do not know if this saw has points or electronic ignition. With regards to the compression I thought it may have bad seals. I also know it may be rings, etc. Where would you start?

You need to get a look in the cylinder to make sure your not pissing into the wind by chasing other gremlins.
Clean and rebuild the fuel system.
Clean the decomp.
Check ,regap coil-flywheel distance.
Post pics.

 

[Vinnywv]

Ive seen this symptom more than once in a saw and it was poor spark. Im not saying to not look at what others have mentioned but simply try a different spark plug. Its worked 4 times for me. The last time it was good spark but an e-something plug. It just wasnt hot enough. Put in an old plug i had and it lit right off. That was a homelite saw. Done the same on macs too. Had spark just not enough. Id go there first. Its easiest. Let us know what you find though.

 

[heimannm]

If it is really 135 PSI it should be pretty healthy. If one or both seals were very, very bad it could prevent it from getting a sufficient transfer from the crankcase to the cylinder but fuel leaking from the muffler would suggest it is getting there. A different spark plug is easy enough to try, carburetor rebuild is likely in order as well.

I would start searching for a longer bar as well....

Mark

 

[Scott Kelsey]

I will hopefully get some time this weekend to work on it. Great info all, thank you.

Mark I thought the same! Ha. I will eventually look for a roller nose for it most likely unless I can find a decent sprocket nose Mcculloch.

I had an individual tell me 135lbs was low for a SP81. I do not know what the spec is so was I wrong thinking it is low?

 

[Maintenance Chief]

I will hopefully get some time this weekend to work on it. Great info all, thank you.

Mark I thought the same! Ha. I will eventually look for a roller nose for it most likely unless I can find a decent sprocket nose Mcculloch.

I had an individual tell me 135lbs was low for a SP81. I do not know what the spec is so was I wrong thinking it is low?

I wouldn't consider 135lbs high? But would definitely run.

 

[heimannm]

New project, not quite ready for market but they should be coming soon for that occasional older 10 Series with the three piece sawdust screens.





And another bit of McCulloch parts trivia. Many models of the 10 Series utilize an additional screw to secure the flywheel cover to the saw utilizing a special stud that also holds the coil down. Most use the slightly shorter one on the left, but the PM800 type saw need a slightly longer/taller stud due to the slightly wider housing required by the taller fins on the flywheel. It you work on a lot of different saws it is important that you keep the two studs separate or you will have problems fitting the cover to the saw.

I can only presume the two different part numbers I've found for the sorter ones reflect the older with the full hex body and the later one with the cylindrical body and head at the head only. I may one day uncover another part number for the different version of the longer one as well.



Mark

 

[Al Smith]

On that compression several things .First a static test is exactly that ,static not under power .Under a dynamic condition, under power it will be higher .Stihl for example suggests 100 psi static is the lower static limit .
FWIW with a brand new rebuild one of my Partner P-100's only shows about 130 static and it runs very well but of course that's 99 cc's .It's not broken in yet so it will improve .Another thing those readings could vary depending on what type of compression tester is used. In short if it runs okay don't worry about it .

 

[Vinnywv]

Very true al, my sp105 when i got it, showed 130psi. I thought i was screwed. Called bob j and we chatted about it and he said leave it alone and use it. I listened to him and its a very strong running saw. Quite surprising witha 36 inch bar on it, barely slows it down.

 

[Al Smith]

I have an sp 105 and assume it uses the thin tool steel rings as an sp 125c .As such it would make sense under dynamic conditions those rings would expand greatly .Thus the actual compression should be higher .
I had one of my 125's swallow a part of the clip holding the choke knob and got hung in the right hand side center transfer ports and nicked it .Although it pulls over easier after I cleared it because of the nick it has not hindered how it runs basically going back to the port time area opened theory .Little area ,short time open under running conditions .

 

[Scott Kelsey]

Guys what is the purpose of the muffler reed on the 81?

 

[Steve]

Guys what is the purpose of the muffler reed on the 81?

Dampen various high pitch frequencies from the operators ear but in reality it just robs power. Sounds cool at idle though.

 

[Vinnywv]

Yep, for noise. Take it out. Where ear protection. Have fun

 

[Al Smith]

Most of them are rusted shut .

 

[heimannm]

I've never seen a reed that was rusted shut, but I've seen several that were broken off. It may surprise you on the power output, they certainly are quieter than the other mufflers but in head to head competition with other 70 cc McCulloch saws my freshly rebuilt SP70 with the reed muffler was definitely the fastest. It was not a scientific study and I was unimpressed with the SP70 due to the lack of noise, but when it actually came down to cutting speed it was clearly superior.

Mark

 

[Al Smith]

That reed muffler has been kicked around a time or three .I think perhaps part of the design acts like a
"power valve " on a tuned exhaust used by for instance KTM on hot rod trail bikes .My neighbor has one the valve got stuck ,rust .I had to Google it to figure out how it worked .That said I think that thing was like 27 HP and 200 cc and quite fast in the short run .It did make a difference once the valve was working .However as I understand it it was designed to cover the RPM ranges where as a chainsaw for all intents would be at full throttle from my perspective . .If I get or find the time I'm sure I have a rusty cover some place in all my junk as I never throw anything away .With that you have to consider many of my 10 series Macs were dumpster finds given to me .Many in terrible shape I some how brought back from the dead .