Kensie1988
Vintage Saw Maniac
You weren't joking! $50+ it's just as cheap to buy a parts Saw that still has the filter in it...
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It depends on how much milk you gave it and if you burped it correctly. But man does it stink.
Steve Sidwell, Samsung On5 using Tapatalk
Certainly you could write a book on the issue of spit back in two stroke engine, I will let Steve cover the other topic.
In a nutshell, most of the time when we see spit back or the results of it and it is objectionable, it is a result of either reed valves not closing/sealing properly, or a piston ported engine with a worn piston/cylinder. If the reeds or piston don't seal, some of the charge in the crankcase will be ejected back out the intake.
Eccentric wrote a nice dissertation on the subject one time discussing the length of the intake tract and the impact on the momentum of the air moving through the carburetor and noted that it was a common misconception that reed valve engines were more likely to suffer from spit back problems.
McCulloch attacked it a bit differently, rather than adjust the length of the intake tract to try and minimize spit back, they installed some form of "spit back shields" or "collectors" on many saws to try and collect the fuel and direct it back to the intake. The covers over the carburetor inlet on the 10 Series saws is one example (early models didn't have this feature) and the collector and hose on many large frame saws was another way to try and capture the fuel and get it back into the intake system.
If you open the air box and the AF is soaked with fuel or the interior is dripping wet with fuel, spit back is probably excessive.
Older 10 Series McCulloch with no spit back shield (custom fuel line came with the saw...)
Later model 10 Series with a spit back shield
Large frame McCulloch saw with collector, that plastic box behind the inlet to the carburetor is supposed to have a foam insert, the hose from the bottom connects to the carburetor to allow the collected spit back to be introduced back into the intake to be burned.
Mark
In a nutshell, most of the time when we see spit back or the results of it and it is objectionable, it is a result of either reed valves not closing/sealing properly, or a piston ported engine with a worn piston/cylinder. If the reeds or piston don't seal, some of the charge in the crankcase will be ejected back out the intake.
Eccentric wrote a nice dissertation on the subject one time discussing the length of the intake tract and the impact on the momentum of the air moving through the carburetor and noted that it was a common misconception that reed valve engines were more likely to suffer from spit back problems.
McCulloch attacked it a bit differently, rather than adjust the length of the intake tract to try and minimize spit back, they installed some form of "spit back shields" or "collectors" on many saws to try and collect the fuel and direct it back to the intake. The covers over the carburetor inlet on the 10 Series saws is one example (early models didn't have this feature) and the collector and hose on many large frame saws was another way to try and capture the fuel and get it back into the intake system.
If you open the air box and the AF is soaked with fuel or the interior is dripping wet with fuel, spit back is probably excessive.
Older 10 Series McCulloch with no spit back shield (custom fuel line came with the saw...)
Later model 10 Series with a spit back shield
Large frame McCulloch saw with collector, that plastic box behind the inlet to the carburetor is supposed to have a foam insert, the hose from the bottom connects to the carburetor to allow the collected spit back to be introduced back into the intake to be burned.
Mark
Kensie1988
Vintage Saw Maniac
Beautifully written, that helped out a lot, and that's also why the Mac 10-10 filter element I have had the split rubber piece directly over the carb instead of part of the filter, it's so the spitback doesn't soak the element correct?
Kensie1988
Vintage Saw Maniac
And one more question while I have you here, the right hand starter covers, I noticed it has the hex head bolt/nut holder for a bucking spike but the hole isn't fully drilled, is this so you can finish drilling out the hole to add a bucking spike later?
My pm605 has that spitback shield, never knew why they covered the carb like that, now I know why.
Steve Sidwell, Samsung On5 using Tapatalk
Steve Sidwell, Samsung On5 using Tapatalk
Yes on that 10 Series AF, in essence you have the spit back shield built into the AF rather than being a separate piece.
Also yes on the clutch covers, the hex is there to hold the head of the screw that attaches the spike, you can punch it out or drill it out and add the spike if you wish.
Mark
Also yes on the clutch covers, the hex is there to hold the head of the screw that attaches the spike, you can punch it out or drill it out and add the spike if you wish.
Mark
Kensie1988
Vintage Saw Maniac
Awesome! Good to know!
Remember that the early 10 Series saws have a different bolt pattern and so have a different spike that the later PM and 600 Series saws.
Early
or
For the later saws, PM models with the long clutch cover that also covers the muffler and for 600 Series saws the spike is different and much more common. It won't fit the short clutch covers.
Mark
Early
or
For the later saws, PM models with the long clutch cover that also covers the muffler and for 600 Series saws the spike is different and much more common. It won't fit the short clutch covers.
Mark
Mac&Homelite
Addicted to ArboristSite
Shoot, that's not looking hopeful with my mac 250 and that excessive spitback. Really don't care to tear it down that far, but perhaps I will find another saw this weekend to distract me for the meantime.
Is a 10 series too much to ask? Also have to order a new carb for my ms361. Something is still up with it, and it's definitely carb related, something I cannot determine for sure. Weekend is already filling up even before it comes. Got 3-4 lawns to mow, and I want to hang out with a friend and the family obviously.
Is a 10 series too much to ask? Also have to order a new carb for my ms361. Something is still up with it, and it's definitely carb related, something I cannot determine for sure. Weekend is already filling up even before it comes. Got 3-4 lawns to mow, and I want to hang out with a friend and the family obviously.
Mac&Homelite
Addicted to ArboristSite
Guess I wouldn't mind a husky large mount either as I have that 16'' bar I have no use for currently. That would be absolutely perfect on a 50cc+ saw.
Kensie1988
Vintage Saw Maniac
Awesome! Thanks for that I sure would have bought the wrong one!
Made mine for my 605, copied a Sthil, stretched it to fit and then drilled out the mounting. Easy to cut one out with a plasma cutter and a steady hands.
Steve Sidwell, Samsung On5 using Tapatalk
Steve Sidwell, Samsung On5 using Tapatalk
astnmacgto
Carnac The Magnificent
That would be disheartening to find on a 101 block....
astnmacgto
Carnac The Magnificent
Keep an eye out on the bay, I bought an early spike for like 12 bucks shipped a few months ago.
Also, I have a couple nos filters, i know I only paid like 7 bucks each for them.
RE: 101 destruction - Terry Ives was able to weld it, machine the bore, and fit a new piston. It is still just waiting some carburetion and fuel to make it go again.
Mark
Mark
LonestarStihl
Addicted to ArboristSite
I was with you on yellow but you went off the deep end.
astnmacgto
Carnac The Magnificent
I was hoping you had it welded up. How much over std bore was it taken?
Yellow is certainly the predominant member of my collection by perhaps 40:1, hey, I just solved the fuel mix question as well...
I think the 101 ended up around 0.040" oversize, been a while since I have been inside that one I am sad to say.
Mark
I think the 101 ended up around 0.040" oversize, been a while since I have been inside that one I am sad to say.
Mark
LonestarStihl
Addicted to ArboristSite
Speaking of the fuel mix problem...Poulan apparently solved it all for us.... why not have both...
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