McCulloch Chain Saws

Shop deals on ebay
Rugged made
Wesspur
Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
promac610 said:
It shows up here... can anyone else beside me see it?

----------------

I hate to say this, but since I have higher priorities (paying off student loans, gotta find a newer less rusty car/truck/jeep, etc.) chainsaws (yes, pretty much all of them) will be put on the back burner.
Click to expand...

Pic showed up well ... nice beastie you have there. :clap:

Please let us know what kind of fuel-proof paint solution you arrive at. I am limited pretty much to rattle-can technology since the powder coat guys all (apparently) think I'm some kind of crackpot. :dizzy:

I'd even off you a deal on my Jeep Cherokee .... but I cannot find a similar-sized 4WD vehicle that will take a 2" hitch ... :msp_confused:
 
Warped5 said:
Pic showed up well ... nice beastie you have there. :clap:

Please let us know what kind of fuel-proof paint solution you arrive at. I am limited pretty much to rattle-can technology since the powder coat guys all (apparently) think I'm some kind of crackpot. :dizzy:

I'd even off you a deal on my Jeep Cherokee .... but I cannot find a similar-sized 4WD vehicle that will take a 2" hitch ... :msp_confused:
Click to expand...

I would generally use any type of yellow paint that matches McCulloch yellow and give it a coat of PPG Quik Clear on top of it to make it fuel proof. The clear takes a hardener so you'd have to shoot it from a spray gun. I use a touch up gun on chainsaws, no need to bring out the big spray gun for a small job.
 
I know this was addressed with Promac 610's 790 built but the search function is now next to useless. What is the proper size difference between the bore and the piston? My memory says .005".

Since I haven't been able to figure out a safe way to remove the kart saw wrist pin, I've been measuring, wiggling and comparing things. The kart piston and rod appears to have no more wiggle than my SP81 piston and rod. But what I have noticed is a lot of piston rock in the cylinder. The top of the cylinder is .008" bigger than the piston. I can't accurate measure any other points on the cylinder but the binding on the crank occurs just before bottom dead center. The cylinder is bored .05" over and appears to be round and measures2.330". The piston is also round and it measures 2.322". The cold compression on this beast was 196#. Later today, I'll give a shot at measuring the bore through the exhaust port and come up with an approximate average. Any advice wold be appreciated. Ron
 
rwoods said:
I know this was addressed with Promac 610's 790 built but the search function is now next to useless. What is the proper size difference between the bore and the piston? My memory says .005".

Since I haven't been able to figure out a safe way to remove the kart saw wrist pin, I've been measuring, wiggling and comparing things. The kart piston and rod appears to have no more wiggle than my SP81 piston and rod. But what I have noticed is a lot of piston rock in the cylinder. The top of the cylinder is .008" bigger than the piston. I can't accurate measure any other points on the cylinder but the binding on the crank occurs just before bottom dead center. The cylinder is bored .05" over and appears to be round and measures2.330". The piston is also round and it measures 2.322". The cold compression on this beast was 196#. Later today, I'll give a shot at measuring the bore through the exhaust port and come up with an approximate average. Any advice wold be appreciated. Ron
Click to expand...


I think 8 thou is a bit much. Where on the piston are you measureing?
You should use and inside mic or a bore gauge to accurately measure
the bore.
Promac 610's 790 will have a bit tighter piston clearance than a kart motor.
I gave my 101G motor 5.5 thou and a saw motor of the same size would
usually have around 4 thou. Kart motors need a little more room for
expansion do to the power they put out.

Removing a wrist pin is pretty easy, But it depends on the bearings.
Some have one bearing that is closed on the end. That type you have
to press out with the bearing.



Lee
 
leeha said:
I think 8 thou is a bit much. Where on the piston are you measureing?
You should use and inside mic or a bore gauge to accurately measure
the bore.
Promac 610's 790 will have a bit tighter piston clearance than a kart motor.
I gave my 101G motor 5.5 thou and a saw motor of the same size would
usually have around 4 thou. Kart motors need a little more room for
expansion do to the power they put out.

Removing a wrist pin is pretty easy, But it depends on the bearings.
Some have one bearing that is closed on the end. That type you have
to press out with the bearing.



Lee
Click to expand...


Lee, I am using the inside "knives" of a digital caliper for the bore and the outside "knives" for the piston. Due to the shape of the piston the only place you can measure 360 degrees is just above the top piston ring and just below the bottom ring. I checked the roundness by making multiple measurements. On the bore I used the centerline of the head bolt holes as a reference to make sure I was going straight across. Maybe the fix is as simple as not turning the saw on its side until it is nice and hot. :msp_unsure:

As you know the piston only has one wrist pin hole (the other side of the piston is solid) so you can't just press the pin out nor can you press the bearings out while the pin and rod are still in place. My bearings are open so I can actually pass a small bolt though the wrist pin and thread a nut on the other side. Another member has offered to explain over the phone how he does it, but after comparing the "wiggle" with my SP81 and noticing how much I can rock the piston in the cylinder I thought I would pursue my present question before trying further to remove the wrist pin.
 
rwoods said:
Lee, I am using the inside "knives" of a digital caliper for the bore and the outside "knives" for the piston. Due to the shape of the piston the only place you can measure 360 degrees is just above the top piston ring and just below the bottom ring. I checked the roundness by making multiple measurements. On the bore I used the centerline of the head bolt holes as a reference to make sure I was going straight across. Maybe the fix is as simple as not turning the saw on its side until it is nice and hot. :msp_unsure:

As you know the piston only has one wrist pin hole (the other side of the piston is solid) so you can't just press the pin out nor can you press the bearings out while the pin and rod are still in place. My bearings are open so I can actually pass a small bolt though the wrist pin and thread a nut on the other side. Another member has offered to explain over the phone how he does it, but after comparing the "wiggle" with my SP81 and noticing how much I can rock the piston in the cylinder I thought I would pursue my present question before trying further to remove the wrist pin.
Click to expand...


Ron, You need to measure the piston in the skirt area.
Torwards the bottom. There is always more clearance at
the top of the piston in the ring area do to all the heat
at the crown of the piston. You won't be able to measure
360 around the skirt but do the best you can.
On the type of wrist pin you have i use a 1/4 threaded rod.
I put it through the wrist pin and then a 1/4 nut on the end.
Then a socket at the other end and a nut and tighten that nut
to pull the pin out.
To put the pin in just add a washer behind the first nut so it
rests agains't the inside bearing and pull the pin in.
very easy.



Lee
 
leeha said:
Ron, You need to measure the piston in the skirt area.
Torwards the bottom. There is always more clearance at
the top of the piston in the ring area do to all the heat
at the crown of the piston. You won't be able to measure
360 around the skirt but do the best you can.
On the type of wrist pin you have i use a 1/4 threaded rod.
I put it through the wrist pin and then a 1/4 nut on the end.
Then a socket at the other end and a nut and tighten that nut
to pull the pin out.
To put the pin in just add a washer behind the first nut so it
rests agains't the inside bearing and pull the pin in.
very easy.



Lee
Click to expand...

Lee, as I told Stude54 Friday night, I would have a duh moment when the wrist pin removal procedure was explained. Wrist pin is now out. One bearing is 1/2 out - I need to build a block to get it the rest of the way out and I need a half nut to get the other one out. I took the measurements you suggested. The bottom of the piston is almost a uniform 2.324" or .002" bigger than the top (one place it was 2.3235" but that's splitting hairs). I also checked the bore at the exhaust port with the depth rod. It measured 2.330" just like the top of the bore. Summed up this leaves a clearance of .006". Since I can't find a piston, I plan to just replace all of the bearings and see how it turns out. Would you replace the wrist pin as well (I don't have one, but I believe they can be found)? Thanks for your help. Ron
 
Lee, while looking for a new wrist pin I ran across some 101 NOS pistons. If the measurements given are accurate then the stock piston is 2.2730" or .007" undersize of the bore of 2.28". It looks like I should be good to go on the piston. Let's hope the bearings will do the trick. Ron
 
rwoods said:
Lee, while looking for a new wrist pin I ran across some 101 NOS pistons. If the measurements given are accurate then the stock piston is 2.2730" or .007" undersize of the bore of 2.28". It looks like I should be good to go on the piston. Let's hope the bearings will do the trick. Ron
Click to expand...


Ron, You should be able to use the wrist pin over as long
as it looks good on the bearing surfaces and presses into
the rod tight. I would say reuse the piston but maybe replace
the rings. There is a guy in canada " Karts and Parts" that
may have rings in a 50 overbore. If you need his contact
i can get it.



Lee
 
leeha said:
Ron, You should be able to use the wrist pin over as long
as it looks good on the bearing surfaces and presses into
the rod tight. I would say reuse the piston but maybe replace
the rings. There is a guy in canada " Karts and Parts" that
may have rings in a 50 overbore. If you need his contact
i can get it.



Lee
Click to expand...

Thanks. The wrist pin is a tight fit; it took some effort to remove it. I have bought from Karts and Parts several times. It was his site that had the piston measurements listed with the pistons. Unfortunately, he doesn't list any thing in stock for .050" nor does he list any 1/2" wrist pins. I'll go with what I have and just replace the bearings once I get them. Thanks again. Ron
 
heimannm said:
Kart engines were expected to run a lot hotter (higher tempertures) than saw engines so the clearance between the piston and the cylinder were greater initially.

Mark
Click to expand...

I assume your back home. It's been pretty quite here lately; I think some folks decided to nap while you were away. Anyway Welcome Home. Ron
 
Ron, Karts and Parts has more than whats listed
on his web site. Give him a call, He is a nice guy
to deal with and might have 50 over rings.
The wrist pin bearings can be bought at a bearing
supplier. If you strike out i can help as i have bought
them before.




Lee
 

Similar threads

R
McCulloch ProMac 700 Bar
Replies
8
Views
623
Syncop8r
Syncop8r
C
Want to Buy McCulloch Super 250
Replies
6
Views
806
Bill G
B
Chainsaw Collectors
McCulloch 610 chain brake guard install, help?
2
Replies
20
Views
1K
singinwoodwackr
singinwoodwackr
B
New from Bavaria
Replies
5
Views
527
Syncop8r
Syncop8r
J
A few very nice old saws
Replies
0
Views
498
jackdaripper
J

Latest posts

Back
Top