372 Connecting and bore questions

Treestuff
Rugged made
Advertise with us
Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
T

telemaster

ArboristSite Member
Joined
Sep 20, 2010
Messages
69
Reaction score
8
Location
Taconic Mountains
Hey guys,
I am working on a bit of a frankensaw and have a few questions.

I am going to bore out a cylinder to take the 52mm big bore piston for the 372. The first question is what should I have the cylinder bored to? If the piston is 52mm, would I bore to exactly 52mm or a thousandth(s) over?

Never done this before and looking for some advice.

Also, does anyone have a con rod for a 372 that they could measure the ID of the wrist pin bearing hole? I need to know how big the hole in the con rod needs to be to accept the wrist pin bearing.

I know these are specific questions with out much other detail, but I promise to post pictures of the completed project once done. I think it is going to be pretty freakin' sweet!

Thanks in advance.
 
Do you know that the cylinder is plated? If you were to bore it out you would need to have it replated. The cost of that would far outweigh the cost of a used cylinder (probably a new one as well). You can find about any size cylinder you need new or used.
 
telemaster said:
This isn't for a 372. So the 372 BB cylinder won't fit on the saw. Need to modify the original that I am working with.
Click to expand...

You need atleast .003 piston to cly clearance.
I dont understand why if the 372 cly will fit why the BB wont, there the same physical size other than the bore dia.
 
formersawrep said:
Do you know that the cylinder is plated? If you were to bore it out you would need to have it replated.
Click to expand...

No, I did not know I would have to have the cylinder plated. Good info to have. This sends me wayyyyyyy back to the drawing boards.

Out of curiosity, what are cylinders plated with? (yes, I'm a rookie, but gotta start somewhere) Must be chrome plated says Google. Correct me if I am wrong.
 
Last edited:
Ecopsey said:
You need atleast .003 piston to cly clearance.
I dont understand why if the 372 cly will fit why the BB wont, there the same physical size other than the bore dia.
Click to expand...

Thanks for the clearance data.

I am not using a 372 cylinder. I have an old saw that is not a husqvarna with a fouled P/C. I cannot find parts for the old saw; so I am trying to find available parts that would fit with as little modification as possible. A 52mm piston is the closest I can find... unless someone knows of a saw that take a 51mm?

My original plan was to bore out the fouled cylinder to 52mm, and modify the con rod to take a readily available piston. Stroke and squish is all good.... got that figured out. The real problem now seems to be this plating issue.
 
Last edited:
It is almost never as simple as bolting one cylinder onto a different saw, there are issues with the deck height, port locations, skirt widths, lower transfer ports, connection points at both carb and exhaust, fin locations, bolt patterns...

Rods and cranks in saws are very difficult to modify and pretty much require a machiene shop and $$$.

Likely going to be easiest to find parts for the old saw, what are you looking for. Worst case the cylinder could be re-plated and pistons can usually be found somewhere.
 
timberwolf said:
It is almost never as simple as bolting one cylinder onto a different saw, there are issues with the deck height, port locations, skirt widths, lower transfer ports, connection points at both carb and exhaust, fin locations, bolt patterns...

Rods and cranks in saws are very difficult to modify and pretty much require a machiene shop and $$$.

Likely going to be easiest to find parts for the old saw, what are you looking for. Worst case the cylinder could be re-plated and pistons can usually be found somewhere.
Click to expand...

OK, time to put all the info out on the table. I have a Poulan 245 with a bad P/C. (Try finding those parts) I also have access to a friend's machine shop; so the cost there would be minimal. The plating would be $$$$.

My plan was to take the scored cylinder from the 245, bore it out to 52mm, bore the connecting rod to accept a 12mm wrist pin & bearing combo, then use the 372 BB piston in the bored out 245 cylinder.

I know I could scour the interwebs and find a P/C for the saw after some time and $$$. But.... I am a tinkerer and like to wrench/modify/build/tinker with things so the idea of modifying what I have to use readily available parts has more appeal than scouring the interwebs.

This might be a futile project, but that's why I'm here. After all, the worst I can have is a saw that doesn't work.... wait... I already have that!
 
Here's the issues:

Getting your 245 cylinder bored and replated is going to run you in the neighborhood of at least $245, and that's if you can even find anyone willing to do it. US Chrome turns away more projects that they take.

The connecting rod small end is not easily bored- especially without ruining the heat treated hardness of the material. I don't know of anyone who has bored the small end of a chainsaw connecting rod successfully and I know plenty of talented people who have tried (a couple are members here.) Having custom bushings made would be your best bet and the longevity on bushings in the small end of the connecting rod is questionable.

If you were successful in doing this, you'd end up with at least $450-500 in a Poulan 245. You'd probably have to refresh the bottom end as well to handle the additional power of the larger top end.
 
Jacob J is bang on!

Do yourself a huge favor and set it on the shelf but keep the feelers out for a servicable piston and cylider.

If you want a project there are many more doable box projects to dig into. LOL I have boxes of such projects...
 
Jacob J. said:
Here's the issues:

Getting your 245 cylinder bored and replated is going to run you in the neighborhood of at least $245, and that's if you can even find anyone willing to do it. US Chrome turns away more projects that they take.

The connecting rod small end is not easily bored- especially without ruining the heat treated hardness of the material. I don't know of anyone who has bored the small end of a chainsaw connecting rod successfully and I know plenty of talented people who have tried (a couple are members here.) Having custom bushings made would be your best bet and the longevity on bushings in the small end of the connecting rod is questionable.

If you were successful in doing this, you'd end up with at least $450-500 in a Poulan 245. You'd probably have to refresh the bottom end as well to handle the additional power of the larger top end.
Click to expand...

Understood. I'm a bit bummed, but kinda knew this was a ridiculous project the whole time. Back to the drawing boards.
 
The 245 is a great old saw! I ran one from 1977 to around 1997 and it ran perfect when I traded it. Keep looking, parts are out there.
 
In case you do not already have a IPL for that saw
http://s30387.gridserver.com/partsDiagrams/Poulan245A.pdf

Looks like you need the following part numbers
Piston and pin
23253
Lock ring(need 2)
15347
Piston rings (need 2)
2638
Cylinder
11564

Edit:
Won't the 306 p/c fit on the 245 also? It is a smaller bore but I believe it would fit.
 
Last edited:
sunfish said:
P.S. You might want to ask for parts in the Pouland thread.
Click to expand...

Thanks, I have been in the Poulan thread a bunch of times. Good folks over there.

Roanoker494 said:
In case you do not already have a IPL for that saw
http://s30387.gridserver.com/partsDiagrams/Poulan245A.pdf

Looks like you need the following part numbers
Piston and pin
23253
Lock ring(need 2)
15347
Piston rings (need 2)
2638
Cylinder
11564

Edit:
Won't the 306 p/c fit on the 245 also? It is a smaller bore but I believe it would fit.
Click to expand...

Yup got the IPL from Modified Mark a bit ago.

Yes, the 306 p/c will fit, but at the sacrifice of displacement. There is no replacement for displacement.
 
P&C are not that hard to find and that saw is well worth the effort.


attachment.php
 

Similar threads

D
Husky 61 big bore - is this too much slop in piston bearing?
2 3
Replies
42
Views
2K
Drillerman
D
Kylewebb95
Homelite 1050 Help needed
Replies
1
Views
462
Maintenance supervisor
Maintenance supervisor
K
Jred CS2145 questions
Replies
13
Views
935
kevin j
K
N
268 piston for a 372 xp
Replies
0
Views
131
Nitris223
N
woodrat
372xp questions
2
Replies
23
Views
2K
Aknutter
A

Latest posts

Back
Top