Ported a Chinese Chainsaw Pics and Video

[Chris-PA]

it has a 2 piece head just like a "pro" saw,not a clam shell . interesting.the japs are getting smarter.

The Japanese designed it (RedMax) and the Chinese built it. Maps are not that hard to use.

 

[stinkbait]

Using two different chains and bars seems to make everything void. Dosn't show me anything. I appreciate what you attempted to do but it dosn't show anything. You gotta run the same chain and bar.

Here's a video for the technical folks. Same bar and chain as before video.

[video=youtube;dp7kmMJAE5g]http://www.youtube.com/watch?v=dp7kmMJAE5g&feature=share&list=UU3rhK5rqK8s_FJlPeHEi-Mw[/video]

 

[stinkbait]

Did you change the drive sprocket? I actually like LoPro so i don't intend to change it, but I was curious as in general 3/8 LoPro and 3/8 are not completely compatible.

I just slapped a 3/8 bar and chain on the saw off of a 10-10. Oil holes line up and the sprocket works perfect. No binding at all. The Chinese's tolerances on their sprockets must be pretty sloppy. I'm going to look into the low pro chisel though. Didn't even know that it existed.

 

[hqv]

Not bad. Works better. :msp_scared:

 

[discounthunter]

The Japanese designed it (RedMax) and the Chinese built it. Maps are not that hard to use.

i thought these were echo's.

 

[millbilly]

Here's a video for the technical folks. Same bar and chain as before video.

Hey cool beAns! good job thats tellin me something.

 

[Chris-PA]

Here's my attempt, somewhat more conservative:

I didn't mess with the upper transfers, but I did a little clean up on the lowers. I tried to direct that flow to the intake side runners:

The squish band on mine was a mess, with strange casting defects and two lumps under each side of the spark plug boss:

That concerned me as I'm removing the gasket, so I did a bit of sanding with a big dowel and some 220 grit:

It's not perfect, but it's better.

 

[BlueSmoke12]

I'm going to attempt some MODS to one of my Quakes. In this order;

Muffler MOD

Remove Base Gasket

Some Mild Porting

I've got some questions;

When removing and re installing the cylinder can you get the piston back in with out a ring compressor? (Please I know to some of you this sounds like a stupid question.....but its my first time....)

What about the torque spec for the cylinder bolts? Must it be to a torque spec of the manufacturer? Do I need a torque wrench or can I wing it and make them snug, but not too snug?

Any answers will be appreciated.....

 

[excess650]

Using two different chains and bars seems to make everything void. Dosn't show me anything. I appreciate what you attempted to do but it dosn't show anything. You gotta run the same chain and bar.

I understand what you're saying, but the fact that he has this 38cc saw pulling 3/8 .050 (not low pro) speaks volumes. 40cc and under saws almost always run the 3/8 low pro, and up to mid 50s cc quite often run .325.

 

[excess650]

I just slapped a 3/8 bar and chain on the saw off of a 10-10. Oil holes line up and the sprocket works perfect. No binding at all. The Chinese's tolerances on their sprockets must be pretty sloppy. I'm going to look into the low pro chisel though. Didn't even know that it existed.

Oregon 91VXL is the longer cutter replacement for 91VX. Bailey's - Oregon 91VXL Chainsaw Chain

Bailey's also carries their WP Bailey's - WoodlandPro 30LP Chainsaw Chain

Both of these are of the non-safety variety, so more aggressive than typical low pro.

 

[Chris-PA]

I like the chamfer chisel cutters on the PX and VX, although the WoodlandPro/Carlton is very good too.

 

[Chris-PA]

I'm going to attempt some MODS to one of my Quakes. In this order;

Muffler MOD

Remove Base Gasket

Some Mild Porting

I've got some questions;

When removing and re installing the cylinder can you get the piston back in with out a ring compressor? (Please I know to some of you this sounds like a stupid question.....but its my first time....)

What about the torque spec for the cylinder bolts? Must it be to a torque spec of the manufacturer? Do I need a torque wrench or can I wing it and make them snug, but not too snug?

Any answers will be appreciated.....

I didn't use a compressor, I just sqeezed the ring to the piston with my fingers as best I could. I smeared a light coating of 2-stroke oil on the inside of the cylinder. There is a decent bevel on the bottom of of the cylinder and it is chrome plated and it went on easily.

You will need sealant where the gasket used to be, I used Yamabond4 but there are other possabilites. I put the jug partially over the piston and then put on the sealant so as to keep from getting it everywhere while ptting on the jug. Not sure how the pros do it!

As for torque, I used my carefully calibrated hand on the Torx driver - it is a $40 saw after all, and I don't know the torque spec or have a torque wrench in that range (well, we do at work but I didn't bother). I put Loctite blue on the threads.

 

[muggermike]

nice sounds like fun. maybe if i try one i can give it to my bil:cool2:

 

[Spectraman]

Nice work I did basically the same thing really enjoy using the saw now.:msp_biggrin:

 

[Chris-PA]

I finally got around to measuring the timing on the one I did. Not very aggressive. I had not really changed the timing other than removing the base gasket. I only brought the top of the exhaust port up to the top of the notch that was cast into it originally. Here's the numbers:

I could take it farther, and maybe someday I will, but it runs quite nicely this way so I'm in no hurry.

 

[eat a peach]

Oregon 91VXL is the longer cutter replacement for 91VX. Bailey's - Oregon 91VXL Chainsaw Chain

Bailey's also carries their WP Bailey's - WoodlandPro 30LP Chainsaw Chain

Both of these are of the non-safety variety, so more aggressive than typical low pro.

the WP low profile NK is a real good runner on a 346xp .

 

[millbilly]

I finally got around to measuring the timing on the one I did. Not very aggressive. I had not really changed the timing other than removing the base gasket. I only brought the top of the exhaust port up to the top of the notch that was cast into it originally. Here's the numbers:

Man I hate feelin dumb, but they never taught that stuff in my school. I have no idea what your talking about but dang I wanna learn.

 

[Chris-PA]

Man I hate feelin dumb, but they never taught that stuff in my school. I have no idea what your talking about but dang I wanna learn.

Sorry about that, that was rude of me. The dotted line represents TDC.

The angle between the blue lines represents the time the intake is open.

The angle between the red lines represents the time the exhaust is open.

The angle between the black lines represents the time the transfers are open

The angle between the red and black is the "blowdown", or the angle between the time the exhaust port opens and the time the transfers open.

If you picture the crankshaft angle as rotating from TDC clockwise, it's a map of the major
port events.

 

[SierraWoodsman]

I like the chamfer chisel cutters on the PX and VX, although the WoodlandPro/Carlton is very good too.

You should try running a loop of Square 3/8 chisel, should reduce your times even further. Nice work though and interesting thread.

 

[Chris-PA]

You should try running a loop of Square 3/8 chisel, should reduce your times even further. Nice work though and interesting thread.

I have square ground 3/8 on my McCulloch 3420, mostly as a lark because I wanted to learn to file it. I have not found there to be enough difference to justify the time compared to round ground, but I'm still playing. It does work.

However, this saw will stay Lo Pro because I want the narrow kerf and semi chisel is far better suited for the kind of stuff I cut with it. This thing is only 38cc and while I woke it up it's still not very aggressive. If I could find a 0.325 sprocket I'd put a loop of 20BPX on it, that would be perfect for it.