Anyone port a Makita 6421 cylinder?

[Shane¹]

I have a nice 6421 cylinder I keep looking at wondering if I did some grinding on it how would it run? Anyone done one with success? How do you think it would compare to stock 7900 or big bore cylinder?

 

[stihl livin]

@huskihl @Miller Mod Saws

 

[huskihl]

I’ve only ported one 6400 cylinder. I thought it ran alright. Didn’t get the gains I get from a 7900 cylinder, but I’ve only had the 1 to practice a few different recipes on. I get better gains on a 7900 but I’ve ported quite a few more. Belongs to a friend of @Wood Chopper. He might know if he’d do it again or opt for the 7900 instead

 

[Shane¹]

I’ve only ported one 6400 cylinder. I thought it ran alright. Didn’t get the gains I get from a 7900 cylinder, but I’ve only had the 1 to practice a few different recipes on. I get better gains on a 7900 but I’ve ported quite a few more. Belongs to a friend of @Wood Chopper. He might know if he’d do it again or opt for the 7900 instead

How do you think it compared to a stock 7900?

 

[stihl livin]

@Woodhore

Nathan has a solo 665 that Carl did and it’sa stout saw. @Hedgerow can probably comment on said solo as well

 

[huskihl]

How do you think it compared to a stock 7900?

I’d say it ran better than a stock 7900

 

[Wilhelm]

No porting will make a open port 64cc saw perform close to or as well as a stock closed port 79cc saw - You are looking at a 15cc gap to make up for.
I do believe gains can be achieved though as a stock 6400 is quite conservative.

I love my PS-6400.
Curious to see what You can get out of Yours.

 

[Wilhelm]

I’d say it ran better than a stock 7900

Really?!

A stock PS-7900 is one torquey saw , I should know as I own and run two.
That is a lot of UMPH to make up for on a PS-6400.

Just saying.

 

[Shane¹]

I’d say it ran better than a stock 7900

Did you take any pics or remember about what you did for numbers? I have not done any real porting just cleaned up some ports but don't want to mess up a good cylinder so I thought this would be a good one to try.

 

[huskihl]

Really?!

A stock PS-7900 is one torquey saw , I should know as I own and run two.
That is a lot of UMPH to make up for on a PS-6400.

Just saying.

I’m just going by memory. It probably ran a 20” bar better than a stock 7900 but I doubt it would run a 32 as well.

 

[huskihl]

Did you take any pics or remember about what you did for numbers? I have not done any real porting just cleaned up some ports but don't want to mess up a good cylinder so I thought this would be a good one to try.

I don’t remember seeing it in my book so I probably didn’t write it down. I usually run them stock, run them after lathe work, and see what they need to make it run how you want. Widening/flattening the exhaust will wake it up. Just need to decide if it has enough balls to raise it also.

 

[Shane¹]

I don’t remember seeing it in my book so I probably didn’t write it down. I usually run them stock, run them after lathe work, and see what they need to make it run how you want. Widening/flattening the exhaust will wake it up. Just need to decide if it has enough balls to raise it also.

Do you do anything with the transfers on an open port cylinder?

 

[Wilhelm]

I’m just going by memory. It probably ran a 20” bar better than a stock 7900 but I doubt it would run a 32 as well.

Even fully stock (no MM on mine) a PS-6400 pulls a 20" B&C setup with authority!
Extremely underrated saw being overshadowed by her two stronger siblings the 73 & 79.

A PS-6400 has much more grunt than a PS-6100 even though their specs on paper are very close to each other.

 

[huskihl]

Really?!

A stock PS-7900 is one torquey saw , I should know as I own and run two.
That is a lot of UMPH to make up for on a PS-6400.

Just saying.

About 5-6 seconds slower than a ported 500i. Consecutive saws in my YouTube a day or 3 apart in the same log.

 

[huskihl]

Do you do anything with the transfers on an open port cylinder?

I would have raised them up a bit after lathe work

 

[huskihl]

I know it’s not a 7900 but mine run about the same and this was right before the 6400 in the same log. Not certain if I sharpened the chain in between but it doesn’t sound like it

 

[Shane¹]

@huskihl thanks for all the help I will see what I can come up with do you happen to have any pictures of some open transfers and what you would grind on them I don't really understand how it works

 

[huskihl]

Lol. Did some digging. This is that^ saw. Uppers look raised. Or at least cleaned up. Either way, this is where I ended, good, bad, or indifferent

 

[whitesnake]

About 5-6 seconds slower than a ported 500i. Consecutive saws in my YouTube a day or 3 apart in the same log.

Can’t deny that’s a strong 60cc saw!

 

[Miller Mod Saws]

I’ve played with several. IMO just get the 7900 top end. If it was a 665 Solo. I’d put up an argument. But the open port 6400 just dosnt have it or with me behind the grinder. Lol. The 665 is closed port and can be made to run very very very well.