Porting quad transfers

[Matt1183]

Hey everybody.. Im trying to find information on porting upper transfers in 371 365 385/90 and 395 saws. I have a cc specialty right angle with normal and reverse burrs . Sofar iv worked on a 365 special that i tryed to widen the transfers a bit to look more like a 371 size. The timing numbers ended up at 102 ex 79 in 122 trans . 024 squish. It ran ok but not much faster than a stock 371. I worked on a 385 that i cleaned up the intake on and removed the base gasket and cleaned up the exhaust on and left the transfers untuched and it runs quite well. The 371 i ported to 100 ex 80 intake and the main are 122 the secondarys are 126 and squish is 018 . You can push on it pretty good but it seems to lack top end and im sure it has way more in it.its hard to tune also.. It will 4stoke realy high but seems too lean in the cut .. If you richen it up to seeming happyer in the cut it sounds way rich on a free rev.
So basicaly im wondering about entry angle.. More the angle of the roof that will direct the charge close to the piston or up in the cylinder. I have been moving the intake side of the tranfer tward the intake just a bit.. Not much tho and not at all back tward the exhaust side. On all the ones iv done sofar iv tryed to keep the same angles it had from factory. I wonder if the mains should be flatened a bit more? So the fresh charge is aimed closer down to the top of the piston ?They are close to flat now but not quite. The secondarys are pointed upwards more.. Should i try to flaten them more? Im looking for ideas before i ruin a cylinder .
Btw all the saws have a dual pipe mm. The pipes are 1 inch id . I flaten them a bit inside the muffler just cause i think otherwise its a little too freeflowing

 

[mdavlee]

I copy the stock roof angles on the cylinders. Last 365 I did was stronger than my 372 I ported.

 

[Matt1183]

Ok.. How about the angle toward the intake? I was widening them a little forward of stock . And did you widen the 365 ports all the way up from the base? I did on mine but it was a lot of grinding so if its not necessary i def wont bother next time.

 

[Chainsaw Jim]

You might be dealing with too much exhaust with dual 1" pipes. Flattening the end a little doesn't make it smaller it only changes the shape.

 

[Matt1183]

You might be dealing with too much exhaust with dual 1" pipes. Flattening the end a little doesn't make it smaller it only changes the shape.

Ok.. I might try welding up a ring around the inside to bring the inlet id down.

 

[mdavlee]

Didn't widen at all. Just raised to desired timing.

 

[Chainsaw Jim]

Ok.. I might try welding up a ring around the inside to bring the inlet id down.

Or maybe use the available space inside the can and choke them at the outer end.

 

[Matt1183]

Didn't widen at all. Just raised to desired timing.

What do you think of my timing numbers? And the progressive opening ?so i was loosing velocity by widening them then hey?

 

[mdavlee]

The numbers look good. I think mine was about the same. I don't widen if I'm raising them a decent bit.

 

[jb-chainsaws]

The numbers look good. I think mine was about the same. I don't widen if I'm raising them a decent bit.

This is some solid advice for anyone starting out porting, including myself who's starting to degree saws.

It's hard sometimes to think of little gems like that on your own, so thankyou!

 

[Matt1183]

This is some solid advice for anyone starting out porting, including myself who's starting to degree saws.

It's hard sometimes to think of little gems like that on your own, so thankyou!

X2

 

[drf256]

Matt, thanks for this thread. This interests me very much.

Most of the newer models I've seen open quads live a "V" if you stare down the cylinder. At least this is true of the Stihl 661.

The 661 main opens first and on the exhaust side. The intake side of the secondary opens next.

 

[mdavlee]

Husky and dolmar open them flat for the most part. Roof angles are different on the main and secondary. I have opened them like a V just to see if there was a difference. It may have made a little wider power band is all.

 

[Red97]

Think your 371 has just a bit much stagger in the transfers for your intended purpose. Think if you set the mains to 124/5 and flat. You will have killer top end but sacrifice a little with a long bar.

Last one I did was 78/100/120 really liked that saw. Set round 14,500 ran a 32 pretty easy in hard wood.

Agree the muffler needs to be choked down just a bit.

 

[mdavlee]

I had missed that part on the staggered uppers. I run them even on huskies. Try both at 122.

 

[Matt1183]

Ok.. Thanks guys . Im thinking about getting some cheap ebay cylinders to try different angles and opening progression in. Il post what i find when i do.. Its going to take awhile ... Lots on the go. But i think it would be worth it..plus i get more grinding practice

 

[Matt1183]

O

I had missed that part on the staggered uppers. I run them even on huskies. Try both at 122.

ok i will try that

 

[GoBigBlue1984]

I've found these little nuggets help when polishing in the transfer angles and smoothing out any grind marks. They are little sanding mandrel and drums. The mandrel is slit all the way around which keeps the drum biting and it doesn't slip. They also sell them cylinder shaped and coned. The diameters range from 3/16, 9/32, 5/16, 3/8. I like the smaller diameter for cleaning up transfer work especially on the quad ports where there isn't a lot of room. Coarse and medium grit.

 

[NCFarmboy]

Where did you find them? I like.
Shep

 

[GoBigBlue1984]

Woodcarver supply sells them


Sent from my iPhone using Tapatalk