Quads!

[Ketchup]

I have a preference for quad transfer cylinders. I started laying out a couple and got a little carried away. So I figure I might as well post up some pictures. Hopefully it stimulates discussion.

 

[hacskaroly]

I have a preference for quad transfer cylinders. I started laying out a couple and got a little carried away. So I figure I might as well post up some pictures. Hopefully it stimulates discussion.

Are those just extras you have or do they go to saws you are working on? For Huskies, Stihls or what?

 

[Ketchup]

I’m not sure what the biggest quad cylinder is. It kinda depends how picky you’re being about defining a quad. Maybe 881 is the largest. The biggest I have is a 395 Big Bore at 58mm. This one ingested the keeper screw on the choke butterfly.

Then we have an OEM 395 at 56mm. I started porting this one then noticed a chip at the upper. Might still do this one for a personal.
And here’s the piston style. I think the piston informs how the transfers feed.

 

[Ketchup]

Are those just extras you have or do they go to saws you are working on? For Huskies, Stihls or what?

Some are slated for saws, some are just part of the collection. I realized I didn’t grab any 50cc. I’ll bring some of those in a bit.

 

[hacskaroly]

Some are slated for saws, some are just part of the collection. I realized I didn’t grab any 50cc. I’ll bring some of those in a bit.

Nice, I will have to take a look at what I have, I had not paid that close attention before. Very cool!

 

[Ketchup]

Next up, 390xp Big Bore. This one arrived in the mail yesterday. Although the transfer lowers are as small as I feared, I’m still excited about this one. 57mm!


Then 390xp OEM 55mm. Kind of a Gold standard cylinder design. Like a dirt bike inside of a chainsaw.


And because they run so darn well despite the smaller displacement, a 385 oem at 54mm.

All 3 for comparison and the 57mm Piston (what a lunker).

 

[Ketchup]

Nice, I will have to take a look at what I have, I had not paid that close attention before. Very cool!

Please do! I’d love to see more Stihl, plus Pioneer, Mac, Efco and Olympic (sp?)! If it’s a quad cylinder, post it here. I’ve got some Stihls in the lineup, but I’m definitely Orange heavy.

 

[Ketchup]

On to my latest flavor of addiction, Dolmar/Makita 7900 and its variants. First up is a Hyway Big Bore at 54mm.



And then a 7900 OEM Jug I got off Ebay. 52mm.



And an OEM 7910 jug I bought new off Amazon. 52mm. Subtle differences to the 7900. I think this is the better jug but I haven’t timed them yet.



And the BB piston above the 7910. I think the slab side makes more sense.



Almost forgot a side-by-side. The BB has a very thin base at the side of the transfer lower, and you can see in one of the photos above the tunnel flare is quite different from OEM.

 

[Ketchup]

Back to the Husky club. Perhaps the most infamous bottom fed quad in existence, the 50mm 372 OE. THAT, my friends, is a good primary.



Hyway Big Bore 372 at 52mm. It’s too bad Hyway botched this. With better squish and casting (not to mention plating) these would have been unbeatable. This one caught a ring and smeared. Will probably clean up. I experimented a bit with grinding casting flash out of the uppers.



And I’ll toss in a 372xt for comparison. Note this is NOT a quad. I’ll be the first to admit these run pretty nice but in my opinion this was a step backwards. Husky could have easily made a quad cylinder that appeased the EPA using Strato technology. Proto 5-series.


Pistons.


Group shot.

 

[hacskaroly]

Perhaps the most infamous bottom fed quad in existence, the 50mm 372 OE.

That's where I saw some, got to work on two 372s...ok, I have worked on one!

 

[Ketchup]

Unfortunately, I don’t have any 365 cylinders, or 362 husky. 365 is 48mm quad. It’s been one of the major contenders in the 4 cube stock appearing races for a long time. 362 is dual, and a turd for the weight.

Nor do I have a Dolmar/ Makita 6100…yet.

So we have to bump on down to the 60cc class. None of which are actually 60cc.

First, a big nod to the Stihl 361, 47mm. Why is this a design outlier?



Speaking of working backwards…ms362. I think the design is interesting, but especially the V1 just didn’t deliver in the power department.



OEM 359xp 47mm. Is this a quad? Yes…but…those lowers. Maybe the mold maker left early that week? Surprisingly, they make good power, if not speed.



And OEM 357xp 56mm. One hell of a cylinder on too much case. I find these very fun to run ported, but they don’t handle longer bars well. The middle child in the 372, 357, 346 family.



Grouped with pistons. Sorry, 357 slug, but it looks very close to 359.

 

[Powerstroke Cowboy]

Very nice thread @Ketchup ! This will also help folks that might try to run down the hybrid rabbit hole. Tjats another thimg we need, dimensions of bolt patterns of cylinder bases.

I just took some pictures of the dolkita 79xx OEM 52mm and BB 54mm cylinders and got on to share them, but see you have that covered already!

 

[Ketchup]

On down to 50cc, we have the jug that ruled them all. My favorite quad of all time. The 346xp New Edition 44.3mm. Not the best example here. Brand new kit that I cut the base on when porting a batch of these. I owe this one to a friend when I get caught up.



Unfortunately, I don’t have a lot of 50 cc jugs knocking around. 346 OE (42mm), Ms261 (44.7mm) and Echo 4910 (44mm) need mentioned as they are all butt haulin’, work doin’, tree destroying machines. Why don’t I have more 50cc saws in my shop? Because they’re all out getting the work done.

I do have some Echo 490 jugs (44mm). Another knee-jerk reaction to EPA regs that weakened performance. The lowers on these are banger, but the side cover and upper design really holds the saw back. Echo improved on this with the 4910, but still choked the transfers in a way that’s hard to fix.



And just because I have room for more photos, heres the transfer cap. It shows how sharp the angle is in the roof of the upper, which constricts flow a surprising amount.



Also, they let the new guy design the intake. Or maybe the old guy. It’s certainly the kind of stuff that you see in saws from the 70s and early 80s. Maybe it passed emissions by killing case compression?



Groupie:

 

[Ketchup]

Very nice thread @Ketchup ! This will also help folks that might try to run down the hybrid rabbit hole. Tjats another thimg we need, dimensions of bolt patterns of cylinder bases.

I just took some pictures of the dolkita 79xx OEM 52mm and BB 54mm cylinders and got on to share them, but see you have that covered already!

I’m just skimming the surface. If you have stuff to share post it up. I want to hear what other people notice and think about. There’s no way this will stay organized. Fire away! Just try to keep it related to quads.

 

[Powerstroke Cowboy]

Here's a OEM 52mm dolkita 79xx cylinder this cylinder came with the slab side piston, and a 54mm BB hyway cylinder.

OEM on the left and AM BB on the right. Right away you can see the OEMs lower transfer opening are bigger. There is room on the AM BB to match the size of the OEM piston.

A close up shot of the AM BB cylinder.


A close up of the OEM cylinder.


Another close up of the AM BB cylinder.

Another close up of the OEM cylinder.

As you can see the quite a bit of difference in tranfer port size. This is one of the reasons a BB will generally not make as much power an OEM cylinder. Again, The AM BB can be opened up to match the OEM. It just takes time.

 

[Powerstroke Cowboy]

A continuation of the above post. This time looking at the shape of the transfer ports. As well as how they direct the air from the case into the cylinder.


The first two pictures are of the OEM transfers. The first picture is of the transfer closest to the exhaust port. The second picture is the transfer closest to the intake port. Note they both direct the air/fuel mixture towards the intake side of the cylinder.




Here are the transfer ports of the BB AM cylinder. The pictures are in the same sequence as the pictures above were.

You will notice that the AM BB ports don't direct/angle the air/fuel charge quite as quickly towards the intake side. Its definitely lazy in that department. Plus there's less directing the flow in general. All this can be fixed, but will take lots of time.

 

[Powerstroke Cowboy]

Another continuation. The Last one as well. This next is a little subjective. I treid my best to take the dimensions in.the same place. But will admit, it was hard due to the shape of the port.

Fist picture is the OEM cylinder, second is the AM BB cylinder. You can see in the pictures the ports are small on the AM BB vs the OEM cylinder. This was probably the worst case. Most places it was just one mm difference. Still, that's a lot.

OEM cylinder.


AM BB cylinder.


OEM cylinder upper transfer ports.


AM BB upper transfer ports.


Ounce again there's a difference in the angle of air flow out of the ports. The OEM definitely is angled more towards the intake side of the cylinder.

It might be hard to see. But the OEM ports are bigger than the AM BB cylinder.

With these small but big differences one can see why the OEM cylinders run better.

I do believe the AM cylinders ports can be made to match the OEM ports. It's will just take time and maybe some epoxy.

 

[Ketchup]

Welp, it looks like my photos got a little jangled in the 50cc post. The 490 pic is at the bottom if you wanna look.

Where were we…

40cc. Sorry, I got nothin. Ms241 should be mentioned. School me on what else is out there.

35cc. Hell yeah. Top handles.

Wait. Most top handles are junk. All I have here is 200t an 201t. I have a 540xp carcass in the pile, but no time for that right now.

Alright. So if you count 200t then you have to count a whole bunch of other saws that have open ports. But they are quads of a sort. The 200t deserves mentioning because it was such a game changer for top handles. The king of the tree tops for many years with great rpm and distinctive sound that made groundies scatter. I came on the tree scene at the end of the 200t era. In my opinion the transfers give up a lot. If they had been closed with better transitions at the back of the upper THAT would have been a hell of a saw. The 200t screams on piss rev, but doesn’t grind well when the nose is buried. Still, it’s a piece of history. 40mm


And 201. This is a strange version of a quad that has gained a lot of popularity in modern saws. Dual lowers that wrap around the exhaust and divide into 4 uppers. Several modern Stihls are built this way and Husky 5-series have a very similar dual transfer design. I wish I knew why the designers went this way. 40mm



Here’s a meteor 201t jug. Note the poor casting in the chamber and the giant chamfers. Surprisingly, this jug made good power. Maybe because the transfer uppers are cast instead of the two piece caps that Stihl uses.



Echo cs355t and several other small Echoes are quads, but if we let in all the open ports and clamshells we’ll be back buying chainsaws at Lowes.

 

[Ketchup]

Okay, final post for the night.

Some 25cc.

Stihl 151t. 34mm. These saws have a popup piston that was the only significant change from 150t. When these puppies hit the market they really changed tree climbing. For an engine smaller than most weedeaters, they cut really well.




And then the echo 2511t came along. 35mm. With better ergonomics, less weight and a traditional non-strato design. It makes a shocking amount of power despite the silly cylinder flange and transfer stuffer. It not only kicked 150t to the curb, but stole 35cc market share as well. The 150/151 transfer design looks better, but the 2511 outperforms it in every way.

 

[Ketchup]

A continuation of the above post. This time looking at the shape of the transfer ports. As well as how they direct the air from the case into the cylinder.


The first two pictures are of the OEM transfers. The first picture is of the transfer closest to the exhaust port. The second picture is the transfer closest to the intake port. Note they both direct the air/fuel mixture towards the intake side of the cylinder.

View attachment 411977
View attachment 411978

Here are the transfer ports of the BB AM cylinder. The pictures are in the same sequence as the pictures above were.

You will notice that the AM BB ports don't direct/angle the air/fuel charge quite as quickly towards the intake side. Its definitely lazy in that department. Plus there's less directing the flow in general. All this can be fixed, but will take lots of time.
View attachment 411979
View attachment 411980

I really like these just as photos. They also show how subtle differences matter. I keep scrolling up and down to compare.