Porting the dolmar 421...

[Red97]

Your probably right Joe. Just thinking out loud...


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I thought long and hard about putting the ex around 108.

Decided not to stray too far from factory, as those that have these saws love the way they run with just a mild muffler mod.

 

[CoreyB]

I honestly think Dolmar just puts a bit more into their stock saws. Not leaving as much to gain as some other manufacturers do. At least that is what I tell myself to ward off the porting cad!

 

[paragonbuilder]

I honestly think Dolmar just puts a bit more into their stock saws. Not leaving as much to gain as some other manufacturers do. At least that is what I tell myself to ward off the porting cad!

Once you start it's all over Corey. Don't go to a gtg...

 

[David Young]

The 7900 liked more ex and t it there is only one way to know.

You could try what moons does. Give it 2 degrees see what it does.

 

[paragonbuilder]

The 7900 liked more ex and t it there is only one way to know.

You could try what moons does. Give it 2 degrees see what it does.

Or file the piston and see what happens. Easier to go backwards that way.

 

[fordf150]

Or file the piston and see what happens. Easier to go backwards that way.

that is a much cheaper way to go. P&C is $190. piston is only $63

 

[drf256]

Realize guys, 8cc is a 20% reduction in size at this displacement. On a 90 cc saw is half of that.

 

[Red97]

I honestly think Dolmar just puts a bit more into their stock saws. Not leaving as much to gain as some other manufacturers do. At least that is what I tell myself to ward off the porting cad!

Think it has more to do with the short/narrow pistons dolmar likes to use

The 7900 liked more ex and t it there is only one way to know.

You could try what moons does. Give it 2 degrees see what it does.

Still have to check the comp. That will let me know bout raising the ex further.
Just with a limited coil, I can't see it being a huge benifit. May be wrong tho.

 

[drf256]

The echo is 32.5648976542786% faster.

 

[Red97]

Before I ship the dolmar back, I will do some more compisons between it and the 241c.

Now if you were in the market for a stock saw, and couldn't afford to port it, the dolmar may be the better option. The echo really needs to be ported where the dolmar just needs a muffler mod.

 

[Backtroller]

Realize guys, 8cc is a 20% reduction in size at this displacement. On a 90 cc saw is half of that.

Exactly (well not exactly, it's been a long day)

I looked up a Stihl MS261 it is 50.5cc while a MS362 is 59cc. Approximately 8cc difference.

 

[Red97]

Forgot to mention the echo is running a std 3/8 rim vs the correct lo pro on the dolmar. You can feel a slight "rumble" from the chain. I would say it is worth it to run the correct sprocket for the lo pro chain should one choose to go that route.

 

[Backtroller]

I'm thrilled with what Red97 did with this saw. The porting and machine work look great and Joe's level of attention is first rate. The saw definitely sounds better and obviously is stronger in the cut. With a broader power band and more torque, I think I'm really going to enjoy using it.

I know Joe was hoping for more but he created a beast out of 490 to compare it against. Displacement is hard to overcome and with the lack of a better coil and carb, I'm totally satisfied.

When I get it back I'm going to try a 18" .325 bar (but will probably run the same low pro set up Joe used for general use) and compare it to my stock 026 Pro with the same chain and 18" bar. We'll see how badly it beats up on my second favorite Stihl.

 

[paragonbuilder]

I'm thrilled with what Red97 did with this saw. The porting and machine work look great and Joe's level of attention is first rate. The saw definitely sounds better and obviously is stronger in the cut. With a broader power band and more torque, I think I'm really going to enjoy using it.

I know Joe was hoping for more but he created a beast out of 490 to compare it against. Displacement is hard to overcome and with the lack of a better coil and carb, I'm totally satisfied.

When I get it back I'm going to try a 18" .325 bar (but will probably run the same low pro set up Joe used for general use) and compare it to my stock 026 Pro with the same chain and 18" bar. We'll see how badly it beats up on my second favorite Stihl.

I'm looking forward to that comparison!

 

[Red97]

The echo is 32.5648976542786% faster.

Your not a convert are ya???

Hate to see ya give up the 026 thing

 

[Red97]

I'm thrilled with what Red97 did with this saw. The porting and machine work look great and Joe's level of attention is first rate. The saw definitely sounds better and obviously is stronger in the cut. With a broader power band and more torque, I think I'm really going to enjoy using it.

I know Joe was hoping for more but he created a beast out of 490 to compare it against. Displacement is hard to overcome and with the lack of a better coil and carb, I'm totally satisfied.

When I get it back I'm going to try a 18" .325 bar (but will probably run the same low pro set up Joe used for general use) and compare it to my stock 026 Pro with the same chain and 18" bar. We'll see how badly it beats up on my second favorite Stihl.

Thank you for the kind words.

Had I not compared directly with the echo I think the gains would be more noticeable.

Never ran a stock 026, but the little dolmar should hold its own against a stock one. Make sure to try the .325 vs the lo pro.

 

[Backtroller]

Yes I'll try lpvs .325. I need to go and get a loop of Lp made. Been putting it off since I'm not a big fan of my local Stihl dealers

 

[Red97]

Healthy bump, it will probably go up a bit once fully broke in.

Don't think 108 would work well in this saw at all. Even at max off the base comp would be around stock. Think most of the torque I gained was from the comp bump. And the little bit of top end was from the port shaping. Man if it just had a wider piston, unlimited coil and a better carb setup....

This thing is still very well mannered, starts easy runs/idles all day. What more could ya really ask for.?

 

[RIDE-RED 350r]

Goes to show ya (as I have been learning), there is no universal set of "tricks" that works perfect for every different saw out there.

And on your tach doing weird things: I was attempting to clock my ported 372XPW after my first stage of porting changes and was still running the limited coil at that time.. I would throttle the saw, RPMs would climb on the tach then tumble down. The rev limiter plays hell with the tach.

Nice work on the 421. I've had a bit of an itch for one for awhile, thanks for making it a full blown case of the hives!! LOL!

Question on the 421: Does it have "pro grade" type cases or is it clamshell with a plastic case/oil tank?

 

[Steve NW WI]

Healthy bump, it will probably go up a bit once fully broke in.

Don't think 108 would work well in this saw at all. Even at max off the base comp would be around stock. Think most of the torque I gained was from the comp bump. And the little bit of top end was from the port shaping. Man if it just had a wider piston, unlimited coil and a better carb setup....

This thing is still very well mannered, starts easy runs/idles all day. What more could ya really ask for.?

Joe, if it's still 4 stroking at the limiter, you aren't out of carb ... yet.

Nice work BTW.