First build 365 special to 372 XPW

[mdavlee]

I had to cut the old muffler off with a cutoff tool otherwise i'd have used it.


I realized i'd ordered the wrong rings before they got here. The listing said big bore and so did the p&c listing.


I spent some more time looking at the cylinder and i'm not going to do any porting right now. I'm going to run it stock so then I know what to expect and I can mod it in the future. I also see no point in removing the restriction on the transfer ports if I don't open up the area where the transfers go into the cylinder. I thought it looked like a large restriction compared to the 48mm cylinder but every port on the 51.4 is larger. I have to do a lot more reading before I port the entire cylinder.

Turbulence is power lost. Just that makes a slight difference in power. I’ve tried it both ways just to see. Anytime you dead head the flow coming into them since the engine works at about 0 psi with a touch of vacuum and a tiny bit of pressure smooth flow will make more power

 

[Ketchup]

The 385 or 390 carb is an easier swap than RBJ. You can swap the carb for added power later too. It's all about cutting wood, so get it off the bench and run it!

 

[vienster]

There's more to it than upgrading carbs. You'd need to re-clock the boot or use one from a 390, different filter elbow, and bolts.
I'd use the one you have for now. Once it's ported, it may be worth upgrading

One post I read said the boot needs to be clocked and something with the hole for the impulse and that was it. I'm going to use the one I have for now. I did run into an issue with the old style boot clamp coming into contact with the new case and impulse tube. They moved the impulse tube location and there was also an added piece on the casting. I had to cut the bolt so it didn't cut the impulse hose and clock the clamp slightly.

Turbulence is power lost. Just that makes a slight difference in power. I’ve tried it both ways just to see. Anytime you dead head the flow coming into them since the engine works at about 0 psi with a touch of vacuum and a tiny bit of pressure smooth flow will make more power

I wasn't sure if it was worthwhile to do the porting without opening up the cylinder ports. I'd also like to read more so i can get a better feel for how much to remove. I do have snap gauges but i'm not sure that's necessary or if i'd even be able to use them.

The 385 or 390 carb is an easier swap than RBJ. You can swap the carb for added power later too. It's all about cutting wood, so get it off the bench and run it!

If I didn't get side tracked with working on a rifle it would've been done, but I agree. I'm sure i'd be satisfied without doing any porting compared to what i've ran over the years, but now I have the tools.



Thank you guys for the help and advice.

 

[huskihl]

One post I read said the boot needs to be clocked and something with the hole for the impulse and that was it.

If you didn't get a different filter elbow, the filter and elbow would be tilted to the left about 1.5". Lol. Not saying it wouldn't work.
And if you use an xtorq elbow to straighten out the elbow and filter, the bolts will be too short.

 

[vienster]

I was just reading word for word what some idiot said on another forum. People love to give people advice on things they've never done or even seen done in person. It's hard to believe anything I read sometimes on certain forums because of posts like that. I've spent money on **** that was supposed to work, but didn't.



This saw is an animal. I didn't install it with the base gasket and I can barely pull it over. It is by far the fastest cutting, most powerful saw i've ever used. The instructions say not to give it full power for the first few hours of operation so I didn't adjust it to full rpm with the tach I have. It passed pressure and vacuum tests. For ten dollars I bought the blockoff plate and intake boot cover. I also bought the oil seal drivers and i'm glad I did. I had one cocked pretty good, yet it looked fine. The driver on the flywheel side has a step so you drive it even.

For some reason I had an exhaust leak and I torqued it to spec. I mixed the fuel 40:1 and there was quite a bit of **** in the exhaust port which people said wouldn't happen with the new modern oils. It was nearly like that black **** my dirtbikes would leave coming out of the tail pipe years ago.

I'm going to end up pulling the cylinder this weekend and doing some port work on the transfers and maybe the exhaust. I hogged out a 1" hole in a muffler last night, I just have to weld/braze it. The other dual port muffler I brazed sounds great.

 

[huskihl]

I was just reading word for word what some idiot said on another forum. People love to give people advice on things they've never done or even seen done in person. It's hard to believe anything I read sometimes on certain forums because of posts like that. I've spent money on **** that was supposed to work, but didn't.



This saw is an animal. I didn't install it with the base gasket and I can barely pull it over. It is by far the fastest cutting, most powerful saw i've ever used. The instructions say not to give it full power for the first few hours of operation so I didn't adjust it to full rpm with the tach I have. It passed pressure and vacuum tests. For ten dollars I bought the blockoff plate and intake boot cover. I also bought the oil seal drivers and i'm glad I did. I had one cocked pretty good, yet it looked fine. The driver on the flywheel side has a step so you drive it even.

For some reason I had an exhaust leak and I torqued it to spec. I mixed the fuel 40:1 and there was quite a bit of **** in the exhaust port which people said wouldn't happen with the new modern oils. It was nearly like that black **** my dirtbikes would leave coming out of the tail pipe years ago.

I'm going to end up pulling the cylinder this weekend and doing some port work on the transfers and maybe the exhaust. I hogged out a 1" hole in a muffler last night, I just have to weld/braze it. The other dual port muffler I brazed sounds great.

The added oil spooge is probably due to your rich tune

 

[vienster]

It is running pretty rich. I saw a listing on ebay and this guy was selling a $2800 dollar stihl saw and he said you want it to be rich on the break in. People on here have said the same. It doesn't four stroke under full load.

I ended up brazing a muffler. I never would've thought about going with such a large hole, but it seems like a good idea. I just got done powder coating it. It came out decent for my second time brazing and powder coating ever. The other is the one on the saw now.

I experimented with carbides on the old cylinder I have to find out what bits work best before I port the cylinder I have. I was happy with the results at first but I kept trying different bits and it seems it's harder with smaller bits to make it uniform.

 

[vienster]

I ported the exhaust outlet and transfers, hopefully I didn't take too much off the transfers.

The pedal on my flex shaft grinder went bad. I read the reviews on the harbor freight one and apparently it's junk now as well. I ordered an old foredom bench top model and returned the broken unit to amazon.

Anyway I got a deal on a new rwj4b for 55 dollars and I ordered the intake, bolts and a new impulse hose. Is there anything else I need to install it and tune it? I can't find much information on the swap by searching. If I clock my boot will the throttle cable holder be an issue?

 

[vienster]

That carb made a big difference. It made no sense a couple times what happened while tuning it, but in the end I got it where I wanted it. I don't think it was as bad as people make it out to be but I haven't run it in any weather over fifty. I can not believe how much I had to change the high screw when the temperature changed from zero degrees to fifty for a day. I didn't have to touch the low screw, but it did start harder one time throughout the day. I cut up thousands of dollars worth of 1&2" oak blocking to really test it and that saw doesn't flinch when the 20" bar is buried. It will hold 12k in the cut. I can't imagine what a real port job would do.

I read that there was reason to suspect that since I installed the higher 372xt top cover that I may have cooling issues in hot weather, but that seems hard to believe. Does anyone know if this is true? I was going to leave the stock top cover on but i'd have to force the filter cover down to snap the cover. I can't see the boot lasting with all that pressure down on it.

I may use another boot in the future I don't know if I can gut an xt boot. I will probably just get the 390 boot and flange.

I've put seven hours on the saw so far and it's nice to have a real saw. I did put on a wrap handle and the big dawgs but it's unreal how much another pound adds to the weight of the saw. When I swapped back to the regular handle and single dawg I took fifteen ounces off the weight, I also got a tsumura light weight bar which was another 8oz.

I just received an older obsolete clutch hub in the mail today and it actually has a bronze bushing in it unlike the one I replaced. I wonder if it's oil impregnated bronze like oilite pilot bushings. I should've replaced the hub when I replaced that clutch that was stupid. To me that's like not resurfacing or replacing the flywheel. I also upgraded to the better oiler gear.

I may pick up a 51 tomorrow to have a backup/limbing saw. The craftsman piece of junk I have was giving me problems again. I don't need it but i'd rather learn how to properly port with something decent.

 

[vienster]

I'm not sure why the 372xt shop manual shows that the lever arm is supposed to be level with the carb body but on this rwj4 the lever is recessed and the diaphragm has a nipple?

I cut a piece out of the old cover and epoxied it in place on the xt cover. I used jb water weld because that was all I had and it held up so far. It took some time and patience to make it fit.