372xt carb on 390xp?

[idiotwithasaw]

I have never tried it, but there is always a first time.

 

[Mastermind]

they tune piggy rich even with the the high speed closed. the nozzle of the 394 is drill so it is a nozzle and fix jet all in one. i put one on a 272 last and it ran pig rich but just fit the perfect size sewing needle in the hole and snapped it off as a plug. all fuel then goes through the high speed needle. worked good but the needle was out a ways. gonna try solder it closed and redrill next time as per tree monkey suggestion. it's my grandpa's firewood saw now. also to note. boring a 296 over 19mm creates a serious hesitation off idle which is another reason i would never do it again. the one i went to 20mm i'm upset about. i may dry bore the throttle bore larger when i find or make a larger butterfly to see if that fixes it. at 20mm the venturi is very close to the throttle bore which is what i think the problem is. the 39 throttle bore also matches up to the 385/390 intake boot the best out of all the carbs.

Good info again. I've been getting deeper into carb mods, but rarely have the time to spend on it I would like too. I do too many saws.

 

[mdavlee]

I'd like to find a different Tilly to run on some of these saws.

 

[Mastermind]

I've bored out a few carbs, but never really liked the end result. On a couple though, I took the time to overbore the throttle end, and replace the plate with a larger one. That did net some good results. But I had a lot of time in those carbs.

 

[fin460]

they tune piggy rich even with the the high speed closed. the nozzle of the 394 is drill so it is a nozzle and fix jet all in one. i put one on a 272 last and it ran pig rich but just fit the perfect size sewing needle in the hole and snapped it off as a plug. all fuel then goes through the high speed needle. worked good but the needle was out a ways. gonna try solder it closed and redrill next time as per tree monkey suggestion. it's my grandpa's firewood saw now. also to note. boring a 296 over 19mm creates a serious hesitation off idle which is another reason i would never do it again. the one i went to 20mm i'm upset about. i may dry bore the throttle bore larger when i find or make a larger butterfly to see if that fixes it. at 20mm the venturi is very close to the throttle bore which is what i think the problem is. the 39 throttle bore also matches up to the 385/390 intake boot the best out of all the carbs.

I'm learning a lot from you guys, but still don't know much about carbs.

I don't know my carb numbers, but for example on the 296 that you bore the venturi out on to say, 18.25, 19, 0r 20mm on, what is the original venturi size?

 

[fin460]

17.46mm i believe. honestly though fin, if you only have one 296 leave it and practice on a less valuable carb. not enough gain for the risk of *f-word'n up. there really is not much gain at all. they do change the way they run but i'm not convinced it makes more power. i'm of the thought that it changes the powerband range of the saw. (moves the powerband higher in RPM with the bigger throat) the 20mm bore was a dud and so was the 19mm which is why i said i would never go over 18.25 which is the stock 39 size i believe.

Ha no worries, I don't plan to do any carb work, I was intrigued by boring out carbs, and was just sitting here reading wondering, how much was actually being removed.

I have no skills yet, I still want to know how to set the metering lever on the average carb.

 

[SawTroll]

I was wondering if that 394 carb I have would fit a 372....cause it looked like it might. ...interesting

As I recall it, the RWJ-4 of the 372xpXT have a larger venturi than any of the 394/395 carbs (19.05 mm)?

 

[Mastermind]

As I recall it, the RWJ-4 of the 372xpXT have a larger venturi than any of the 394/395 carbs?

Your recollection is perfect sir.

Now.......fix that avatar.

 

[SawTroll]

Your recollection is perfect sir.

Now.......fix that avatar.

My avatar is too large to fit here, and I have long forgot how to resize pictures....

 

[Mastermind]

Send it to me.

mastermindworksaws@gmail.com

 

[Mattyo]

so, basically the xt carb is the best out of all of them, but will a 394 carb work? if it'll work thats awesome because I have an extra one of those and I'm saving my extra xt carb for my hybrid saw

 

[Mastermind]

Largest ain't always best.

The XT carb can be weird at idle and off idle.

 

[Mattyo]

but ...but .... 08f150 says bigger is better

 

[Mastermind]

I'm sure the 394, or 395 carbs can be made to work without much drama. I've not done that swap though. I try my best to use the carb that is stock for each saw I do. Of course, that's just because I'm strictly a worksaw builder.

 

[Mattyo]

frankly i'm super impressed w/ the $16 chinese knock off carbs ... put one on a 365 that I was trying to tune, and it did beautiful.

just nice to know other parts work with different saws is all... i'm more of a parts changer than a saw builder, just love to know what is even close to compatible.

 

[Mastermind]

It's a shame Shane bailed out on us. He seemed to have quite a bit of knowledge on these swaps.

 

[Mattyo]

Sorry...not familiar with what'd going on with the board...

 

[Mastermind]

No worries.

 

[Postrip]

The Walbro carb off a 394/395 does work quite well on a ported 372!
It's a bit of a tight squeeze , with the 385 filter mount, but it does all match up.
I have learned , that it is a bit hesitant off the bottom, however some slight changes in the transfer ports solved my problem.
I'd say go 4 it!, you have nothing 2 lose!

 

[angelo c]

Our tech guy isn't here everyday.

I've been messaging him.

maybe you should send him a text instead of massaging him....