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372xt carb on 390xp?

idiotwithasaw

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Ok guys I'm about to tear into my 390 xp to replace the aftermarket top end I put on it to her it going with a new oem kit. Since prices have dropped I figured why not. Anyway I was wondering if any has put the xtorq carb from a 372 in one. Would doing this with a muffler mod be of any benefit or would I be wasting my time?
 

mdavlee

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It can't hurt. It's a bigger venturi and bore. I don't know if I would go through the expense for just a muffler mod. Does it have the Tilly or Walbro?
 

idiotwithasaw

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I think it has the walbro
 

mdavlee

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You can try it and there's no harm. It does allow more air in.
 

idiotwithasaw

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I think I will leave it alone till I'm ready to mod the muffler.

I'm a little concerned right now about my top end. The one I took off of it was an aftermarket no name kit with a golf piston. It had less than an hour run time on it and it had transfer on the right side of the exhaust and intake. I vac and pressure tested it and it passed rotated the crank and everything.

I went on and put the new oem cylinder and piston on but I'm worried that it will do it again. I vac tested it every time I took the cylinder off, from checking squish to installing the rings and circlips, and final assembly. Passed every time. Carb was set 1-1/3 out on both high and lo side. And the bearings looked good and the cages were intact.

Do you think this could just be a case of a bad am cylinder. Or am I missing something.
 

idiotwithasaw

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Now lets get back on track for a minute. If I were to muff mod this saw and put an xtorq carb on it, would I benefit from replacing the limited coil. Or should I leave that alone?
 

SquareFile

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Now lets get back on track for a minute. If I were to muff mod this saw and put an xtorq carb on it, would I benefit from replacing the limited coil. Or should I leave that alone?
Coil replacement makes it easier to tune.

I've tried wj118, 39, 71, rwj4 & tilly 296 on mine and found absolutely no difference in actual time cuts in consitant wood
 

mdavlee

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I do like the 14.1k could on them with a timing advanced.
 

idiotwithasaw

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Ok there is something funky with the site. Everyones pictures show up as huge and i can only see the left side of the picture. And I can't click them to make itbwhere I can see the whole thing. Also I'm not using tapatalk
 

idiotwithasaw

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I just left it as is. I didn't do anything to the muffler and I'm saving the carb for a 372 build. But it is the walbro. And I did notice some wear on the metering lever when I disassembled for inspection.
 

Mastermind

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i did a swap back to back on my walkerized saws and a stock saw. it did change the way they run. maybe not to a significant advantage but it did. i have a 385 ported from down south and it did make a noticable difference on it so i left it on that one. would i go buy a larger carb just to put one on? heck no! would i do it if i had the carb, heck yes. the 296 is the most reliable carb IMO. after a year of solid work you can pull apart a 296 and it's still in good shape. the walbro's wear weird on the metering diaphragm nipple/lever and need a rebuild after so many hours. the tilly's last the life of the saw if not left to sit. i've bored the 296 out to as far as 20mm even. takes some work with JB plugging the fixed jet passage and drilling the nozzle same size to compensate. i would never bore one out past 18.25 max if i ever did it again. i found the WJ39 stock to run the best but i didn't time any cuts. i also didn't leave it on there because the throttle and choke shafts are wackey for the 385/390. gonna try the 118 shafts in the 39 next time i get a 118 in here.

Here's one rigged with a 39. Definitely the most difficult of all the swaps. Might be easy with the 118 shafts?

089ba119abc8a2fc3aec06ea7e419b50.jpg

Good info sir. :)
 

idiotwithasaw

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It's very aggravating. Lol
 

idiotwithasaw

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What is that carb out of?
 

idiotwithasaw

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I'm just glad it ain't just me
 

Mattyo

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