Want a bigger carb for your hopped up 372/375?
- Thread starter TK
- Start date
Help Support Arborist Forum:
So, I guess you are doing this mod???
Yes. I want the HD filter though. Would I use the 372 XT filter adapter, or the one for a 385/390?
The HD filter for the 390 is different, so it's the 372XT filter adapter that's needed.
kodiakyardboy
ArboristSite Operative
The AS community had determined it's bad.. Even without looking at it. Tell your customer right away so they can order a new one.
nmurph
ArboristSite.com Sponsor
- Joined
- Nov 26, 2007
- Messages
- 16,162
- Reaction score
- 7,168
Old post...that saw was returned to the tree service and is out making bacon everyday.
SawTroll
Information Collector
I didn't know that bacon was growing on trees! :msp_w00t:
half_full
ArboristSite Guru
Yep, the 372 fits for sure. I tried the low top version of the 390 filter at first for a better filter seal but it's too wide to fit in there. The HD filter is narrower and taller - but I think it would fit. I didn't bother to check though, as I had no intentions of any HD filter for mine.
SawTroll
Information Collector
Maybe I'll start a bacon farm, without any pigs! :msp_biggrin:
There's some other tricks to this swap
You need a 365XT or 372XT choke lever for the choke arm is different. It stick up instead of down.
The boot adapter and ring for the carb needs to be the 385/390 to match the boot for the 372XT boot adapter doesn't use the ring and will not fit the 385 boot. The interior pins interfear with the flanges of the 385 type boot.
You will need a longer impulse line than the old one that was on the chainsaw.
You need a 365XT or 372XT choke lever for the choke arm is different. It stick up instead of down.
The boot adapter and ring for the carb needs to be the 385/390 to match the boot for the 372XT boot adapter doesn't use the ring and will not fit the 385 boot. The interior pins interfear with the flanges of the 385 type boot.
You will need a longer impulse line than the old one that was on the chainsaw.
Also the is something wrong with the part number for the carb screws on the 372XT for when they come, they are the same as the old style 372XP and too short. You will need the longer carb screws and sleeves from the 385
kodiakyardboy
ArboristSite Operative
Big carbs and bacon, can a thread get any better?
SawTroll
Information Collector
I'm thinking de-stratified 372xpxt carb, with a well ported 51.4mm top end - who knows how that would perform?
SawTroll
Information Collector
Not a lot, as larger carbs changes the game more than some members think....
Today I installed the Walbro from a 390XP that I bored out to .745". This carb is identical to the one on my modded 390XP. The 372XP runs perfectly and still has lightning quick throttle response.
I recommend not using the 390XP intake boot. It does not fit the cylinder well at all, and I didn't want to risk an air leak. All you have to do is trim the rubber off the side of the 372XP boot where the impulse tube runs through. You can then index it as needed for the new carb. This does leave a small opening from the carb box to the cylinder, but so does the 390XP boot.
You do need the 390XP flange that the carb bolts to. The 372XP flange does not hold the throttle cable in the correct position, preventing the carb from returning to idle.
You will need the bolts for a 390XP. The 372XP bolts are too short.
I used the 372XP X-Torq HD filter adapter. After grinding the divider out of it, it worked great. The assembly does hold the filter a little high, but it pushes down easily and does not cause any problems. Pics below will show this.
You do need to use the 372XP X-Torq choke rod. It has a bend in it that's not in the original choke rod. It does stick out a tiny bit more than needed, but not enough to be an issue or even look odd.
I think that about covers it.
Here's the list of parts I used.
[video=youtube_share;snXfTr8vRhs]http://youtu.be/snXfTr8vRhs[/video]
I recommend not using the 390XP intake boot. It does not fit the cylinder well at all, and I didn't want to risk an air leak. All you have to do is trim the rubber off the side of the 372XP boot where the impulse tube runs through. You can then index it as needed for the new carb. This does leave a small opening from the carb box to the cylinder, but so does the 390XP boot.
You do need the 390XP flange that the carb bolts to. The 372XP flange does not hold the throttle cable in the correct position, preventing the carb from returning to idle.
You will need the bolts for a 390XP. The 372XP bolts are too short.
I used the 372XP X-Torq HD filter adapter. After grinding the divider out of it, it worked great. The assembly does hold the filter a little high, but it pushes down easily and does not cause any problems. Pics below will show this.
You do need to use the 372XP X-Torq choke rod. It has a bend in it that's not in the original choke rod. It does stick out a tiny bit more than needed, but not enough to be an issue or even look odd.
I think that about covers it.
Here's the list of parts I used.
[video=youtube_share;snXfTr8vRhs]http://youtu.be/snXfTr8vRhs[/video]
I didn't have any issues running the 390 boot on my cylinder, snugged up perfectly? I mentioned the 365xt choke lever in the original post, but while obvious to some but not others - the 372xt lever is the same as the 365xt so whichever you order will work fine. I was hoping someone would try the 390 setup under there, I think it would fit. Guess it really doesn't matter though in this case. I just wanted the low top 390 filter vs the 365 filter for the screw fitting vs the wire clip.
I hope that's a good quality impulse line, I've tried a couple different yellow ones and they hardened up solid - and I only did the carb swap back at whatever date this thread was started. I went back to the original black rubber husky line and it stays nice and soft and flexible. I won't use an aftermarket line anymore unless absolutely necessary. I've been curious about the WJ series carbs also but the quality looks down compared to the older walbro stuff. It just looks "Chinese-ey" to me lol. I like that others are doing this setup, makes me feel more like keeping it than swapping back to an HD walbro setup. Ill never go back to the 365 zama carb I had though
I hope that's a good quality impulse line, I've tried a couple different yellow ones and they hardened up solid - and I only did the carb swap back at whatever date this thread was started. I went back to the original black rubber husky line and it stays nice and soft and flexible. I won't use an aftermarket line anymore unless absolutely necessary. I've been curious about the WJ series carbs also but the quality looks down compared to the older walbro stuff. It just looks "Chinese-ey" to me lol. I like that others are doing this setup, makes me feel more like keeping it than swapping back to an HD walbro setup. Ill never go back to the 365 zama carb I had though
Last edited:
I didn't have any issues running the 390 boot on my cylinder, snugged up perfectly?
I hope that's a good quality impulse line, I've tried a couple different yellow ones and they hardened up solid - and I only did the carb swap back at whatever date this thread was started. I went back to the original black rubber husky line and it stays nice and soft and flexible. I won't use an aftermarket line anymore unless absolutely necessary. I've been curious about the WJ series carbs also but the quality looks down compared to the older walbro stuff. It just looks "Chinese-ey" to me lol. I like that others are doing this setup, makes me feel more like keeping it than swapping back to an HD walbro setup. Ill never go back to the 365 zama carb I had though
When I saw how much bigger the 390 boot was, I didn't even tryi snugging it up. Also, that's just another part that others won't have to buy to make this swap.
Stihl makes a black hose that I like to use for impulse lines. I didn't have any on hand, so threw this on temporarily.
Thanks again for posting this thread!
Hmmmm, you make me want to tear mine apart to check the fit now lol, but it's ran this long with no adverse effects! Can never be too safe.
On the fuel line note - have you noticed any issues with the yellow stuff? And what is it? I've used Oregon and tygon, Oregon is crap, tygon is better but still should have better life than a few months as an impulse.
And did you do a stopwatch test before and after? I'm hoping for some facts as to whether the carb swap really is better or not. I never timed mine so I don't know for sure. It "feels" better but we all know how that goes.
