Basic 3120xp Mods

[jaywebb916]

3120 xp

hey guy's
I'm new to this so please be patient. first off I hope I'm in the right place. I have an older husky 3120xp. it has new top end and a complete carb rebuild. the saw syarts and runs but it feels like it should rev alot higher. it doesn't have that wide open feel of a nice running two stroke. any suggestions would be welcome...thanks

 

[jaywebb916]

3120 xp

hey guy's
I'm new to this so please be patient. first off I hope I'm in the right place. I have an older husky 3120xp. it has new top end and a complete carb rebuild. the saw starts and runs but it feels like it should rev alot higher. it doesn't have that wide open feel of a nice running two stroke. any suggestions would be welcome...thanks

 

[Wet1]

What color is the coil?

 

[jaywebb916]

black

 

[Wet1]

Well, that is the higher limiting coil. What's it turning for max rpm?

 

[jaywebb916]

do not know. I'll need to but a tach tool. is a tool I could find at sears or autozone?

 

[jaywebb916]

the tach on my 3120 is bouncing from 10,250 to 10,440......at wide open. it just doesn't feel crisp. any help would be appreciated.

 

[MCW]

Well, that is the higher limiting coil. What's it turning for max rpm?

12,000RPM for the black coil I think?

 

[B_Turner]

If your tach reading is at all steady, then you are not on the limiter. When on the limiter the tach will read nonsense -- like it will jump around and read 4k etc as the spark is interrupted.

 

[jaywebb916]

why would I only read 10 to 10-5 at full throttle?

 

[Chad Schlise]

Great info, and also a good way to turn the 3120 into a chainsaw instead of a air conditioner.

 

[B_Turner]

why would I only read 10 to 10-5 at full throttle?

I'll leave that to the saw techs to really answer but it seems to be like it's probably a fuel thing. If it were an adjustable carb (which it probably isn't) then I would say it was adjusted way too rich.

Did they mess with the jet, drilling it out too much (I think it was brncreeper that had the same issue after he accidentally drilled his jet to 1.6mm reather than 1.16mm.)

Air filter?


Flywheel slipped on keyway?

Tach wonky?

 

[jaywebb916]

I wish I knew. I just pulled the plug and it's really black,which I think indicates way rich???? I rebuilt the carb myself with all new parts. I guess I could fool with the H and L settings but I'm terrible with those things. I'm going to check the compression right now. thanks.

 

[Wet1]

I wish I knew. I just pulled the plug and it's really black,which I think indicates way rich???? I rebuilt the carb myself with all new parts. I guess I could fool with the H and L settings but I'm terrible with those things. I'm going to check the compression right now. thanks.

Sorry, I didn't see this. Based on what you've written, it sounds like the saw is running excessively rich. Check to see if your carb has a high speed jet adjustment, most do not, but yours might if it's old enough. If so, turn it in some until it starts four stroking or hits the limiter. You should be able to reach around 11.6k (+/-) with that coil in it. If you do not have an adjustable high jet, it sounds like someone has reamed out (or exchanged) the factory jet... and went too far doing so. Assuming it's a fixed jet, I'd start with a factory 1.12mm jet and go from there.

All this is assuming you didn't screw anything up when rebuilding the carb.

Good luck.

BTW, you might want to make sure it has the correct plug in it as well.

 

[ASEMASTER]

3120k

Hi guys I have 3120K at work and it needs a new upper end .I know this saw has no oiling ability but would it be worth fixing to do some racing or milling with water as a lube (this does work as I use it on my other saw).
I am a good mechanic and would like to take all this info and make one screaming saw out of this if you think it would work .. the saw will be free but it has been blown up.

 

[ritchie.426]

3120 carbs

Hey guys, I had two of these brought in from oz in bits, 1 had an adjustable hs, the other fixed. Im sure the adjustable was a 95, the other is a 98. I rebuilt the 95 stock with oem bits and put the fixed carb on it. Both have black coils. With the fixed carb on it it ran like a dog. I swapped them over and it ran alot better but still had room for improvement. Ive sold the 95 and will try and track it down to see if I can get the carb model no. Ive asked around and no one has heard of a hs adjustable carb for these, but trust me they do exsist!!

The 98 is getting a rebuild at the mo, polished the cases so far, have one other mod to make to make to them then will throw the bottom end together. I work at a husky shop so will look on epc tomorrow regarding the jets and perhaps earlier carbs.

 

[B_Turner]

Hey guys, I had two of these brought in from oz in bits, 1 had an adjustable hs, the other fixed. Im sure the adjustable was a 95, the other is a 98. I rebuilt the 95 stock with oem bits and put the fixed carb on it. Both have black coils. With the fixed carb on it it ran like a dog. I swapped them over and it ran alot better but still had room for improvement. Ive sold the 95 and will try and track it down to see if I can get the carb model no. Ive asked around and no one has heard of a hs adjustable carb for these, but trust me they do exsist!!

The 98 is getting a rebuild at the mo, polished the cases so far, have one other mod to make to make to them then will throw the bottom end together. I work at a husky shop so will look on epc tomorrow regarding the jets and perhaps earlier carbs.

My understanding was that the adjustable HS on the 3120 was gone by 95. I think the saw began around 89 and the fixed carb came in a couple years later.

I had hoped that walbro sold the adjustable HS carb for some other application still, but have not found one available new.

Also as far as I can tell, for some reason in the US the 3120 OEM non epa jet (1.16mm) cannot be found in the us (even through Walbro), although it can be easily had in NZ (thanks stevethekiwi).

The 3120 non epa coil (black) and flywheel are still readily available here new through husky, just not the jet. (Course one can ream the 1.12 jet bigger.)

 

[dbabcock]

Getting rid of the 3120 rev limit

Check out my thread, "Getting Rid of the 3120 Rev Limit" from a long time ago.

 

[rupedoggy]

Wow speaking of a long time ago. "Daniel Boone Babcock" how the heck are you? Flying any Helos lately? Mike

 

[blsnelling]

An excellent read here. I'm bumping this since I will be working on a 3120 soon.