365 special won't richen up on low side

[Mattyo]

Ok, thoughts and differential diagnosis needed.

I have a freshly rebuilt 365 special, decked, ported, new bearings and seals. carb has been cleaned. (and has plenty of fuel in it when I pull the carb cap ...its a zama) ...

so... the low idle screw will lean out the saw if I screw it in, but past about 1.25 turns out... to 4 turns out, does not richen up the saw. ...there is significant hesitation off idle no matter what I do ....

what are we thinking..... massive air leak?

saw starts fine, no issue there.

guess I should pressure and vac test...just hate doing that... other thoughts?

 

[Ironworker]

Do you have a spare carb

 

[Termite]

Do you have a spare carb

That is a great way to trouble shoot. I wish I had a RWJ4 to test my 365xt.

 

[Mattyo]

i sorta have a spare carb.... gotta scavenge... hehe

 

[AVB]

Check your metering lever height sounds like it might be too low.

 

[Mattyo]

had an idea when i was in the shower.... how about... could the carb needle lever be set too low?

 

[Mattyo]

LOL

 

[Mattyo]

Idle is better....still have a high end stumble....sometimes it revs smooth up....sometimes it stumbles getting up there

 

[Mattyo]

stumble is gone, just needed to warm up.... I think that low needle lever did it... interesting.

saw is smooth at the top end now

 

[Ironworker]

I have similiar problems with a 346 I just ported, ordered a 357xp 191 carb.

 

[Big_Wood]

it's the zama. i like walbro's and tilly's cause their pump side is overkill for the metering side. with zama the pump is more closely matched to the metering side but then if the pump becomes weak it will not feed the fuel needed for the metering side to fuel the engine. raising the metering lever from spec only masks the real problem which is a weak pump due to stiff pump diapragm or a restricted fuel pickup. IMO a saw with that carb has a new carb cost less value because of it but that's just cause i really hate those carbs. i'd rather see a chinese copy of the walbro on these then a zama.

 

[Mattyo]

on the other 365 I have, the Chinese walbro copy worked brilliantly... maybe I'll just go buy a few more on the bay

 

[jmssaws]

I never have liked a zama carb

 

[Mattyo]

just bought a couple cheap ones on the bay... we'll see how they do... though I think the zama is gonna be ok for this build... thanks guys

 

[jmssaws]

I've never had a problem with them cheap walboro knock offs from ebay

 

[Poleman]

Mattyo, did you get the Zama or Walbro copys? Some of the Walbro copys turn out to be built like a Zama inside. I had issues with some of these being too rich.
You can mod the Zama copys to run more fuel since you've performance tuned your saw....will give you some torque!!

 

[Mattyo]

Beats me which one I got lol...

 

[Mattyo]

http://m.ebay.com/itm/US-Replacemen...hainsaw-New-/151712437625?txnId=1348533460005

 

[Poleman]

Used those with good results!!

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[jmssaws]

Beats me which one I got lol...

Did you ever get another 394?