Makita 6401 big bore

[dahmer]

If putting a big bore kit on a Makita 6401 would a Zama C3M be the correct carb to use? Any recommended kits or any to stay away from? Thanks.

 

[elmcuttr]

The Zama C3 should work fine. On my 6421 I had to modify the high screw which was meant to be non adjustable. Dremel made notch works (slightly crooked, but functional).

After my first tune and use, the saw would not restart. Not sure what I did. Rather than clean and rebuild, I replaced the Zama with a Walbro HD12. Fitament is perfect except the hole for the choke linkage on the Walbro is larger. I filled the original hole with JB Weld and drilled the same size hole as the Zama. Took the limiters off, tuned it. Saw runs awesome now. Price for the Walbro wasn't bad either. Got it off of that auction site.

 

[elmcuttr]

I went the cheaper route and went big bore rather than oem. My reasoning was that my rookie mistakes might cost a little less, if I messed it up. Popular opinion by those in the know is to go oem rather than big bore. If I do it again, I will go oem.

I installed the cylinder with gasket at a squish of .026". Compression after first couple of tanks was 130psi. I took it apart, deleted the base gasket, and installed a Caber ring. Squish is now .020". Compression improved to 165psi.

 

[dahmer]

After weighing pros and cons and getting a good deal I went with oem. Found out a 6401 carb will work, only need to change carb if it’s a 6421. Thanks.

 

[David _4]

What is the reason for changing the carb on a 6421 when going BB? The reason I ask is I have a 6421 with an OEM 790o P&C and it runs very strong with the carb that came on the 6421. According to the IPL's the carb # is the same.

 

[NCFarmboy]

The C3M runs good on BBK. Walbro HD-12 from 372 Husky is a direct bolton for upgrade. @Poleman reworks C3M drills jets, etc. Nothing but praise for his carb.
Shep

 

[OldRed1]

Did a carb mod on a dolmar 7910 that I ported with a Zama as per Poleman's thread. Saw runs like it hates the wood and wants revenge!