Makita/Dolmar High & Low Adjustments with Limiter Caps Removed

[Jonny Quest]

Gents:

My Dol-Kita 6421 now has a new OEM 7910 top end and muffler mod (guts pulled out). The carb has been tuned for a 6400, so now I need to tweak the H & L screws now to deal with the higher displacement. The limiter caps have been removed, but I can't see the heads of the screws. What type of carb adjustment tool do I need? Obviously a simple flat-head or phillips screw driver won't work, but I've only got the Husqvarna tool and it doesn't seem to fit the Dol-Kita.

I've seen some data that says the 7900 should be tuned for 13,500 rpm -- but that the 7910 should be tuned for 12,800 rpm. Thoughts?

[even though I've not yet tuned the carb, this thing has tons of torque and feels like a beastie. It just may give my 390XP some competition.]

JQ

 

[Deleted member 149229]

Mine are 6401/7900, the carb screws are standard straight slot. I checked with @fordf150 and set mine to 13,000, 13,200 was max. Both had muff mod.

 

[Tree Feller]

My 6400 takes just a straight screw driver. I up graded to the BB kit and had very little adjustment to do from how it was set for the 64cc top end. To run during break in, I set mine at 12,800-13,000 then leaned it our to around 13,500 ish just before the limiter hits.

 

[SOS Ridgerider]

The 6421 coil is limited to 13,500, and you probably need a single D or double D to adjust the carb, if they’re not slotted. I hear all the time that the double D is the correct one, but I can only fit the single D on any of my saws. It could just be the cheap china tools I have that aren’t exactly precisely made. Lol.
You can pick up a carb tool kit cheap on eBay or Amazon, it’ll have both the single and double D in it, and it’ll do the job.
You can also slot the heads of the needles with a Dremel if you don’t want to buy the carb tools, and just use a flat head. Tune it to clean up in the cut, and you’re good to go. You’ll enjoy that saw, for sure. They’re sweet.

 

[Jonny Quest]

Thanks, gents, for the replies. I'll pull the tachometer out and see what kind of rpm it's turning. I'll order up a carb tool kit from Amazon. The cheap-O Chinese made stuff looks to be $10 to $12.

JQ

 

[Jonny Quest]

Threw the tach on last night and we RPMs reached 12,800 (with bar/chain attached). I'm gonna leave it there.

JQ

 

[Jonny Quest]

Got my Chinese carb tools and the H screw is a Double-D. Thanks gents for the tip.

JQ