Makita 7900 or 6400

[CentaurG2]

I added an extra port with a spark screen and Husky 288 deflector.
View attachment 865349Sold to vinpie1
I don't think the 6421-7900 Dolmars are any bulkier than the Husky-Jonsereds.

I always thought they looked and handled just like an old four slice dualit toaster.

 

[KarlD]

Exhaust is gutted, oem outlet is enlarged and spark screen remains in place. White nylon filter is fitted. I’ve not adjusted the carb yet because the bar isn’t here yet...

 

[TimberWolf530]

Yep, I had a non cat muffler on mine, but it had a cage inside with holes, I drilled the holes larger
and opened the outlet under the spark screen a bit, not big enough so the original spark screen no longer works,
its all you need to waken them saws up, getting one ported is another story, but you can only go so far without
requiring a bigger carb, some can run the 7300 carb on a 7900 cylinder, so that makes a cheap upgrade from 73 to 79,
the 6400 carb really is no good on a 7900, nor a 7300, so that adds a carb to the equation if you want to get it spot on.

The specs I've seen show the same carb for all 3. Can you provide the part numbers for the different carbs you're seeing?

 

[KarlD]

Just getting my head around adjusting the carb when the bar comes.
Am I correct to say that the effect of removing the gubbins inside the muffler and enlarging the outlet makes the saw ‘breathe’ better...more air through the saw...possibly running lean? Only a problem at wot? so will probably have to riches up the H a little?
I will keep checking the plug when I run the saw.
Will I need to adjust the L?
I know all saws / mm’s are different, just wondering about what is likely.
I’m not super confident about adjusting the carb in wood...
TIA

 

[Rob Stafari]

Carb is same for all three in current lineup. Only thing that has changed through the years to my knowledge is the tamper resistence. Same part number, as seen in the Makita manual....

 

[KarlD]

Carb is same for all three in current lineup. Only thing that has changed through the years to my knowledge is the tamper resistence. Same part number, as seen in the Makita manual....
View attachment 865824

I’ve just found this crap out; no bar yet but I was going to richen up the H by eighth of a turn and start the saw from there

 

[Rob Stafari]

The carb is perfectly sufficient for all three models in stock form, Ported may be a different story depending on who ports it. There are mods to be done to the carb that can fix that though. Tuning with a limited carb does suck. If it sucks that bad you can always fit a 272xp(I think that's the model) carb to it with some mods. I just learned how to tune in the cut. If you have a tach, tune it to just under the limiter then an 1/8 turn in from there as a starting point then work from there. Make sure it is good and warm before you get to your final tune.

 

[KarlD]

I like the 7900

How does the tune sound to you guys?

 

[KarlD]

I lean on my saws quite hard...time is money

 

[KarlD]

This is what the plug looks like

 

[holeycow]

The dolly Sounds good

the first stihl sounds good

the second stihl is good too, but a hair lean for my tastes.

anyway, you got'er covered.

oh, and the plug looks good, if a bit fat (probably due to idle time).

 

[KarlD]

The dolly Sounds good

the first stihl sounds good

the second stihl is good too, but a hair lean for my tastes.

anyway, you got'er covered.

oh, and the plug looks good, if a bit fat (probably due to idle time).

Thank you

 

[holeycow]

 

[Fatherwheels]

The specs I've seen show the same carb for all 3. Can you provide the part numbers for the different carbs you're seeing?

HI, just getting back here.
I found out the carbs were different from reading posts where people added bigger cylinders
than what came on their particular saw, some pople did not want to spend the extra money
on a bigger carb and just made do with the 6400 carb on the 7900 saws, I do not have part numbers
as I bought the 7900 and would not have needed to touch the carb.

You can always try the carb you have, it will either work or not for most people,
unless you are a perfectionist or want the last drop of power from your saw.

 

[Fatherwheels]

I like the 7900

How does the tune sound to you guys?

When you stopped the Makita, was there a pop when she went down to idle.

 

[KarlD]

When you stopped the Makita, was there a pop when she went down to idle.

I don’t think so, I think the clicks are the chain brake? I’ve got a feeling the saw is rich after my mm, but wouldn’t the mm tend to lean and not rich?
I’ve been on the th saw every day since the vid but should get to try the Makita again this week and definitely next

 

[KarlD]

I still like the saw but something is not right. Starting it cold; decomp in, choke out and it will not burp...then choke in and the same. Twice I’ve pulled the plug to find it soaking wet. Dried it off and pulled it without the choke and it’s started up within 6 pulls.
I’ve not tried starting it cold with no choke yet, that’ll be my next move.
I like saws to start easy

 

[cuinrearview]

Sounds like you're missing the initial pop.

 

[old guy]

My 7900 does not pop either, and I had best not pull it on choke more than once or it is flooded, it sometimes starts on that first pull.

 

[JP Norris]

Morning guys
I’m replacing my ms362c with a makita (would love a Dolmar but that won’t happen) and I’ve pretty much decided I want a 7900 running a 22” bar. I will also get the HD filter set up. Before I pull the trigger, am i right in saying the chassis of the smaller cc saw is exactly the same as the 7900...ie there is zero point buying the smaller saw and fitting the bits to take it up to 78cc? There’s no weight saving implications etc? I think I’ve seen mention of an 84cc 7900 esque saw; I’ll look into that whilst I’m waiting for your feedback.
Thanks in advance

Morning guys
I’m replacing my ms362c with a makita (would love a Dolmar but that won’t happen) and I’ve pretty much decided I want a 7900 running a 22” bar. I will also get the HD filter set up. Before I pull the trigger, am i right in saying the chassis of the smaller cc saw is exactly the same as the 7900...ie there is zero point buying the smaller saw and fitting the bits to take it up to 78cc? There’s no weight saving implications etc? I think I’ve seen mention of an 84cc 7900 esque saw; I’ll look into that whilst I’m waiting for your feedback.
Thanks in advance

There was a post on here earlier this morning a guy selling a NOS Dolmar 7900 powerhead.