79cc Power Upgrade! +15cc Makita Dolmar 6421 to ea7900
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- เผยแพร่เมื่อ 6 ต.ค. 2024
- Makita 6421 gets an upgrade. New 7900 piston and cylinder fully ported. Make some catless baseline runs then tear down for the cylinder swap and extra power.
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I love it a sleeper saw. One you pull up to a wood pile on a sat. Morning with some buddies and throw chips like it’s nobody business 😎👍
Exactly. Even better if they has seen the stock 64cc version run before.
The charts are a good visual but I think even a half deaf person could hear those gains. Very impressive both the saw and your skills sir.
Thank you.
Glad you liked the video.
Hey Joe I appreciate the way you start your tear downs with a spotless clear work bench !
Then you set parts in different locations according to reassembly. Love it. Wish I was more organized!!
Thank you, trust me that is the only flat surface in the entire shop that is half clean. The rest is super cluttered.
That's some impressive gains 👍
Thank you
Heck yea.... love these videos... your tone is emotionless, it adds horsepower to your Chanel 👍🏽🔥🔥
Thanks I think? Lol
Glad you enjoyed the video.
Awesome gains Joe! It’s just phenomenal!! With that kinda of power you could probably file the rakers/depth gauges down and it would be squirting out woolly worms for chips! That’s over double the hp my 460 rancher is advertised at. And no additional weight!!
Excellent build sir hope u are well.
Thank you.
Awesome video. The Dolmars/ Makitas are one of the most underrated saws. Keep going! Looking forward for more videos! Cheers from Germany!
Thank You!
This does feel like a very comfy saw. Not crazy popular around my area either.
@@dynojoemods2764 it is. I got a ported PS7910. Just a freaking beast
I love my 7900. People always ask alot of questions about. Are they made in Hamburg Germany?
@@samh803 the 79er were made in Hamburg, Germany. Unfortunately Makita quit producing petrol saws
Just get new unit EA 5001 that was made in Germany. Best 50cc saw in class.
I would love if you would dyno a oem piston cylinder combo vs a aftermarket to see the difference
That is in the works
On stihl i think oem is superior vs aftermarket .... least what I hearing ..... ported and stock
@@lagoonrd4173 all oem quality controls is far superior to aftermarket as far as consistent numbers.
Nice upgrade! Is that new 79cc cylinder a Gilardoni?
Loving the dolmar’s man. Keep ‘em comin!!
Was considering the 7900 as a new saw to get.. as if I don't have enough already. Definitely sending it your way if I get one
a perfect video. not to long and detailed enough. wached every second of it. very interesting build!
Thank you
Awesome video man!!!!
Just picked up a 6421 with a bad top end. Gonna do the 7900 P&C and muffler mod. Eventually gonna port it but gonna run it with the stock 7900 top end for now.
Nothing with that at all. Muffler mod, good gas, and a sharp chain It will really sling chips.
Friend, what is the best oil blend?
1:50 1:40 1:33?
@@Sensei948 I run 40:1 in all my two cycle machines. In a hard use application like milling or 90cc and up with 36” or longer bar I’d run 32:1.
@@eurokid83 33: 1 Am I causing more carbon and can I damage the engine by peeling off the carbon deposits?
@@Sensei948more oil equals more carbon deposits. That being said if your making long cuts in big wood it will be pretty minimal. It’s all about what your using the saw for.
Wow, great gains, the other thing to note is that this is a new topend, I expect the ported topend will gain a bit more as the ring seats in.
Excellent video. Thank you for the great video
Those look like great saws to port....seems like the only EPA controls are the cat muffler. Plus single ring piston. Good video Joe
Dude you know what I think. These videos are the bomb!!!
Thats perfect build brother. I run saws every day all day. I run my saws at higher rpm. Keep the chain tuned to my saws power i mean. That thing has perfect power band!!! Out of all the saw you have dynoed.
Thank you.
Should make a very enjoyable saw to run.
What power! Monster saw right there!
Should make a nice runner!
@@dynojoemods2764 nice is an understatement! Keep rocking you guys!
Great video! That one really woke up!
Thank you.
Coming from a stock 6421, that would be a whole new animal.
Damn nice job you do!!
That’s a nice saw. I wish we had them here
They are pretty neat, I'm sure one will pop up when you least expect it.
I’d like to see the owner of this saws face when he puts it in the wood , imagine the difference lol .
You built a monster!👍👍👍👍🇺🇸🇺🇸🇺🇸🇺🇸🙏🙏🙏🙏
My saw can’t wait to give her a rip video will be coming on my channel
I've got one of those with an ironhorse style exhaust and it just rips!
Nice job as always,
Wow, what a screamer!
I've had a 6400 and didn't know you could swap the cylinders!
Yep, direct bolt on.
You might as well, since you are not gaining any weight by going to 79 CC's. This series was either 64cc, 73cc, or 79cc. There's actually an 85cc aftermarket kit too, but I hear that it's no better than the stock 79 cc top end. This 6421 is my go to saw, been wanting to go to a ported 79cc with the HD filter kit, but it cuts so well for a stock saw, cat in the muffler even, that I haven't bothered to yet.
Makita they startin' to look like a Faberge egg with a chainsaw bar .. kind of reminds me of an old AMC pacers shape .. even the color is about the same as they head back in the day.. let's see how many horsie it can push ?! 😁👍
Great video bud 👍
Thank you
That owner is going to kiss you on the lips!!! That is bad a$$. It’s like a different saw all together!!
Amazing gains!
Excellent work Joe!! I want you to do my saws!!
big gains!
Great video as always!
Good stuff!
That’s going to be a pulling machine!!!
Should make a stout runner once fully broken in.
@@dynojoemods2764 will make any more on dyno you think after broken in?
@@Dolmar-Rick
Be safe to guess 3-5% more once fully broken in
Great video and work!
🤝🤝🤝
Thank you!
I’d like to see you make a quick video of how you modded that muffler. Please keep the Dolmar stuff coming.
Heat the crimp with a torch and pry open with a flat screwdriver. Remove all the extra pieces other than the front and back cover m, and the 2 support tubes. Then I trimmed and added 1 of my medium deflectors.
If I come across another I will be sure to make a video.
You should try out the factory HD filter kit and show us if it actually makes more power than the standard one. I've got a bone stock 6421 with cat still in the muffler to test as well if you need one.
That would be a fun test sometime. Lots of people say the hd filter makes less power.
I got the Dolmar red version of that saw I kinda want to find a Makita blue one to play with too
Sounds good 👍
Thank you!!
I don't know why but every time i see one of these or hear it idling, i think of Harley-Davidson...
AWESOME VIDEO!!! Do you think the carb is big enough and estimated gain from a bigger carb? Man I want to see that thing with a pipe on it. Beings my go to saw is a 7301 I really enjoyed this video. Only issue I've seen is the pulse hose will pull of if you get it hung and jerk on it. That was its only issue when I got it for $150 from original owner who thought it was blown up. As always another perfect video! DYNO JOE FOR PRESIDENT!!
Carb is decent for a work saw. Larger one should make Better power.
But hard telling exactly how much.
Good job!
Could you dyno a cylinder with long blow down tranferports and then show short blow down on the same cylinder. I'd like to see what power/ torque difference might be.
I will be trying a few different tests like that as time allows.
The manual states
4,7 hp @ 9000 rpm for 6421
6,2 hp @ 9500 rpm for 7900/7901
I know these can't be compared to ur dyno, but helps explain how peak was moved up so much
Yep, really wish I could have tested with the cat still in the muffler.
Pushing the power up a bit in the band, paired with the right chain makes for some quick cutting.
cutting the squish band and the base also changes the timing this might have something to do with it as well
@@dynojoemods2764 where are you at? I've got a bone stock 6421, all stock muffler too here to test.
@@tomjahn6896
I'm in Michigan, South of Lansing. I'll find a stock one eventually. Thank you for the offer.
@@dynojoemods2764 I'm in southeastern WI, and drive through Lansing in Spring on the way to a chainsaw get together. I've been looking to go to 79cc one this saw anyway.
WOW!
Classwork!!! after such an upgrade, what will be the safety margin of the chainsaw?
The chassis was offered with that larger piston/cylinder. Should be plenty stout enough to hold up.
Get a cheap chain saw and do a nitro fuel test with Rc fuel would be a cheap and easy vid to make
Will have to try that some time.
@@dynojoemods2764 thanks for replying Joe love your videos, I understand that it’ll be hard to run it off pure Rc but I’d rather see what the everyday guy can do with a mix and a carb retune thanks agn keep up the good work
Thats a great improvement. Have you done the husky coil conversion to eliminate the limiter? I have that same build I just can't seem to get back to and the husky coil floating around somewhere also.
No, I have not done the swap.
@@dynojoemods2764 thinking of trying it?
@@billdorell8351
Nope, not really interested in it at all. I have seen good power from the limited coils. And tune isn't crazy far off tuned just under the limiter.
@@dynojoemods2764 understood. I was always kind of concerned with the mounting on a work (ish) saw with the conversion. Thanks for the insight
Nice build, did you notice any vibration caused by the larger piston, ?
Thank you.
No noticeable vibrations, this chassis was made in 3 different sizes, I am pretty sure they all share the same exact crank.
Joe few things…
1) where did the low and high speed carb screws end up compared to stock?
2) do any builders run thermal couples on these hopped up saws? Be it either in exhaust or spark plug? If so what temp differences do you see?
3) what kind of warranty if any do you provide with this type of work? Any use restrictions? Premix recommendations?
I didn't check the carb screws. I did end up leaning the H just a touch and Richen the L
I don't know of many/any builders that use thermocouple, unless it is a 1 off experiment.
I will stand behind the cylinder/port work, hung ring etc.
40:1 fuel and a good safe tune generally don't have many issuesm
Is that a oem cylinder
Yes
Hey Joe. Can you please explain exactly what it going on when you are turning the knob and what is hooked up to the saw to make the RPMs drop like they do. I’m confused how it’s all working ?
Hi Joe, Just bought a Makita EA7900. Plan on doing a muffler mod in the near future. Doesn't seem like a straight screwdriver adjusts High and Low jet. Do the new Makita 7900's have screw that requires a special tool?
It should be a D shaped driver sold in the carb adjustment kits online.
@@dynojoemods2764 thanks I appreciate your response. I just ordered a kit. Ran the saw tonight for the first time. I am assuming it will wake up a little the more I run it. Anything else besides a muffler modification you would recommend? I am running a 28" bar. I have 15 acres and I am cleaning up several 24" ro 36" red oaks. Pretty hard wood.
Does the 64xx weigh the same as the 79xx series? If so, wouldnt you be money ahead to buy the 79xx?
Pretty much identical, other than the piston and cylinder weights. Yes if buying new probably a good idea to go with the big one. At one time they made the 64cc, 73cc, and 79cc all on this chassis.
1 year later hows the makita saw running? Lightwork or work it hard?
As far as i know it is still running well. Just home firewood type use.
Nice, would like to try it on one of my Solo 675/681s as well, but I'm a little afraid of messing it up.
How much difference between cat and ripped cat btw?
Guess if the cat blocks the exhaust, porting won't help much ;-)
I never did a pull before removing the cat. It showed up with a large hole and pieces inside the can.
On the Stihl 026 ripping the cat out makes a world of difference. I'd just do it, noise barely louder
@@7eis stihls are notorious for restrictive mufflers.
Bonjour, vous avez fait une deuxième sortie à l'échappement, avez-vous enlevé la chicane à l'intérieur ?. Merci.
Did you do a timing advance in this build?
How do you zero using a digital angle finder? I’ve been using a hollow threaded plug in the spark plug hole and a dial indicator.
Piston port, just make sure the intake number is the same both sides of TDC. But a piston stop will work too.
I got a 6401 from the local pawn shop for $200 and have been pleasantly surprised. Want to increase the exhaust flow, does the muffler just split apart?
You have to uncrimp the seam. Heating with a torch helps. Then pry it open, remove the cat and baffles. Then pound the crimp back over
Would a 52mm piston from a Stihl or Husqvarna work?
The dolmar used the shortest compression height of the 3. The others could work but a lot of extra machine work and makes a super small combustion chamber or a weak piston after all the material removal.
Holy crap!!! She’s a ripper!!!
hi joe wondering if you could explain why you always cut the squish band before checking it? you said " i didnt check the squish because i plan on doing machining anyways"
90% of the saws I do will get the Squish band cut so I can lower the cylinder. More compression, a little more intake duration etc. Just saves a step while I am building these customer saws.
Looks like a great result!
How poorly do the Chinese big bore (85cc?) kits compare? I'm guessing the HP curve comes out a lot flatter?
Not sure. Have not had one on the dyno to measure. Most say they are decent runners.
@@dynojoemods2764 most say that the 85cc kit doesn't gain anything over the 79cc kit, just more fuel used. Then again, I don't think they dyno'd them, just based on feel.
More bore means less transfer port. It does matter.
question why didn't you cut the base deeper and use a base gasket instead of deleting it just wondeing
Flange is already fairly thin, the extra off would make it even thinner. Have seen a few cylinders crack off the corners. I like to leave as much material as possible.
@@dynojoemods2764 glad im not alone in this matter, sometimes i dont even cut squish band if the particular model has thin base
It looks like the Intakeport is wider than the Pistonskirt? Does that work?
Awesome Job , impressive Power
Ports can't be wider than the skirt otherwise the charge would pass through the ports at the wrong time. Also if it is passing by the sides the case won't build enough pressure to run right.
It is possible in slight cases that they run, but not well or to full potential.
@@dynojoemods2764 ohh , that’s definitely right. How much smaller the Port has to be to get enough sealing and guiding of the pistonskirt. 2mm per side?
@@Witschor
Normally 1mm is absolute minimum, but a bit more has a better seal. Race stuff will push the 1mm minimum for sure.
@@dynojoemods2764 Thanks for your Knowlegde. I wish i have such a Dyno to measure the Progress on my Saws.
I don’t know anybody than you owning one.
@@Witschor
Just let me know if you want to send in one of your builds. I do dyno runs for others as well.
Do you need to put a different carburetor on it for bigger bore?
I'm not 100% sure but I believe the 64,73,79 all share the same size carb.
@@dynojoemods2764 they did all have the same carb.
I would like for you to upgrade my Makita. How can I get in touch with you?
I would like to see what the HD filter does to one of these good or bad.
That would be a good one.
they make less power
How long bearing last?
Hi Joe. It's me. Again a Question from Argentina. I have this saw with this setup (79 cc muff mod) and according to your data at 8-9000 rpm reached 5.5 HP. In your previous ECHO 620 video, a 60 cc chainsaw with muffler mod reached 5.5 HP as well. Ported they reached above 8 and 6 respectively. How do you explain that? that a smaller saw with muff mod gave more HP ......but ported the biggest cc gave more (which makes logic, isn't it?). Thanks in advance. Cheers
That was the 6421 64cc stock vs the 60cc of the echo so they were close in size. Ported was the 79cc cylinder.
@@dynojoemods2764 Thanks Joe. Clear enough.
Joe
If the piston is slightly domed do you try to cut the squish parallel to the dome on the piston??
Yes, or I will cut a popup and flatten the squish band
Exhaust at 98 durations seems so low to but is that to basically keep it power at a lower or high rpm for torques. Jw thanks
These saws with box mufflers tend to use a lot lower numbers than high performance 2 strokes.
98 is actually on the higher side for most of my saw build until they get over 90cc.
@@dynojoemods2764 o wow that’s good info to help me understand how each top end is designed for it’s desired performance or what have you. Thanks for answering my questions. BUT I have one more if you please, what’s the blowdown? I don’t think I caught you saying it in the video or I might have missed it but I’m trying to get an all around basic understanding of what each number does for the revs and where the horsetorques are made in said revs. Thank again.
@@JMB676
Blowdown was around 28 ported. Which is also more than most other saw builds. Most are happy with 18-20 blowdown
hi i have a 6401 Makita that it have a limited cap on the H screw the L doesn't have any limited cap what adjustment do i need
Do you have any shops you can recommend on the West coast of Canada? 7900P
Sorry, I don't.
They told me that makita stop the gas machines such chainsaws. Is this true ? And that in the close future someone who have a makita gas machine will not find any parts of this company.
I'm sure parts will be around for the next 5-10 years after that it May get hard to find.
Co may husqvarna 288xp ko vay chu oi.
Hi I have a ms311 I would like ported do you have time and what is the cost
Sorry. I am not taking new port work at this time.
Hi. Question from Argentina. I own the same saw machine but 7300 model and would like to up grade to the 7900 cylinder kit. Do I need to change something else.../buy something else or just order a new cylinder kit and change it. Thanks in advance
Should just need to buy the piston/cylinder kit. You will want to Check the part number and make sure it is for the same model years as your saw. The early ones had different decompression location and muffler flange.
@@dynojoemods2764 Thanks Joe. God Bless you
@@dynojoemods2764 Hi Joe. It's me again. It is done. The piston/cylinder was upgraded. Now my last question is did you upgrade @change the carburetor as well or just kept the carb of the 7300 model? BTW- Can see/feel already the upgrade in the saw ..only few more cc but way stronger
@@bernardosuarezcretton622
I used the stock original carb.
Joe was that an aftermarket or oem piston ??
Was all oem kit.
【from Hipa】Do you like to test accessories for your equipment?thanks
How much would it cost to perform this mod on a stock 6421? Parts and labor?
What did the squish end at?
.025"
@@dynojoemods2764 What do you think 020 would do for the number? I'm kinda assuming the 025 is to make it more reliable?
@@REDRIDER101
.020 may give it 1-2 psi more, I just like the little bit of extra room.
wouldnt 4 to 8 be almost a 100%
Isn't that nearly 200% not 50 %?
From 5.5 to 8.26 is right close to 50%. Way up in the rpm where the ported saw peaks now, vs the stock saw it is up closer to 85%.
@@dynojoemods2764 I'm thinking the other way. I saw 4.46 and 8.26. 2x4hp is 8hp. I suppose if you said improvement it's nearly 100% improvement(nearly) so yes you are right.
can you supply a ported piston barrel kit for my 6400 taking it up to 7900 spec?
Would need the saw and the piston/cylinder kit. The oem kits are fairly expensive.
@@dynojoemods2764 ok. Thanks for the reply. Good video by the way.
Too cheap to smoke.......familiar?
You lost me lol.
@@dynojoemods2764 It's a channel here ......check him out.
Toocheaptosmoke dabbles with saws at times....humorous...kinda like ziptiesandbiasplies...with less profanity...lol
@@brunomahle1618 I will check them out. Thank you
What style orodel 79cc OEM cyl is best or do a after market bore n port get it nicsil coated reliable badass saw ??what u think Joe