Will Dolmar muffler fit Makita 7900

[Greenerpastures]

Hi everyone
Found a muffler on online, hope I don't get in trouble for posting the address,
as I have no other way for you guys to know what it is am refering to, and I
can not find another so here goes, www.eabay.co.uk/itm/222510499824
or if the above is not allowed, w?w DOT fleabay.co.uk/itm/222510499824

This is advertised as from a from a Dolmar 7900 so am wondering if it is a straight swap
to my Makita 7900.

If so did this Dolmar muffler come without the obstructions that are in mine.
I see no tail sticking out the back of this muffler, like there is on the back of mine,
which has quite a substantial piece of steel tube that slots into the wall of the cylinder,
though it obviously does not go in to where it can contact the piston or ring.

If this Dolmar Muffler will fit on my Makita 7900, will the fact it has no tail cause the exhaust gasses to damage the cylinder wall as they leave they cylinder, the only good thing about my own muffler is that it looks to provide some protection against such damage to the outlet from the cylinder.

Your advice would be much appreciated as I want to get this before it disapears off the flea bay.

 

[Miller Mod Saws]

@Mastermind

@Jon1212

I think he would get much better advice if y'all could move this to the chainsaw section.

 

[Jon1212]

@Mastermind

@Jon1212

I think he would get much better advice if y'all could move this to the chainsaw section.

I agree with you, Carl. Thanks for looking out.

 

[Mastermind]

I do believe it will fit.

 

[Poleman]

Which muffler do you have??
7900 muffler
7901 muffler SLR type
The sleeve doesn’t protect the cylinder it forms a chamber for emissions.
This is what’s inside. You can see how restrictive it is.

Not knowing what sure you have but the one your looking at is a less restrictive muffler. Slight modification to make it fit your saw. Offset opening and upper support tube needs shortened.
The best muffler would be one you split and take the insides out but stock, the one you looking at would be my choice, you can open it up some without
splitting it.

 

[Greenerpastures]

I do believe it will fit.

Hi Mastermind
Thanks for commenting, I kind of went off topic in another
thread and others have said this muffler should fit on,
One comment mentioned its the older style muffler and I should
use my Makita muffler gasket as a pattern, may be they mean I
will need to trim the Dolmar mufflers inlet to reflect the outlet from the Makita barel, I will know when I get the muffler, but am the kind that will be thinking about it untill its done, so if anyone can
put me out of my misery feel free to do so.

In any even, I am pleased with the response, so no need to move the thread less the powers that be feel the need.

Thanks & Regards to all, john

 

[Greenerpastures]

Which muffler do you have??View attachment 91660
7900 mufflerView attachment 91661
7901 muffler SLR type
The Steve doesn’t protect the cylinder it forms a chamber for emissions.View attachment 91667
This is what’s inside. You can see how restrictive it is.

Not knowing what sure you have but the one your looking at is a less restrictive muffler. Slight modification to make it fit your saw. Offset opening and upper support tube needs shortened.
The best muffler would be one you split and take the insides out but stock, the one you looking at would be my choice, you can open it up some without
splitting it.

Hi Poleman
The muffler on my 7900 looks like one you posted with the piece
coming out the back that sits into the housing on the barell.
And I do see there is a difference in the inlets between the picture I posted and yours, so some work may be required, I am not looking forward if cutting is required, as I will not be happy without opening the muffler to ensure no parricles are left inside it that could come back into the cylinder.
The Dolmar muffler comes with the collar / spacer that the top bolt goes through, so it will most likely be the correct length, I also have a heat shield behind my own muffler to factor in.

There does not look to be a spark arrestor on the Dolmar one,
the outlet also looks bigger than my makita outlet, so I may get away without opening up the outlet, I don't need much of an
improvement, just enough to keep things running cool, I have more than enough power for all I do, though I am certainly open to advise.

 

[Poleman]

There should be a spark arrester on both. Easy to make one out of stainless screen if needed.
If you have a Dremel you can easily make the mods needed. Also if need be you can open the exhaust outlet from the outside with it the just drill out the front of the internal baffel.
The mods are easy and it sounds like you have a good grasp and understanding of things!!

 

[dustinwilt68]

It will fit, long as you use a gasket, no gasses will damage any thing. Harder to find with out the tail honestly, the Dolmar 7900 had no tail, 7910 and the new makita ea7900 have it.

 

[Greenerpastures]

It will fit, long as you use a gasket, no gasses will damage any thing. Harder to find with out the tail honestly, the Dolmar 7900 had no tail, 7910 and the new makita ea7900 have it.

Hi dustinwilt68, thanks for commenting.
The muffler came, there is no tail on it, just a piece
pointing forward towards the outlet, with a lot of holes drilled
in that piece. I can see the outlet through the inlet, so at least
not enough obstructions for me to require gutting it.

Regards, john

 

[Greenerpastures]

There should be a spark arrester on both. Easy to make one out of stainless screen if needed.
If you have a Dremel you can easily make the mods needed. Also if need be you can open the exhaust outlet from the outside with it the just drill out the front of the internal baffel.
The mods are easy and it sounds like you have a good grasp and understanding of things!!

Hi Poleman, thanks for commenting.
The Muffler arrived, there is no tail, just an insert inside
the Muffler, it has a lot of holes drilled in it, looking in
through the inlet, I can see the outlet, and there is indeed
a spark arrestor screen, that I will be taking off.
When I took this screen off the original Muffler, that alone
made a big difference, I could tell the engine was not as hot.
It is the smaller back entry to this Dolmar muffler that has me concerned.
Am wondering if it will now become a bottle neck, though if it was capable of working with
the original Saws that created more power because it had better flow, then may be I don't need to worry about this aspect.
I was also concerned regarding the gasket on this
muffler, burning at the edges, where the original could not do so because the tail enclosed that area of the gasket.
Would not want her to burn this gasket, and pieces of it that may not make it out the port getting into the cylinder.
Your comments are welcome on this issue.

Thanks and regards, john

 

[Poleman]

John, what I do when I put a7900 muffler on a 7910 type cylinder is port match it to the cylinder. I use the aluminum heat sink as a guide. I match that to the cylinder then adjust the gasket to fit then the muffler. Because of the muffler bolts it limits what you can do but should be good on a stock cylinder.
Splitting the muffler can help on that but I don’t feel nessassary on a stock saw....and I really struggle splitting them cuz I’m pretty ocd and don’t want to make it all bent up. Good time to remove dents tho!!!!

 

[Wilhelm]

Splitting a PS-7900 muffler is fairly easy, I did mine cold with pliers.
I like to think that my PS-7900 likes me having maxed out the original muffler outlet hole while maintaining the ability to use the stock spark arrestor screen.
I have pictures of me splitting the muffler on my desktop PC, too late to fire the old beast up though.
I'll try remember to post some pictures at my earliest convenience.

Definitely keep the spark arrestor screen in play, You don't want anything to fall inside the muffler and find its way to the cylinder!
Hollow muffler, direct access for dirt to the cylinder.

If it weren't for shipping I'd offer to mod Your 7900 muffler to fit Your Makita.

 

[Greenerpastures]

Hi Wilhelm
I understand what you mean regarding getting things into the cylindr through the exhaust.
The only real way to over come this then would be to make a second exit and also put a screen
on it, or enlarge the original exit.
Seems to me the original single outlet is too restrictive, for as soon as I removed that screen
the saw definately ran cooler.

 

[Greenerpastures]

John, what I do when I put a7900 muffler on a 7910 type cylinder is port match it to the cylinder. I use the aluminum heat sink as a guide. I match that to the cylinder then adjust the gasket to fit then the muffler. Because of the muffler bolts it limits what you can do but should be good on a stock cylinder.
Splitting the muffler can help on that but I don’t feel nessassary on a stock saw....and I really struggle splitting them cuz I’m pretty ocd and don’t want to make it all bent up. Good time to remove dents tho!!!!

Hi Poleman
When you say the muffler bolts limit what can be done, do you mean they are in a different place
on both mufflers,
or are the centres different spacing if measured on the Dolamr 7900 cylinder as opposed to the Makita 7900
cylinder, I don't have the Makita muffler off yet, and would just leave it alone if the bolts were not the same spacing on both cylinders, as moving them is not simple, as the piece inside the myffler will also be in the
way regarding bolt spacing.

Thank's for posting, john

 

[Poleman]

Wilhelm....I don’t know how you can do it cold....I tryed your way and still have a nasty bump on my finger from where the pliers slipped and pinched. If I add heat just a burns.... it’s ugly!!!!! Lol

John, what I’m referring to is the space between the two tubes. You can gain more if you you split and remove the internals.

I like Wilhelm suggestion of always figuring in the spark arrestor!!! I cut on Forest Service land and is required....or a BIG fine if your caught without one. Just ran avdsw in the dark without one.... a lot of glowing sparks exit the muffler...,.not worth paying for a fire.
You can guestamate how much the screen blocks the exit and just make it that much bigger....but keep the screen.

 

[Greenerpastures]

Wilhelm....I don’t know how you can do it cold....I tryed your way and still have a nasty bump on my finger from where the pliers slipped and pinched. If I add heat just a burns.... it’s ugly!!!!! Lol

John, what I’m referring to is the space between the two tubes. You can gain more if you you split and remove the internals.

I like Wilhelm suggestion of always figuring in the spark arrestor!!! I cut on Forest Service land and is required....or a BIG fine if your caught without one. Just ran avdsw in the dark without one.... a lot of glowing sparks exit the muffler...,.not worth paying for a fire.
You can guestamate how much the screen blocks the exit and just make it that much bigger....but keep the screen.

Ok, then a larger outlet with larger screen will sort me.

Thanks, john

 

[Miller Mod Saws]

Wilhelm....I don’t know how you can do it cold....I tryed your way and still have a nasty bump on my finger from where the pliers slipped and pinched. If I add heat just a burns.... it’s ugly!!!!! Lol

John, what I’m referring to is the space between the two tubes. You can gain more if you you split and remove the internals.

I like Wilhelm suggestion of always figuring in the spark arrestor!!! I cut on Forest Service land and is required....or a BIG fine if your caught without one. Just ran avdsw in the dark without one.... a lot of glowing sparks exit the muffler...,.not worth paying for a fire.
You can guestamate how much the screen blocks the exit and just make it that much bigger....but keep the screen.

Rich. Try this next time. Takes a little longer. And dosnt work well for the stainless mufflers. But for the galvanized muffler it and a straight screw driver work pretty nice. And ya won't leave the black spots on the muffler so easy.

 

[Poleman]

Thanks Carl.....regular propane isn't hot enough.......or I'm just too slooooow!!!! Lol

I ALWAYS like the results when done but I dread doing it....no knack on these!!

 

[Wilhelm]

Hi Wilhelm
I understand what you mean regarding getting things into the cylindr through the exhaust.
The only real way to over come this then would be to make a second exit and also put a screen
on it, or enlarge the original exit.
Seems to me the original single outlet is too restrictive, for as soon as I removed that screen
the saw definately ran cooler.

A stock PS-7900 runs pretty awesome with a single but enlarged muffler outlet!
I am obviously referring to my PS-7900.

Wilhelm....I don’t know how you can do it cold....I tryed your way and still have a nasty bump on my finger from where the pliers slipped and pinched. If I add heat just a burns.... it’s ugly!!!!! Lol

John, what I’m referring to is the space between the two tubes. You can gain more if you you split and remove the internals.

I like Wilhelm suggestion of always figuring in the spark arrestor!!! I cut on Forest Service land and is required....or a BIG fine if your caught without one. Just ran avdsw in the dark without one.... a lot of glowing sparks exit the muffler...,.not worth paying for a fire.
You can guestamate how much the screen blocks the exit and just make it that much bigger....but keep the screen.

I utilized side cutter pliers, worked great.
No heat, no pinching the fingers, one hand holds the muffler and the other is working the pliers.
Once You bent a corner up You just continue little by little along the folded metal and before You know it the muffler splits in two.

Ok, then a larger outlet with larger screen will sort me.

Thanks, john

No other screen needed, You can enlarge the existing muffler outlet plenty while still leaving enough material to use the stock screen!
Turned out great on my mod.

Have patience, I'll up some pictures once I catch some time.