Dolmar 5105 high-speed bog

[coloradotrout]

New fuel added. Spark arrestor clean. Sharp chain. When I give it gas it doesn't seem to rev up to the same RPMs that it used to. And it seems to be cutting out; not running smooth. It just doesn't have the same zip that it used to and when cutting in cedar it bogs down and I have to really let up in order to keep going. I think compression is okay it's still pretty firm to pull.

Do I look into cleaning the carb? How do I do that? I only use it a few hours and it probably set with gas in it for 4 or 5 months.

Any help appreciated. Thanks.

 

[SOS Ridgerider]

New fuel added. Spark arrestor clean. Sharp chain. When I give it gas it doesn't seem to rev up to the same RPMs that it used to. And it seems to be cutting out; not running smooth. It just doesn't have the same zip that it used to and when cutting in cedar it bogs down and I have to really let up in order to keep going. I think compression is okay it's still pretty firm to pull.

Do I look into cleaning the carb? How do I do that? I only use it a few hours and it probably set with gas in it for 4 or 5 months.

Any help appreciated. Thanks.

Is it kind of popping and skipping, and not getting the rpms as before?
I have a 5105 where that happened, and it was the coil gone bad. The early 5105 coils went bad fairly easily. Got a new coil and it’s back in business.

 

[coloradotrout]

Yeah I guess. My cheap tach shows about 8K when it seems to miss, "surge", "momentarily stall". Hard to explain but pop and miss could be one way to describe.

 

[coloradotrout]

Any recommendations on coil manufacturer? I see generics under 20 and oem up to 90

 

[SOS Ridgerider]

Any recommendations on coil manufacturer? I see generics under 20 and oem up to 90

The am coils say they work on 5100 and 5105, which can’t be true, as the crank timing is different on those two saws, and coils are not interchangeable. I wouldn’t take the chance on them, and end up with a dud I can’t use.
Get an oem legit 5105 coil and you won’t have any issues.

As long as you get the part number below you’re good. There are many websites that offer them.

Part # 181143213

 

[coloradotrout]

Can anyone suggest a place to buy from. Googling up that part number and 'dolmar' doesn't offer much. Sawagain.com is about it.

 

[SOS Ridgerider]

https://sleequipment.com/makita-genuine-part-181-143-213-ignition-coil-ea5000.html
https://www.sawagain.com/dolmar-ps-5105-makita-ea-5000-ignition-coil-new-oem-181143213/
Those are the two I can find quickly. There was also www.performanceoutdoorequipment.com , but his shop recently burnt down.

I‘m sure the guys at The Cutting Edge in NY has it in stock. They’re the biggest Dolmar/Makita dealer I know of.
www.fastcutting.com
These guys are extremely knowledgeable, and can definitely help get you the right part if there’s any confusion.

 

[coloradotrout]

It was the coil.

I played with my cheap tach and saw rpms go to about 4K then drop (even though it was spinning faster) then max at 7 to 8K. The drop is what nudged me to try a coil. I put the cheap tach on my other 2 stroke engines and it climbed steadily to their max.

https://www.amazon.com/gp/product/B083QV7MQW/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1 is the coil I bought. $45. It does not look the same quality as the Dolmar I removed, but works so far. The OEM parts are about $65 shipped.

I also pulled the carb, tore it down, cleaned it out, and pulled off the limiters.

I set the low (just a nudge towards rich from the sweet spot between rich and lean), idle to 2500, and then the high to 12.6K. Spec says 13.8, but I could only get to around 13.0 and then dropped it down to where there is the "gurgle" sound. I ran it today and no bog, plenty of power through live cedar, live hedge, and some 6" dry oak. (Mostly I clear brush.)

I also had been running Opti oil at 75:1. But from now on I'm going with 50:1 and will swap to a quality oil I can get locally. Husq or Stihl or Echo most likely.

Thoughts on the
- cheap coil?
- high rpm setting?

 

[cuinrearview]

Spec says 13.8, but I could only get to around 13.0

This is the problem with aftermarket

 

[super3]

OEM not worth 20 bucks...smh.

 

[coloradotrout]

I was unsure if the coil was the cause. So for no risk I bought the Amazon aftermarket - which I can now return for no cost.

 

[cuinrearview]

So what do you tell Amazon is the reason for returning?

 

[JimmyT]

Sounds like the carburetor needs cleaning and the fuel pump diaphragm needs to be replaced. I use 93 octane ethanol free with Maxima K2 full synthetic oil at 32 to 1 Also run your saw completely out of fuel if it is not going to be run for several weeks.
Been running a 5105S for 11 years cutting around 10 cords of red oak firewood per year without any piston and cylinder scoring whatsoever.

 

[coloradotrout]

So what do you tell Amazon is the reason for returning?

You gave me the answer to that one a few posts up.

 

[coloradotrout]

Sounds like the carburetor needs cleaning and the fuel pump diaphragm needs to be replaced. I use 93 octane ethanol free with Maxima K2 full synthetic oil at 32 to 1 Also run your saw completely out of fuel if it is not going to be run for several weeks.
Been running a 5105S for 11 years cutting around 10 cords of red oak firewood per year without any piston and cylinder scoring whatsoever.

I tore the carb down and washed out with std carb cleaner as best I could. The root cause was the coil. Good point on running it dry. I go months - sometimes a year - between uses. Clearing small trees, lopping off pieces for the fire pit, etc. It's not an easy life for a chainsaw. It's not much work but dirty work. Appreciate the tips. I do have some scoring visible on the exhaust side of the piston. I'll try to take some pics and attach them. With the new coil I'm back in business, but just never felt at-ease running Opti at 100:1 or even 75:1.

 

[JimmyT]

Prufrex manufactures Dolmar's Coils in Germany. Was your old coil a 181143211 or 181143212?
Evidently they must have produce a bad run of coils.

 

[coloradotrout]

Prufrex manufactures Dolmar's Coils in Germany. Was your old coil a 181143211 or 181143212?
Evidently they must have produce a bad run of coils.

I don't recall seeing a number like that on it. "CDIM/ 6" was what I wrote down.

 

[JimmyT]

I don't recall seeing a number like that on it. "CDIM/ 6" was what I wrote down.

CDIM/6 is the Prufrex number. If you ordered a new Makita Coil #181143213 from SawAgain Dan Dean owner then the Prufrex number on the coil will be CDIM 100/11 A lot of times the coils will start breaking down and performing erratically when they get hot.

 

[coloradotrout]

CDIM/6 is the Prufrex number. If you ordered a new Makita Coil #181143213 from SawAgain Dan Dean owner then the Prufrex number on the coil will be CDIM 100/11 A lot of times the coils will start breaking down and performing erratically when they get hot.

Cart Items	SKU​	Qty​
Dolmar Ps-5105 Makita Ea 5000 Ignition Coil New Oem 181143213	SAD0071​	1​

is what I ordered. I forgot to look at the number on the part when I installed yesterday.

The best I could get at high was 13200, but my tach is https://www.amazon.com/Docooler-Tachometer-Resettable-Inductive-Motorcycle/dp/B00F40Q5UA so not sure how accurate it is. I backed it off (counterclockwise to more rich) just a bit so I think it runs around 12.8-13.0 now. It's barely a nudge of the needle to see changes.

I slipped a piece of typing paper between the coil and magnet to set the spacing. I hope that is right.

The Makita "looks" a little more polished, but near as I can tell they performed the same.

 

[JimmyT]

The 5105 is one of the few 50 cc saws that performs well with a .375 pitch chain like the Stihl 33RS but I have been impressed with the Oregon narrow kerf 20" speedcut bar with a 95TXL078G chain .325 pitch. You might want to give it a try.