Stihl Oil Pump Flow Mods

[Mastermind]

Lots of ways to increase the flow on a Stihl (or other brand) oil pump. You can alter the control bolt, or the ramp on the pump shaft. But....quick and simple rules when doing a production volume of units.

MS261 oil pump.



MS460 high volume control bolt.



See the difference?



Aside from that, they are the same, and completely interchangeable.

 

[Stump Shot]

I like what you're stepping in here.

 

[Mastermind]

In case anyone is wondering why I'm modding an oil pump on a 5occ saw.....

This saw is going to a tree guy in California, and he plans on using at least a 20" bar and chain on it. It's got the ass to pull it.....but the oil pump gets stingy in sticky conifer at that diameter.

 

[Stevetheboatguy]

So why don't you just remove the o-rings off the original instead of buying a new one it will use more oil for sure





Steven

 

[deye223]

In case anyone is wondering why I'm modding an oil pump on a 5occ saw.....

This saw is going to a tree guy in California, and he plans on using at least a 20" bar and chain on it. It's got the ass to pull it.....but the oil pump gets stingy in sticky conifer at that diameter.

Thanks for doing this thread Randy looks like I will be ringing my local STIHL dealer today I know he will rip me off blind but I'm going to do this to my 261.
there are a few trees in my neck of the woods where're the bar needs more oil especially the 261.

 

[Stem]

years ago I put the OEM high output/aussie oiler parts in my 650. I've got pics somewhere...

 

[Stem]

 

[qurotro]

Just the control bolt? No shaft? I got another oiler thread book marked...
That thread shows how to mod the ramp of the shaft too.


Edit: My brain hurts understanding just replacing the control bolt would increase the flow. I thought they have to pair together to work. Just the control bolt wouldn't get more stroke of the pump shaft.

 

[Mastermind]

Just the control bolt? No shaft? I got another oiler thread book marked...
That thread shows how to mod the ramp of the shaft too.

You can do both. Like I said at the beginning of this thread....there are many different ways to do this.

Just swapping out the control bolt is simple, and increases flow quite a lot.

 

[deye223]

Well I just got off the phone to my local dealer was quite surprised control bolts were only $7 each so I order 3 then I made the mistake of asking how much for a roll of still semi chisel 404 46 rm $750 lucky I was sitting down

 

[drf256]

Here’s a pic of the pump piston and control bolt in proper geometric assembled orientation.



Turning the control bolt to max allows the low end of the ramp to actually hit the circumference of the larger/lower symmetrical portion of the control bolt. The offset cam is where the non-ramp portion rides.

Just a pic to help boggle the mind a bit more.

 

[qurotro]

Here’s a pic of the pump piston and control bolt in proper geometric assembled orientation.

View attachment 261810

Turning the control bolt to max allows the low end of the ramp to actually hit the circumference of the larger/lower symmetrical portion of the control bolt. The offset cam is where the non-ramp portion rides.

Just a pic to help boggle the mind a bit more.

Yep. That's my understanding. The H.O offset cam is all the way max doesn't make the ramp rides more stroke hence more oil.
My understanding is the offset cam is used to control how much the lower step rides the ramp. Min setting means only the highest point touches the lower step hence little oil output.

 

[ManiacalMark]

Yep. That's my understanding. The H.O offset cam is all the way max doesn't make the ramp rides more stroke hence more oil.
My understanding is the offset cam is used to control how much the lower step rides the ramp. Min setting means only the highest point touches the lower step hence little oil output.

It's simple, all about the pistons stroke, just the stroke is moved perpendicular to it but controlled inline.

 

[GoBigBlue1984]

Very nice Randy! Thank you for sharing.

 

[ferris]

Lots of ways to increase the flow on a Stihl (or other brand) oil pump. You can alter the control bolt, or the ramp on the pump shaft. But....quick and simple rules when doing a production volume of units.

MS261 oil pump.

View attachment 261702

MS460 high volume control bolt.

View attachment 261701

See the difference?

View attachment 261704

Aside from that, they are the same, and completely interchangeable.

View attachment 261703

I think everyone can see the difference, I don’t know if anybody knows which one is the 460 version

 

[huskyboy]

I think everyone can see the difference, I don’t know if anybody knows which one is the 460 version

460 is the one with more “offset”.

 

[Maintenance Chief]

Sorry for my ignorance but I don't understand how the ramp works in conjunction with the bump on top of the screw?

 

[huskyboy]

Sorry for my ignorance but I don't understand how the ramp works in conjunction with the bump on top of the screw?

The bump is what limits the travel of the stroke. Notice the offset in it? Well when you turn the oiler adjust screw it changes the offset to allow more or less stroke... changing the oil output. There is a point where you have to steepen the ramp if the increased offset has surpassed what the ramp can allow. This can be checked by meshing the two together and seeing if there is clearance or not at the “max” setting. The control bolt mod alone is probably enough for a 50cc saw, unless you want to run out of oil before the gas. I mod both the ramp/control bolt on the 441/460/461/660 standard pumps though.

 

[ferris]

460 is the one with more “offset”.

So the left one?

 

[huskyboy]

So the left one?

Yes