Tuning question

[Jeff Lary]

I have been sawing up some tree length for next years firewood and I had something sort of strange happen. I generally run Partner 5000's and I was yesterday too but for a second saw I brought with me a 500.When I ran the 5000 out of gas I grabbed the 500. Now it has been a very long time since I have run the 500 series so it may just be the difference between the two saws.

When I got to running the 500 I noticed it did not seem to be "peaking out" like I thought it should. As an example let's say the 5000 revs up to 14,000 rpm's the 500 seems to give up at 10,000 ? I have tuned the carb all I can but it really does not get any better. The 500 runs fine no issues at all.

What would be the cause with the carburetor to run on the rich side ? Would the metering lever being set to high be the cause maybe? I have not looked into the saw yet but was wondering what might be the cause of the lower than expected rpm's. Maybe it is just the difference between the two saws, there is a noticeable power difference between the two models and it has been a while since I ran the 500.

 

[cus_deluxe]

Metering lever height can absolutely cause running rich/flooding. Youll have to look up the setting for ur carb. A little bit of debris, or a stiff diaphragm due to sitting w fuel in it for a long time could also cause this. Hows the air filter?

 

[Jeff Lary]

Thanks for the response.
The saw has sat for 2-3 years I ran it out of gas and choked and re started it many times along with many others . I will have to take the carb apart and check the diaphragms out and the metering lever height. I will also wash her out good. Maybe even put it through the ultra sonic cleaner. I kind of figured it might be the metering lever but It is good to hear it from someone else. I was beginning to wonder if anyone would ever respond.

 

[cus_deluxe]

Dont sleep on the air filter either. If its clogged up it would act the same way. Good luck!

 

[Leerod83]

Second the air filter. Pull it and run it without to check. I've had it happen more than once on saws that sat a while.

 

[Jeff Lary]

The filters on these are not prone to clogging up. It is a 4" by maybe 5" mesh screen it will not be plugged . Not to sound like a jerk but that will not be the issue, it has only run 20 minutes. It will be something inside the carb I think I just could not think of what would cause it other than the carb. The kit could have gone stiff I suppose I have the grand children over today so I will not have a chance to look at it today.

 

[Jeff Lary]

I am back with another question and I am baffled by it sorry to say. So way back when I posted this thread it did turn out to be an out of adjustment Metering lever. I set it with my Walbro gauge and she started right up fine maybe 3-4 pulls.

But then something else began to happen. When I shut the saw off after cutting for 15 or 20 minutes then tried to re-start it you sometimes could pull it over 5-15 times and maybe it would re-start and maybe not.
So I changed out the coil thinking maybe weak spark it was a tad yellow / orange not bright blue/ purple - rechecked compression 185#, and checked out the impulse grommet its in fine shape.
However I still had a re-start issue," until I tried the throttle lock" then it would pop almost immediately but here is the issue with that too. If it pops and you don't catch it,.. you may be in for more pulling than cutting ha ha .

So to recap I run the saw then shut it off then try to re-start it using the throttle lock, and it will re-start especially well if you are on the ball and catch it when it pops. What causes me to have to use the throttle lock? I have other running saws and can switch out carbs from them to this one but this whole throttle lock re-start baffles me. Is it starving for fuel? When it starts it runs absolutely great. Thanks Jeff

 

[Westboastfaller]

Hard to say, don't know the saw, more so, I don't know that particular saw. IDK if it's something temperamental that you need to figure out and can live with.
Could be a few different things going on. A trigger lock position or fast idle is nothing more than a temporary high idle if I'm not mistaken. may clear fuel faster? I really think it has more to do with a charge of fresh oxygenated air flow.
As to say, a flooded saw can start faster with a wide open throttle..
On my 372's, It's an on going battle to maintain a working on/off switch.
After shutting it off with the choke,
I was in a the habit of hitting the trigger and knocking of the fast idle.
If I only shut off for a very short time them it starts on 3 pull with fast idle and 5 with it off after it was just flooded out. Now I'm in the habit of pulling it out and back in after it shuts off. It should be set from the first time but it keeps me from hitting the trigger after...lol

It can work good on a low idle saw too.


OK so when you hit the trigger after it pops then you are knocking that position off probably and may need to reset back?
I learn from 'hands on'. I don't have any book education on this sh*t. I want to tell you to go figure it out and tell us? I've been running 371/372 for over 20 yrs and I get tripped up now and then wondering if it flooded or is starved.
Nobody is paying me to play guessing games on the hill, in every sense imaginable nor do I want to pull it over more that I have to so that cap comes off very very fast and the plug comes out. If it's dry I'm priming it. If it flooded, then the cap and filter stay the heck of the saw. maximum ventilation is needed until it's resolved. There is a chance you have a needle drip down but it starts proper the first time you say.
Possible your metering may now be a bit high causing overflow or bypass when it's warm? or dripping gas line
fumming out the air box?.
After you use it then put it down with the bar elevated. Dry out any fuel under the filter first and see if there is a pool of gas. It doesn't need to be much. Could be or at least adding to the problem. Best if you change temps like going from the shade and setting it in the sun or outside to a warm shop. Now go figure it out

 

[Jeff Lary]

Ha Ha thanks for the reply. On these old Partners when you throttle lock you are actually locking the trigger in the wot position. I don't know anything about the new saws really but like on my brothers Stihl he has a " high idle?" position on the choke switch. That is way more high tech than mine is.
I was just standing in the shower thinking wth is the reason the thing has to be throttle locked to start sometimes then it "may".... have come to me.
When an engine is flooded they tell you to open the throttle all the way just like you say till the saw can clear itself. So if I need to lock the throttle maybe it is flooding some?

I have had issues with another saw when turned on it's side a little fuel would leak around the gas line into the carb area and then flood out so I know what you meant there. I will try sitting the saw down with the bar elevated up some it is worth a try for sure. Sometimes you just need a fresh set of eyes to get me thinking differently.

When you say my "settings" may be to high do you mean the metering lever setting? I set the metering lever by gauge but I wonder if I should have set it a fraction lower? When I say runs great that is true,.. after initial warm up.. maybe from the 4-5 minute mark on . I do know when it starts you cannot get on the throttle too soon,.. you have to play with it kind of, (it is kind of like It may be getting too much fuel???) till you can get it up to speed so to speak. Thanks for the reply and advice I know you must be beat by the end of the day, it is cool to hear from someone who actually makes a living working in the woods. Jeff

 

[Westboastfaller]

Sorry Jeff, I need to edit that. I did mean metering. Terribly unclear I was. OK I understand then, it locks into WOT. It's just going to be a trial thing. It does seem it is getting to much. Look at the plug 'now' and if the needle is dripping down the plug will be socked before you start. I'm use its OK as you said the first time starts good. It just may be when it's presuming up and it may be from the level. definitely good to have your covers of so you can see what's going on or if there is differences.
No real magic answer from me. Just how I would go about things.
Don't ever let the bastard win
If it looks dry prime it...But you have to look.
Just do a really good inspection for fuel seeping out off the carb or anywhere..

I know what you mean about bouncing stuff off people. .
Sometimes we do pieces of what we do expertly without theory and someone triggers something that makes you think on a different level.
It's happened on here a few times in my trade and it can come from anybody.

*Edit
may have really rich low jet?

 

[Jeff Lary]

I have had the low jet rich thought too. It is hunting season up here right now so I kind of hate to be out working in the woods. I don't want to mess anyone up that may be trying to hunt, but to be honest there are more deer walking around inside my woodstove than there are in my woods most of the time. I have a stand of Sugar Maples / Rock Maples that I need to get into and thin out the undesirable wood. So that will be my next saw running project I will get a years firewood from that area (about 900' square) so next time I use the saw it will be here. I mat just swap carbs to see if that solves the issue first, if so I know where to concentrate my vast diagnosing skills.

 

[Jeff Lary]

Well I got in a few shop hours today getting a couple saws ready for the next firewood session. That saw we have been talking about was first on the list. I figured I would just swap out the carb to see if that made any change. I took the cover off to get at the carb and when I put the socket on one of the carb bolts it was already loose. So I don't know if that could have been an issue but maybe the bolt was a full 2 turns from being tight. Maybe she was sucking in too much extra air and causing all sorts of issues ? I will have to go run it now to see,...it gives me hope though or not...... depending on how you look at the issue I guess ha ha.