help tuning saw and tach

[aaronmach1]

i just got my tach in the mail for my ms250. The tach can be found in my last post. Now that i have muff modded the saw i need to get it tuned right. Im having some issues. I think i finally have the idle fixed up so it isnt stalling but now the H screw and tach are giving me issues.
1) the tach seems slow. i rev then saw up then let off throttle and after i have let off then the tach goes up to the rpm it should.
2) Setting the H screw. I set the saw with some some 4 stroking and ill get like 12800 rpm in the wood when im backing off the cut and like 11200 while cutting. But if i go wide open throttle out of the wood and hold it, the tach will eventually climb to 14800 once i let off. but if i turn down the H to bring down the rpms then the saw will have even more 4 stroking.
heres a vid let me know what you guys think. i tried to prop up my phone to take this vid.
3) also, how the %&$@ are you guys rapping the tach wire around the spark plug wire!? i cant get to the plug wire very good at all. Do i have to tear the saw apart? i think i have 3 maybe 4 wraps on it and they arent wrapped close togather. Instructions say 3 or 4 wraps though.

 

[tommyus4]

Not sure of the tach you have but mine is the fast tach without wires.

I did not time mine in wood as I don't have 3 hands. All I know is my saw seemed perfectly tuned with the tach reading 26 to 2800 idling and 14800 at WOT. So I brought it down to 14200.

Without a tach, just by going by what others have written, follow the manual on the settings and turn your H out 1/4. I believe that would be ONE full turn.

That is what I did and I got the 14800 and my saw ALSO seemed to be running perfect. It made me a bit nervous so I brought it back down to 14200 at WOT.

So mine is one full turn and then just a bit more.

This is ASSUMING you did the standard ms250 muffler mod by making the opening a shade smaller than the screen and opened the baffles a little bit. Also assuming your saw was not cold. Also assuming your filters are clean.

As per your tach, there is something amiss there. These tachs are used for the exact opposite reading and that is the ability to read fast revs.

 

[tommyus4]

PS

You can't make a huge mistake by turning the H too far to the left. The mistake is not turning it far enough.

Some people did a MM on the 250 and didn't remove the cap limiter. Some went 1/8 to the left past the limiter. 14800 means it is not rich enough (for my liking) although someone might come in here and say that is perfectly fine. It might be. I just didn't like it that high, even though the saw seemed to run fine in that range.

 

[aaronmach1]

the H is 2/1/4 out. thats toomuch. but 14800 is too much too!

 

[tommyus4]

Come to think of it, I think mine was 13800 turned down to 13200. I'm using my phone away from home and will look tomorrow.

The side of the saw says the stock settings and the H should be in the 1/4 more range.

 

[H 2 H]

Both my 250 are different (settings)

I just redone both saws the other day when I got fresh fuel; I will be able to give you the settings I have mine at but cant do it till Sunday Im at a three day race and wont be home till then

I remember setting mine at 1 1/2 turns on "H" screw and 1 turn on the "L" just to start the saws then worked off that (they are both not set there now)

One of the 250 MM is at 95% exit exhaust (to inlet) and the other is 90% exit exhaust - why did I do that I dont know

And my idle for both are about 2700 +/- 100 they sound good at that level

 

[watsonr]

That's not rich enough, turn the H needle CCW some more, it's not 4-stroking yet.
Was the saw new or used when you got it or are you just now beginning to play with it because of the MM? Are the limiters on the H/L needles still in place, if so, use an exacto knife or razor knife and shave them off so you can get full turns on the screws. Lightly seat the needles and then back them out the recommended amount and 1/2 turn more on the High only, low should be close to factory. If the high is calling for 1 1/4 turns, give it 1 3/4 and then start from there. If you need to, make adjustments and post another video so we can hear the saw.

Your tach is slow, the best tach is an induction tach, like the tiny tach. There are a bunch of them out there, but expensive. The tiny tach was like $60-75. You could take the cover off and tape the tach in place so you don't have to hold it.

Anybody else from the board here close to you? Someone here may have you come by and help you tune it, once you hear and understand what it sounds like properly tuned, you'll never forget.

 

[H 2 H]

Here is the tach I use on my 250's

I've doubled check this one with other tachs I have

Man I wish I could walk out in the barn now and just check each one but I do know there detuned after i hit a real high rpm number a few weeks back

I have a 16" dia but Alder that I will check them tomorrow when I get home

 

[aaronmach1]

That's not rich enough, turn the H needle CCW some more, it's not 4-stroking yet.
Was the saw new or used when you got it or are you just now beginning to play with it because of the MM? Are the limiters on the H/L needles still in place, if so, use an exacto knife or razor knife and shave them off so you can get full turns on the screws. Lightly seat the needles and then back them out the recommended amount and 1/2 turn more on the High only, low should be close to factory. If the high is calling for 1 1/4 turns, give it 1 3/4 and then start from there. If you need to, make adjustments and post another video so we can hear the saw.

Your tach is slow, the best tach is an induction tach, like the tiny tach. There are a bunch of them out there, but expensive. The tiny tach was like $60-75. You could take the cover off and tape the tach in place so you don't have to hold it.

Anybody else from the board here close to you? Someone here may have you come by and help you tune it, once you hear and understand what it sounds like properly tuned, you'll never forget.

yes the saw was new a couple months ago. When i did the mm i removed the limiter on the H screw.I agree im definatly having issues with this tach, and it is fastened to the handle. Ill try a little more juice tomorrow. thanks alot for all the replies guys! its helps me alot and sooner or later ill have this one tuned, then ill want a bigger one!:msp_biggrin:
H 2 H how did you find was the best way to get to the spark plug wire to get the tach wire wrapped around it enough times and tight enough?

 

[tommyus4]

I agree with R. Watson. I was using my phone yesterday and I just saw the video. Turn it ccw some more. You sure it is at 2 1/4? That does not seem right. The factory setting is 3/4s. Mine is now 1 and 1/4 give or take.

Anyway, your saw is what mine sounded when I first started it after the MM. I didn't tach it, I turned it off. I turned it out some more and then some more to get it to 13200. I obviously didn't start it at the recommendation settings from the above two guys. I was going by other (not as sound) advice. In the end, it about 1/2 turn out past the limiter.

ps

I did my 346xp the same day, thus the original numbers confusion in previous posts.

 

[SierraWoodsman]

I just bought one of those "Fast-Tach" Wireless Tachometer's. I'm Looking forward
To trying it out to see exactly where my saws are running. Up until now I've just always used
the tuning by ear approach like Madsen's try's to explain on their site using the sound files.
Saw Carb Tuning

 

[watsonr]

I have a tach and ALWAYS use the ear for a perfect tune. I use the tach after I'm done to just check the low idle, that's it.

 

[FastGame]

What part of Michigan you in ? maybe I could help you. My mod MS250 is tuned to ear and runs just fine. I don't have a tach and I replaced the stock carb with the Walbro WT 215, it tuned faster (or better) than the old carb.

 

[H 2 H]

.....
H 2 H how did you find was the best way to get to the spark plug wire to get the tach wire wrapped around it enough times and tight enough?

The Works Connection Tach has 10 wraps around spark plug wire then wire wrap and black elec tape - it isnt going any were

My "H" scew on #1 250 is 2 3/4 out and #2 250 is 2 1/2 turns out

I also has another adjustable carb seating in the barn ready to go

 

[tommyus4]

Must be different carbs or you all have more aggressive mm's. I just read two 250 mm threads and the furthest out was 1 full turn. I've seen others at 1 1/4 but nothing more.

What does the side of your saw(s) say? Or manual.

 

[aaronmach1]

The Works Connection Tach has 10 wraps around spark plug wire then wire wrap and black elec tape - it isnt going any were

My "H" scew on #1 250 is 2 3/4 out and #2 250 is 2 1/2 turns out

I also has another adjustable carb seating in the barn ready to go

what i mean is how are you guys getting to the plug wire to wrap it this many times. i cant hardly get to mine to wrap it very well. didnt get a chance to work on the saw this weekend, i will this week, this weekend was taken up working on this:

 

[aaronmach1]

The Works Connection Tach has 10 wraps around spark plug wire then wire wrap and black elec tape - it isnt going any were

My "H" scew on #1 250 is 2 3/4 out and #2 250 is 2 1/2 turns out

I also has another adjustable carb seating in the barn ready to go

glad to see your adjustments are near mine.
just curious which one runs stronger, the more agressive one? or is it too much?

 

[aaronmach1]

ok worked on it some last night. let me know what you think guys..heres some more vids with different adjustments.
This video is from last night 2/1/2 out on the H:


this second video is 2/3/4 out on the H:


This last video is the idle. why does it do this. idles normal then out of nowhere it idles up high and stalls out everytime.and somtimes is hard to get restarted.

 

[nmurph]

You have an air leak: racing idle, creeping top end, and needle settings far beyond stock.

 

[deye223]

what i mean is how are you guys getting to the plug wire to wrap it this many times. i cant hardly get to mine to wrap it very well. didnt get a chance to work on the saw this weekend, i will this week, this weekend was taken up working on this:

just take the top cover of it aint a tear down