An Autotune Husqvarna Model 550 challenge

[Karla]

What a challenge to get a Video posted here, first it was in the wrong format, Not an MP4 file, needs to be a MOV file , Yike. Then the file is too big, and how do I make it smaller compress it, or Zip it. I need more Knowledge ???

Ok, I hope this sort of works. Now its too short - Lol.

But the link works

 

[hamish]

More Info - I ran the Diagnostic Tool Kit on my Model 550, and I was surprised to see "No Error Codes" , I checked out all the numbers, and looked at all of the graphs and the Engine last run for 3 minutes (as found condition, and before the engine scored and possibly seized, Oh the engine also had 32 starts, that's a lot of pulling) was running mostly in the lower RPM's but was run for 20 seconds at 14,050 RPM's (No Load) which seemed a bit excessive.

Most likely the last 3 minute run on the saw was after it had already had a seizure, just added enough run time to finish it off. 32 starts is the number of starts since new. n What was the total run time on the saw? How were you able to determine the saw was run at no load at 14050rpm?( is doesn't read load vs no load rpms, and rpms were well within the acceptable range). The fuel settings are well within range.

The saw had a bad dose of fuel, that it that's all.

 

[Karla]

Hamish,
Yes I agree, and I am still learning. I saw that mistake of mine a couple days ago and I just didn't go back to correct it. The 32 starts are the accumulated number of starts and when the saw has run for at least 60 seconds, so a quick pull or two would not be recorded, so in reality it probably had a lot more than 32 pulls on the cord, I now realize that too. The 14,050 Rpms was taken from the bar graph, explained on page 8 of the Diagnostic Manual, which stated "Wide Open throttle and speed >12,000 rpm (No Load)" so an assumption was that the 14,050 rpms was with No load.

In answer to your question, the total accumulated run time was ( 1 hr. 36 minutes), and the total time "Last run" was ( 3 minutes 1 second). I think I had some of my numbers mixed up there too, but I am again still learning.

Some additional new Information, and may explain the overheated clutch, Tonight after I gave it another 30 second test, I found the Oil pump is not working. I didn't get the Original Bar with the chainsaw but I am betting it was probably burned up pretty bad, and that was heating up the clutch. Anyhow tomorrow, I will take apart the oiler, I think it might be missing the little pin that holds the adjuster screw for the pump, I gave the adjuster screw a turn back and forth and the adjuster screw actually dropped down about a 1/4 inch and I was able to push back up. I didn't notice the oiler not running on its first run, because I always squirt the new chain and bar down before its first run, but I believe it was not working initially. Anyhow, something to do tomorrow, I might also take another look at the diagnostics tomorrow, and see If any of the numbers changed. Thank you for your Info, and Yes this is the first Autotune that I have had a chance to experiment with a little. I also yesterday while doing more research, saw an auto tune Model 362 that had a fuel setting of 90/122 and my Model 545 was 75/ 70 and then My Rebuilt Model 550 was inbetween with fuel setting of 99/100.

Do you Know if there is a default table that would show the typical values for different Model Autotunes ?

Thank you for your confirmation, and from your comments, I assuming the carburetor is probably in good condition and working the way its suppose too.
Thank you again,
Karla

 

[fordf150]

Very limited experience but I think all autotune should have the same ballpark fuel settings in the neighborhood of that 70-75 range.

 

[Karla]

Fordf150,
Yes, I agree it does seem strange that the numbers on the different Model chainsaws, would have such a different settings. I would really like to "reset" the numbers, and then run the diagnostics again, but I can't do the reset yet with the software setup that I have, and Not sure If its really reading the error codes either or Its just that their are no error codes. Anyhow, I did run it again today, and cut some wood for a few minutes, It seems like the RPM's are screaming and not sure why, so I still may have a problem and obviously don't want to score a brand new piston and cylinder, so I'll wait till I can get my diagnostic tool working with resets.

Oh, I did check the oil pump this morning too, and its definitely Not putting out the amount of oil to my liking, I am only using a little 16" bar, and I have the adjustable oil pump maxed out, and also put some thin winter weight barchain oil in the chainsaw, and the bar is just barely getting oil on it, also laying a shop towel on the ground with the bar over the top of the towel, I am just barely getting the shop towel wet after a 30 second run. Today, I ordered a New Oil pump, and when I get the new one I will take the old one apart and check all the lines and plummet in the bottom of the tank. I did rinse the oil tank out with some kerosene this morning too, but it was perfectly clean, so I doubt the plummet is plugged, but my next step will be to remove it from the tank, replace the pump, and make sure the lines are not plugged. Also the gear appears to be turning freely, and is definitely properly engaged with the drive drum, and If I turn the drive drum by hand I can definitely see a little bubble or drop of oil coming out by the bar, and of course the bar is brand new and clean, so only thing left is the pump. Lol.

Oh, one more question, I have a handheld wireless digital tachometer, I can read the Rpms at Idle with the tach, but I can't read the WOT Rpms', any clue why ? I have used this Tach on many engines and never had a problem, but I was wondering If with the programmable autotune is there something strange going on with the ignition module firing of the plug ? I could probably take my tach and one of my old engines and make sure it still reads, I know it worked on my Model 435 when I checked it last, I also know the tach is suppose to read (2 stroke, single cylinder engines up to 20,000 Rpms), so another challenge and puzzle. I may have to wire up my old tachometer that had the wire wrapped around the spark plug lead, and see if that one reads the high Rpms, just very strange, but just by ear the Rpms, do sound like they are screaming, a guess over 14,000.

Thanks again for your thoughts,
Karla

 

[Karla]

Fordf150,
I just hooked up my older wired on type tachometer, and I definitely got some good RPM readings, Hooray. Although the older tachometer is not as responsive and takes a few seconds between readings, I read idle speed at (2760 -2820), so definitely around 2800 Rpms, and WOT Rpms (no Load) 10,200 - 12,100 Rpms, again it jumps around a little but definitely above 10,000 Rpms, So Maybe everything is good. Also my oiler seems like its producing more oil now, not sure why and maybe its a finicky Oil pump, but I will still probably replace it, I like Oil when I am cutting. Lol

I didn't try my digital wireless handheld tach again, maybe I need to read the Instruction book on that one, and then try it on WOT Rpms on another chainsaw. I think it has like a memory, but when I have used it before It was very responsive and would change constantly, so I need to check out my digital tachometer a little bit more, I did try putting a new battery in it, but anyhow Just too much fun.

Bye again,
Karla

 

[Old2stroke]

Back to the overheated clutch. You cannot seriously overheat a clutch by heat transfer from the bar. The only thing that causes that kind of overheating is a clutch slipping under load. One way is to hold the throttle wide open with the chain brake on and not being able to figure out why it won't rev up, but the usual culprit is an operator who consistently lugs the engine down while cutting, to the point that the clutch slips. The other popular way is getting the saw pinched and holding the throttle open hoping that a lot of power and twisting and pulling will get it free.

 

[Karla]

Old2stroke, Thank you for the information.

 

[Karla]

Another attempt at showing the Model 550 rebuilt, also run #2. oiler looks better today. Maybe since the tank was emptied during shipping it needed time to purge air out of lines and prime pump, not sure.

A little better video but still not to my liking, Lol

 

[Karla]

One more run today on my rebuilt Model 550, and great News, It go a cold start today it was 42 degrees outside but still started in three pulls. I let it idle for about 5 minutes and gave it a couple throttles until it was warmed up, I read the exhaust temperature with my heat gun and it read 156 degrees at the spark arrestor which sounds reasonable. Also took another set of RPM readings and Hooray the idle RPM's 2800 rpms, just perfect, and also figured out it was operator error using my wireless digital tachometer, I re read the manual and found out I should be holding the antenna side of the tachometer towards the top cover to pick up the magnetic coil at the spark plug, I had it reversed and never did that before. Also without taking the oil pump apart, It is now delivering oil, so everything there is good too.

Anyhow with a quick throttle for a second or two, It was reading over 12,500 RPMs and I am sure IF I held it at WOT longer it would have gone to 14,000 plus but I definitely don't like running WOT with No load for that Long.

It also would be interesting to see what the RPM's are when buried into a log cutting and holding it at WOT too. I might need an extra set of hands to get that reading or Duct tape the Tachometer inplace.

Anyhow Sorry to be so wordy but I am definitely enjoying experimenting, and reading the results, and of course getting the chainsaw running. Oh I did do another set of diagnostics on the autotune carburetor and yes the numbers changed with the new Top end, fuel setting are a little different, New fuel settings (H/L) = 104/98 and original or before rebuilt were 99/100, but temperatures of carburetor about the same. Also strange that the H/L numbers almost reversed themselves with a higher "H" number now. I still have so much to learn and try to figure out what this all means. Also comparing it to my Model 545 the (H/L) was 75/70. so it seems like the "H" number should be higher than the "L", not sure ?

The accumulated numbers, like number of starts just added on to the original numbers, However Interresting that it did take and correct a New record in the Autotune diagnostics automatically, I still haven't done any resets or a Master reset yet. Now I am kind of wondering how many records will it create ? Does it create a New record of the same chainsaw each time you hook it up to test it ?

So back to the original problem, I still can't say conclusively what fixed the problem or If the original problem is fixed, or did I just fix the symptom of scored engine, open decompression valve, dirty air filter, and burned or overheated clutch. The rebuilt Model 550, got a new cylinder and piston, a new decompression valve, a new clutch, and a cleaned air filter. I wish I had another Model 550 to do some more comparison readings, and I am now curious How Hot is the exhaust on a Model 545 on a day like today with the same temperatures outside ? So I guess I can get that comparison, and see If the 550 is running hotter than the 545. Lol.

Any thoughts ? But maybe it was a bad fuel mixture or No mixture at all ? The voting is almost over, I think it will only Poll the question for a week.

Thank you everyone for all your thoughts, Information, and Help. I am still experimenting ........

 

[Karla]

Just ran the Model 545 for about the same duration as my previous run on the Model 550, and at the exact same ambient temperature outside of 42 degrees F, and the results were identical exhaust at about an inch away from spark arrestor screen on muffler was exactly the same 156 degrees F. I am sure on a warm summer day when the ambient temperature is much higher the exhaust temperatures would even be much higher but its good to know they are the same right now. Readings were taken with an Infra-red gun, Non contact type temperature. I also just thought, that I could do a thermocouple direct contact type temperature readout, That would be interesting, maybe right on the cylinder, too.

But Not sure what I am proving or what I would solve, Lol. .... Maybe just some data for future troubleshooting or diagnosis. I often hear of individuals that say there chainsaw is running very hot, but I don't know If they have measured what very hot means ???

 

[SCHallenger]

Karla, thank you for all of the informative posts! This has been quite interesting. FYI, I have a 562XP which tachs at 37,500 when held at WOT. My impression of these AT saws is that they control max RPMs by virtue of the air-fuel mixture rather than by a rev limited coil. Whether or not this is correct I'm not sure. My main reason for this is that the tach reading is steady, & the saw sounds like it is 4 stroking rather than bouncing off an electronic limiter. Another thing that seems to support this theory is that the tach reading will bounce around by 2,000-3,000 RPM when you exceed the max RPM allowed by a limited coil. FWIW, it sounds as though you are using the same tach as I have which is the DTI 20,000.

 

[Amp4027]

I am just trying to really rationalize and understand what went wrong, I may even try to contact the seller to see If he Knows for sure, like he ran straight gas in it or something, but he is under No obligation to tell me.

My guess is the decomp was stuck open and the saw would not start with next to no compression. Owner would probably remove the sparkplug, then spray starting fluid in it until it was essentially full of liquid, put the plug back in, and then crank it over, which would get it to fire and run for a little bit, but not before completely de-oiling the system and the volatile explosion hammering the piston off the sidewall (which also bound the ring in the piston groove on the opposite side and chipped it off on the return stroke)

Great videos. I like to use a 2ml pipet and fill it with 2-stroke oil and use it to drip oil direct on the crankshaft needle bearings, rings & etc, thru the exhaust or intake port then shake the flywheel at BottomDeadCenter during a rebuild just so everything is nice and lubed. It will be a little rough to start the first go-around (and be sure to use your old sparkplug so you don't foul the new one) and will smoke like crazy, but at least everything will be coated really well. And don't WOT it for a few minutes until the smoke clears because the air/gas mix will be on the extremely lean side, just use the throttle to keep it barely running.
Not sure how it would affect that AutoTune.... Which is a really neat thing to find on a chainsaw imo.

The videos you posted sound good. Personally, I thought they were just a bit on the lean side, but Husky engineers & AutoTune would probably know better than my ear.

Your threads are outstanding! The empirical data and thoroughness of your methods and procedures is mentally invigorating.

 

[Karla]

Thank you so much for your thoughts and idea's. and also thank you for the compliments. I think this is a great site to write blogs about chainsaws that we work on or rebuild, and learn from each others experiences both good ones and bad too. In-addition I always use this site to search out similar problems like scored pistons on a Model 545, and learn what were there symptoms and repair. Anyhow for me its just alot of fun Hobby. So I definitely do alot of reading on this site, and listen to everyones opinions. Thanks again & bye.

 

[SCHallenger]

Karla, thank you for all of the informative posts! This has been quite interesting. FYI, I have a 562XP which tachs at 37,500 when held at WOT. My impression of these AT saws is that they control max RPMs by virtue of the air-fuel mixture rather than by a rev limited coil. Whether or not this is correct I'm not sure. My main reason for this is that the tach reading is steady, & the saw sounds like it is 4 stroking rather than bouncing off an electronic limiter. Another thing that seems to support this theory is that the tach reading will bounce around by 2,000-3,000 RPM when you exceed the max RPM allowed by a limited coil. FWIW, it sounds as though you are using the same tach as I have which is the DTI 20,000.

Wow! I just read the RPM in my post. That would some hot saw. I don't know if I mistyped the no., or if it was incorrectly copied (unlikely) by the computer. Anyway, the correct RPM is 13,750, not 37,500.
I can't believe nobody nailed me on this! LOL

 

[Karla]

I did see the mistake, the day after you typed it but I'm Not good at slamming someone on a mistake. I know that I make alot of them, usually because my typing can't keep up with my brain. Lol But it does bring up a curious question, and I may have to google it, What is the highest speed that a chainsaw has run ? I'm thinking like maybe in 20,000 + Rpms, like maybe one of those "Race Chainsaws", any thoughts or does someone know ? That has to be alot of fun, building and racing chainsaws, but besides having the fastest, there is an awful lot of skill that goes into that without getting seriously hurt.

 

[ANewSawyer]

I wish I could like this whole thread. Karla, some tachs have problems with these fancy new saws, I believe even the non autotunes can have that problem too. Keep up the good work.

 

[Amp4027]

I did see the mistake, the day after you typed it but I'm Not good at slamming someone on a mistake. I know that I make alot of them, usually because my typing can't keep up with my brain. Lol But it does bring up a curious question, and I may have to google it, What is the highest speed that a chainsaw has run ? I'm thinking like maybe in 20,000 + Rpms, like maybe one of those "Race Chainsaws", any thoughts or does someone know ? That has to be alot of fun, building and racing chainsaws, but besides having the fastest, there is an awful lot of skill that goes into that without getting seriously hurt.

As for a piston driven one, No idea lol. 14,500RPM = 241.67 strokes per second.

I wonder when they are going to go to direct-drive 960V mini fusionreactor-powered

 

[ironman_gq]

You should look at what the RC guys do with little nitro motors 5cc and 4+HP at 30,000RPM. The large scale guys are getting close to 10HP on a 34cc gas engine at 20,000+RPM and that's on regular premium pump gas.

 

[Karla]

Thanks for the Info & too funny on direct-drive 960V mini fusionreactor-powered. I am sure that NASA can do it, I can see an RITG chainsaw in the future.
I mean if they can make an RITG (Radio Isotope Thermal Resistant Generator) that can power up an instrument panel for several years and send it to the moon, then an RITG chainsaw should be duck soup. Lol.