Chainsaw Repair
How To Basics - Carb Fixes + Mods - IPL and Service Manuals => How To Basics and Fixes => Topic started by: flatsix on January 10, 2014, 12:22:08 pm
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I have 2 chainsaws STIHL - manufacturing date 2013 : type MS362 and type MS150TC;
I bought the tachometer TECH TACH DTI 110 - the one that everybody says they are so good. I tested both of my chainsaws- result: when rpm goes over 10.000 rpm then the reading suddenly drops to 5000 - 6000 rpm while the saws are yelling at 10.000 rpm+. No way to measure more them at more then 10.000 as I see Always readings between the 5-6000 rpm.???
So I sent back the tach. My STIHL -dealer uses a OPPAMA 1100 - he measures the rpm while I am next to him : what happens - exactly the same: rpm gets higher till 10.000 rpm and then suddenly again the readings between 5-6000 rpm while the MS150TC is screaming around 11-12000 rpm.
We both are very surprised/ Then we take a brandnew tacho STIHL EDT8 out of the box - again we try on my littlre chainsaw 150TC : the same happens.
So: conclusion - my 2 chainsaws are not possible to read the max. rpm with the tacho's actually on the market - even STIHLS newest tacho cannot give an rpm reading.
HOW COMES - WHAT IS HAPPENING ???
Can anyone explain this to me, please.
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Just a guess but could the saws have a limited coil? The tach could be reading every other rev.
Did the dealer try the tach on any of his saws?
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Yes, the coils are going into rpm limiting.
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I'm guessing the saws are hitting the rev limited coils. Just my WAG too. Richen aka fatten your saws up.
My 7900 365 did the same thing if they hit the rev limited coils on my EDT-5
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I do not thnik so - when you slowly rev the chainsaw then the rpm is getting higher and higher 8-9-10.000 rpm - the rpm off the saw get's higher (must be 12 to 13000 rpm the max. rpm) but once the meter get's to 10.000 +- the display of the tach gives suddenly between 5000 and 6000 rpm.
If there would be a limited coil, then it would certainly not get in action at 10.000 rpm as the max. rpm must be around 13000????
The Stihl dealer has no explanation.
Very strange....though
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Have you tried using the lead (supplied with the tacho) and attaching different points near the high tension lead.
Limited coils often make rev counters play up soon as the coil shorts out (reaches rev limit).
For example,
try clipping it onto the lead 1st, and get the counter away from the saw.
try other places close to the lead, like onto starter housing etc, the lead will pick up the pulse same as pointing the counter at the saw.
I still use an old 2 stroke / 4 stroke REVCO rev counter, works as good today as when I bought it back in the 90's.
I'm not saying they are the best, there are a few different ones on the market and they all work, I guess you get used to reading different saws a different way.
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No, I have thought about doing what you describe about using the lead ^but when I saw that I had the same result on my 2nd chainsaw I thought the tacho had a technical failure.
It is only when I saw the same bad result of the 2 other tacho's at my Stihl's dealer that I realised that my Techtach tt20K in fact was allright. In the meanwhile I sent it back - so at this moment I don't have any tacho at all......
I should have connected it with the lead before sending it back - my mistake...
Strange that the new Stihl tacho edt7 and 8 don't work either.
????? ??? ??? ???
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Try to set the high speed in the wood as the load will keep it off of the limiter, that is how I adjust my 201t. If you do it this way be gentle with as you want the saw to do the cutting and kind of hold it out of the cut. Don't push on it.
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The cut off speed for your 150tc should be 12800 rpm. The service manual says that the ignition module limits the speed to approx. 12,800 rpm. Your 362 should be around 14,000 max high speed rpm. I could not verify that the 362 has a limited module. The one the I have worked one does not have that. But that does not mean that they are not out there.
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The regular 362 has a black unlimited coil. The 362Special has a blue coil at 13,500
This is in error
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Thanks for clarifying
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I have a regular MS362 - so a black unlimited coil according to you.
Does not explain why the techtach, nor the Oppama 1100 nor the Stihl edt8 can work with my MS362 nor with my MS150TC ??
For me it is a mistery and I am not able to see the highest rpm - once past 10000 all tacho's read between 5 and 6000 rpm??
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I have a regular MS362 - so a black unlimited coil according to you.
Does not explain why the techtach, nor the Oppama 1100 nor the Stihl edt8 can work with my MS362 nor with my MS150TC ??
For me it is a mistery and I am not able to see the highest rpm - once past 10000 all tacho's read between 5 and 6000 rpm??
My error, I was talking about Husqvarna saws. I don't know about the Stihl MS362 coils? I do not own a Stihl MS362 and know nothing about them.
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I would think that a lot of the new saws are coming with limited coils. I would try to set the saw in the cut and see what you can come up with. It work good for me on my 201. The 362 I have worked on is an older one. From when they first came out. So they could have changed the module to a limited one at some point along the way.
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Since my last post I have been searching in a couple different Ms362 Service manuals and the only MS362 Illustrated Parts List I came across.
The only coil number for the MS362 I came across is a 1140 400 1302 as listed in the Illustrated Parts List. This coil appears to be limited to 14,000 rpm? It is black and rectangular in shape.
There is another coil floating around through the system 1140 400 1303, which by the number (1140 Stihl engine family) one would think it belonged to the MS362? But it belongs to the MS311 & MS391. It appears to be limited to 13,000.
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The early 362 I had was turning 14,200 rpm with the factory carb limiters, and it was quite lean at that rpm. I don't think the early production models had rev-limited coils, if so they cut in higher than the saws limits. I do know most of the other newer Stihl models have limiters, I know my 211 does. When the limiter cuts or alters timing my tach will start to go crazy. Now I'm not saying that's what's happening to flatsix saw, it could just be a bad signal, I'd try the lead like Neil said and see what happens.
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One thing I did notice is that the coil for the MS 362 only has two poles. It does not have the 3rd part of the armature.