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sliderxc

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sliderxc

hey all I have a question I have 2 k 341 and when I use a hand held tach I get 2 different readings one shows 1800 rpm wich you have to double for a single cylinder and the other shows 3500 rpm they are both single cylinders what would cause this the tach is the one with the coil spring comming out of the back of it

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PhanDad

It's my understanding that some single cylinder engines fire the plug every revolution (both compression and exhaust stroke), while others just fire on the compression stroke. Hence the need to double the reading in one case and not in the other.

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powerking_one

Paul,

Based on your comparison of the 2 different K-341 engine RPM's via the tach, I would submit that one engine has solid-state ignition (firing once every crank revolution; trigger on the flywheel)and the other having points/condenser ignition (firing off the camshaft; once every other revolution); hence the 1/2 or 2x the tach reading depending how you look at it. If the above are true, then this expected behavior.

Tom (PK)

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powerking_one

Quote:

"Wow I can't beleive that just 2 guys have any info on my problem I figured there would be more kohler guys on here its a k341QS spec#71366 serial #1507361"

Any engine with points running off the crankshaft will fire the spark at every 360 degrees or solid state ignition engines with coil over magnets flywheels.

Crickets chirping is all I can say on that comment. Maybe it's time for a new tach??

Tom (PK)

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sliderxc

didnt mean to cause trouble I did try the tach on my other engines and it shows 1800 then I double it so it works perfect went to the k341qs and shows 3600 on tach it has points and stator I put them on new

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powerking_one

I thought about this tach reading anomaly again and a couple of things come to mind.

It's possible the points cam lobe had a mfg defect in that there's another slight hump on it indeed enough to open/close the points somewhere during the rotation. Maybe roll the engine over by hand and carefully watch the point gap for this; better yet take a test light to the points and look for 2 transitions over 720 degrees of rotation ??

Tom(PK)

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HubbardRA

Buy a Vibratach. They work on any engine. There is no electronic hookup of any kind. They work on crankshaft vibrations. They are accurate. All you need to do is sit it on the head with the engine running and adjust it to maximum vibration, then read the scale. I have had one for years and they work great. Mine came from Tecumseh, but they are also sold by B/S. They are the standard RPM measurement device of most garden tractor pulling organizations in this area. Easy to use and accurate.

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powerking_one

Good point Rod about the Vibra-tach, and/or you could use one of these pretty accurate digital tachometers (from China, of course) to confirm the engine RPM's. My last post was an effort to help Paul try to figure out why he's getting screwy readings with his R.F. tach.

Vibra-Tach/Tachometer Tecumseh PN=670156 (~~$24.00 from Jackssmallengines.com)

Cheapy laser tach example: http://www.ebay.com/itm/Handheld-Digital-Photo-Laser-Tachometer-Non-Contact-Tach-Tool-RPM-Tester-/330964244645?pt=LH_DefaultDomain_0&hash=item4d0f0198a5

Tom(PK)

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dhoadley

This brings up a subject I was thinking of starting a thread about. I need a tach for these small engines. My 35 year old handheld Sears car tach does me no good. What do you good people recommend? Thanx, Dave

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MikeES

I have 3 Tiny Tachs that I have used on many different engines, both Kohler and Briggs, single and twins.

I bought the "fire on every revolution models" which worked on the Briggs the KT and Magnum engines and gave 1/2 rpm on the K engines.

But I could not get a constant reading from a K361.

I had an optical tack looking at the PTO as a comparison (pulling tractor revving to 4000rpm). The Tiny Tach would read an rpm completely different than the optical, not 4000 or 2000 but some number like 3250. Idle the engine down and then open it back up and it would read a completely different number like 5700, while the optical went back to 4000. ?

I just put it down as I can't use this tach on that engine.

BTW the vibatach is good and usable for a working tractor but not accurate enough for competition which you can be disqualified for 1 rpm over the rules.

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powerking_one

So, Paul, is what you are saying is that when rolling the engine over (720 degrees of crank rotation) that the points are opening/closing twice? If so then that explains why you are seeing the tach reading of double what a normal cam lobe'd points ignition would normally be on a single cylinder engine. Like the dealer said if the engine runs OK, then just accept/live with it. It still seems strange why this engine's points lobe(s) are like this VS your other engines.

Tom (PK)

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HubbardRA

If the points are triggered from the camshaft, they will open once every two revolutions or 720 degrees. This ignition fires only on compression stroke

If the points are triggered from the crankshaft, they will open once every revolution or 360 degrees. This will fire ignition on both compression and exhaust strokes.

The camshaft turns at half the speed of the crankshaft on all of the gasoline engines.

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GrincheyOne
quote:Originally posted by dhoadley

This brings up a subject I was thinking of starting a thread about. I need a tach for these small engines. My 35 year old handheld Sears car tach does me no good. What do you good people recommend? Thanx, Dave


id="quote">
id="quote">Dave,I use the Sen-Dec (latest) from DRPower ("Mantanence Meter") it is an induction fed Led display, Displaying RPMs, running time, and has an alarm function every 25 hours.The September 2014 catalog (page 17) shows a price of $39.99. I have them mounted on my LT4212G, and my Earthquake log splitter. there are many varients out there, not just in auto stores, and OPE equipment dealers, but check out the ATV and Cycle shops.Wayne

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sliderxc

only thing I can think of is this motor was made to run a generator I had to add a stator to it because it didn't have one so mabey firing twice makes it run cleaner because it was made for a generator

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