Tohatsu 70hp Timing (model M70A)

Junedog123

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I’m trying to get the right timing information for a Tohatsu 70hp. The model number is M70A. It’s probably from the 80’s. From my research the timing should be 5 atdc at idle and 20 degrees btdc at wot. I think the service manual has long been out of print but am hoping someone out there has the information. Any advice is appreciated. Tom
 

racerone

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Maximum timing usually does not go out of adjustment.-----And be very careful if you decide to adjust the idle timing.-----What is your motor doing / not doing ??
 

Junedog123

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I agree it usually is good to go but the previous owner did some “work” and I’d like to make sure things are set up properly. When I got it the timing was way off. It seems to run good now that I adjusted the timing/carburetor pickup (5 ATDC and 20 BTDC). I just don’t want to burn a piston up if I’m not in spec. From my understanding, it can run good but still damage things if the advance isn’t right. Thanks for the reply.
 

pvanv

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[h=5]SERVICE MANUAL : 3 & 4 CYLINDER 2-STROKES[/h]
003-21036-1_lg.jpg

Description

Covers all 3 & 4 cylinder 2-stroke models.

Part #: 003-21036-1

List Price (MSRP): $50.00
 

Junedog123

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That’s it? Buy a manual to verify a timing spec? Count me out. I help a lot of people (Locally) with their motors for free when a shop would charge them a $120 just to peek at it. Anyways thanks for the reply-that’s answer enough for me.
 

pvanv

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The Factory service manual is your friend. Not just for specs. And not even half of $120.
 
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Junedog123

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You’re right, just bought it on eBay for $14.99. That’s less than half of $50.00 MSRP that you quoted earlier. And it’s not even one of those fireplace SELOC or CLYMER manuals (even though they’d probably have the spec I need).

https://www.ebay.com/itm/TOHATSU-NIS...72.m2749.l2649

BTW, the M70A is a two cylinder so the manual you pointed me to would be the wrong one. Plus, it’s a free pdf download (I already have it, downloaded it prior to my first post on this thread).

http://www.tohatsu.dk/forhandler/Service/Service Manual_3-4 Cylinder 2-Stroke.pdf
 
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ahicks

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If you had the correct manual prior to posting, I would have expected you to be an expert at answering your own question regarding timing. What happened? Just curious.
 

Junedog123

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Hello, I didn’t have the correct manual prior to posting. I was pointing out that the manual recommended by an expert to buy was not the correct one and that it’s a free download (so why buy it). I ordered the correct manual this morning on eBay for a 2 cylinder 70hp Tohatsu (what I have, not a 3 cylinder). I simply was asking to see if someone could verify a timing spec on a m70a Tohatsu. I didn’t get a solid answer other than to buy something.
 
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pvanv

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You’re right, just bought it on eBay for $14.99. That’s less than half of $50.00 MSRP that you quoted earlier. And it’s not even one of those fireplace SELOC or CLYMER manuals (even though they’d probably have the spec I need).

https://www.ebay.com/itm/TOHATSU-NIS...72.m2749.l2649

BTW, the M70A is a two cylinder so the manual you pointed me to would be the wrong one. Plus, it’s a free pdf download (I already have it, downloaded it prior to my first post on this thread).

http://www.tohatsu.dk/forhandler/Service/Service Manual_3-4 Cylinder 2-Stroke.pdf

The paper manual is cool. I do have a reprint of it. They are copyrighted, so the PDF could incur the wrath of attorneys. I would zap that link if I were you.
 

Junedog123

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It’s also cool to help people out. The manual from eBay came in. The answer to my original question is 0 degrees at idle And 20 degrees BTDC at WOT. If anyone needs any questions answered for a M70A just ask I’ll be happy to try and help. I won’t try and sell you anything.
 

pvanv

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Yeah, but you can't get parts. Not even a water pump kit, They are 40 years old. Keep that in mind.
 

Genesis10gt

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Hey junedog. I have a m70a as well. The carb air fuel adjustment screws are out of adjustment. Is there a baseline number of turns out from a seated screw. I think I saw 1 1/4 turns but I'm having some trouble getting it right without a tachometer. Thanks.
 

pvanv

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Of course, then after starting and warming, you must adjust the screws by shop tachometer as per the Factory service manual.
 

natvalve

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I have a Tohatsu NS70, 2 Cylinder also. I have purchased a few service manuals including the one on Ebay that was mentioned. Can somebody tell me where the mark is on the engine to line up the timing adjustments? I have not received the manuals yet for this engine and I believe they have been lost in the mail. I do have the Tohatsu 1 & 2 cylinder manual and the Tohatsu 2.5-140HP two stroke manual and neither have my engine in them.
 

pvanv

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You really should start a new thread, as your issue is different from the original poster's.

Tohatsu never published a 2.5-140 hp manual. Beware aftermarket doorstop manuals. The line for the two halves of the block is the timing reference mark.
 

natvalve

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The original post was asking about setting the timing on a M70A engine which is a 2 cylinder. The M70B is a 3 cylinder. I have a NS70A which is a 2 cylinder and I am assuming is the same engine as the M70A. Both have "360-1" to start the serial number. I purchased this engine not working and somebody replaced a lot of parts on it. The guy that sold it to me said there was a spring he found laying there with no idea where it went and it is now lost anyway. I have not seen any diagrams showing a spring. The part with the timing marks has some play in it, so I thought it may go up under the fly wheel, but I am not sure. I replaced the fuel pump and the CDI unit and the motor will fire up and run at fast speeds if I play with the throttle link between the 2 carburetors. When I let them return to idle, the engine stops. Compression is good and I cleaned the carburetors. The fuel jets are adjusted at 1 turn and I have played with them also. The engine seems to fire up when I first try to start it. When I continue to try and start it after it has died, it does not even try to start. If I spray starting fluid though it will fire. It seems to me it has something to do with the fuel not getting through the pump..I know there is also this reed block assembly, but I do not know if those can go out of adjustment.
 
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