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Old 25 March 2020, 15:46   #21
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Good idea from what I understand those tachs are quite cheap. It’s a zapcat so the wire doesn’t need to be long.
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Old 26 March 2020, 06:38   #22
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Hey Ali,

While your tinkering check that when you twist the throttle to WOT the stater plate reaches its stop and the timing is correct.

At the same time ensure that the link bar connecting all three carbs are traveling fully down.

what plugs are you running ?

Finally check all your vacuum hoses around the block some times they can perish and your have the same problem like a coil miss firing.

The bottom Cyld not firing sounds like a bad coil they always seem to fail there do you have a spare ? id carry one at least anyway

Also i know you checked your reeds but they do fail... But it would be hard to start and keep running at low RPM so you know your fine there.

hope you fix it soon
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Old 26 March 2020, 06:55   #23
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Not sure if Iíd mentioned but I suspected this thing to have been upside down more than once...

New CDI today and no difference. Save my £100 and send that back. Further upstream and have a look at this stator. Iíve given up trying to attach photos but believe me this thing is a state, properly rusty, tried a quick clean up of the surfaces and no change. Before I try another stator what Iíd like from you lovely lot if possible is information as to which pickup on the stator controls cylinder 3? And whether you can change individual pickups or just the entire lot?

Iíve rebuilt my fair share of car engines and gearboxes in the past, have to say itís a pleasure working on something so simple!

Thanks in advance once more.
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Old 26 March 2020, 06:57   #24
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Quote:
Originally Posted by smiffy422 View Post
Hey Ali,

While your tinkering check that when you twist the throttle to WOT the stater plate reaches its stop and the timing is correct.

At the same time ensure that the link bar connecting all three carbs are traveling fully down.

what plugs are you running ?

Finally check all your vacuum hoses around the block some times they can perish and your have the same problem like a coil miss firing.

The bottom Cyld not firing sounds like a bad coil they always seem to fail there do you have a spare ? id carry one at least anyway

Also i know you checked your reeds but they do fail... But it would be hard to start and keep running at low RPM so you know your fine there.

hope you fix it soon
Thanks for the help, Iíve narrowed it down to the stator which youíve mentioned!
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Old 26 March 2020, 07:15   #25
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Ok not to worry, I’ve done a resistance check on the three pickups and found one to have no resistance what so ever compared to the other two at 200 give or take. Safe to say thats the culprit. Just need to find a replacement now.

Edit, second hand tested one on eBay for £60, individual pickups - £20. No brainer.
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Old 26 March 2020, 08:01   #26
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Hey Ali,

On the Stater plate under the fly wheel there are three units one is for all three coil packs one is for lights for a panel and once for charging battery's if you had the electric start fitted.

Have fun pulling the fly wheel off post some pics of what you find underneath.
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Old 26 March 2020, 08:11   #27
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Got the flywheel off without too many problems, coming from the world of seized crank pulleys and ball joints this is a breeze.

When you say three units, are you referring to the copper coils or the outer pickups? I assume the outer pickups where linked to each coil, hence one of mine is showing no resistance in line with one cylinder not firing.

I’ve got some good pictures of the state of the flywheel and stator but the uploaded didn’t like my files or photobucket so I’ve given up!
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Old 26 March 2020, 08:44   #28
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im 99% sure all three Coil packs run off one copper coil on the stater plate the Mod class use to cut the other too copper ones off " To reduce magnetic drag ... "

Clean the bullet connectors to the CDU too

here is a fairly helpful manual too

http://www.tohatsu.dk/forhandler/Ser...202-Stroke.pdf
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Old 26 March 2020, 08:47   #29
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Alternator Coil Resistance
40, 50: W - Y, 0.3 - 0.5 Ω

Ignition Coil Resistance
Primary Coil
40, 50: 0.16 - 0.24 Ω

Secondary Coil
40, 50: 2.7 - 3.7 kΩ
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Old 26 March 2020, 09:00   #30
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As said it’s one of the pickups on the outside of the stator (small black coil pickups) which is showing zero resistance which is sure is the issue.

Is there any other way to identify ignition coil other than resistance? Would be nice to bin the other two for less magnesite drag whilst I’m in there.
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Old 26 March 2020, 11:00   #31
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Is there any other way to identify ignition coil other than resistance.
Besides checking coil resistance, can check the voltage each electrical component is producing while the motor is being electrical or rope cranked. The tech specs are in the PDF, a matter to find them. Will nned a special testser that reads DVA volts which are different to AC/DC volts.

Happy Boating
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Old 26 March 2020, 11:25   #32
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Think I’ll just leave them in there then!
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Old 26 March 2020, 11:29   #33
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Check my thread on here, called "My Thundercat" have photos of the coil you can remove under the flywheel. If you have all the parts you can rebuild one of these engines in a couple hours, plenty room for improvement and especially strengthening on the tohatsus, solid mounts, welded crank.
No real need for a tach if you still have the limiter on, it cuts in at 5850 anyway which prevents you twisting the crank. If you weld the crank then you can cut the limiter
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Old 26 March 2020, 11:35   #34
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Thanks for that, Iím familiar with your thread so Iíll have another look through.

Found it for anyone looking.
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Old 26 March 2020, 11:35   #35
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Thanks for that, Iím familiar with your thread so Iíll have another look through.
just checked maybe I don't have a photo on there! I'll check my phone
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Old 28 March 2020, 06:27   #36
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New stator is in (coils removed) and she’s running on three at along last, sounds lovely!

For anyone reading the future with a similar problem you’re looking for 200ohm resistance on the pickups under the flywheel. Good video on YouTube showing you how to check (same as lots of quads/atvs) As a couple of you mentioned it’s rarely the CDI.

Found a disgustingly naughty 50hp Yamaha in Australia tuned to 60hp for £1500, pallet shipping is £260 to UK. Must resist.
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Old Yesterday, 07:11   #37
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Had the carbs off again today as 2 are weeping from the bowl seal. (Can you tell I’ve got some time on my hands?!) soaked them in boiling water and throughly cleaned all mating surfaces, it’s much better but still a tiny weep after a while of running.

Assuming the rubber seals are a dealer only part?
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Old Yesterday, 09:35   #38
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The rubber seal will be compressed if it's weeping. Think the part number: 3C8-03121-0. Double check on online diagrams here: https://www.scribd.com/doc/187767999...gue-M40D2-50D2

You can get genuine Tohatsu parts online from Rib Shop, assuming they have them in stock
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Old Yesterday, 10:25   #39
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Legend. Seems like the correct gasket, I’ll try my local dealer too.
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