# 30 hp yamaha 2 stroke



## Sevensurfer (Nov 9, 2016)

I picked up a non-running Yamaha 30 hp 2 stroke with controls today for $150. The motor was on a river boat and has no corrosion so I believe the owner when he says its never seen the salt water as long as he has had it. It has good compression but no spark in the lower cylinder. (2 cylinder single carb model). I switched the leads for the ignition coils coming from the cdi and got spark back on the lower coil but lost it on the upper one. I think it is just a bad CDI powerpack. Im going to start there before I dig into the triggers on the stater, seems like a simpler step. Has anyone used a cheap cdi pack off of amazon instead of the 450 dollar yamaha one before.


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## Sevensurfer (Nov 9, 2016)

Also I will keep posting to this as I try to bring this old outboard back to life


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## Monty (Jan 10, 2018)

Wow. I thought a power pack for small motors would be cheaper. So you don't think its the lower coil?


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## Guest (Mar 30, 2020)

You need to check the triggers if it has two. I can upload the all the specs later. Don’t spend the $ swapping parts.


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## Sevensurfer (Nov 9, 2016)

Monty said:


> Wow. I thought a power pack for small motors would be cheaper. So you don't think its the lower coil?


I swapped the leads for the upper and lower coil coming out of the cdi and got spark on the lower cylinder showing that the coil is good. Also how do you check the triggers, im still kinda new to 2 stroke electronics as simple as they are.


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## Guest (Mar 30, 2020)

Sevensurfer said:


> I swapped the leads for the upper and lower coil coming out of the cdi and got spark on the lower cylinder showing that the coil is good. Also how do you check the triggers, im still kinda new to 2 stroke electronics as simple as they are.


A simple voltage check, but it requires a peak reading volt meter or a peak reading adaptor for a dmm. You can do a resistance check but doesn’t always show a faulty part.


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## Sevensurfer (Nov 9, 2016)

I checked the ohm readings on all of the wires going from the triggers/stator to the power pack according to the yamaha spec sheet. Seems the trigger is fine. ordered an aftermarket power pack last night, should be her by Thursday. Does anyone know where i can find a wiring diargram for these motors. c30elru the new power pack is used for both mariner yamaha and mercury motors in the early to mid 90s and im worried that some of the lead colors wont line up.


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## Guest (Mar 31, 2020)

Should be plug and play. The mercs/mariners of that model were simply rebranded yamaha motors with an adaptor for merc harness amd controls if I’m not mistaken.


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## Sevensurfer (Nov 9, 2016)

bad news on the outboard. It had ok compression when i picked it up (90 on both cylinders) but had just been unlocked, tested compression again today and upper cylinder is at 60, lower is at 90. I pulled the head and cover and cleaned them up and there doesnt seem to be any scoring to the cylinder walls. I hope its just a stuck ring. Im now waiting on a set of gaskets for the head and cover. On a positive note i put in the powerpack and have spark on both cylinders.


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## Guest (Apr 1, 2020)

Sevensurfer said:


> bad news on the outboard. It had ok compression when i picked it up (90 on both cylinders) but had just been unlocked, tested compression again today and upper cylinder is at 60, lower is at 90. I pulled the head and cover and cleaned them up and there doesnt seem to be any scoring to the cylinder walls. I hope its just a stuck ring. Im now waiting on a set of gaskets for the head and cover. On a positive note i put in the powerpack and have spark on both cylinders.


Find an Evinrude dealer or Mercury dealer nearby. Buy a can of BRP engine tuner or mercury power tune if at a mercury shop. Tilt motor up and spray in the cyliders concentrating around the piston and rings. This might help free a ring if it a problem. You can also buy a bottle of ring free from yamaha dealer but costs more.


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## Sevensurfer (Nov 9, 2016)

Boatbrains said:


> Find an Evinrude dealer or Mercury dealer nearby. Buy a can of BRP engine tuner or mercury power tune if at a mercury shop. Tilt motor up and spray in the cyliders concentrating around the piston and rings. This might help free a ring if it a problem. You can also buy a bottle of ring free from yamaha dealer but costs more.


I reassembled and put some 2 stroke oil in the cylinder just to sit and lubricate until my gaskets come in next week


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## Guest (Apr 1, 2020)

Sevensurfer said:


> I reassembled and put some 2 stroke oil in the cylinder just to sit and lubricate until my gaskets come in next week


The products I mentioned are to dissolve any rust/carbon that may be sticking rings not to lubricate.


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## Sevensurfer (Nov 9, 2016)

well i got the new head gasket in an reassembled the motor, I still have low compression in the top cylinder, 60 psi and 90 psi on bottom. Now i have to decide if i want to attempt a full tear down or just part the motor out and start to look for another yami


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## Monty (Jan 10, 2018)

Yeah, from my dirt bikes, that means new rings, piston, wrist pin bearings and bore out cylinder.
I bet on an outboard that would be $350 or so. Just guessing. 2 strokes just wear out rings eventually.

I think just rings might be a good and cheap solution, just to see if the compression comes back. How do the cylinders look, any bad scoring?


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## Sevensurfer (Nov 9, 2016)

Monty said:


> Yeah, from my dirt bikes, that means new rings, piston, wrist pin bearings and bore out cylinder.
> I bet on an outboard that would be $350 or so. Just guessing. 2 strokes just wear out rings eventually.
> 
> I think just rings might be a good and cheap solution, just to see if the compression comes back. How do the cylinders look, any bad scoring?


Not to bad, I'm going to run a hone through just to get cross hatching back


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## Monty (Jan 10, 2018)

I bought a hone for $40 years ago. Run it with a drill. It'll take any "burnishing off the cylinder wall. Also, the very top of the cylinder gets less wear than lower down and needs some extra work. I ended up buying a ring compressor too. Made life easier.


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## ek02 (May 8, 2012)

The bore should be checked with a dial bore gauge and the pistons checked with a micrometer to determine piston to bore clearance. Putting new rings in with too much piston to bore clearance may not end well. It will work for a while, but I have had piston skirts break from excessive clearance. Boring the block with new pistons is the best solution if you intend to keep the motor.


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