1984 Suzuki DT-30 2 stroke sputters at high rpms

[spooled65]

Hi Folks,
I have alot to cover, but I'll keep it as short as I can. I recently bought a 1984 suzuki Dt-30 Serial # 03001 410335. It is both electric and pull start. The motor was brand new. It had zero evidence that it ever ran. It came with the original 6 gallon metal can that never had gas in it before. Also included was the original fuel line with primer bulb. All the lines are soft and free of any cracks or dry rot. I rigged it on a boat with a new battery, and it ran like a dream. Ran it about 15 miles with no problems. Refilled the tank, 50:1 and went to go out the next day, and it idled kind of ruff. Took it out, and it acted like the plugs were fouled on initial take off. It smoothed out with more throttle, but at about 3/4 throttle it started sputtering. Took it back to the dock and found the plugs were fouled. Bought some new plugs and it ran good for the first minute of so and did the same thing. Plugs were wet, and black. It is getting worse to the point it doesn't even want to run. Any suggestions on even where to start with this one?

 

[spooled65]

Re: 1984 Suzuki DT-30 2 stroke sputters at high rpms

Well I figured that because it was pumping so much gas that maybe the float bowl was stuck, or gaskets in the fuel pump were maybe torn from being 28 years old then suddenly introduced to gas. I rebuilt the fuel pump, and put a new float bowl in the carb along with all the gaskets. I knew once I was in there from how clean everything was that I was barking up the wrong tree, and sure enough it ran the same. Now it's on the electrical system. This motor has a lighting coil under the flywheel as well as the ignition coil. Then there' s the CDI assembly. I hope it's not the CDI because it will cost between 300 and 400 depending upon the model. Does anyone know how to troubleshoot the coils with a meter? Any help would really be appreciated.

 

[99yam40]

Re: 1984 Suzuki DT-30 2 stroke sputters at high rpms

where did you find a new 1984 model?

I would test compression to start out with, a motor sitting that long with no oil on internal shiny parts could have rust pits and not sealing well.

Test spark with a spark tester to see if it will jump a 1/2" gap or better yet measure the peak volts to CDI and out of it to coils. Probably need service manual to get specs. Should have ohm tests for coils also

 

[spooled65]

Re: 1984 Suzuki DT-30 2 stroke sputters at high rpms

Thanks 99,
I'll do some checking. I found the motor on Craigslist. A woman was selling off her father's estate, and the motor was one of a pair he bought new and it never made it to the water. He must have gotten a deal on two. I took the plugs out before ever starting it and looked at the cylinders as best I could with a flashlight. You could see the crosshatching, and from what i could see it was shiny as new. I guess they must figure at the factory that these motors may sit for a year or two before being run so they must do a sort of pickle to them. I'm sure they never figured on 28.

 

[spooled65]

Re: 1984 Suzuki DT-30 2 stroke sputters at high rpms

Well it turned out to be the cdi ignition coil. Of course the most expensive part in the electrical system. In this area outboard mechanics are hard to come by, and if you take your boat to him you may wait weeks. I just decided to start changing parts until I hit the right one. At least now I have a box of spare parts for the next time. Thanks for the suggestions.