Suzuki 115 hp DT 1987 2-stroke wont go past 1500 rpm

Glaspar80

Recruit
Joined
May 24, 2013
Messages
3
Just picked up a 21ft v-hull with a 115 1987 Suzuki DT with a 13 1/4 - 17 "turning point express" prop. So we took it out on a beat run, and it starts easy and idles calmly. Works great till we get it to about 1500 RPM and it just won't go over that, doesn't die or do anything weird it just won't go any faster than that... I would say 5-6 mph or so. Talked to the previous owner and he was told that it was a bad magneto coil, is there any way that could be the cause? I am going to go down and swap the Primary No. 2 coil for the battery charging coil to see if that fixes it, but I don't know if it is really the cause. Any thoughts on other causes? Thank you very much for any light you can shed on this problem -Glaspar
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
Re: Suzuki 115 hp DT 1987 2-stroke wont go past 1500 rpm

Test compression, spark, and the timing to see if it is advancing properly and in spec.
Timing light should show if it is loosing spark if you move it to the different plug wires.

Check the alarm system to see if it works properly as there may be a problem with motor and it is limiting RPM but alarm is not sounding

If loosing spark, then test voltages coming from under flywheel going to CDI and the outputs from CDI to ignition coils to see what is in spec and what is not. That should show you what the problem is instead of just trying fix it by replacing parts randomly.

If all of these things a OK then look for a fuel problem, probably carbs.
 

stylesabu

Master Chief Petty Officer
Joined
Aug 2, 2009
Messages
849
Re: Suzuki 115 hp DT 1987 2-stroke wont go past 1500 rpm

i would check fuel first. try enrichening it while running.then check spark on all four cylinders, spark should jump 3/8" and be bright blue. if you find weak or no spark then follow 99yam40 instructions.
 

Glaspar80

Recruit
Joined
May 24, 2013
Messages
3
Re: Suzuki 115 hp DT 1987 2-stroke wont go past 1500 rpm

Thanks, will try all of the suggestions when the weather clears tomorrow, any other thoughts while I've got my gear out and she's opened up?
 
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