15hp idle issue update and charge coil question

[iwombat]

I had a post about not being able to adjust my 15hp into an idle with the normal cable adjustments. Well, I found out why.

Nothing was really making sense so I decided on an invasive inspection. After pulling the powerhead and removing the exhaust tube I discovered an almost completely carboned over exhaust tube. There was about 1/4" passage down the middle and the rest was 1.5" thick carbon deposits. It's still not totally cleaned out, but it's getting there. The powerhead was fairly clean and the rings were floating nicely which is why I believe I got satisfactory compression numbers. However, I'm surprised this thing could flow at all with that kind of restriction out the back end. I also tore apart the powerhead for a re-ring while it's out. Gasket sets and rings are pretty cheap for this powerhead.

Also, after checking the charge coil with an ohm meter it's only showing 450ohms, which is about 100ohm out of spec (575 +- 25). Is it worth replacing, or can I run it like that? The spark seemed plenty strong when I tested it.

 

[DaveInGA]

Re: 15hp idle issue update and charge coil question

I don't know about motors, but I'm an electronics technician and do know about coils and transformers. When a coil is showing a lowering of resistance (lower Ohm reading) the coil is beginning to short out. What is likely happened is some of the insulation of your coil has failed, causing part of your coil to short and thereby show lower resistance. If it were mine, I would replace it, especially since the specification is plus or minus 25 ohms. You're significantly out of spec.

Regards,

Dave

 

[iwombat]

Re: 15hp idle issue update and charge coil question

That's my inclination too. I was kind of wondering how often these things show up out of spec and work anyway (factory QA issues).