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The 2-Stroke Garage => Turning Wrenches => Topic started by: 4schizzle on May 21, 2025, 04:55:49 PM

Title: HPI ignition Coil
Post by: 4schizzle on May 21, 2025, 04:55:49 PM
Hello again,

I am still having issues with my RD.  When pulling a heavy load while racing while rolling on full throttle it sputters/breaks up.  It does not do this at all during "street riding" or just riding it around.  It also starts every time on the first kick.  As I reported in earlier posts the full lines do not always fill up with fuel and I initially believed it was starving for fuel.  I took apart the carbs and cleaned several times not finding any issues.  Then one day a friend of mine noticed the coil mount I made had broken and the coil was just hanging there. I fixed this and it seemed to run great.  The other day I was racing it again and it did the same thing.  I believe it is jetted correctly as when it is running right it screams and no issues.  This problem seems to come and go as by the end of the day last Saturday it was running better.  Does anyone know how to test and resistance for the HPI ignition coil?  I am starting to think it is an ignition issue, maybe the flywheel moved or there are problems with the CDI.     

Thanks again for all the help,
Title: Re: HPI ignition Coil
Post by: 1976RD400C on May 22, 2025, 07:17:33 AM
A few things to check: install new spark plugs, make sure the coil ground is good, don't mount the cdi box next to the coil, check timing with a light, petcock fuel flow.
Title: Re: HPI ignition Coil
Post by: m in sc on May 22, 2025, 08:19:58 AM
honestly i've never had an issue. reach out to Willy @ HPI ask what the procedure is for testing maybe?
Title: Re: HPI ignition Coil
Post by: 4schizzle on May 22, 2025, 09:47:02 AM
Thanks for the suggestions.  I will try to implement and test the all the suggestions and let you guys know. 
Title: Re: HPI ignition Coil
Post by: 4schizzle on May 22, 2025, 03:59:51 PM
FYI: Flat terminal to ground 0.3 ohm, between the two wires 8K ohm or 8000 ohm.  Response received from HPI.
Title: Re: HPI ignition Coil
Post by: Yamanatic on May 22, 2025, 05:16:42 PM
Pulser coil? Had a similar ultra-intermittent issue on a TZ250. Everything checked out fine on the bench ... then I checked it hot at the track, during a failure - bingo! Nearly impossible to find, easy to fix.

Warren
Title: Re: HPI ignition Coil
Post by: 4schizzle on May 27, 2025, 11:03:37 AM
I was away for the weekend.  I still need to check the coil but I will also include the pulser coil on my list of things to check.  Thanks for the advice.