1985 CR500RF CDI ? need some brain storming here.

[Hoony]

Ok here goes.

My 1985 Honda CR500 will not start. last fired it up October last year (2015) and raced it for a meeting washed it then stored it. no issues at last meeting.

i have the following spares which i have tried every combination and process of elimination

- Spare stator complete with pulse coil (both the spare and one originally on bike - check out to spec's in manual for ohms and also insulation resistance test between coil and ground shows infinity)
- spare ignition coil (both the spare and one originally on bike - primary and secondary check out to spec's in manual for ohms)
- Spare flywheel
- Spare CDI
- all earth's are good, frame has not been powder coated or painted
- trigger Pulse coil gap to flywheel is in spec.

- yes i have disconnected the kill button.

i have no or a weak spark when pushing kick start down rapidly by hand.

if i spin flywheel over with my battery drill with 1/2" square drive and socket (plug out and on head) i get spark but a bit weak i reckon (from both CDI's and ignitions coil combinations)  and i get an output of approx 45 Vac direct from both of the stator coils i have.

i am thinking i have 2 poor condition CDI's (breaking down). once under compression i reckon i have no spark at all.

i did manage it get it fired once (with start ya forker) and once warm - it responded, revved hard and was crisp so no issue there, a good reliable spark once running. it was run for a good few minutes and up to running temp. i shut it down to check some things and tried in about 5 minutes could not get it fired again or since.

your thoughts?

i have a meeting this weekend but looks like i may miss it. i took a leap of faith and bought a aftermarket CDI for this model but i don't think it will make it from the USA in time.

anyone know of a place that will repair an OEM CDI ( encapsulated in resin ) i have seen a few that look like they have been done before.

[OverTheHill]

http://www.partzilla.com/parts/search/Honda/Motorcycle/1985/CR500R+A/LEFT+CRANKCASE+COVER/parts.html

I'm probably wrong 'but' still sounds like a weak stator cdi charge coil. Had an "85 at work with the same symptoms & kick start lever was too short on the sticky out bit & also came around past square on & my bloody foot slipped off. Light-ish flywheel gives bugger all inertia for starting too. Dunno how you guys do it especially if you drop it in the mud. Anyway, partzilla pic shows 3 different set ups & i'm talking the single stator charge coil shown in 18 which is all i'm familiar with on my yz490k & others & generally speaking i'd expect 160 peak volts at kick start speed straight to 'that' stator wire with it 'not' connected to anything else up top. Plug out & kick it. If you don't have access to a 'peak meter' [which is real good to have] you should get 80 ordinary AC volts [approx]. Trigger coil i'd expect a few or 5 but maybe only a couple on a std meter [AC volts of course], Umm--the reason i'm aiming at the stator is it's the exact symptoms as you say no spark or very weak spark. Very weak immediately points to crook stator coil thinking. In saying that, no spark 'at all' would have me looking there first too, but for an open circuit rather than a low resistance. Anyway, new stator got mine [customers] going then doing endless effortless wheelies around an unfamiliar paddock--hit a lump of dirt hidden in the long grass when i decided time to put the front down & woke up in intensive care sometime later [lol-not]. Life changed from then on--october "99. Have a Happy Day--now i'll go read your story properly & ignore my rambling if leading know-where. Cheers.

[Hoony]

Thanks for the reply. You may be correct. I will check this out and report back. It's definately not open circuit but could have some bad insulation of windings causing shorted turns

[FourstrokeForever]

Might be a silly observation but i'll throw it out anyway......Seems to be no coincidence that the problems started after the last wash. Is there surface rust inside the flywheel or in any of the connectors?

[Lozza]

Apart from the above with h/r faults on connectors. 45Vac from stator is wayyyyy to low. Good news is that the stator/rotor appear to be Kokosan which are common across Hondas, KTM's and Suzuki 125's.
Stator resistance should be less than 100 Ohms and about 250 Ohms through the pick up. More than 100 Ohms drops the voltage at the coil.

I doubt it is a CDI problem.

[Hoony]

Thanks guys. No rust on flywheel at all. The stator checks out to spec Lozza with mutineers but could be breaking down at higher voltages (shorts between turns) does not look like it was hot or stressed. I though maybe the capacitors have failed due to age (electrolytic capacitors do this).

[pokey]

I will echo Lozzas view with stator.

I read the symptoms of the system not producing sufficient current to energise the other components . CDi either work or they dont or they behave erratically, This is just consistently weak so its receiving a week current