Help with a diagnoses.

[connor]

Hello Folks

Can anyone assist with the following.  Am having a problem with my 94 3rd gen Magna.

The engine will not start.

Having fitted a new starter clutch it is now cranking over ok.

Am getting a spark at the plugs. (New plugs fitted.)

Having checked through all the voltage and resistance checks according to the manual I can only find one reading which is not within specs.... ie the ignition pulse generator should show a resistance reading of 450 to 550 ohms...it is showing 310 ohms.

Anyone experienced this problem ? Is that 310 ohm reading enough to cause a problem.?  The spark reaching the plugs looks good and healthy...however it sounds to me as though the ignition timing is out..backfiring through exhaust and popping back through the carbs. 

The ignition control module may be at fault but there is no way I can test this apart from substitution.  Before I shell out on a new control unit I'd like to know if the 310 reading  on the pulse generator can maybe cause these symptoms.

Anyone with experience of this ?  Obviously any advice would be much appreciated.

Regards to all....Connor.

[Greg Cothern]

Conner has the bike sat for a long period of time?  The Magna's are known for clogging the slow speed jets and therefore are a ROYAL pain to get fired again. 
I would squirt a little fuel into the rear cylinder and see if it fires up on that, if it does then you know its fuel related.

[roboto65]

How long has it been since this bike ran if you are getting good spark it should fire. I have never seen a Magna go out of time like that but you never know just not typical.. Most of the time it is the carbs getting gunked up OR the battery is low which they are finicky about fully charged batterys!!!

[hootmon]

IF you wind up needing a new control unit... Check out this thread..
http://www.magnaownersoftexas.com/forums/index.php?topic=2676.msg22583#msg22583

[connor]

Thanks for the replies gents....the history is as follows.

I purchased the bike after it had been standing for 4 years.

The carbs were clogged...they were completely stripped and cleaned out.

After sorting numerous other minor faults the bike ran beautifully.

The starter clutch gave up..it cracked.

The bike was laid up for 2 weeks waiting for a new starter clutch.

I fitted the new starter clutch unit...I hasten to add that I did not interfere with the pulse generator at all.  The new starter clutch is a genuine Honda part complete with new rollers and springs and caps.

After fitting the new starter clutch the engine cranked over fine...but will not start.  Fuel is getting through ok and the spark at the plugs is strong.  However it is backfiring through the exhaust and popping back through the carbs...its as if the ignition timing is way out. 

Removing the new starter clutch I compared it again to the original unit and its an exact match.  Its not possible to fit the starter clutch incorrectly..it will only slide onto the crank splines in one position.

As I understand it the control module controls the ignition timing advance etc.

The pulse generator shows 310 ohms...should be 450 to 550.  Not sure if this lower reading is enough to upset things.  But the spark at the plugs is very strong.  Thats why I'm suspicious of the ignition control module.

The starter clutch is a purely mechanical device and is working fine...the puzzling thing is that only 2 weeks prior to this the bike ran brilliantly the only problem was the starter clutch.

Maybe no connection but....the day before I fitted the new clutch we had a pretty violent thunder storm.  lightning struck the metal roof of my garage.  It knocked out my computer...damaged my sons internet router and knocked out his TV.  The Magna was parked inside my garage at the time.  Just a thought but the ignition control unit is a box of electronic tricks...am wondering if the lightning strike to the roof has affected it.

[roboto65]

Hmmmmmmmm May have Lightning does some tricky stuff but I would think like a car with the rubber tires it would protect it.

[L J VFR]

I have had lightning strike my house!!    What was weird besides frying all of my phone lines, computer, satellite tv, etc,  was it did not take out my garage door sensors.  You are right, lightning does do funny things. 

[hootmon]

Hmmmmmmmm May have Lightning does some tricky stuff but I would think like a car with the rubber tires it would protect it.

Then there is always the kickstand as a path..

[roboto65]

OHhhhhhhhhhhhhhh See thats what I get for thinking LOL 

[lragan]

Lightning doesn't even have to strike through the bike.  A strike that close creates a huge magnetic pulse, which is what damages most electronic modules that don't sustain visible burns. 

When lightning struck our house once, it welded the seams in the foil wallpaper (yes, it was a long time ago, and yes, I actually hate foil paper -- forced the replacement, which was fine with us.), destroyed the security system central unit, turned on all the sprinklers at once, etc. etc.  The fire chief that came to put out the roof fire advised me not to settle too quickly with the insurance company.  That was prescient advice, as we later found plugs, telephone units, a boom box unplugged that was stored in a closet, etc. that were damaged beyond repair.

So, yes, it could well be the ignition unit.  The manual offers no schematic about what is in the beast, so I can't offer a better informed opinion.

I would buy a new one, and claim it on my homeowner's insurance.

[ezrydr]

Maybe Somebody's trying to tell you something.

[Chad in Michigan]

If i remember right, there is something with the starter clutch that has to do with timing. there are marks that have to line up correctly or the pulse will be generated at the wrong time. i think it shows this in the service manual. it may be just a mechanical device, but im pretty sure there is a 'flag' of some sorts that passes by the puse generator. i'll look at the diagram and write back.

EDIT: Look at pages 17-10 of the service manual if you have it. there are some alignment marks there. Hopefully this is all it is.   The tabs on top of that gear, on page 17-10 (labeled #3) are the pickup points, telling the pulse generator when to fire/not fire.

[connor]

Good Evening

Thankyou very much for your replies gents.

Have double..in fact treble checked all electrical readings and have concluded that the ignition control module has failed.   Have managed to locate a second hand unit and when that arrives we'll see what happens.

I contacted a UK supplier of Honda parts....They quoted me 424 sterling pounds....OUCH...! I think Mr Honda knows how to make money..!

Thanks again for your input..much appreciated.

Regards...Connor.

[roboto65]

Good Lord that is what 800 some odd dollars !!!

[Chad in Michigan]

If you're going to spend that much on a new module, (i'm sure you could find one used, i sold mine for $50 us dollars to a forum member) you could buy the upgraded ignition module from Dyna. it's called the Dyna 3000. it allows the stock timing curve, plus a few others. Its around $300 / $350 US if i remember correctly, but shop around. If you have a stock bike, there is a timing curve on there just like the stock curve, minus the -5 degree timing the stock module retards the timing at 9000 RPM. It allows more tuneability to the bike. Just a thought.