Help needed 1986 interstate GL 1200 starts Warms up turn off go back to start only backfires very loud

[Bozco5.0]

I have a 1986 Honda Goldwing inters

tate I’ve rebuilt the carburetors sank carbs adjusted air fuel changed ignition coil wires and plugs. It starts beautifully runs great, until it warms up and you turn it off after letting it sit for a minute if you try to start it just has a loud backfire. I am very good at remove and replace. Troubleshooting I’m weak need help

 

[zman]

First thing I do is check how the plugs are burning, after it backfires does it go back to running good?

 

[Motörhead]

Fuel seeping past a float needle into a cylinder and out into the exhaust maybe?

 

[Motörhead]

Nice looking paint scheme, gold pinstripes on black reminds me of the JPS Lotus F1 back in the day.

 

[Bozco5.0]

First thing I do is check how the plugs are burning, after it backfires does it go back to running good?

After it cools down it starts up

 

[zman]

I would let it sit after a run for maybe 10 min. and pull the plugs, if you have a camera all the better, have a look inside the chamber and see if there is wetness, smell the plug for fuel smell, I am not sure if 1200 has a wasted spark ignition but my gut is telling me you have a cylinder flooding after shut down, heat can cause ethanol laced fuel to purge under heat, it has about a 170 degree boiling point and if a cylinder is flooding during a wasted spark an exhaust valve is open causing a backfire.

 

[DaveO430]

It's probably the pulse generators.

 

[Motörhead]

I knew a guy that put a Mazda rotary into a Triumph Spitfire. Overfueling caused a backfire that blew apart the muffler and lifted the car off the ground. It was loud enough for the police and fire department to be dispatched for a terrorism attack lol

 

[Bozco5.0]

It's probably the pulse generators.

That’s what I think it is I have a parts bike I have four GL 1200s to aspens and two interstates one is a parts bike on the yellow and white leads going to the four-way plug. It shows that it’s a closed circuit on the blue and blue and white lead to the four-way plug. It reads open. I have been looking in all the wrong places for information on this and have not found what I’m looking for. Maybe you can help me.

 

[julimike54]

Look at this wiring diagram....
https://classicgoldwings.com/media/page-142.19766/

It shows the color of wires and based on what you state the 'blue' doesn't sound right. You need to measure ohms on the pairs to see if they are good or bad. I don't remember the resistance (ohms) it should read (memory is thinking in the 300 range). If you have other pulse generators you can measure them to compare to what you have. You need to have the unit unplugged for measurements.

Best of luck...

 

[Bozco5.0]

Look at this wiring diagram....
https://classicgoldwings.com/media/page-142.19766/

It shows the color of wires and based on what you state the 'blue' doesn't sound right. You need to measure ohms on the pairs to see if they are good or bad. I don't remember the resistance (ohms) it should read (memory is thinking in the 300 range). If you have other pulse generators you can measure them to compare to what you have. You need to have the unit unplugged for measurements.

Best of luck...

Thank you very much for this information. I am on vacation right now. Sorry I didn’t get back to you earlier. When I get home next week, I will get right on it. I have a parts bike. I might pull one side of it out of my parts, bike, and Mary it together With my problem bike they should both be the exact same so I do not think I will have a problem. What do you think?

 

[julimike54]

If it was me, I would replace both while I was in there. My luck would be the other one fails right after it's all put back together.

I may not have been clear on the ohm test, the measurement would be done without the part being in the bike (ie the sensor not sensing anything metal).

 

[Bozco5.0]

If it was me, I would replace both while I was in there. My luck would be the other one fails right after it's all put back together.

I may not have been clear on the ohm test, the measurement would be done without the part being in the bike (ie the sensor not sensing anything metal).

Hey there thank you very much I got back and yes, one is bad. The other is showing about 330 ohm. I understand I do not like using use electrical parts myself. Do you know anywhere I could find the replacement part Honda says it’s discontinued. I’d search a couple of other websites eBay and Amazon and haven’t found a set. I would really like to get this bike back up and running. Thank you very much for your time.