Possible Ignition Issue

[johnr6874]

Hey guys, haven't been on here in a while cause I been too busy riding :biglaugh:. But now I have a new issue forming on my '90. Lately as I've been riding, I've noticed that at around 4,000 rpm during cruising speed, the bike will start breaking back. Feels like it's dropping 1 or even 2 cylinders. It started out a couple weeks ago and I thought I may have gotten some bad gas maybe. But even when I refueled with BP 87 ethanol free, it still would do it at cruising speeds. Being an auto mechanic, it feels like a coil dropping. I was just wondering if anyone has experienced this before and what's the best fix? Now that it's about to start getting into the colder weather, I'll be riding less and will have time to get it fixed right! Not that I'm gonna stop riding just because it's cold, just not as much.

Thanks,
Richard

 

[Lew L]

Hi John,
Try this( costs nothing but time)

Remove tank cover and air box to get to the coils and cut about 1/4" off the end of the spark plug wire. If you see any corrosion at the end of this wire it could be the problem. Also check the coils for cracks. If the problem happens when the motor is hot could be to coils shorting out because of the heat but they might read good continuity when cold.
If you think is a fuel problem try a good dose of Seafoam or Berrymans B12 in the fuel for a tank or two. If it still misses as speed maybe do the shotgun cleaning. and lastly--- How old is the fuel filter??

There will be more good suggestions to cure the missing. Good luck, Lew

 

[jfeagins]

Does it correct itself at higher rpms after it breaks up at 4k? If not, it might be a fuel delivery problem such as a plugged filter, or an ailing fuel pump.

 

[adambweird]

Hey guys, haven't been on here in a while cause I been too busy riding :biglaugh:. But now I have a new issue forming on my '90. Lately as I've been riding, I've noticed that at around 4,000 rpm during cruising speed, the bike will start breaking back. Feels like it's dropping 1 or even 2 cylinders. It started out a couple weeks ago and I thought I may have gotten some bad gas maybe. But even when I refueled with BP 87 ethanol free, it still would do it at cruising speeds. Being an auto mechanic, it feels like a coil dropping. I was just wondering if anyone has experienced this before and what's the best fix? Now that it's about to start getting into the colder weather, I'll be riding less and will have time to get it fixed right! Not that I'm gonna stop riding just because it's cold, just not as much.

Thanks,
Richard

Mine did the same thing. I switched to COPS and in the process found both my back coils were cracked. Not sure about the front, they didnt want to come out, lol.

 

[huskyman510]

Mine did the same thing. I switched to COPS and in the process found both my back coils were cracked. Not sure about the front, they didnt want to come out, lol.

Yeah mine also same issue, did the same swapped to cops and found my 2 rear coil leads were corroded badly

 

[johnr6874]

Does it correct itself at higher rpms after it breaks up at 4k? If not, it might be a fuel delivery problem such as a plugged filter, or an ailing fuel pump.

Yes, when I roll back on the throttle, it seems to get better! But when I go back to cruising speeds, it starts breaking back again. It's not a carb issue as they were just rebuilt by Danny on here! The carbs are performing awesome!! I was thinking coils or wires as well myself. Just wanted a second opinion before I went to ordering new ones. I don't have the $$$ at the moment to switch to COPs. But definitely going to probably next Spring!

 

[alorio1]

I think it may be a fuel related problem like JF mentioned, could be a plugged vent line off fuel tank also.

 

[jfeagins]

Yes, when I roll back on the throttle, it seems to get better! But when I go back to cruising speeds, it starts breaking back again. It's not a carb issue as they were just rebuilt by Danny on here! The carbs are performing awesome!! I was thinking coils or wires as well myself. Just wanted a second opinion before I went to ordering new ones. I don't have the $$$ at the moment to switch to COPs. But definitely going to probably next Spring!

Why would a coil crack up at mid range rpms, then clear up at higher rpms?:ummm:

 

[alorio1]

You being an auto mechanic, maybe you have a small electric pump you can hook up to feed the carbs (3-5 PSI) and see if the problem goes away. your pump may have this problem, I have a pump sitting on the shelf that I cannot keep this little diaphragm in place...read this post.

http://www.vmaxforum.net/showthread.php?t=8775

 

[johnr6874]

Hey guys, I checked my coils just today as it was the 1st chance I had from work, and found the 2 rear coils severely cracked! Haven't gotten to the fronts yet, but plan on pulling them down tomorrow. So I guess I'll be replacing coils next. Here's a picture of the coils.

 

[sdt354]

Hey guys, I checked my coils just today as it was the 1st chance I had from work, and found the 2 rear coils severely cracked! Haven't gotten to the fronts yet, but plan on pulling them down tomorrow. So I guess I'll be replacing coils next. Here's a picture of the coils.

I'd suggest you ohm them out before springing for new coils.
Most used coils are cracked and still can work ok. Investigate cops as a cheaper alternative and an upgrade. The front coils are a bitch to get off.