Only firing on 1 cylinder, stuck at work!

89 R100RT. Went out to do an errand and had trouble starting was reak rough. Pulled out of the parking lot and no power. Right side header pipe hot, left side cold. There is gas in the float bowl. I pulled the plugs and switched sides. Same side still does not fire. Plug wires? They are old with some cracking. Carb issue?

How far from home? I rode mine 100+ miles on one cyl...dead coil.

Good luck!

20 miles. Limp home would be ok? I don't want to cause further damage.

I had a similar problem...

The "bad" cylinder would fire at higher revs, but never at idle or lower revs.

Mine was a bad coil.

just trying to learn
so your coil did not work at low speeds ????
at the same time did you replace the condensor?
I thought that coils were either work or no work
or work at low speeds and arc at high speeds
excuse my ignorance, and poor spellin
just tryin to learn

Dylan76 said:

20 miles. Limp home would be ok? I don't want to cause further damage.

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No, you should not do any further damage... Just remember that you are one cyclinder down with half the power... No wheelies!!!

Thanks, coil sounds like the problem.

Only firing on 1 cylinder, stuck at home with crazy woman!

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this just happened to me too! out of the blue, very hard to start, and right side was barely firing, whenever i pulled right side throttle cable it would almost die. thought it might be a carb issue. checked the plug which was black, and started thinking the choke was stuck on. it wasnt. played back and forth with the choke and the throttle cable while the bike was off and tried starting it again and everything was fine and smooth. took it for a couple test rides, its all good.

for now.

Dylan76 said:

89 R100RT. Went out to do an errand and had trouble starting was reak rough. Pulled out of the parking lot and no power. Right side header pipe hot, left side cold. There is gas in the float bowl. I pulled the plugs and switched sides. Same side still does not fire. Plug wires? They are old with some cracking. Carb issue?

Click to expand...

I had this happen to one of my R100RT's. I went to fill the tank before leaving on a trip and only one cylinder would fire at the gas station. Got it home on one cylinder and swapped plug wires. The right side plug wire was dead inside the molded plug cap. Installed a spare wire and completed a 3,000 mile trip without further incident.
The plug wire should measure about 5K OHMS tip to tip.

Isamemon said:

just trying to learn
so your coil did not work at low speeds ????
at the same time did you replace the condensor?
I thought that coils were either work or no work
or work at low speeds and arc at high speeds
excuse my ignorance, and poor spellin
just tryin to learn

Click to expand...

To be honest, I can't remember exactly how it sounded, because since I knew I had a problem with one cylinder, I didn't want to run the bike very much. But it seemed like it would fire on both if I rev'd it a bit.

I redid a lot of my ignition, including condenser, when I replaced the bad coil. My ignition was due for an overhaul.

Bad plug wire on left side was the problem. Up and runnin' again.

Could be much worse...

I own a 1973 R75/5 and had a similar situation.... Got on the freeway after a fuel stop and wound it up to accellerate into traffic and felt a stutter. So I wound it down a bit until it stopped and checked to make sure my petcocks were in the 'on' position - they were. So I wound it back up slowly and noticed a huge reduction in power and pick up, however I was able to get up to 70mph eventually.

This was the middle of the night last Thursday. I was on a bit of freeway that was very dark and upon looking down I noticed my header pipe on the side I believed was misfiring was glowing red hot.

Yesterday (Friday) I took my engine apart... top end only. and when I took off the rockers and peeled off the head to inspect the valves I found a hole in the exhaust valve and some aluminum in the cylinder (from the piston). It got hot in there.

Hope that you just got a faulty spark plug, but check out your valves and cylinder.

For parts, just in case, I'd suggest Huky's Toys...

g'luck.

I occasionally have the same problems with my r60/2. It seems that while parked on the kickstand (sidestand), the bike leans to the left allowing a bit of oil to occasionally leak past the rings into the combustion chamber - depending on the position of the pistons when the engine stops. This results in a big puff of white smoke from the left exhaust when it starts. After several of these startups, the left plug gets fouled with a black carbon. If this carbon gets wet with gas, it will short out the plug eliminating the spark jumping the gap. The obvious answer is to replace the fouled plug with a new plug. I have also had good success with cleaning the fouled plug with a bronze brush on a polishing wheel.

However, when I have had this happen on the road and do not want to take the time to replace the plug, I disconect the plug cap and hold it an inch or so away from its seated position causing the spark to jump the gap from the cap to the plug - apparently this causes a much hotter spark that, in turn, jumps the gap of the plug and gets the engine running on both cylinders. After the engine reaches its normal operating temperature, I re-seat the plug cap and the engine runs fine until it cools down or I have a chance to clean / replace the fouled plug.