CB200 Misfiring 1 side when hot

adventurco

Nick Ol' Eye
DTT BOTM WINNER
So we picked up a CB200T a couple weeks ago for Kayla to ride...I replaced the battery, cleaned the carbs and she's a runner.

The bike idles great and runs perfectly at low RPMs, I can take it for laps around the yard all day with no problems.

When I take it around the block and get it revved up to 5-6k, the left cylinder starts breaking up and misfiring. Once this happens, it'll just about stop running on that side until it cools down. I have had to walk it home a few times, but I can usually keep it running and get it home under its own power if I try hard enough. Then it starts back up like normal once its cooled down for a few minutes. The issue starts happening just about at the same point on every ride. I get about halfway around the block and it starts to misfire and bog, by the turn back onto my street it barely wants to stay running.

So I set out to do the necessary maintenance...set the cam chain tension, set all the valves to .002" as per FSM specs. After valve adjustments I took it for a run and ran into the same problem with same symptoms.

Checked the timing and it was a bit advanced. Adjusted the point gap and then timing and hoped it would solve the problem, but still experiencing the same issue. I also clipped the spark plug lead wire and made sure the cap had a good bite. In fact I tried a brand new NGK cap on the culprit side just to rule that out, same problem.

It really seems to me like a bad coil since it only does it when hot and then will start up again no problem after a few minutes resting. Odd thing is, this bike has a single coil with dual leads, so if it was the coil causing the problem I'd think that the problem would happen on both sides instead of just one (correct me if i'm wrong).

Next step is to double check the points to make sure they are clean. Maybe replace points and condenser before spending the cash on a coil?
 
Another thing I thought of after our last conversation, could it be the one lead coming out of the coil. I would imagine it's a wasted spark so a troubleshooting idea would be switching the spark plug wires and seeing if the problem persists only on the other side. Could be wrong though, but seems like an easy test if your leads are long enough

Sent from my SM-G900V using Tapatalk
 
HURCO550 said:
Another thing I thought of after our last conversation, could it be the one lead coming out of the coil. I would imagine it's a wasted spark so a troubleshooting idea would be switching the spark plug wires and seeing if the problem persists only on the other side. Could be wrong though, but seems like an easy test if your leads are long enough

Good call. Upon visual inspection the leads at the coil seemed OK, but I will give that test a shot and see if the problem follows.
 
advCo said:
Good call. Upon visual inspection the leads at the coil seemed OK, but I will give that test a shot and see if the problem follows.
Yeah, the issue I'm thinking of wouldn't necessarily be something that Could be seen visually

Sent from my SM-G900V using Tapatalk
 
beat me to it,
but swap the leads and see if the problem changes side. If it does replace the coil, if it remains on the same side you know it's not the coil and can start looking elsewhere.
(carb probably)
 
Look under the points cover for a mark (probably black, or a divot) to see if it's shorting out on the cover. Inspect the insulation on the points wires and check the washers. It could be bad coil, but I'd make sure it's not shorting during advance.
 
irk miller said:
Look under the points cover for a mark (probably black, or a divot) to see if it's shorting out on the cover. Inspect the insulation on the points wires and check the washers. It could be bad coil, but I'd make sure it's not shorting during advance.

360° engine on the 200. Only one point.
 
Fiurst, pull both carbs off and clean them a couple of times. The trick with carbs is to squirt fluid (WD40 or carb cleaner) through one passageway and then repeat on that same circuit on the other carb. It's the easiest way to see what is going on. make sure all teh jets flow the same side to side and theat the float valves are clean and no garbage trapped above them.

Next, I would replace the coil. They are cheap and available on ebay or other suppliers.

Then I would look at the most likely cause and that's a blockage in the fuel system. Could be the tap or the filler cap breather hole which tends to get rusted and the rubber/cork seal often obscures it. It could also be a slow fill on one side but you wiil have fixed that when you clean out the carbs.
 
Thanks for all the responses.

I swapped the coil leads and the problem remained the same, left side misfiring once engine is at temp. I made it a little further this time before it started but I didn't let the bike idle before I took off.

The points seemed a bit burnt, so I just ran some 400 grit through to clean them up. I'll take it for a test ride momentarily.

It just feels like an electrical issue, not fuel or carbs. The carbs are CLEAN and the bike pulls through all the gears perfectly on the first straightaway. For the sake of ruling them out, if the points don't clear anything up then I will clean the carbs for a third time this afternoon and see if that helps.
 
Have you pulled the plug itself to ensure you're actually getting spark? Is the plug gapped to spec?
 
coyote13 said:
Have you pulled the plug itself to ensure you're actually getting spark? Is the plug gapped to spec?

That would be funny.
I've had it happen before though.
In the end it's a good thing because you end up with new coils, new points, new condenser, new plug wires, and squeeky clean carbs before you realize that it's the 2 dollar spark plug 8)
 
irk miller said:
Or a resistor cap going bad. Haha
He said in the o.p. that he replaced the cap

Sent from my SM-G900V using Tapatalk
 
HURCO550 said:
He said in the o.p. that he replaced the cap

Sent from my SM-G900V using Tapatalk
Wasn't suggesting that it's his issue. It was with one of mine. I was replying to SONIC's comment. I replaced everything only to find out the resistor cap on one cylinder was bad.
 
irk miller said:
Wasn't suggesting that it's his issue. It was with one of mine. I was replying to SONIC's comment. I replaced everything only to find out the resistor cap on one cylinder was bad.
Oh haha that sucks man

Sent from my SM-G900V using Tapatalk
 
Took another ride after cleaning the points. Same issue. On to the next.

I may just replace the coil since they are relatively cheap and might as well rule that out for sure.
 
Plugs are not fouled, gaps within spec on both sides and nice blue spark on both sides. I tested compression while I had the plugs out and everything is right there, 120 psi each on a cold engine, should be sufficient.

Next step is going to be another carb cleaning. I need to order vacuum port adapters for this bike so I can put the gauge on and sync it.
 
Back
Top Bottom