74 Honda CB200/Runing on only one cylinder.

[wildfirexxl]

Hello ton doers,

I've been working on this bike sense may; all summer. It's been left to sit for many years before I got it but I've done a ton of work to it and it's now running. Almost ready for the road, but it's only running on one cylinder(left leg side). If you juice the throttle it'll rattle the other cylinder a little bit. Almost like it's back firing. When driving this makes it tough because when that second cylinder hits the power boost is noticeable; it'll jolt you.


1. Maybe it's fuel.
That may be, but I've adjusted the jets, idle screws, floats, fuel lines and the petcock has been cleaned. When the good side is running the bad side is still blowing gas through the carb if you put your hand over it. I know fuel is making it into the cylinder because if you run it without the exhaust pipes on it blows fuel out of the exhaust valve side of the block. Also I've only run it on high test(93) gasoline.

2. Maybe it's air.
That may be, I replaced the stock air boxes with the cone shaped air filters. Simply because they're easier to clean. But these air filters have about the same enough of drag as the stock one's do. So i doubt it's air.

3. Maybe it's spark.
That may be, but both sides have new plugs (nice NKGs), I've also taken each plug out and sat it on the block and they're both showing very nice strong spark. Both have been properly gaped.

4. Maybe it's points.
That may be, but two buddies of mine at two separate times have adjusted the points/timing. Both of my friends are mechanics who work at two different local dealerships, so I should hope they know what they're doing.

I don't want to be that guy who say he's fixed everything and expects you to know why my bike still isn't working. If you feel I've not done something listed above correctly, please let me know. I just wanna get this thing fully working.

It's too late for me to shoot a video of it running tonight but I'll upload one in the morning so you guys can see what it's doing.

Thanks so much for any help.

 

[Big R]

A sporadic firing cylinder is usually an electrical issue. Maybe it's a connection that works fine when checking for spark, but not while the engine is running?

Also, check for gas on the plugs - that's a great way to see if you are getting gas. Which also leads me to compression testing and valve clearances. Checked those too?

My money would be on electrical though.

 

[session101]

im having the freaking same exact issue as you with my BMW freaking kidding me right??

ive done all of the the above and adjusted the valves too with no luck

im going to check the timing with a timing light tomorrow, then going to sync the carbs and then after that im up shits creek...

im curious as to what your fix is... i was thinking leaking valves maybe on mine but who knows...

 

[session101]

if you replace your coils, let me know

 

[wildfirexxl]

Me and a buddy went over the major electricals and tested them with a voltage meter. Good coil, good rectifier and a few other things.

Like I said, I'll post a video in the morning of it running so you guys can see what I'm talking about.

 

[wildfirexxl]

http://www.youtube.com/watch?v=QtOlcI8zHPE&feature=share&list=UU8TKDq6LL12fE_0uem-2_Kg

 

[Big R]

Did you do a compression test and checked the valves?

And I can't remember: does the 200 run a single coil with dual plug wires coming out?

 

[wildfirexxl]

I've not done compression but i could do it at my buddy's shop this coming week.

And yes, single coil, dual plug wires.

I've attached a diagram...

 

[Big R]

Valve clearances?

I know you said you have strong spark on each side, but I would swap the spark plug wires left to right anyway. Aside from that, the only things left are valves and compression.

Nice looking bike and gnarly beard btw!

 

[wildfirexxl]

Are there any cool tricks to checking/adjusting valves? This is my first bike so I'm trying to learn everything i can.

Hmmm, I've swopted the plugs themselves, but good idea on the wires. I can't remember if anyone who's helped me with it has tried that yet, but eitherway I'll do that.

Just watched a youtube video on checking compression, I thought that was more to it than that. I can knock that out tomorrow morning. The stock psi should be 170psi. We'll see.

I wonder if it is that valves now that you mention it. Because, and I know you can hear it in the video too, the left leg side makes a very noticeable clatter/hissing sound. I thought it might just be because it doesn't have the sound of the cylinder firing, you can just hear more of the engine noise.

But thanks man! The beard's gettin' beastly. And the bike will look even better once she's riding down the street haha

 

[Big R]

No real tricks, but proper tools go a LONG way. Find the valve clearance spec in the manual and then try to find the proper size shim stock (feeler gauge, whatever) . And please don't use a crescent wrench on the valve cover bolts - I think they are 19 or 21mm? Other than that, it's a 20 minute job of so.

Oh ya, the motor has to be stone cold to check the valves - so wait til morning.

 

[wildfirexxl]

Ok, good news bad news.

Good news: Got to check my compression today.

Bad news: The cylinder that's firing(right leg side) is at 98psi and the other side, the one that's not hitting is actually at 110psi.

Given these are both far below the factory suggested 170psi. I don't think I'll be able to check/adjust the values till monday due to my lack of a torque wrench. A friend of mine should be able to help me out monday with one of those...

 

[teazer]

170 would be pretty high, but agree that sub 100 is low. Did you use a cheap gauge or a good one? The reason I ask is that cheap ones tend to be very inaccurate and often read low.

Either way, if the left is running at 98, the right should run at 110. Right? That bike uses a single coil with to plug leads coming out. If the plug caps are both good and the plugs are new (please confirm on both issues), you should have a nice spark on both sides.

If that';s OK,. we can move on to carbs, filters and exhaust. Sometimes exhausts get clogged with small ctitters and wasps nests.

Filters should both be clean and can be swapped or try the bike without them to test it.

And that brings us to carbs. The carbs on that bike are fairly simple but jets are small and the holes in those jets tend to get clogged. First test is to see if both float bowls are filling. Turn off the fuel at the fuel tap and unsnap the clip on each carbs to see how much fuel and crud is in there.

Both should have about 1/3 to 1/2 full of fuel after they are removed, so be careful and no naked lights anywhere close. If one is dry, fix it. If they are both "full" remove the pilot jets (aka slow jet) and clean them. blow through them both to be sure they are clean. Then please tell us what you found.

 

[wildfirexxl]

170 would be pretty high, but agree that sub 100 is low. Did you use a cheap gauge or a good one? The reason I ask is that cheap ones tend to be very inaccurate and often read low.

Either way, if the left is running at 98, the right should run at 110. Right? That bike uses a single coil with to plug leads coming out. If the plug caps are both good and the plugs are new (please confirm on both issues), you should have a nice spark on both sides.

If that';s OK,. we can move on to carbs, filters and exhaust. Sometimes exhausts get clogged with small ctitters and wasps nests.

Filters should both be clean and can be swapped or try the bike without them to test it.

And that brings us to carbs. The carbs on that bike are fairly simple but jets are small and the holes in those jets tend to get clogged. First test is to see if both float bowls are filling. Turn off the fuel at the fuel tap and unsnap the clip on each carbs to see how much fuel and crud is in there.

Both should have about 1/3 to 1/2 full of fuel after they are removed, so be careful and no naked lights anywhere close. If one is dry, fix it. If they are both "full" remove the pilot jets (aka slow jet) and clean them. blow through them both to be sure they are clean. Then please tell us what you found.

I made a video that covers most of you're questions.

http://youtu.be/QtOlcI8zHPE

Carbs: Cleaned, disassembled, cleaned again, soaked for two days in carb cleaner, reassembled. That's plenty of fuel getting into the cylinder.

Exhaust: I have the mufflers on now but I've had them off with just the headers on with the same problem.

Filters: Removed stock airboxes. I've now got new cone filters on it. I've also tried it without filters, still only one cylinder fires.

 

[wildfirexxl]

A sporadic firing cylinder is usually an electrical issue. Maybe it's a connection that works fine when checking for spark, but not while the engine is running?

Also, check for gas on the plugs - that's a great way to see if you are getting gas. Which also leads me to compression testing and valve clearances. Checked those too?

My money would be on electrical though.

I checked the coil today by swopping the wires to the opposite cylinders and it's still only firing the same single cylinder.

 

[teazer]

If you swap the carbs from one side to the other, what change does that make?

 

[wildfirexxl]

If you swap the carbs from one side to the other, what change does that make?

Haha it funny you mention that because I just got back inside from doing just that! Ha weird.

It runs, but still only on one cylinder and on the same side. It doesnt run nearly as well tho and smokes a lot.

 

[jonnymedia]

I've had similar strange things like this happen to my bike (69 Cb350) even after replacing wires, coils, points, etc. My right carb is the problem child. The bike will run great, then stalling will become frequent, then the right carb would refuse to fire up. Each time, I forget to check the first thing that almost always seems to solve this issue for me. Battery. Top up the fluid, make sure it's charged, and trickle charge it all the time. At least on mine its very sensitive to a low charge and doesn't charge well (especially now I've got my iPhone charger wired in).

I'm no mechanic, but this works for me.

 

[wildfirexxl]

I've had similar strange things like this happen to my bike (69 Cb350) even after replacing wires, coils, points, etc. My right carb is the problem child. The bike will run great, then stalling will become frequent, then the right carb would refuse to fire up. Each time, I forget to check the first thing that almost always seems to solve this issue for me. Battery. Top up the fluid, make sure it's charged, and trickle charge it all the time. At least on mine its very sensitive to a low charge and doesn't charge well (especially now I've got my iPhone charger wired in).

I'm no mechanic, but this works for me.

That's interesting. I don't think i have the same problem tho. I've got a brand new battery in there that's getting full charge...

 

[teazer]

If swapping carbs makes no difference to which side fires, that's not the issue. It doesn't mean the carbs are OK or fine- just that it runs on either carb on one side and neither carb on the other side.

Try it with your car/truck battery jumpered across to the bike and see if that makes any difference.

There are only 1 set of points and one condenser and one coil, so that system either works or it doesn't as a rule but low voltage is a known issue on some bikes. On a single lead coil, one side of the coil is grounded directly and teh spark lead grounds through teh plug. On a twin lead coil both sides of the secondary coil are grounded through the plugs. One side is +ve and the other is -ve and one way is always stronger than the other.

I think you said that you swapped over the plug leads complete with their plugs and the dead side stayed the same.

Just for giggles, you might try swapping the plugs from one side to the other. It's possible that one is fouled and is grounding out and not sparking under pressure in the cylinder.