1981 Honda CM400 right cylinder not getting fuel / firing

[system9]

Me and my son picked up this 1981 honda CM400 at a garage sale. It had been stored for 8 years. It did start, but sounded rough. I pulled out the carbs, cleaned them, and also changed the oil, and oil filter. After this it started right up, and idles smoothly.
I've since pulled the carbs out 3 times, scouring them for defects, or reasons fuel isnt going to the right side. My spark is good on the right side, but when i pull the plug after running the bike, the plug is dry, so no fuel is getting over there. I swapped the floats, and the needles to see if the problem might change sides, and it didnt. Bike started right up again, but only on the left cylinder. Right cylinder is still out. When idling, both exhaust pipes are kicking out good compression.
any ideas?

[Johnj]

Try swapping the jets that the needles sit in.

[BuzZz]

If it is idling fine, then it may be the main jet that is clogged and needs cleaning.

Does the header on the suspect side get hot?

[system9]

Try swapping the jets that the needles sit in.

ok, i swapped he floats, and the main jets. and still, only the left cylinder would fire. It ran just like it did before the swap.
Also, while the bike was idling on the left cylinder only, i sprayed some carb spray into the right carb, (i disconnected the air hose) and the right cylinder wil fire and run, but only until it burns off the carb spray. So thats good, because i know the right cylinder is working, its just not getting fuel for some reason.
I'm pretty intuitive, but i'm not a professional mechanic, so my brother asked me to give him the carbs, and he is going to see if he can find a problem. Hes more experienced than me at this. Hopefully he will find something.

[system9]

If it is idling fine, then it may be the main jet that is clogged and needs cleaning.

Does the header on the suspect side get hot?

no, thats how i initially realized that it was only running on one cylinder. The right side stays cool. The muffler and header never even get warm.
But, like i was saying to the other poster, i did force feed it some fuel while it was idling, and it fired up a few times. After i did that the header was warm. So the right cylinder is functional, just not getting fuel.

[system9]

Try swapping the jets that the needles sit in.

oops, i misspoke. I swapped the floats and the needles, but not the jets. I'm still getting all the part names down, and unfortunately all i've had is phone conversation with my brother as he yells out carb part names at me. ^^

[system9]

I finally got the 2nd cylinder running.

Kind of due to lack of experience, one of the smaller brass screws, which i assumed was only a screw, was actually a smaller jet. It wasnt till i inspected it in the setting sunlight that i could see that it wasnt supposed to be solid. It was so crapped up, that i assumed it was just a screw!
I chipped away at the grime till i could see in fact that there was a small hole in it. Anyway, i cleaned it out thouroughly, and now the bike is running on both cylinders. Its not running great, the exhaust is kinda smokey, like its running rich.

[BuzZz]

It may well be running rich, or be burning off years of build up crud in the fuel system and cylinders. From your description, I would guess rich....

The hole in that jet is a very, very specific size, it controls how much fuel is fed into the intake air. If you enlarged it, even slightly, when cleaning the varnish out, it will act as a larger size jet. If that's what happened, the only cure is to replace the jet with a new one of the correct size.

[lamimartin]

I finally got the 2nd cylinder running.

Kind of due to lack of experience, one of the smaller brass screws, which i assumed was only a screw, was actually a smaller jet. It wasnt till i inspected it in the setting sunlight that i could see that it wasnt supposed to be solid. It was so crapped up, that i assumed it was just a screw!
I chipped away at the grime till i could see in fact that there was a small hole in it. Anyway, i cleaned it out thouroughly, and now the bike is running on both cylinders. Its not running great, the exhaust is kinda smokey, like its running rich.

I agree with Buzzz entirely. You should get a new set of jets. Running your bike too rich is like riding with the choke engaged: performance won't be there and you may just overheat and damage your engine. By the way, don't run the engine without the mufflers. If mufflers are in poor condition, get new ones that are OEM equivalent, or you may have to work very hard matching jets with bargain price universal mufflers.

Black smoke = too rich White/bleuish smoke = burning oil.

So far, you only tried to make it start. Before you spend too much time and money on the bike, I strongly suggest you get a COMPRESSION TEST done. You should get at least 100psi evenly on both cylinders (ideally 130-150). If not, you have to find out wher the loss of compression is from:
Wear form high mileage on the engine ? Poor storage precautions causing cylinder rust pitting ? Worn, burned or poor valve adjustment ?

Let me know what exact 1981 model you have, (CM400T or C or A ) so that I can help you find the exact specifications you need. I currently ride on a CM400T 1980. I've got the original Honda's 78-81 CB/CM400's as well as the CB/CM450 OEM Shop manual and the Clymer's manual. I strongly recommend you get one of them, matching your bike version. Without it, you will certainly end up causing expensive damages you could have easily prevented. I'm not a mechanic, but I do all maintenance by myself now, including some engine repairs.

If you got that far, I'm confident you will be able to do something with that bike. I could also indicate good sources for parts if you need to.[/list]

[system9]

The bike is a 1981 CM400T
The smokey cylinder is in fact the same one as the side that had the severely clogged Jet. The smoke isnt too noticeable while running, but, after i turn the bike off, the right side muffler oozes a small stream of smoke for about 2 minutes, while the left side doesnt.
The bike has the original mufflers on it, and they seem to be in pretty good shape, there is a small hole in the right side muffler though, at the back tailpipe.
The one thing i'm not familiar with, are the 2 screws that sit on the bottom of the carbs. They are adjustment screws, but i'm not sure where they should be at. There is also a rather large knob type screw, that directly adjusts the throttle, i guess its for setting the idle? or is it some kind of air/fuel setting? see, between the 3 different screws, there is plenty of head scratching.
I have a checklist of settings for the bike, and I also just recently got ahold of a pdf clymers manual, but i think the best info comes from people who ride the actual machine, so thank you very much for the good advice.

I finally got the 2nd cylinder running.


I agree with Buzzz entirely. You should get a new set of jets. Running your bike too rich is like riding with the choke engaged: performance won't be there and you may just overheat and damage your engine. By the way, don't run the engine without the mufflers. If mufflers are in poor condition, get new ones that are OEM equivalent, or you may have to work very hard matching jets with bargain price universal mufflers.

Black smoke = too rich White/bleuish smoke = burning oil.

So far, you only tried to make it start. Before you spend too much time and money on the bike, I strongly suggest you get a COMPRESSION TEST done. You should get at least 100psi evenly on both cylinders (ideally 130-150). If not, you have to find out wher the loss of compression is from:
Wear form high mileage on the engine ? Poor storage precautions causing cylinder rust pitting ? Worn, burned or poor valve adjustment ?

Let me know what exact 1981 model you have, (CM400T or C or A ) so that I can help you find the exact specifications you need. I currently ride on a CM400T 1980. I've got the original Honda's 78-81 CB/CM400's as well as the CB/CM450 OEM Shop manual and the Clymer's manual. I strongly recommend you get one of them, matching your bike version. Without it, you will certainly end up causing expensive damages you could have easily prevented. I'm not a mechanic, but I do all maintenance by myself now, including some engine repairs.

If you got that far, I'm confident you will be able to do something with that bike. I could also indicate good sources for parts if you need to.[/list]