Honda MC help?

[imagesinthewind]

I've got a 1981 Honda CM400E that is running badly.
Backfires a LOT, and at the last ride, the thing rev'ed so
high it couldn't get into 1 gear from 2nd.

Anyone have ideas of what I should look for?
I was thinking of cleaning the throttle cable shaft in case the cable was getting stuck.

Backfiring? I know nothing of motorcycles, but wlling to learn!

[Rebel]

May 5, 2010 16:54:29 GMT -5 imagesinthewind said:

I've got a 1981 Honda CM400E that is running badly.
Backfires a LOT, and at the last ride, the thing rev'ed so
high it couldn't get into 1 gear from 2nd.

Anyone have ideas of what I should look for?
I was thinking of cleaning the throttle cable shaft in case the cable was getting stuck.

Backfiring? I know nothing of motorcycles, but wlling to learn!

high revving can be from a stuck throttle cable. You should take it loose at both ends and see if you can pull the cable out. If you have a bunch of wire messed up in the cable it is best to just get a new one, if it is intact, see if you can pull it out and clean it up, if an old bike is stored outside dust and insects can get in there and cause corrosion. You need to use some 3 n 1 oil on the cable after it is cleaned and slide it back in. Check for gummed up linkage at the carb end too. This bike I'm pretty sure has two carbs and linkage between them to sync it that need to be oiled too.

Back firing can be caused by it being out of time, might also be from an exhaust leak, at least that is my experience with them.

[imagesinthewind]

Okay I checked all down the exhaust and found nothing but pretty exhaust, shiny, no rust and no holes.
i will check the throttle cable and see what I can find as well as the linkage.

I did pull both spark plug and the left side one is a bit white looking, the right one was sooty and tight. I wiped off the soot and regapped to .028 from less than .025.

He wants to ride again tonight so i'll check it over after he rides and see what's what.

[imagesinthewind]

Rode it tonight for 6-7 miles after new gas an seafoam. I did regap one plug.
A LOT less backfiring, almost none.

The first gear thing is more operator error. I told Tom that he needed to downshift as he was coming to a stop, but he never really did that. He'd come to a stop and then I'd be behind him watching him stomp it down through the gears but never be able to get it into 1st. Then he'd move the bike a little and it would pop into gear. I tried telling him again how to downshift, but he just wasn't getting it. I finally told him more step by step and that he needed to be in first gear BEFORE he came to a stop and he understood. He'll try that at tomorrow's practice ride. He does say it's still sometimes hard to get it from Neutral to first even at a stop, so I have no idea what he's doing wrong.
I'm thinking the backfiring was something to do with the way he was riding that first time and now it's so much less that it may be none tomorrow.
I doubt a little seafoam and a plug re=gap is all it would take.

Thanks!
Ginny

[Rebel]

I wasn't expecting holes in the exhaust system, but perhaps a loose nut at the exhaust port.

Operator error, is something that will go away on its own usually.

[imagesinthewind]

Ah, nope, nothing loose.

[Rebel]

Hey give the old man a ride on the back of yours so he sees and feels they way you ride. That might help him lern how to do it faster.

[kz1000st]

See if the carburetor has that anti-backfire valve on the side and if the hose to it is healthy. I have to check mine.

I just went out on my Kaw. Tell Tom the easiest way for him to find first, for now, is to pull in the clutch, downshift and coast and when he sees the neutral light come on he has one more push to go. I tried it coming into my driveway. Coasted in with my clutch in, downshifting up to the garage until the neutral light came on. Then I let out the clutch and parked it. He doesn't have to let the clutch in and out. Just snick the gears until he finds first.