Vintage and Classic Hondas

jumping first gear

_‹ Previous Topic Next Topic _›

Classic

List

Threaded

8 messages Options

cribbas

jumping first gear

Recently I replaced the clutch in my 73 CB 750. while rolling it off the lift I accidentally dropped it on it's right side. I righted it and no apparent damage so I took it for a test ride. Right away I noticed that if I got on it, it clunked when I took off in first gear, that is it seemed to skip a lug then went back into gear. the rest of the gears worked perfectly but when I shifted back to first it did it repeatedly. When I take off slowly it works just fine but under strain it pops out then catches, every time. I rebuild these motors regularly and have one apart on my bench right now and looking at the transmission I can't see a rational reason for this anomaly. The transmission was working fine before the clutch repair and I don't abuse this bike. Any suggestions?

TOOLS1

Re: jumping first gear

Administrator

I had a 78 F-3 do the same thing. Unfortunately I never got the chance to work on it. I wonder if there could have been some crap (you know these bikes are known for having little shavings, and junk in the bottoms) in the bottom of the transmission that moved when it fell over. It could be keeping the gear from fully engaging. I have noticed that every transmission that I have taken apart, and cleaned shifts a lot smoother afterwards.
TOOLS

Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

cribbas

Re: jumping first gear

I just pulled the oil pan and ran a magnet over the bottom of the crap built up there and pulled out a small amount of filings. I think you may be right. I shone a flashlight up into the cavity and only can see a couple of gears which look good. but I think I will need to pull the motor again and flip it over and remove the bottom to see what is going on. I'm afraid I might do some catastrophic damage if I keep riding it like it is, I do like to get on it in first gear and it's not fun clunking like it does. Thanks for the reply.

cribbas

Re: jumping first gear

I'm stymied, split the cases and there is no damage, everything is really clean. No shavings no pieces of metal everything slides easily. the only anomaly is there is some wear on the lugs on the first gear and the side of the gear that it slides into, it is shiny where it has been rubbing. Anything else I could have missed?

cribbas

Re: jumping first gear

I also examined the shifter forks and they appear fine, nothing bent.

TOOLS1

Re: jumping first gear

Administrator

In reply to this post by cribbas

If they are worn where they engage, that would cause them to slip.
TOOLS

cribbas

Re: jumping first gear

I might have found the problem, the first gear that spins on the bushing is sloppy. do you know a supplier for that bushing. I've looked all over for a new one and can't find what I'm looking for. I appreciate your advise on the worn dogs but all the transmissions that I have looked at seem to have the same wear marks.

cribbas

Re: jumping first gear

Like many problems in life if you wait a while and look things over several times you discover things that upon first inspection you didn't see, like unusual wear on the sides of the shifter forks. I was on the verge of putting things back together when I noticed the wear and so I looked on e-bay and found a practically new complete transmission with forks for $100. I bought it and will let you know how it turned out.