Topic: Shift Order/Gear Changing out of order.

[JavvyMoto]

I have a 1976 cb750A

Just got it fired up and timing set/carbs synched
Went to take it for a spin and almost launched myself off the bike. Seems my Neutral Gear is somehow High and my High gear is somehow Low.

Here's the scary one. Low Gear completely locks the bike to a dead stop. Anyone with an understanding of these bikes have a guess??

[TdLpps]

Have you, or a previous owner, had the Change Unit apart?

Can you post a picture of your side stand and linkage?

[Don R]

 Look in the stickies at the top and find the cb750A service manual, here is part 4.
http://manuals.sohc4.net/cb750a/service_manual/SM750A_4.pdf

[JavvyMoto]

I've only had the cover off for paint/cleaning/gasket replacement. Previous owner never had any of the engine apart.

I'm considering the oil pump may be an issue or torque converter. However the bike only has 5k-ish miles and I'd find it weird if anything was already work or broken.

Not ruling anything out though...

I do have video of the changing case.

[jonnycakes]

I had one do strange things...............it was rust on the internal shift mechanism.  It sits way above the oil line.  That's where I would start

[TdLpps]

Since you've owned the bike has it ever operated properly?

A picture behind the side cover of the manual valve position would be helpful.  When the bike is in neutral (or indicating neutral on the display), is the manual valve plunger in the highest position?  In '2(D)' is it in the lowest position?

The transmission in the A is simple.  To have the symptoms you're having to occur it would be necessary to have the manual change valve diverting oil pressure to both clutch packs when indicating "L".

[JavvyMoto]

The valve is Fully Up in Neutral and Fully Down in Drive 2 (High) Naturally my video is too big to upload here ...

I forgot to snap a pic as I was disassembling the changing unit. I now have it stripped down to the Oil Pump to assess if anything there was broken and it all appears to be pristine and nothing damaged or worn.

[TdLpps]

Have you downloaded the Service Manual?

[JavvyMoto]

Yes, the only thing close to related to the problem is the oil pump/bad oil pressure. So, I'm in the middle of checking those parts and the torque converter.

[Don R]

 The powerglide in my race car acted up last year, wouldn't even pull itself, it had a tiny piece of metal shaving in the relief valve sticking it open. Checking the pressures located the issue.
 Probably not what is happening here, but illustrates what kind of weirdness can happen in an auto trans.

[JavvyMoto]

That's a thought for sure. I'm gonna have the whole thing opened up and make sure it's not some dumb piece of metal like that...

[JavvyMoto]

*Updates*. Got the oil pan and screen filter out. The screen filter had a pretty big glob of gunk on it toward the center. Possibly ruining my oil flow. Cleaned it all out really well. Also, noticed a missing o-ring around an alignment sleeve on the torque converter case. I still think it's leaking from the seals on the main shafter of the torque converter, but, I imagine not having an o-ring where it belongs probably causes a small leak, although I'm confused why oil would be flowing through those two bolt areas to begin with.

Anyway, waiting on new gaskets for my change case side. Gonna pop it all back together and hope maybe just cleaning everything helps the oil flow and it'll work itself out. Otherwise I have to tear it down and pray nothing is stuck in my gears.

[jukku]

Do you refer to the two o-rings on the lower picture in the shop manual page 8-4?
Look at the oil circulation on the picture in the shop manual page 9-2!
Both o-rings are essential!

[JavvyMoto]

They're both now replaced. Waiting on the gasket for the little cover on the front of the torque converter and I'll try to fire it back up.