Topic: Where's my 5th gear? SOLVED!!!

[Bailgang]

I might however, play around with this if i dont come across anything in the next few days.  http://www.ebay.com/itm/371256866775

You better nab it quick because I've got my eyes on it too.  The issue I'm having is my F2 trans popping out of 4th gear when under load. I replaced all the roller bearings in the trans this time last year to deal with a vibration issue and the new bearings took care of that but even though it had a tendency to pop out of 4th before I replaced all the bearings it seems to happen more often now that it has new bearings and I've got my trans apart again now.

[HondaMan]

If I was closer I'd bring one over and we could take it apart for reference. I have  a low mile rotating assy in a complete F2 crankcase and a seperate freshly backcut trans.  Good luck.

Don, that would be ideal    brandEn even mentioned to me the back-cut trans from cyclex, but because this bike doesnt slip out of gear even when I get after it, i cant justify the $200 cost to the bosslady.

I might however, play around with this if i dont come across anything in the next few days.  http://www.ebay.com/itm/371256866775

Anyone see any issues with this trans from the pictures?  It looks as clean as the one I currently have 
...and or it has a bronze M5 bushing that I can use instead of my current cast-iron bushing.

That's a young-looking trans! I like 'em young...

[scottly]

I like 'em young...

Dirty old man!!!
I found a short bit in the Honda manual F2 supplement about the trans on page 270: "The countershaft thrust washers have been integrated into the gear bushings."

[flybox1]

I like 'em young...

Dirty old man!!!
I found a short bit in the Honda manual F2 supplement about the trans on page 270: "The countershaft thrust washers have been integrated into the gear bushings."

Scottly...did they happen to list a part number for this?

[scottly]

The only numbers I found related to the engine number when the change took effect: CB750E 2600004 and subsequent.
Just a SWAG, is it possible you have an earlier countershaft assembly mated to an F2 mainshaft?

[flybox1]

The only numbers I found related to the engine number when the change took effect: CB750E 2600004 and subsequent.
Just a SWAG, is it possible you have an earlier countershaft assembly mated to an F2 mainshaft?

I guess its possible, but I do not have the knowledge to tell the difference 

Pulled the trigger on the ebay trans listed above (sorry Bailgang  )  and I'll compare it to what I have when they arrive.

[Bailgang]

Pulled the trigger on the ebay trans listed above (sorry Bailgang  )  and I'll compare it to what I have when they arrive.

No worries here, that's why I forewarned you to nab it quick if you wanted it. Besides that ebay seller has some other F2 trans as well that I've been checking out in fact I purchased another set of shift forks from that seller about a month ago. I hope this other trans works out for you.

[flybox1]

Pulled the trigger on the ebay trans listed above (sorry Bailgang  )  and I'll compare it to what I have when they arrive.

No worries here, that's why I forewarned you to nab it quick if you wanted it. Besides that ebay seller has some other F2 trans as well that I've been checking out in fact I purchased another set of shift forks from that seller about a month ago. I hope this other trans works out for you.

If you're interested, i'll let you know what I don't use.  Might be something you can....

[Don R]

 I got my F2 trans cheap, the ebay ad was listed as 750 honda not cb750. No one else found it so i got it cheap and the seller included the shift linkage, timing advancer and a bunch of internal parts.

[Bailgang]

If you're interested, i'll let you know what I don't use.  Might be something you can....

I appreciate the offer but I went ahead and picked up another as well yesterday however now that I've got my oil pump apart and seeing how the rotors may have been installed backwards I can't help but wonder if the oil pump is the source of my woes because a properly functioning oil pump is critical for the trans to operate properly in our 750's.
http://forums.sohc4.net/index.php?topic=145634.0

[flybox1]

New trans looks good, is in, and shifting as it should.
New question.  Shift drum lateral movement.....
With the forks and neutral switch in, how much lateral movement is allowable, if any?
It certainly has an effect on 2/3->5 engagement depth..

CB750 shift drum shift:

[Bailgang]

You posting dirty movies flybox because it keeps telling me it's private and wont play? 

[SKTP]

I am about to pull my cases apart due to my 5th gear as well...this is the best diagram I have found for gear order and direction. I am thinking I flipped one of those gears around

http://forums.sohc4.net/index.php/topic,143709.msg1636608.html#msg1636608

[flybox1]

You posting dirty movies flybox because it keeps telling me it's private and wont play? 

haha...nope 
Fixed it.   Sorry guys.

[scottly]

That's waaay too much lateral movement of the drum! I just checked my K7 with a dial indicator and got about .010".

[flybox1]

What else is there to hold it in place? I've got about 3mm lateral movement.
Neutral switch is in.
Shifter mechanism is correct
Forks are installed correct
Head scratcher.....

[scottly]

First guess is the neutral switch isn't fully seated. Pull it out, temporarily remove the O-ring, and put it back in.   

[flybox1]

First guess is the neutral switch isn't fully seated. Pull it out, temporarily remove the O-ring, and put it back in.

Yep.   That was it.      Clearer heads do prevail.
Beers on me, Scottly!  Thanks.

[scottly]

So was that the problem all along? Were there any differences between the old trans and the new one?

[SKTP]

OMG I wonder if that is what my 5th issue is as well?!!!!

[flybox1]

I got all my snap rings and thrust washers correct on both shafts.   
They were correct before,  but with this new trans, it came apart, was measured, and went all back together without beers or anything else
Everything looked good.
Cases closing tomorrow.....

Scottly...I still can't figure out why no 5th before.   Yes,  I did have my neutral switch in all the way before.   Photo proof of it too. 
I simultaneously disassembled the old trans next to the new one.   They were identical in all was except for the thickness of one thrust washer (.005" thicker next to M5) and some wear on the #4 countershaft gear. 
I can't find any other dissimilarities.

[scottly]

Compare the original neutral switch with the new one, from back at the start of this thread.

SK, before you split the case, try pulling and pushing on the shift drum and see how much it moves.

[flybox1]

Compare the original neutral switch with the new one, from back at the start of this thread.

SK, before you split the case, try pulling and pushing on the shift drum and see how much it moves.

The neutral switch on pg2 was original and found to be inop, so it was replaced before the engine was placed into the frame the first time.  I no longer have it.  I have since been using this oem switch, which is fully seated.  Seated, it fixed my temporary drum movement question....   Might it be of a different shape and prevent full 5th engagement?

[Bailgang]

I got all my snap rings and thrust washers correct on both shafts.   
They were correct before,  but with this new trans, it came apart, was measured, and went all back together without beers or anything else
Everything looked good.
Cases closing tomorrow.....

I hope it all goes well for you, I got mine together tonight and so far it shifts nice and smooth but of course the real test will be when it's actually running which should be this weekend.

[scottly]

I was wondering if the part that engages the drum was shorter on the new switch? Not sure just how deep it engages into the drum, but I'm thinking it isn't very much. If you want, I'll flip the K7 motor over and pull the neutral switch out to compare.