Trans lock up

I got the engine in my KZ650 running good now to the transmission. During my restoration I had to find some new transmission parts, pretty much everything. The bike sat for 25 years with very little oil and all the parts that were exposed were rusted and pitted beyond repair. So I got a complete new transmission (Ebay). Before I bolted the case together solid I remember running through the gears making sure everything worked, it did. Now that I got the engine running good, whenever I shift into 1st and 2nd the trans locks up, I have to back the crank up to get it out of gear. I am pretty confused here. Not sure where to look to fix the problem. The clutch is working, in neutral the secondary shaft turns freely. I don't think there is any way to have put something in backwards. If anything I would like not to have to split the case again, but I have done it so many times now I could do it in my sleep. My luck is I didn't get something tight enough and now its messing things up. I think this is normal but I can only shift between 1st, neutral and 2nd. Any help would be much appreciated.
Thanks,
Brian

If you´re trying to go through the gears with the bike stationary that is perfectly normal, except for the fact that you can shift into second.

Most of the KZs have what is known as a positive neutral finder - without going into too much detail (I can if you need the info) that means that you can only shift between neutral and first unless the bike is rolling - output shaft needs to be spinning, engine running isn´t enough.

If, on the other hand, you can´t shift into third etc. riding the bike you have a problem.



Edit: Here´s a link to a thread about the positive neutral finder: CLICK

I haven't taken it out on the road yet because of the lock up, but one thing I didn't mention was that standing still engine off, it will only go into 1st neutral and 2nd, not any other gears. My biggest problem is the gears locking up.

Hmm, standing still it isn´t supposed to be able to into second but that could be a glitch. Try taking the bike for a spin up and down the road and see if you can get above second when it´s rolling - you should be able to, if not we´ll take it from there. No need to go fast, just get the bike rolling and try to shift.

Are you sure its going into second? Kz's should have that lockout a "neutral finder". It may seem like you are going into second but it may not. You might have to take it for a little putt around the block to verify

I can't even take her out on the street yet because whenever I put it into gear the transmissions locks up. I have to back the motor up to get it back into neutral.

I have been tinkering inside the case with the the transmission but can't find any gears that slide freely, so my guess is that I go a fork in the wrong place or something. Not really sure. Is there any way to change the fork positions without splitting the case and what gears should the forks go between?
Thanks,

bubbap wrote:

Is there any way to change the fork positions without splitting the case and what gears should the forks go between?

No, there´s no way to access the shift forks/shift drum without splitting the cases, sorry - the only good thing is that you don´t need to remove the topend to do it.

The forks should go as shown in the pic below, click the pic to enlarge. I guess you already know, but it´s important that the shift drum is in the neutral position when you install the 4th and 5th gear shift forks and shaft, also make sure that the shift fork guide pins are properly seated in the shift drum. Keep the shift drum in the neutral position and adjust the gears to fit the forks when assembling the cases.

Btw, what year is your 650? On the 77 models (only 77) the 4th and 5th gear shift forks are slightly different, don´t know if mixing them up could cause the problem you have though.

It is a 79' KZ650. Do you think having them in the wrong place would cause the gears to lock up?

If it´s a 79 switching the forks is not an issue, only the 77 models had two different shift forks, from 78 and up the 4th and 5th gear shift forks are identical.

I don´t think you would be able to assemble the cases if the shift forks weren´t in their grooves, at least it would take a great deal of violence and you´d probably notice that something was wrong.

I´m still leaning towards an issue with the positive neutral finder - here´s how it works:

The mechanism consists of three little steel balls, on the 650 the they are located inside the fourth gear on the output shaft. Inside the gear there are 6 holes (bottom of pic) - three of the holes go straight through but the other three (120 apart) are smaller at one end, these are where the balls go.

In the output shaft where the fourth gear sits there are three recesses app. 3/4" long also 120 apart (one can be seen in the pic). When the bike is not rolling the output shaft isn´t rotating and at least one of the balls drops in it´s recess and limits the gears travel to first and neutral. Once the shaft starts spinning the balls are slung out and you can shift up.

When reinstalling the fourth gear and balls obviously the holes holding the balls should align with the recesses in the output shaft or the neutral finder won´t work.



What I´m thinking is that when you try to shift into second with the bike stationary, one of the little balls get caught and you need to back up the engine to free it again - I would still take her for a short easy spin up and down the road to see if she can shift when rolling before tearing the engine apart again.

If that still doesn´t help you may have a shift fork guide pin not properly seated in the shift drum or a shift fork cotter pin that´s interfering with a gear.

Thanks, for the tips looks like I will split the case tonight ans see if I can find anything.

Ok I found out a couple of interesting things. For one I can pull the motor ans split the case in 43 min. (cool). But the most interesting is that the ball bearings on the transmission have slots in them, and so does the case. My guess is there is suppose to be a circlip in there but I can't find one in my parts, my manual or on bikebandits exploded views. Any idea if I am right, and what the part is called or a part number to look it up. Because it seems the shafts can slide side to side which throws off the gear alignment causing the gears to lock up.
Thanks,
Another question, how do you add a signature? I have looked in my profile but don't see the option.