2nd Gear Transmission Information - part number trivia

[andyb]

It'll do it progressively more and more over time.  You have a mildly bent shift fork (at the minimum) and some rounding on the gears, on the dog/window portion.

Why are they called dogs going into windows?  Dogs don't go into windows.  Cats maybe.  But dogs?

Anyhow....  It'll do it worst at full throttle, uphill, with a passenger.  It's going to happen depending on the amount of load placed against that assembly.

May as well give yourself a winter project and fix it.  Pull the motor, split the cases, send the trans out for undercutting in second, and get the later shift forks stuck in there.

[Dan Filetti]

As another data point, My '85 had the infamous issue (it would pop out of second under hard acceleration) when I bought it.  The dealer I bought it from agreed to pay 'half of the cost to fix it', which they said would be $1,200.  Not having found the yahoo site, nor did I have a garage at that point, I did not consider doing it myself.  I did find a guy locally to do the work for $600. so I had the stealer pay me the $600, which I gave to the local guy to do the work. 

I put another 18,000 trouble free miles on that tranny before the bike died an untimely (firey) death.  [Another reminder: Twist Ties Those Fuel Line Elbows in place, lest they burn your bike to a moltent mass of never-to-be-ridden again steel.]

Dan

[paulfj03]

thanks for the tip, Dan. Recently I took the tank off and even the clamps on the fuel lines could have been alot tighter. yikes!  Hope you did not get hurt...

I also heard that the undercutting of the gears is the way to go...just to be sure , if I was to replace the gears, get them undercut before putting them in.
My 85 has to be done...caching$$$...ouch.

[capitanoinsano]

According to the Yamaha part numbers the 86-93 shift forks and drum are all the same.  All are "1TX" part numbers.  That was the prefix for the 86 model (I think).  No 3CV or whatever the 91 was numbers.  Not sure why some are longer.

[madman]

My original '86 FJ had the second gear issue. It was an early model. Yamahaha fixed it under warranty. It too would pop out under hard acceleration.

The second '86 FJ does not have this problem. I can only assume that it was fixed while under previous ownership.

--Mark

[capitanoinsano]

Do you know if they changed forks or 2nd/5th gear wheels or other parts?

[Dan Filetti]

Do you know if they changed forks or 2nd/5th gear wheels or other parts?

In my case, the local mechanic replaced the 2nd/5th gears and the forks.  I asked him about undercutting the gears, but he talked me out of it, as I gather, he had never done it before, and also, it would have taken more time for me to get my baby back...  looking back, I would have insisted.

Dan

[thuber3040]

I have undercutting on my kz engine, well worth the investment if you have the time to wait a little, think it was a about a week or two at most on turnaround. Will definitely do that when the time comes on the fj

[capitanoinsano]

It will probably be fine for MANY miles without undercutting.  Based on part numbers I see a change of 2nd or 5th gear wheel and some little parts.  But some claim forks were longer.  Part numbers don't indicate that, but it could be that they re-used the same part number, I'm no expert, but I would think they would have changed the part number.  If shifts are firm but not gorilla hard, it is a good transmission.

[RichBaker]

When they update a part, they change the last 2 digits.... ie: 3cv-xxxxx-xx-oo becomes 3cv-xxxxx-xx-01

[capitanoinsano]

I checked that on the Yamaha parts site, no changes to forks through 93.  But curiously the 2nd gear wheel on the 87 model has a 3CV part number which couldn't have existed in 1987 as that was the 89 code.  There is an optional 5th gear wheel with different number of teeth with a 36Y number, which I think is the 91 prefix.  There are some other assorted little parts in trans with 3CV numbers.

[cadmanmadman]

I have an '86 with only 12K miles. Even at this low mileage I am seeing something. I has never, ever hit neutral on the way up. But on the way down I have this uncanny ability to find neutral much more so than on any of the other bikes I have now or have ever ridden for that matter. The transmission also has a very hard shifting, very unprecise feeling.....just kind of lousy overall.

I suppose a transmission needs to be awfully tough to withstand 120+ Hp.

What is the heavy spring thing? Do the cases have to come apart to do this or is it an external spring?

It would be GREAT if somebody posted a how to do it guide on the better shift forks and how to machine the undercut !!

[SlowOldGuy]

I checked that on the Yamaha parts site, no changes to forks through 93.  But curiously the 2nd gear wheel on the 87 model has a 3CV part number which couldn't have existed in 1987 as that was the 89 code.  There is an optional 5th gear wheel with different number of teeth with a 36Y number, which I think is the 91 prefix.  There are some other assorted little parts in trans with 3CV numbers.

Be careful making assumptions using the parts list.  Depending on which version you're using, you can draw wrong conclusions.  For instance, the 36Y prefix goes all the way back to the '84 model.

DavidR.

[racerrad8]

There is an optional 5Th gear wheel with different number of teeth with a 36Y number, which I think is the 91 prefix. 

I have rebuilt over 150 engines to date. I have rebuilt, repaired & replaced more transmissions than that. I have never seen a different tooth count for fifth gear. Fifth gear is a 29 & 21 tooth gear set. If you can find a different combination, I would be interested in checking it out.

I can tell you that all of the current 2009 shift fork numbers start with 4KG and 3XW.

Randy - RPM

[eclipse3g]

I know this is an old thread, but I am starting my list of projects for my '84 FJ1100 to be done over the winter.  I am starting to experience the 2nd gear slip-out and back in under moderate to high acceleration.

So my question is should I replace all 3 of the shift forks or is it just one of them causing the problem, also I see discussion of undercutting the gears.

As this will be a winter project I'd like to gather all the necessary parts prior to tearing it down, to allow for splitting the cases, replacing the parts, and reassembling hopefully over a single weekend.

Does anyone have a list of recommended parts that should be replaced and where to get them.


Thanks in advance,