2nd gear is slipping, what do I NEED to replace?
 

I have a 99 CBR600 F4 and the second gear is slipping. So far from my research I have found that I will for sure need to replace the 2nd gear fork. However, will I have to replace the dogs, drum, etc.? If so what will I for sure have to replace? Also on a side note, how hard is it to slip the case? Thank!

Moved to F4 section

Just cause I'm there right now on my 900rr, I figure I'll throw you an appetizer.
Now I know it's not the same bike, but it should be fairly similar-

Last time I did this I believe I replaced a total of 5 gears, the drum, all 3 forks, the shift shaft seal, the output seal, and nothing short of the partridge in a friggin pear tree…
And yes- second was the only gear popping out. not slipping, but tossing off to neutral. which is what I think you're talking about.

Survey says, I may have replaced more than I had to, but I don't like going into these engines unless I have to- so overkill is always a good insurance measure-- If you have to think, "is it still ok?" replace it! IMHO….

Splitting the cases isn't difficult, as long as you have a manual in front of you and you follow directions, and steps in the order they are called for.

BTW, sorry the pics are so small- just a feel for what you are in store for if you decide to tackle it though-

Can't see the pictures right now cause my account wont grant me permission.

Anyways, thanks for your imput. That really makes me see there is a lot to replace but also good point, you are there so might as well do it.

Also did you buy the part new or used? How much did you spend if you don't mind me asking.....

So here is my problem: If I am in first and I really gun it and switch to second, it will pop out and go into neutral and then going into first or second from neutral is really hard and makes a grinding noise. However if I switch into second driving normally it goes in fine. If I am in second and gun it it will disengage and engage so it's like it slips or cuts out. Sometimes it will do that and then go into neutral.

my money says it's the shift dogs. they are cast on the side of the gears and mesh together or come apart to change ratios. Where the dogs come together, the tops no longer are sharp and square- they get rounded, and slightly tapered until the spinning force will spin them out of gear. I am 99% confident that this is your issue, as it was exactly what happened to my 900. unless there is excessive damage, you very well may be able to just replace a couple of snap rings, a seal or two, and two gears. but no less than the two gears that are slipping against each other.(its not just one that has the problem, it will be both)

Check this out to clarify "dogs"

Wow, thanks so much! That all really helped. So if I get what you are saying? At min. I will have to replace 2nd and 6th along with the seals and the snaprings right? Sweet! Also is it worth buying the parts used or should I bite the bulky and go with new?

First off, I don't even remember seeing individual gears for sale used- and I scour the forums, and ebay- or at least I used to… I have however, seen entire gearsets for sale used.

That said, if I absolutely had to buy used, I would buy the complete set rather than individuals.

Now, with that being said- I suppose it's the same introducing a brand new gear into a set that has worn as a unit, as it is with a used gear from another set.

From my perspective, this is a hobby for me. I don't need to own my bike, so I can just wait until I have the funds for new. If it were my only means of transportation, then I may explore other options… Now, I'm putting a used engine in my bike- But that's a different story, as my engine is completely junk except for the accy's…. Not to mention that a "new" engine from a 15 year old bike would cost a damn fortune! :icon_saywhat:

So in other words, I should buy the top and bottom shaft with gears like this one?

00 Honda CBR 600 F4 Transmission Tranny 16E | eBay

Essentially- (without looking in great detail.) these parts are a known set, (assumed) and have all been run, and worn together. I would speculate that introducing a new gear into a worn set could possibly wear the corresponding gear differently- good? Bad? I don't know, but I would be skeptical....

oh- by the way- I am looking for seals for my bike, and happened to need this page for the mainshaft seal- it shows gear prices for the 900rr, but they should be comparable. try not to puke on yourself….ron ayers motorsports

I'm pretty certain this is your solution. I had the same problem as you describe and this was how I solved it.

A little info here: https://cbrforum.com/forum/cbr-600f4...-118852/page2/

I would personally find a low milage second hand parts, but here's a site where you can buy individual parts: http://www.wemoto.com/bikes/Honda/CBR_600_F4/04/

Nice thread over there! I enjoyed the read! Keep up the racing!!!

Now, I'm off to look at the factory pro star for a 900rr!

Thanks for the post! So the solution was a new gearset? And that's it? No new forks, drum or anything like that?

I really doubt it would be the forks or the selector drum. The dogs for 2nd, 3rd and 6th are the ones that have most wear. On mine the forks were with in spec and only 1/10 of mm thinner than original. And that's after 11 years and 17000miles. I bought it as worn down track bike and raced it myself for 2 seasons.

I posted the wrong link before, it's http://www.wemoto.com/bikes/Honda/CBR_600_FX/99/
Unfortunately I can see they do not sell individual dogs any more.

In my bike I replaced the tranny with a 05 one. Just be aware that the gear ratio is different because the f4i has more low end power. So if you haven't done any engine work you might suffer a bit on acceleration..

I can only give the factory pro shift star thumbs up. I haven't had a missed shift since I installed it. If it's the new tranny or the shift star I have no clue but something is working! :icon_lolsign:

Next month the old lady will have to show how good shape she's in! 8h endurance race!

Ah, I see. Thanks so much again!

Could I use the f4i trans and then change the gearing to compensate it? Or I will just get a f4 trans