My bike has always been kind of rough shifting from 1st to 2nd and occasionally slipping back into neutral. Well as of yesterday I had the bike up to about 10g on the tach in 2nd and the bike shifted back down into 1st. It kind of scared me, but I didn't think much of it. The next time I got the bike up around the same rpm's in 2nd it downshifted back down into neutral. So I decided to tighten up my clutch lever and changed the oil, (along with new plugs and and adjusting the carb since the bike seemed to be running rich). Well I drove the bike to work but didn't really get on it and didn't seem to have any issues. Well this morning when i left work. I took it out to the country to see if the issue of it downshifting itself had went away. Unfortunately it didn't, and it seemed every time I would put it into 2nd the bike would downshift itself quicker and quicker into the gear. Until finally around 5g on the tach now it will downshift all the time into neutral. My gut tells me that my 2nd gear synchro has went out but I am hoping someone else had this issue and it will be an easier fix. Any suggestions would be greatly appreciated.
Also if it is the 2nd gear synchro a fellow maintenance buddy at work told me to "undercut the gears" when installing them so when you get on it the gears will mesh tighter together instead of trying to separate. Is there any truth to this?

 

your 2nd gear is def shot, I had this problem with my 900rr. not sure on the undercut.

 

I figured that but was hoping for an easier solution. I am a decently knowledgeable guy when it comes to fixing things. But have never done a transmission on a bike. Does anyone have experience on whether it is cheaper/easier to change out my gears or just to buy a new engine&tranny? Also if I am changing gears I assume thats a perfect time to do the clutch, do they sell "lightened flywheels" for bikes like cars? And if so is it cost effective? Is it better to go with used gears or a new set, and if new set where would i find them? Finally is there a write up anywhere on a how to change out the gears on a F3 600 tranny? Sorry for all the questions, I just want to get this right. Thanks!

 

The easy thing todo would be get another motor and change them out,its not the cheapest way. and if you want to strip the motor down and change the gears is possible but not easy. and the gears will run bit.

 

Cobra:
What did you mean by "the gears will run bit."

Does anyone have any recommendations on where to purchase a nice used motor/tranny? What do I really need to look for in a used motor and tranny? When doing the motor swap is there anything else I should check for good operation/preventative maintenance replace while the motor is out?

Sorry for all the questions, I just really want to be specific about this swap because I believe that is the route I am going to take. Any suggestions, links, how-to's, or any form of help anyone know's of will be greatly appreciated!

 

Sorry man i was out of town. If you wanted to buy new gears you would need second gear and sixth gear, shift forks and shift drum. The price for each gear can be expensive for all new but can you really trust a used trans from ebay etc? I wouldn't. And well for a used motor or refurbished motor can run around $800. There are plenty of tuts to swap or replace the trans on here, if you feel comfortable stripping the motor down to the trans.

here is your trans might be the wrong year, but it will give you an idea of how much the gears will cost etc.

GEARSHIFT DRUM Honda CBR600F3 1997 OEM Parts - Cheap Cycle Parts

http://www.cheapcycleparts.com/model...2-transmission

 

cobra:
I agree with your stance on trusting ebay, however i don't know many other places to look for parts. I believe I have decided to go with just replacing the whole motor. So does anyone know of any places preferably in the northwest ohio area to purchase a reliable used or even better a rebuilt/refurbished motor? Also when putting in a new motor is there any mods/upgrades that would be a good idea for a little power upgrade/better performance; such as cams, port and polish the head, different carbs, etc.....?

 

I know a place I go called cycle therapy. Its in north east Ohio though. Its north of Akron. Good ideas for power upgrades/better performance would be cams but I suggest being careful. When replacing cams you want to make sure and replace the tappets also. I suggest a hydraulic rolling cam with matching tappets. Also if you choose to port and polish the heads make sure not to do the intake. Just the exhaust ports. Intake needs to be rough so that air and fuel will mix properly. If you bore the piston walls you will need larger pistons. If you port the combustion chamber then this will reduce your combustion ratio but increase your cc's. Therefore if you port the combustion chamber you could get dome pistons. Make sure you have good clearance. Dont want your intake or exhaust valves being smashed by your piston. Just ideas but they make a big difference. A lot to look at though. A roll of thumb is that when you replace any major part of your engine it results in HAVING to replace a few other things.

 

I had the same problem you're having and I'm in the process of rebuilding my tranny. I've got to replace several gears because the dogs have wore down enough to where it allows the gear to slip out..
If your going to build up a motor, you might as well use what you've got. There really isn't a market for built F3 engines due to the fact that the engine could be 5 times the value of the bike. If you have the tools and space, I would rebuild the tranny because it is cheaper than going the used engine route. The most critical part is to make sure you don't damage the mating surfaces between the two case halfs.

 

Ian:
Are any of those engine upgrades you discussed actually worth it in regards to performance and price?

Marc:
I would be extremely interested in getting every information from you that you could possibly give, ie: if you used any how-to's to go the rebuilt. Everything you replaced along with the bad gears. Where you bought your new parts, pretty much anything you could give that you learned along the way that could help in rebuilding the trans.