CBR400rr gear change query

[Clivoris]

My CBR has developed an interesting problem. It's an intermitent gear selection problem. It's most noticeable when the bike is at a stand-still and I am The grying to select first from neutral. Gear lever will move and return as normal but all I get is a rattle as it fails to engage. Sometimes if I change to second then first, or roll the bike backwards and forward a couple of inches or so, there's no problems and it engages nicely. While the bike is moving the gear selection seems to proceed as expected through all the gears. My Haynes manual is a bit obtuse about this particular problem but it seems most likely to be a selector fork or selector drum problem, or a worn stopper arm, or a worn or broken stopper arm spring. I don't think that it's the gear change lever return spring cos the gear change has full movement and returns of it's own accord. Regardless, I am resolved to pulling it apart to have a look and repair before the winter series.
I have two connected questions. Can anyone help with the diagnosis? Will it survive another trackday without causing further damage or should I bite the bullet and pull it apart now? The problem with pulling it apart now is that I am unlikely to get it sorted before the March 4th trackday due to current business and probable wait times for parts. But there isn't any point lunching my engine is there?
Thanking you briany fullas in advance.

[roadracingoldfart]

Hey Clive ...
The first question is what oil are you using????
If the answer is a fully synthetic oil then change it to CASTROL PROTEC
15w30 and be done with it. (change to using it anyway is my advice )
The other problem may be the free play in the cable as the Honda's are fussy in their set up.
Its a bit long winded to explain the proccess here but your manual will run you through it no worries.
Its very unusual for an early Honda to break / damage gear selectors as they are the toughest in the buisness and generally give no worries.
With regard to the oil the problem i have with synthetic oil is it was developed well after your bike was designed and it was never really developed to work with a WET CLUTCH system. What happens is that the oil is causing "sticktion"between the plates and the biggest pressure on a bow is neutral to first and back the other way.
Try these options / solutions first before pulling bits apart and if i can help, just holler on the land line to ask.
Cheers Paul.

[Clivoris]

Cheers Paul. I don't know what oil is in it currently, Jeff did a change just before I got the bike but it's good to know what I should be using as I will be changing it anyway. The clutch seems to be fine and I have fiddled with the adjustment to get it right. I'll change the oil and filter then give it a go. My biggest worry is that maybe there are bits of stopper arm spring or such-like floating around in my oil. I shall see wont I.

[vifferman]

My biggest worry is that maybe there are bits of stopper arm spring or such-like floating around in my oil.

I believe (from fitting a shifter kit to my Honda) that the stopper arm and spring are outside the gearbox, so this is unlikely.

[Flyingpony]

Maybe the foot gear selector arms need some adjustment/tightening, maybe it has slipped a notch on the spline and therefore you're not getting complete motion to engage the gear properly and hence the rattle.

Maybe you are now wearing different boots which are thinner than the ones you used to wear?

Have you tried fully synthetic Castrol R4 Superbike oil? This has made the box on my Suzuki one slick and smooth puppy, clutch behaves as per normal.

[Clivoris]

I believe (from fitting a shifter kit to my Honda) that the stopper arm and spring are outside the gearbox, so this is unlikely.

Dead right, I think. I just dont have the nouse to know where the oil circulates outside the gear-box.

Maybe the gear selector arms need some adjustment/tightening, maybe it has slipped a notch on the spline and therefore you're not getting complete motion to engage the gear properly and hence the rattle.

Maybe you are now wearing different boots which are thinner than the ones you used to wear?
.

Thanks for the ideas but already ruled those out. I will try the oil that RRoldfart recommended.

[roadracingoldfart]

In the early 80s Castrol developed an oil with Honda and some other car makers to suit the engines perfectly for the time.
It was called Castrol GTX 2 Turbo Tested and its now called Castrol Protec. Its the same oil but with a new name and hence its more than reccomended for that era Honda bike Clive.
As a point of interest as some of you know i am currantly the foreman of a Ford workshop so its interesting that the same oil is used by us daily in the
XR6 Turbo and XR8 falcons as well as a few of the other Ford's .
Aint it good to know an OLD oil is actually so good its been the same for so long and is reccomended for specific performance modern engines as well.