Honda CB400 SuperFour

[Shtoyyy]

Hi relatively new to the whole biking scene and to working on bikes have done a lot of car work in the past but decided to lean more towards bikes for the time being due to a lack of space! Hope im writing in the right place but anyway i have a 1993 cb400sf and when im accelerating up through the gears once or twice when ive gone into 4th and let out the clutch the bike will miss the gear sort of speak and rev with me opening the throttle and then all of a sudden jump into gear! Now its only happened twice and i havent managed to check what gears it goes into so just looking for some advice? Also when im braking with the front brake there seems to be a fast clicking noise. To me it sounds like something to do with the brake light switch as it sounds like an electrical issue? I would really appreciate any help on this as im trying to learn as much as i canabout my bike thanks!
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Stephen Corcoran

[RhynoCZ]

Yes, right section.
What you are describing could be false neutral issue. Mainly caused by the rider not using the gear shifter properly (firmly enough) and/or worn gear selectors. Also, if I remember correctly, your motorcycle has got a gear lever linkage (if that is loose, issues above might occur). To prevent that, check the linkage is set properly (can't be loose), and shift the gears firmly with confidence. Honda uses good gearboxes but 23 years is 23 years.

The clicking noise, I think your steering bearings need changed. It could also be the final drive chain, if it's loose enough, but you'd hear that during acceleration as well.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[Shtoyyy]

Thanks for the reply i will check that linkage tonight! Is the anyway you could better describe what part of the gear lever im looking at! Im happy it doesnt sound too serious if it is just a linkage between the lever and transmission.
In regards to the steering i honestly think it could be to do with the electrics within the brake light switch as i have pressed the brake light switch while driving slow with a small piece of flattened metal and also when i press the back bracke the brake light takes about 2/3 seconds to come on is this normal?
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Stephen Corcoran

[RhynoCZ]

This rod (there are nuts and threads on the rod, set it so there's no excessive free play in the gear lever).

https://exaircorp.files.wordpress.com/2012/05/sv-shift-linkage.jpg
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[RhynoCZ]

The rear brake light switch, no it is not normal. But I wouldn't do much about it at the moment, just use it more often, and it'll start to work properly. The previous owner was not using the rear brake, so the switch got stiff. You may adjust it though.

The FRONT BRAKE SWITCH: Yes, it does click (only one click when you engage the brake), but you shouldn't be able to hear it with the engine on really, but it is possible.

The REAR BRAKE SWITCH ADJUSTMENT: There's something like this (see picture below), as you can see you may move the switch in order to adjust when the light comes on. You could spray it with contact cleaner, as dirt is obviously not letting the rod of the switch to work properly. When you step on the brake pedal, you pull the wire with spring on it, that engages the switch.

https://i745.photobucket.com/albums/xx95/geo46er/Nortonupgrades004.jpg
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[stinkwheel]

It sounds like your false neutral is most likely due to you not allowing the selector to fully return to the "at rest" position before attempting to select the next gear.

The selector mechanism has two little sprung teeth on it that grab a notch and rotate an indexed cylinder to select the gear. If you don't let it fully return, they don't grab the notch fully.

Easily done. Really common when people buy new boots and effectively "leave their foot" on the lever.

Clicking sound. pretty sure they are floating discs on a super 4. It could just be some play on the bobbins. The friction part of the disc is mounted to the rotor on a series of bobbins. They are designed to have some lateral play so the disc self-aligns. There may be a bit of rotational play too that could cause a rattling sound. A little is probably ok, a lot would be a problem. There will most likely be service limits for this in the workshop manual.

Another thing could be chain noise. When you go from under power to braking, the tension moves from the top run of chain to the bottom run of the chain. The rear suspension also unloads reducing the chain tension. This can cause a certain amount of flappig about/rattling. In an extreme case, the chain can sometimes hit the top of the swingarm (you'll see a rubber protector there for this exact purpose). If that's happening, you need to adjust the chain.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.