Steering right = more RPM.

[andrewsw]

This way, there's enough slack (but only just) - I can move the handlebars left/right without problems. Only when I'm already applying throttle it will rise.

Okay, then this is almost certainly just a cable routing problem. I've encountered this on my B4 in the past. Basically, through trial and error I've found a routing that works for me. From a position seated onthe bike, it runs immediately to the right and through the flexible wiring harness clip at the engine mount, then forward past the coil, through the clip mounted on the coil, out through the front between the fork leg and headstock, looping back behind the headlight to the grip. I have it pulled fairly tightly under the tank. It's important to have enough slack in the *housing* so that turning the frontend allows it to flex, but not pull. That's most likely what's happening, you've got too much cable under the tank, so that there's not enough slack up front. When I turn my front end, the cable is flexing back at the fork being forced to bend there because of all the crap jammed in behind the headlight. hope this helps.

A

[Squishy]

This way, there's enough slack (but only just) - I can move the handlebars left/right without problems. Only when I'm already applying throttle it will rise.

Okay, then this is almost certainly just a cable routing problem. I've encountered this on my B4 in the past. Basically, through trial and error I've found a routing that works for me. From a position seated onthe bike, it runs immediately to the right and through the flexible wiring harness clip at the engine mount, then forward past the coil, through the clip mounted on the coil, out through the front between the fork leg and headstock, looping back behind the headlight to the grip. I have it pulled fairly tightly under the tank. It's important to have enough slack in the *housing* so that turning the frontend allows it to flex, but not pull. That's most likely what's happening, you've got too much cable under the tank, so that there's not enough slack up front. When I turn my front end, the cable is flexing back at the fork being forced to bend there because of all the crap jammed in behind the headlight. hope this helps.

A

Well, that's exactly how my cable is routed... as mentioned in the manual.
However it doesn't really matter how I route it. I tried through the middle or to the left, or even through the air with the tank off (nothing touching the cable). No difference.

What happens if you hold it at 2000rpm with the throttle and then move left/right with the handlebars?

[andrewsw]

I'll try it on my way home tonight. In the past I've noticed this problem, so I suspect it's not a problem for me now, I'm daily commuting and have been for two years straight, so I'm pretty sure mine is good ;)

Is the grip end of the cable properly secured? There should be a small metal plate that is secured by the screw that holds the throttle mechanism together. When the throttle mechanism is secured, it clamps the end of the cable to it as well.

The reason it appears when you're turning right is because it puts more bend into the cable housing and can cause it to cam out of the throttle assembly or otherwise stress it so that it pulls the cable. When turning to the left it generally alleviates some of the bend and reduces the stress on it.

Having experienced this problem before, the best advice I have is... just keep messing with it until it stops. heh. not much help, I know.

A

[Squishy]

You think a new cable will help?

[andrewsw]

I can't see how a new cable will help if the one you have is truly stock. But, if all else fails, that's the next thing to try, perhaps.

A

[erict716]

Isn't there a little play at the top of the cable, that goes into the throttle on the handlebars? I thought there was an adjustment screw. You may be able to get some slack out of that.Also are your carbs fully seated in the boots? If they are not in the right location (or angle) it may cause the cable length be longer. Just trouble shooting off the cuff there.

[Squishy]

Isn't there a little play at the top of the cable, that goes into the throttle on the handlebars? I thought there was an adjustment screw. You may be able to get some slack out of that.Also are your carbs fully seated in the boots? If they are not in the right location (or angle) it may cause the cable length be longer. Just trouble shooting off the cuff there.

Adjustmentscrew is turned all the way for maximum slack.
Carbs are seated properly :(

[Squishy]

Can anyone verify/tell me whether this nut is positioned as on the picture or whether the nut goes under the mount on the carburetor?


Thanks

[andrewsw]

the nut goes below the mount on the carbs. In fact, you'll see that there is a hexagonal recess to receive it. It's a royal pain in the ass to get it all together and if the nut isn't there, or is above the mount, that will almost certainly be the cause of your problem.

A

[Squishy]

the nut goes below the mount on the carbs. In fact, you'll see that there is a hexagonal recess to receive it. It's a royal pain in the ass to get it all together and if the nut isn't there, or is above the mount, that will almost certainly be the cause of your problem.

A

Here's a picture I made a while back..
https://dl.dropboxusercontent.com/u/22072961/mf/2014-03-16%2017.35.14.jpg
Either it's beneath the mount or not there (don't remember)..however I don't see how the latter would cause my problem..

Sigh, I had hoped it had to be on above the mount so I had something new to try.. Today I went to the local dealer and the mechanic didn't understand it either..
He said there should be more slack when it's fully loosened and could only guess it wasn't the original cable...
I checked the cable and it says 10D30 which matches part of the OEM cable's code.

[andrewsw]

Can't tell from the picture, because the nut gets recessed into the mounting lug and it not visible from above. If it's missing, then any flex of the cable housing has the possibility of mis-aligning or pulling the end of the housing out of the lug. If that happens, it could easily tweak the throttle, and it only takes a little smidge to make a difference.

A

[Squishy]

Can't tell from the picture, because the nut gets recessed into the mounting lug and it not visible from above. If it's missing, then any flex of the cable housing has the possibility of mis-aligning or pulling the end of the housing out of the lug. If that happens, it could easily tweak the throttle, and it only takes a little smidge to make a difference.

A

You're saying the nut is fixed into the mount from beneath and then you screw the cable in from above?
If I understand correctly you won't be able to feel the nut under the mount and I'd have to remove the carbs to check?

Thanks.

[andrewsw]

You're saying the nut is fixed into the mount from beneath and then you screw the cable in from above?

pretty much that is correct

If I understand correctly you won't be able to feel the nut under the mount and I'd have to remove the carbs to check?

If the nut is missing, you can pull the cable housing out of the lug without unscrewing it.

A

[Squishy]

You're saying the nut is fixed into the mount from beneath and then you screw the cable in from above?

pretty much that is correct

If I understand correctly you won't be able to feel the nut under the mount and I'd have to remove the carbs to check?

If the nut is missing, you can pull the cable housing out of the lug without unscrewing it.

A

Ah..well in that case the nut must be there, because I can loosen and tighten the cable bolt.
I thought the mount itself had a screw thread...It's been a while since I actually removed the cable from the carb..usually I just let it on when removing the carbs.

[Volumetrik]

I know this is a super old thread, but I am interested to know if you have solved the problem ?
Have you tried buying a new throttle cable ? They're like 17 bucks.

I have a smaller similar issue where the bike will rev to 4-5k when I turn the handle bars fully when parking the bike or doing u-turns. I am going to check the cable routing.