Riding bike and Rpms wouldn't drop

[slayerkills123]

I was riding my bike today and on my way home I stopped at a light and my rpms weren't dropping and it seemed to be increasing. The only way I could get them to drop was to release the clutch about half way before it would stall. Any ideas on what this may be?

 

[alfredo]

Did the bike seem to be revving that high, audibly? Could you hear the revs increasing or were they idle, yet the cable still rising? I would suggest lubing the cable either way.

 

[slayerkills123]

Yeah it forsure was increasing. When I was actually riding I would engage the clutch and it wasn't cutting any power. It stayed as if I was still giving it gas. Finally I would get to a light, down shift and it would be reving really high so I would let out the clutch with the brake applied and finally it would drop, but 50% of the time it would drop to normal and stay there and the other half it would drop and then out of nowhere with no throttle applied start reving really high.

 

[bdholsin]

Double check for an air leak around your carb boots. You can use the ether trick by spraying a bit by the boots while the bike is running. If the engine speed increases then you have a leak. Verify your boots are tightened down. Also verify your carb boots are sealed to the head.

 

[Salty Dog]

I agree. Check the boots. I just had the same problem on a XJ750. I had the bike at idle and sprayed some carb cleaner around the boots and the rpm's would start to climb. The boots looked fine but when I took them off and squeezed them a little there were cracks all over them.

 

[STVR]

Yeah my bike seems to be doing the same thing. I was out riding and the RPM's would climb as I got to a stop sign. I'll have to try out the carb cleaner trick at the boots good to know thanks again!

Steve

 

[XSLeo]

If your bike has points or an aftermarket ignition that uses the points advancer the advancer could be sticking, pull it apart and clean and relube the rod.
Carbs out of sync and cause high idle.
Leo

 

[STVR]

Everything is original on it, I just rebuilt the entire engine but I did not replace the carb boots which are original. I re-lubed and cleaned the rod so I'm pretty sure its not that

 

[5twins]

If the carb boots are originals, I would just replace them. They may have been functioning OK before the rebuild and before you disturbed them but removing and installing the carbs has probably done them in.

 

[JP50515]

This is happening on both of my twins....I've learned if you hit the killswitch and then flip it back before the bike dies it will drop to a normal idle....however it really sucks to try and do that while riding. Been chasing this little gremlin for a while now

 

[retiredgentleman]

Remove the air box or pod filters, so that you can view the top of needle jet in the carb throat. Start the engine, and rev it up a few times until the engine is hovering at a high rpm. Use a mirror to view the needle jet. You may see raw gas being sucked from around the needle jet and running along the carb throat towards the butterfly. This means your "O-ring" on the needle jet is worn out. Remove the needle jet and replace the "O-ring". Replace on both carbs even if only one shows leakage.

 

[mrriggs]

Sounds like you need to remove a coil from one of the ATU springs. What happens is the ignition advances a bit at idle, the increased advance increases the rpm, which advances it further, which makes it rev higher, and so on until the ignition is fully advanced and the motor is racing. It's a sure indicator that this is happening when you can drag the motor back to idle with the clutch and the rpm doesn't increase right away when you pull the clutch back in.

If one coil doesn't cure it, remove a coil from the other spring too.

 

[JP50515]

Tried removing a coil from the springs with no success. Not sure exactly what O-Ring we are talking about. I don't remember any o-rings on the needle in my carbs. Any other suggestions? or if someone's got pics of what o-ring we are talking about that would be awesome.

 

[ProSimex]

your timing is fucked I would say. Instead of removing a coil I just heated em red hot and squeezed em tight. never had a problem since

 

[XSLeo]

On the BS38 carbs the float valve was screwed in and sealed with a copper washer.
On the BS34 carbs the float valve was pressed in and sealed with an o-ring, and held in place with a clip and screw.
Leo

 

[retiredgentleman]

Tried removing a coil from the springs with no success. Not sure exactly what O-Ring we are talking about. I don't remember any o-rings on the needle in my carbs. Any other suggestions? or if someone's got pics of what o-ring we are talking about that would be awesome.

The O-ring that I mentioned is on the needle jet, not the needle. The 70 to 79 carb needle jets have the O-ring...............appears that the 80 to 83 carbs do not.

In the picture you will see a groove on the needle jet.............that is where the O-ring fits.

Do a visual check as I mentioned on my other post, to see if yours is passing fuel.

 

[STVR]

ok so I have the same problem I changed my carb holders put new ones in with new gaskets. Now it sounds even worse could this be a cable issue? I ordered new cables man this is so annoying!!!! I have a 75 xs 650 any help here would be appreciated

 

[alfredo]

ok so I have the same problem I changed my carb holders put new ones in with new gaskets. Now it sounds even worse could this be a cable issue? I ordered new cables man this is so annoying!!!! I have a 75 xs 650 any help here would be appreciated

Disconnect the cable, start the bike on its stand and turn the carbs up and down by the lever the cable normally attaches to. Then you should get a feel of where to start looking.