RPM increase when shifting gears on my 91 Bandit.

[Mike H]

Hello everyone. I just found this great site from someone at advrider.com and am looking for some help on my bike.

When I up shift into a higher gear my RPM's increase by about 500 to 1000 RPM's as I roll off the throttle and engage the clutch. This happens after my bike has warmed up for about 10 - 15 min. Also, when I come to a stop with the clutch engaged the engine is rev'ing @ 3500 to 4000 RPM's the slowly drops to 2500 RPM's which is the normal RPM's. The bike idles smoothly (not eratic) and seems to be running good under power.

My bike has been sitting since last November and was running fine when I parked it. I have drained the old gas, ran a can of seafoam thru in and changed the air filter. I pulled 2 sparkplugs and they are light tan (maybe running to lean).

Thanks, Mike

[crashoverrideplik]

Check your throttle cable. Mine did something like what you are describing and I lubed the cable and it went away. You also might want to look to see if the cable is hanging up on anything. Mine was also routed wrong from my the last time I had it apart 

[Mike H]

I checked the throttle cable and it seems to be woking fine. I even disconnected it from the carb and the cable is sliding smoothly in the sheathing.

Last Thursday while riding my bike on my way home from work I was low on fuel on could not switch to reserve quick enough before my bike died. I could not get my bike restarted and finally drained the battery. The bike acted like it was flooded and I saw alot of fuel leaking from the bowels. When I got my bike home I pulled the spark plugs and they were damp with fuel.
I also pulled the top covers of the carbs and the o-rings were deteriorated/flattened which I am going to replace.

I was also wondering if the petcock assembly/gaskets in the tank was not working properly would that allow excess fuel to flow into carbs?

Mike

[crashoverrideplik]

Mike,

Make sure that the petcock was not set to prime (pointing to the top). In this setting it will flow and over fill the bowels. When I pulled my carbs apart the other day mine did the same thing because I forgot to re-set it.

Bill

[Mike H]

Bill,

Thanks, I will check when I get home tonight.

Mike

[Mike H]

Bill,

I checked last night and I still have the original petcock with the stop screw that prevents you from setting it to prime.

I did remove the bowels and checked the o-rings on the float valves last night also. They need to be replaced. If the o-rings are bad would that allow gas to overflow the bowels even if the float valves are working properly?

Mike

[crashoverrideplik]

Mike,

Mine doesn't have a screw stop on my petcock to keep it from going to prime. Did you turn it clockwise?

Bad o-rings on the needle/seat can cause the issue you are talking about or possibly a stuck needle/seat. Another issue that could be a problem is worn emulsion tubes (where the needles ride in) but generally emulsion tubes act like an air leak and make setting idle, etc suck. How many miles are on your bike?

Bill

[Mike H]

Bill,

I have 19,500 miles on my bike.

Mike

[crashoverrideplik]

With that many miles it could be any of those situations I described. You can check emulsion tubes by removing the carb slides and looking thru the carb body. If the tubes are egg shaped then they are bad. If they are still round, then they are Ok. Here's a link:

http://www.factorypro.com/tech/needle_jet_wear.html

[Mike H]

Thanks for your help Bill. I will check when I get home tonight. I will try to upload a photo tomorrow.

This is a great site by the way. I have learned more about my bike and how carbs work by reading old post on this forumn.

Mike