I asked why my bike revs go up when I change gear, I know all about clutch etc and I'm not a novice rider?

Question

I have checked carbs, cable, timing and fuel and still have the problem of increased revs even though I am closing the throttle each time. Why are my revs increasing when I change gear?

Answer 1

Your carb throttle slide--piston is sticking and not returning quickly enough

Answer 2

I had the same problem with my Gsxr 600 last month when i was on the track, every time i pulled in the clutch lever the engine rpm would rise, it proved pretty difficult for smooth cornering.

I found my problem was the secondary throttle position sensor (STPS). I would prob say it could be down to 1 of 3 things.

The first thing to check is the butterflys to make sure they are moving smoothly with no sticky points, if they are sticky just lube them up (use a lube on the end of a cotton bud, DO NOT DROP THE BUD into the engine) a little until they return smoothly to the throttle closed position (the butterfly will sit slightly open when the throttle is fully closed otherwise the bike would stall).

The second item to check is the throttle position sensor (TPS), this is normally mounted to the end of the butterflys, most modern bikes will allow you to enter a dealers mode which will show any fuels with the sensor on the dash. If you cannot access dealer mode then you can slacken the mounting screw slightly and rotate the sensor about the screw (very slightly) and you will notice a difference in the engine note, this is just a try and see fix.

The same goes for the STPS, it is mounted adjacent to the TPS and the setting of this can be done using the above method.

When you get these sensors set up correctly the bike shall feel far better to ride than it ever did as the throttle shall be so much better at pick up. The opposite applies when the sensor is moved in the wrong position ie. The engine shall bog down a little more then normal. Some people use these sensors for fine tuning.

Hope some of this helps, if you need any other info let me know, although it would help to know what make/model engine size etc...

Cheers

Answer 3

If you're changing to a higher gear, close the throttle as you disengage the clutch then as you engage the clutch again gently open the throttle so engine speed matches road speed. When changing down reverse this process i.e. when the clutch is disengaged to make the change increase revs as you re-engage...you will need higher revs if you want to maintain road speed in a lower gear. If you don't get the revs balanced to match speed the bike will lurch as you engage the clutch when you change up or down.

Answer 4

I know when the engine is cold my bike will do the same thing where no matter how synchronized my clutch-work is with my throttle inputs it will surge a bit. When warm I couldn't ask for more responsive throttle inputs -- fuel-injection > carbs that way.

I don't think it's a problem beyond aesthetics, but the answer is clutchless upshifts if it bothers you that much. Dipping the throttle and shifting without disengaging the clutch provides very little opportunity for the engine to spool up without a load. That IS the main reason for the surge: a loaded versus unloaded engine.

Answer 5

Because as you use the clutch the engine is set free of the load of the bike and requires less power at that moment. So the revs increase until you re-engage the engine to propel the bike. Changing up you should close the throttle and changing down leave the throttle setting as it is. This equalises the revs to the load.

Answer 6

how long is the clutch staying engaged, are you unintentionally bliping the throttle, are your carbs jetted right? also are you using synthetic oil? switching to synthetic will sometimes cause this.

go through every thing you can think of one thing at a time. then ride for about 10 miles and then go back to figure out the next thing that might work. I don't know what bike you have, but these guys can help with just about anything. here is a link to their FAQ, it might give you some insight, or let you know something that you might have forgotten.

Doh!... have you cleaned out your clutch switch!?
here is the basics: http://faq.ninja250.org/wiki/Cleaning_and_servicing_the_clutch_switch

this article section is great.

Answer 7

With out knowing what kind of bike it is, It sounds like a problem i had. It was my choke sticking open and when i pulld the clutch in it would rev up.

Answer 8

on maximum persons of mototrbikes you in basic terms ought to apply the seize once you shy away or wanna end. all dirt motorcycles exceptionally have a canine engagement gearbox meaning there are no longer any synchros and are designed to alter kit without using a seize, the only different clarification for having a seize on a airborne dirt and dirt motorcycle is for stunts so which you would be able to improve the revs in an greater kit than 1st pop the seize and wheelie or dip the seize on the foreheadof a hill then wack the throttle returned mutually as letting the seize out to spin the returned tire so it beds into the airborne dirt and dirt givin lots extra effectual traction as you bypass over the hill and so on so in case you in basic terms using oftentimes you dont ought to apply the seize as quickly as your moving i raced motocross for 4 years and that i rarely ever used the seize and now im a bike mechanic

Answer 9

Always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer.
Multiple cylinder - could need a carb sync.
Single or multi - intake manifold air leak.
Old bile with points - stuck timing advancer, or loose springs.
Vacuum carburetors - worn out throttle slide bore, worn out vacuum chamber or damaged diaphragms.

Answer 10

reset the idle
let the bike rev down before pressing in the clutch