my bikes rpm automatically raises to 2000 rpm while standstill. It raises comes down again raises.?

Question

I have a 150 CC bike, 4 months old and done 4100 kms. Two free services have been done. Recently I have observed that while standing at signal lights in neutral gear the rpm automatically rises to 2000 rpm mark, comes down & again raises. This happens despite the throttle is fully released. What could be the problem. This must be having an effect on my bike's economy.

Answer 1

As the first answer states,I also would bet it is an air leak. Check vac.lines ,carb. and intake seals. It is unlikely that it is a mis-adjustment as this would not change while the bike is in use.An air leak will change ,based on the temp. of the motor and the rate of vac. produced by the motor at different RPM's.

Answer 2

Vacume leak, easy way to check is to take a propane torch turn on the gas but DO NOT light it, with the motorcycle running pass the unlighted torch around the throttle body boots or aywhere else there is a chance for a leak, if the RPM's change you found your leak. I would not do anything other then minor tightening to your bike, any other work on your part might void the warrenty which you dont want to do on such a new bike.

Answer 3

Try adjusting the throttle screw at the base of the fuel tank and gently set the idle speed to the one mentioned in the bikes manual.
Might require a little bit of trial and error.

If that dosen't work take the bike to the dealer.Being a 4 month old bike its still covered by the warranty and is under the free service period. The mechanics there will solve the problem.

Also since its a relatively new bike I would suggest that you do not tinker with it too much.It might affect the warranty of the bike.(see owners manual)

Answer 4

If the bike is carburated then the carbs can be out of balance. Another symptom you might notice is additional engine vibration. Balancing the carb is not particularly complicated if you are mechanically inclined but you need a manometer. Even if balance isn't an issue you should balance the carbs anyway. It'll improve fuel efficiency, power, and curb engine vibration. Stay away from Mercury manometers as they are annoying to work with. I suggest the Carb Tune if you do it yourself.

Answer 5

It sounds like the carb is out of adjustment. You need to adjust the idle mixture screw,on some carbs they put a small cap over the screw so you cant adjust them. Look on your carb and see if you have two screws,the smaller of the two will be the idle mixture screw. If you only have one screw that means the mixture screw has been capped with a little metal plug about 3/16th in round. you should be able to pull up a cut-away view of your carb on line and find the location of the plug. After you find the plug you can CAREFULLY drill out the plug with an 1/8th in bit,then use an icepick or an awl to pop the cap out, you will see the screw after you get the cap off. Then screw the mixture screw in all the way,just do it till it stops dont tighten it. Then back out the screw 1 1/2 turns,start the bike up and let the motor warm up completely.Then adjust your idle (the larger screw) down as slow as it will go and still keep the motor running. Then adjust the idle mixture screw until the motor idles as fast as it can. Then adjust the idle screw down to the normal idle RPM, again adjust the idle mixture screw until the motor revvs as fast as it can. If it doesn't make any difference or the motor slows down,turn the mixture screw back to your first adjustment point. Adjust the idle to normal RPM and you are all set.

Answer 6

open the fuel tank while your at idle if this stops the problem your ventline is kinked or clogged.

The bike will idle fine then when the vaccum builds and the gas does not flow the engine goes lean and the revs rise. with the lid off the tank there will be no vaccum and the gas will flow

I had this problem with a 1987 yamaha radian

Answer 7

it easily relies upon. If i'm dealing with a Mic, I postpone the Mic and wave it backward and forward. If he does not call on me i pass truly slow to the brother of sister he does call on. LOL. whilst at my seat, I continuously develop my surprising hand, yet I frequently wait to make certain if everybody else is elevating their hand, except i myself desire to answer that query. once I cope with the sound I back develop my surprising hand, yet I relax in the chair and refuse to place the sound up for everybody else till I answer. back LOL. this query has positioned a large smile on my face. i'm hoping that others that see this see that Jehovah's Witnesses do desire to have exciting, in comparison to what others desire to assert approximately us. Agape to all

Answer 8

two stroke or four? if its a two stroke, sounds like a bad reed valve. four, a carburation problem, maybe even just bad gas. could be a bad mixture of oil and gas in it if it is two stroke. empty the tank completely, letting it run until even the fuel lines are empty. then put fresh, properly mixed gas in it. it will be the cheapest thing to check. other than that, i don't know. could just need some tweaking on the adjustments. check the cheap things first, as always.

Answer 9

Economy not to mention dangerous to yourself and possibly others. It's only 4 mths old so take it to where you bought it as there should be warranty on it since you bought it new. Good Luck to you and be careful.

Answer 10

sounds like you have a vacuum leak or your carb is out of adjustment.