Re: Honda Unicorn Engine Idle RPM fluctuation/variation

Query Approved

First off from what I can understand, there is clearly a difference between "revving" and idling. In your case, the idle 1k, the max after the engine heats it can be around 1.2 to 1.5k manufacturer sets this level in the manual, but mostly, generally this is how it works. if you have an engine that's "revving" to moon and down all of a sudden, you definitely have an issue with your cables. Check your accelerator cable, if it's intertwined or is in the stage of giving up (breaking up) you can have this issue of high revving when moving the bars left and right.

Secondly your choke switch mechanism might be at fault, yes the choke does "rev" an engine to high RPMs so get your choke cable, choke mechanism all checked. Degreasing them with spray won't help if the cable is stuck or the valve is at fault. This revving nature of the motorcycle is very very dangerous and can cause real hazard, especially when you least expect. Change your cables, both accel and clutch, and see how it fares, get your choke mechanism in the carb checked for stuck plunger etc. These things cost very less.

White smoke is caused due to a variety of reasons, worn piston rings, worn tappet oil seals, worn tappet etc. But usually if one goes wrong, it's a cycle effect reducing the life of all the other adjacent components, slowly yet steadily. Considering your bike has clocked 44k it's time to check your cylinder for compression, poor compression means less power, which means oil and all nasty things enter the combustion chamber to produce this white smoke.

I'd suggest you to do an engine overhaul work, replace your valves, springs, piston and rings, and it should be good as new again, considering the job is done right, and correctly.

Cheers!
VJ

Re: Honda Unicorn Engine Idle RPM fluctuation/variation

My Cb Trigger (17000 kms) have also this problem. It was rectified by changing chock cable. Also bit rust in chock mechanism inside carburetor and they cleaned it. Now the engine is smooth and it giving around 60 km per liter

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Re: Honda Unicorn Engine Idle RPM fluctuation/variation

@B7ACKTHORN

I am not that good with the biking tech terms.. :/

Yes, the engine is revving like crazy to 5-6k RPM in idling state, i.e. in neutral or in clutch. When I pull the throttle in that state a couple of times, it returns to normal. But still the idle RPM varies from to 1.2k to 2k RPM. Quite often it is not able to sustain even 1k mark and switches off. So I don't really know what will happen when I pull the clutch.

Thanks for the inputs, I will get the cables checked again.

BTW, can you please tell the following:

1. What is half-engine work? Is Engine overhauling the same thing?
2. Is 44k mileage high time for engine to act like this (smoke)? Or, I am getting this early or late?
3. In general do you suggest to get the engine work done at authorised service centre (ASC) or good local mech? I can complain to Honda about ASC if they screw something up, but if something screws up, it would a real pain. :/

Thanks pradeeppk for the help. I guess the local mech was right, considering the service centre guys need to do this FREE OF CHARGE service, as this arose post regular service, maybe they are acting dumb.