Troubles starting

[Hok]

Hi,

I've noticed that my mk2 sometimes takes quite some time to start. It doesn't matter if the engine is warm or cold, sometimes it is instant, sometimes it takes 2-3 seconds. Things I checked:
 - Sparkplugs are good
 - Battery is new
 - Sprayed loads of contact cleaner into the ignition button
 - It also seems to not be related to the kickstand

Any ideas?

[pedro]

I get that you say the battery is new, but it's not unknown to have new batteries that are duff. Ideally try another. Or give it a good charge, just to eliminate that. Has the bike been laid up for any length of time? Especially with a part full tank of fuel. Might be the petrol going off if so. That's all that springs immediately to mind.

[Hok]

Even if I charge the battery fully, I still have the same issue. This is actually the reason why I bought a new one, thought it would solve it :-/
It also happens with new tank of fuel while constantly riding it so I dont think that would be it either.

[Art]

 

Rule #1 of motor vehicle diagnostics is to confirm the fault, so what's happening here?

When you press the start button does the starter motor immediately crank the engine?

If that is the case then the engine firing up immediately vs taking two or three seconds of cranking to fire up isn't really a fault. If you're looking for a reason for that happening it is most likely due to condensation or incomplete combustion when stopping the engine but could be many other things. Service history could offer some clues, for example, do you know when the likes of the air filter, air filter housing, crankcase breather, valve clearances, spark plugs etc were last tended to?

I don't see how spraying contact cleaner into the start button switch is going to help and is likely to do more harm than good in the long term. I clean handle bar switches with a goodly spray of Triple QX maintenance spray (GT85 or other water dispersant is just as good) to remove any moisture and loosen any grime, followed by a goodly spray of brake cleaner to clean the internals, blow dry and re-coat the contacts and moving parts with silicone grease for a smooth switch operation and to protect from corrosion, before re-assembling make sure the drain hole on the underside of the switch is clear.

As for that battery you should have tested it before writing it off and replacing it, for the future don't think know! Troubleshoot, find and prove any fault or failure before willy nilly replacing parts.

[Hok]

Fair enough. It takes a few seconds of cranking to fire up. So is that normal on the CBF?
The air filter is new, sparkplugs are ok, and the rest I am not sure about but it has about 35k km so it shouldnt be too bad.

About the contact cleaner - I had to do it because I had issues with the headlight and you cannot take the button apart to get to the contacts. I heard the button could influence the power that gets to the starter so that's why I mentioned it

And the battery. The old one didnt have a date on it but 100% was too old and sometimes it was struggling with cold starts.

[Art]

Originally Posted by Hok

Fair enough. It takes a few seconds of cranking to fire up. So is that normal on the CBF?

That's normal for any internal combustion engine, especially in the winter months 

[Hok]

I dont think it is that normal. I got friends with Yamaha bikes that start instantly. Keep in mind that I am talking about a warm engine, not a cold start

[Art]

Get on down to your local motorcycle meet and note the number of motorcycles taking 2 or 3 seconds of cranking to fire up, and some taking longer! Engines become a little tired with age and at 10+ years old 2 or 3 seconds of cranking before firing up is not only normal but to be expected.

Originally Posted by Art

If you're looking for a reason it is most likely due to condensation or incomplete combustion when stopping the engine...

...which means the combustion chamber and spark plugs get damp with water, especially if you've been riding in wet, damp or cold ambient temperature conditions, or damp with unspent fuel or both, either way the end result will be an incorrect air:fuel ratio resulting in the hesitation. Of course, other faults can cause excessive cranking before an engine fires up and it is a fairly long list that includes everything and anything that could possible affect the fuel and/or spark. However, those faults will typically result in needing several 5 second bursts of cranking for the engine to fire up as well an occasional crank no start issue due to flooding the engine with fuel.

If you're friends with Yamahaha's were perfectly honest they'd tell you that they also have experienced instances of 2 or 3 seconds of cranking before an engine fires up.

[jm2]

My mkII always did take holding the starter for 2-3 seconds (which seemed an eternity but isn't).
I had it from nearly new and it was always that way.

The only times it failed first 'kick' was me being too abitious/impatient.

[jm2]

The starter button only operates the start-mag.  You'd know if that was working or not.
Yes, as you've found, it also (separately) disconnects the light to save some energy load (but these are different contacts).