VFR being a complete twat!

[killa]

Right so using the old term, suck, squeeze, bang, blow, between me and the mechanic we have been trying to establish why the VFR isn’t starting.
Before the bike stopped I was getting back firing, poor throttle response, spluttering, so I suspected gummed up carbs from being stood for so long before and also using the Haines for problem solving it lead me to believe they were causing the problem.
The carbs weren’t the problem in the end but thankfully found something that might have been causing the fuel problem when putting the thing back together, the air line that works the diaphragm had a huge gash on the under side, so I changed it.
The bike turned over but didn’t fire, I’ve got spark, the coils are fine to cut a long story short he was checking over it and came to the conclusion the starter motor might be on its last legs.
When you have full charge in the battery (which I have to add isn’t that old) the engine turns over quite quickly at first but seems to die down very quickly, too quickly in fact, we checked the battery when starting and it was giving what it needed to fire.

Does this seem like a correct diagnostic to you guys?

Any advice appreciated.

Killa
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[finpos]

With those sympoms I'd be more inclined to think the battery was done in - it may not be too old, but if, for example, it's been sat discharged for a while, it may not be too clever either.

When in doubt, I always remove the suspect battery (bad battery can act as a huge current drain) and use jump leads to connect up to a car battery - that'll soon tell you which end is at fault. And 99% of the time, it's the battery.

finpos.

[killa]

The voltmeter read the battery was keeping charge when trying to kick over and giving out what it needed.
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[finpos]

Yeah - but you're really interested in the current (Amps) that the battery is kicking out over a period of time; batterys are rated in Amp/Hours. As a battery deteriorates, the number of Amp/hours it can pump out falls. It sounds like your battery isn't producing enough current for enough time - that's why the starter motor is slowing down.

Measuring the battery voltage only gives you a rough indication of the health of the battery. To measure it properly, you need a special (expensive) doofer.

Always simplest to try a good car battery - it will have 2 or 3 times the rating of a bike battery.

finpos.

[killa]

If I whack a heavier battery on there then, and the motor sounds like it isn’t giving me the right stuff, do I look into changing it then?
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[finpos]

First make sure all the connections between the battery and the starter motor are ok - just clean them up.

Then, given that you've eliminated all the simple and most likely stuff, take a look at the starter motor itself. They do fail, but most of the time the problem will be a borked battery or furry electrical connections.

finpos.

[killa]

The connections look pretty good, the battery is a possibility.
Is it possible to leave the normal battery on there running the ignition etc, then whack a heavier battery on it to start the bike?
The carbs were cleaned, so obviously stripped, could this cause the engine to not receive what it needs if it has been setup wrong?
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[finpos]

Well, If you've messed around with the carbs, it's always possible that you've disturbed the settings and it's causing you a problem. If you have a manual, it should give you basic settings to get you started. Of course, you could have re-assembled them wrongly, but that's a can of worms for another day.

But before you go down that road - the golden rule of trying to start a truculant bike is always, always make sure the battery is 100% effective first. Otherwise you'll spend your time chasing all kinds of ghosts around (e.g. thinking your starter motor is knackered )

Sure, you can leave the suspect battery in the circuit. It'll be just the same as trying to jump-start a bike with a flat battery. But I always disconnect it myself, because the second you connect your good battery into a circuit with a bad battery, the bad one will start sucking power from the good one - power that you want to turn your starter motor and run the ignition with. So, if in doubt, take it out. It's a 10 second job to disconnect the earth lead from the bikes battery.

finpos.

[ZZR-Souls]

Check the diaphragm in the fuel tap. If that has a hole in it you wont be getting any fuel through to the carbs. I know you've changed the vacuum pipe, but what about the diaphragm??
This would also give you the backfire and poor power output you've been experiencing.
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[Vin]

Re starter motor......you could try bump starting it.
Vin
Edit But I would try jump starting it from the car myself

[finpos]

One final thing just sprung to mind:

Vacuum fuel taps are great - as long as you have a vacuum. Turning your engine over with a weak battery probably won't generate enough vacuum to actually open the sodding thing up, so it may well be that your nicely overhauled carbs aren't getting any petrol.

Again, this is a consequence of not having a great battery, but I've had more than one (admittedly slightly tired) bike that needed the engine actually running before the vacuum tap would open up, which was rubbish if the engine cut out as it ran onto reserve.

So either:
Turn the fuel tap to "prime", if it has such a setting.
Or:
Disconnect the vacuum tube from the carb end* and suck on it. This method has the bonus of telling you if the diaphragm is knackered (you shouldn't be able to suck and suck and suck)

finpos.


* Ooooh ask me about the time I absent-mindedly disconnected the wrong end of the tube and sucked in a hearty lungful of hot fuel vapour from the inlet manifold. Now THAT was funny.

[killa]

I've tried all the above, diaphragm is good, filter in tank is good also.
The carbs are getting fuel i took the pipe off after trying to start it and fuel gushed out....

Petrol on lips burns man!
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[EuropeanNC30R...]

If i was you I'd just mod the tap so it's gravity fed, it's an actual HRC race kit mod. You've just got to rearrange some parts inside the tap. There's a guide on the net somewhere.

[craigs23]

https://akhara.com/nc30/fueltapmod/index.html

Did you get a good reading when revving the bike with the voltmeter across the terminals? Sounds like a dodgy rec. ruining a battery to me