Okay 1st things 1st.

I have VFR400 NC24, the engine blew its head gasket before i got it so i deceided to get a new engine installed.

Ive installed a NC21 engine and that struggled to start and when it was running it seemed okay until i put a pillion on the back and it struggled to pull.

We had worked out that the carbs might have been to blame as they were very very early NC21 AOA carbs with out the velocity stacks.

Ive since cleaned and installed a set of NC24 carbs to the bike which is jetted to 120 all around and 35 pilots. with the pilot screws Screwed 4 1/2 turns out (2 full turns)

It really struggled to start after doing this, I put it down to the fact it was a new set of carbs on the bike. After i finally started the bike (had to jump start it off my car as it was draining the battery so much) i managed to get her running well and set the idle screw so when warm the bike was running at 1500rpm at idle.

I then turned her off as was going out, she cooled down for about 5 or 6 hours (she was stone cold when i tried to start her again)

I tried to start the bike, it took ages again with the choke on full. Finally after about 20 or 30 attempts she fired up and run okay, left her to warm up and then took her on a good 5 mile ride. She got back idleing at 4000rpm so i adjusted the screw so it was 1500-2000rpm again.

I then put the bike away into the garage and as soon as i put it onto the side stand and leant it over onto the stand and she stalled. I thought this was weird so tried to start her again and she wouldnt start. She did finally start and did exactly the same thing when i put her back onto the side stand.

Does anyone know what this could be down to??

4 1/2 turns, 2 full turns?? which is it mate?

i think he meant 4 half turns equally 2 full turns

lizard821000 wrote:4 1/2 turns, 2 full turns?? which is it mate?

thats the same you turn a screw 4 x 1/2 a turn and it is 2x full turns.

lol, i thought you ment 4 AND half turns dude.

whats the stock air screw turns as per w.s.m mate? is it 2 full turns?

no worries,

yea its 2 full turns

my guess is the second time the revs were most likely just hanging up, maybe throttle stuck open a little or something similar..... then you readjusted the idel AGAIN which simply made the idel too slow, making it stall.

iv had bikes befor set on a very slow idel which have always cut out when i side stand them.

when you set the pilot screw, did you set the idel completly shut first, then adjust the idel screw after to get the right speed. otherwise the slide opening can miss lead some of the air flow straight into the carb rather than going purly through the pilot circet.

ill need some one to back me up here tbh cos im going off my 2T carb knoledge only, im a 4T new owner so untill i dismantle my bike and tinker with it im unsure if there the same in set up.

I must mention i cleaned the carbs and did all the pilot screw settings before installing them on the bike. the idle screw was removed at this time.

A friend of mine suggested it could be over fueling slightly so the ignition timing needs advancing slightly.

I will see how she starts tomorrow. (its not the idling im really worried about, its the starting problem that worries me)

chownsy wrote:I then put the bike away into the garage and as soon as i put it onto the side stand and leant it over onto the stand and she stalled. I thought this was weird so tried to start her again and she wouldnt start. She did finally start and did exactly the same thing when i put her back onto the side stand.

Very wierd!

Sounds electrical related. Start with the basic stuff - check battery connections, earth leads connections, spark plug leads, coil wiring connections, check for water in the spark plug recesses, etc. What condition are the spark plugs in?

This really could be a whole lot of things. I've heard of faulty generators being able to turn the engine over but not provide a strong enough spark to ignite the fuel - just to make things more confusing, electrical checks on these have not always shown a fault either!

Cammo wrote:

chownsy wrote:I then put the bike away into the garage and as soon as i put it onto the side stand and leant it over onto the stand and she stalled. I thought this was weird so tried to start her again and she wouldnt start. She did finally start and did exactly the same thing when i put her back onto the side stand.

Very wierd!

Sounds electrical related. Start with the basic stuff - check battery connections, earth leads connections, spark plug leads, coil wiring connections, check for water in the spark plug recesses, etc. What condition are the spark plugs in?

This really could be a whole lot of things. I've heard of faulty generators being able to turn the engine over but not provide a strong enough spark to ignite the fuel - just to make things more confusing, electrical checks on these have not always shown a fault either!

When i did the tappets, the engine was clean inside, the speark plug ports were blown out with a air blower.

The spark plugs looked normal operating condition (im a mechanic so knew what i was looking for on spark plugs, but im not used to working on a bike so old for problems)

The coil wiring looks in good condition and once running at high RPM seems like its not breaking down or struggling to fire.

Coil wiring connections are tight and all earth points have been sanded to give better contact

new starter solenoid fitted.

When running, output was 13.5v on idle

I will take a plug out tomorrow and see if she is over fueling.

EDIT: Also the bike is linked to an optimate permently when not in use to keep the battery in tip top condition.