Went out for a ride yesterday, did about 35 miles, all good.
Decided to stop somewhere for a brew for about 15 mins.
Pressed the start button, turned over but didn't start. Did it again with throttle open and it started
but just held onto idle with the throttle wide open. Let the throttle go and it cut out.
Started it again and the same happened for about 2 mins, then it cleared and revved as normal and
I rode home with no issues.
Bit embarassing and bothered about stopping anywhere now until its sorted.
Always starts from cold on choke with no issues !!!!!!!!

Another quick question. What would be the symptoms of worn emulsion tubes ?

Cheers

That's odd - has the bike been owned by you for a while ?
Could it be a bit of dirt in the carbs from sitting at any point .... Have you had the carbs balanced recently (or not if you see what I mean)
The only time my 3en2 became hard to start was when the valve tolerances needed doing but it might not be the ase with yours.

Emulsion tube wear - the bike won't idle and is harder to find a constant speed because the tubes are ovaled. Look at the needles there will be a shiny mark where the it rubs against the tube

The carbs were ultrasonically cleaned during my rebuild, balanced last month and have new lite tech seals all round
The bike idles nicely at 12-1300rpm. It still has that slight mid range holding back, as in an earlier post
viewtopic.php?f=37&t=52056
but pulls right through to the redline
Maybe I'll check the tank breather as it was a hot day. Might be a vacuum.
Sounds as though the emulsion tubes are ok then

Sounds like one of those things, you might have just caught it wrong

Try the pickup on the crank, these fail, hot starting can be a problem!

Where are these and are they easily replaceable
Took it for MOT last week, 4 mile ride max. Left bike for 25 mins and the mechanic tried to start it
Sat there for 5 mins with throttle wide open to keep it ticking over. Then it just burst into life like nothing is wrong with it !!!!!
Surely after 25 mins, there is still petrol in the carbs. Should the pump be priming then or does it sense a drop in the carbs??

redbandit12 wrote:Went out for a ride yesterday, did about 35 miles, all good.
Decided to stop somewhere for a brew for about 15 mins.
Pressed the start button, turned over but didn't start. Did it again with throttle open and it started
but just held onto idle with the throttle wide open. Let the throttle go and it cut out
Started it again and the same happened for about 2 mins, then it cleared and revved as normal and
I rode home with no issues.
Bit embarassing and bothered about stopping anywhere now until its sorted.
Always starts from cold on choke with no issues !!!!!!!!

Another quick question. What would be the symptoms of worn emulsion tubes ?

Cheers

I have this issue but when my engine is cold, won't start on the button but it will push start with the throttle wide open but it only idles with the throttle wide open and then after a minute the revs will pick up and it will start running fine! and then it starts on the button once the engine is warm and again runs fine straight away, odd, my carbs are off at the minute, rebuilding with LiteTek seals and going to replace my really badly cracked inlet manifolds for 1wg ones, got new emulsion tubes and needles too, just hope it's not a compression issue, I'll be screwed if the rings go! i think it would benefit from having the valve clearances reset though, another thing i came across was a burnt spade connector in the connector block that comes off the stator it had melted the plastic block too so that's all replaced now, only had 12.8 volts coming from the battery when the engine is running and it only increased by 0.1 volts in the higher rpm's so I've also fitted a new reg/rec, going to see if any of what I've done helps when i "eventually" get it all back together! lol

Sounds like the valve tollerances have closed up to almost zero. When you bump it it warms the engine which makes the metal in the head expand closing the tollerance.
Do the valves

Evilchicken0 wrote:Sounds like the valve tollerances have closed up to almost zero. When you bump it it warms the engine which makes the metal in the head expand closing the tollerance.
Do the valves

Never done valves before I've a friend though that is a mechanic and he's recently rebuilt his cbr400 so I've someone i can go to if need be, will i need to buy any shims or anything ?

Yes, you will (almost certainly) need shims, but before that you'll need to measure the gaps so you'll a metric feeler gauge the cranked one is probably a little bit more easy to use for this job.

This is easier with the engine out of the frame but doable with it in .... first things first though - wash the bike and use degreaser on the engine.