Anyone able to diagnose dodgy running from this audio?

[Riknos]

Video here:

https://www.youtube.com/watch?v=-DHrmx2ydTA

So far on my bike I have:

• Cleaned tank and filled with fresh fuel
• Taken carbs off and cleaned (were clean already, didn't really need doing)
• New plugs
• New coils
• New airfilter
• New hoses to fuel tank

Yet it still dies on idle after about 20 secs off the choke?

Someone suggested carb balancing but I don't want to buy the gauges and learn how to use them for it to be another dead end.

Any ideas?

Thanks.

[xeny]

What kind of revs is the idle at the beginning of the video? It seems a bit low generally.

If you get it warm and off choke, does it ride OK apart from the flaky idle?

[Riknos]

xeny said:

What kind of revs is the idle at the beginning of the video? It seems a bit low generally.

It was on about 5k ish rpm as still on half choke for the first 20 seconds (hard to tell the rpm as the digital dash is crap)

xeny said:

If you get it warm and off choke, does it ride OK apart from the flaky idle?

Nope, will often die when I come to a stop, or after about 15/20 minutes riding

Edited by Riknos on Wednesday 9th May 14:20

[pozi]

Look for cracks in the carb boot, easy check is when it is running spray WD40 around the carb rubbers and see if the revs go up, just make sure you do not accidentally get any near the intake.

[Riknos]

pozi said:

Look for cracks in the carb boot, easy check is when it is running spray WD40 around the carb rubbers and see if the revs go up, just make sure you do not accidentally get any near the intake.

Good shout - I had the carbs off last week to clean them and checked all the boots, all good, although I will double check they are all tight now, thanks

[xeny]

Riknos said:

It was on about 5k ish rpm as still on half choke for the first 20 seconds (hard to tell the rpm as the digital dash is crap)

That really doesn't sound anything like as high as 5000 rpm - is there another 4 cylinder bike engine you can listen to in comparison, or a tacho function on a multimeter or similar?

[Riknos]

xeny said:

Riknos said:

It was on about 5k ish rpm as still on half choke for the first 20 seconds (hard to tell the rpm as the digital dash is crap)

That really doesn't sound anything like as high as 5000 rpm - is there another 4 cylinder bike engine you can listen to in comparison, or a tacho function on a multimeter or similar?

My bad, just went out and check the dash and it was on about 3k

[xeny]

Riknos said:

My bad, just went out and check the dash and it was on about 3k

What's the actual idle speed you're aiming at once it is warmed up?

[WinstonWolf]

Riknos said:

Video here:

https://www.youtube.com/watch?v=-DHrmx2ydTA

So far on my bike I have:

• Cleaned tank and filled with fresh fuel
• Taken carbs off and cleaned (were clean already, didn't really need doing)
• New plugs
• New coils
• New airfilter
• New hoses to fuel tank

Yet it still dies on idle after about 20 secs off the choke?

Someone suggested carb balancing but I don't want to buy the gauges and learn how to use them for it to be another dead end.

Any ideas?

Thanks.

Always test with the fuel cap open (trust me on this to eliminate a blocked breather.

You can balance the carbs with some lengths of welding rod, it's how I used to set my old LC up. It might not be perfect but at least you'll know if the slides are moving in unison.

[PIGINAWIG]

That’s definitely not idling around 5000 revs at the start of video.more like 1500-2000

[Riknos]

Update: Had a loose clamp on one of the carb rubbers so tightened that up and it idled but was erratic, turning the idle screw up to 1500-2k ish seems to get it to idle steady, if I turn it down a notch toward 1200 ish it will idle erratic then die

So is this carbs need balancing?

[orangefzr]

pozi said:

Look for cracks in the carb boot, easy check is when it is running spray WD40 around the carb rubbers and see if the revs go up, just make sure you do not accidentally get any near the intake.

It sounds like a vacuum leak to me as well.... Did you check the diaphragms in the carb tops for rips or tears ? Also make sure that all the screws or caps are In place on the intake balance points and all the vacuum pipes are in good condition. Possibly also the diaphragm in the fuel tap

[liner33]

orangefzr said:

It sounds like a vacuum leak to me as well.... Did you check the diaphragms in the carb tops for rips or tears ? Also make sure that all the screws or caps are In place on the intake balance points and all the vacuum pipes are in good condition. Possibly also the diaphragm in the fuel tap

Agree with this , have you removed fuel pipe from tap to check for steady flow ?

setting the idle up high and then spraying easy start around the carbs and rubbers can sometimes pick up an air leak , the idle with change

[Riknos]

liner33 said:

orangefzr said:

It sounds like a vacuum leak to me as well.... Did you check the diaphragms in the carb tops for rips or tears ? Also make sure that all the screws or caps are In place on the intake balance points and all the vacuum pipes are in good condition. Possibly also the diaphragm in the fuel tap

Agree with this , have you removed fuel pipe from tap to check for steady flow ?

setting the idle up high and then spraying easy start around the carbs and rubbers can sometimes pick up an air leak , the idle with change

I fitted a new fuel pipe so it should be good, perhaps it's the tap itself? I'll do the spraying for an air leak and see if that yields anything

[liner33]

yes the tap itself

[orangefzr]

I meant to say that if the bike ran well recently then started fking up then I'd very much doubt that the carbs would need re balancing as modern carbs hold their balance well