Twin 40S Fitted, Won't Start

[theduck]

Tbh it doesn't run at all, just a couple of times when first fitted I thought it had caught but hadn't.

 

Latest developments

 

Fitted correct idle jets

 

Set timing to approx 8degrees advance

 

Checked spark on all plugs and all sparking in correct sequence and not 180degrees out

 

When removing plugs tonight I notices two things

1: plug 1 was black, all others were wet

2: header 1 was warm, all others stone cold

 

Would others agree that sounds like an air leak on 2,3 and 4?

[Guest zerorace]

did it run ok before fitting the 40`s

[theduck]

Yep.

[Guest mcramsay]

Are the bodies balanced correctly on the linkages? Not trying to make you feel stupid but I'm assuming you have tried to give it a little throttle wen starting?

[Guest mcramsay]

Even try opening the throttle a fair bit and starting,

[theduck]

As balanced as can be without having engine running.

 

Just put old carb back on. Started first time

[theduck]

So plan of action is to set ignition timing properly while the 34ich is on and to strip the carbs and make sure floats are set right and give everything a good clean. Then put back together using misab plates instead of the O rings.

[maccavvy]

its obviously a carb issue then.. I thought they had to be regulated too. ??

[keith kelly]

Should be 3psi

[MarkBzero]

With safety specs on (H&S) looking down the carbs do you get fuel when you operate the throttle? If yes ask another person to turnover and spray manifold with carb, brake cleaner. Maybe it will fire, alternatively a bit of easy start down the carbs (I know most people don't like using easy start).

[Guest mower man]

If its wetting plugs I doubt it is an air/vacuum leak what capacity was the engine they were fitted to may be mains to big , have you checked float levels and are float valves ok ?, throw the wetted plugs away leave plugs out over night to dry cyls out ,don't use the choke levers , hold thottle slightly open when cranking , get someone to swing the dizzy alittle when trying usual a little more advance helps it should run if all points have been checked /rectified oviously you have checked cam timing ,valve clearances etc , is battery fully charged ,is engine earthed properly ,I ask this as I recently changed a few things on my car and while it started and blipped up ok it was pants on the road ,I had left off an earth on the inlet manifold put it back no more probs[ this was before my non starting epic] I hope this helps mower man

[theduck]

Main jets are right size for the venturis (30ventrui 115jets)

 

Emulsion tubes aren't matched. One side of each carb has .1 other side has .5 daveandrews site suggests .10s for a standard 1600 but I think .5a should be ok and will future proof for when I get round to fitting my 2.0cam.

 

All other jets and tubes are correct.

 

I am going to check floats and change emulsion tubes.

[theduck]

Checked the float levels and they were way out. Set them correctly, cleaned and rebuilt and...

 

IT WORKS!!!

 

Have to use the cold start valves to fire it up so will be ordering up some proper levers but it works and sounds amazing! Will get a video once have sorted it out properly.

 

Edit. Forgot to say thank you everyone for your help.

[keith kelly]

Should start with a couple of pumps of the peddle before turning the key. Removed my cold start and blanked off as they were leaking which is quite common.

[Guest mower man]

RESULT !! two pumps is as good away of starting as anythe choke mechanisms are notoriously iffy even when new, I have found in the past how float setting get disturbed when carbs are taken off transfered etc glad youare up and running mowerman