7 replies to this topic

[minied69]

Hi,

I removed my working twin SU to test a Single HS6 setup. After 3 months, decided to go back to twins. Fitted the twins back and it refused to start. Did everything I know and it wouldnt start. As it was on the bench for 3 mths, thought could be a clog issue so cleaned and serviced the carbs. Note carbs has been rebuilt already with a full service kit a year ago. After cleaning, tried again and no luck. Troubleshooting done :
 

1) Checked fuel - Blew from Float bowl fuel inlet and saw fuel does come out the jet in the Main Chamber.
2) Lowered Jet by 9 flats and 12 flats as practice, removed dash pot and confirmed visually they are lowered

3) sprayed some fuel into chamber via filter side , car start a bit then dies when fuel finishes in chamber

4) Sparks from plugs are working, check one by one

5) Full Choke and no choke

6) Fethered throttle and closed 

 

Suspect there is a vacuum leak causing hole in straw effect.. visually none visible.. what can I do to check and where?

Any help is much appreciated.

by the way if I fit back my HS6, car runs fine again so nothing to do with ignition.

 

[Spider]

If there was any fuel left in them when on th bench, that would have dried out and possibly left a vanish or gum in the jets.

If you lift the lids on the float bowls (check them both), is there fuel in them ?

If you remove the bell chambers and look in to the Jets, can you see fuel in there ? It'll be about 5 - 10 mm down from the bridge.

[minied69]

Yes fuel.in float bowl. No fuel in chamber when remove dashpots. If I blow the float bowl fuel intake, fuel.comes out the jets so no clogs for sure.

[sonscar]

Gasket leak?have you fitted the air filter correctly?inlet manifold gasket leaking?basically everything you have touched.Steve..

[mk1leg]

look at AC Dodds videos in base carb set up pre to starting very usefull

[Steam]

Dribble a small amount of fuel into air intake chamber and try to start.

[minied69]

Found then issue, vacuum leak..manifold cracked and broke at cyclinder head.. back to my HS6...until get another manifold.. will try to weld back and test..

[minied69]

Found then issue, vacuum leak..manifold cracked and broke at cyclinder head.. back to my HS6...until get another manifold.. will try to weld back and test.. thxs all for the help