No start

[Sandy Gibson]

I’ve renewed the throttle spindles on my HS2 Mk3. Gave everything a good clean while I was at it and now engine won’t start. Plugs are dry so no fuel getting through

Engine was running well before I started so didn’t touch the jets other than to blow them through with carb spray.

Float chambers are filling and fuel pump working fine. Pistons are free and operating as normal. All linkages operating fine.

I can only think I have somehow blocked the jets in the process of assembly and am about to take them off for a look.

Can anyone suggest anything else that may have gone wrong?  Seems odd that both carbs seem to be affected.

many thanks in advance 

 

 

 

[Pete Lewis]

have you removed the fuel line pump to carbs   is the pump pumping ???

its quite common to make the dreaded rubber slivers , when you refit rubber hose to a metal pipe it slices a bit off anf that often blocks the back of the float needle valve 

do make sure none of the air filter gaskets are blocking the front face ports 

other things are the tube to the jet on su becomes kinked under the spiral wrap 

and there is often two jet tube rubber 0 rings in the float chamber ,decomposed and blocking flow

then what else did you work on ...always go back to the last job you did, or forgot about

are you getting a spark at the plugs?? 

Pete

Edited February 23 by Pete Lewis

[Sandy Gibson]

Thanks Pete

Float chambers are filling normally and spark/ignition side is fine.  I’ve got Grose valves but unite possible some rubber has found its way to the jet.  Many thanks.

[Pete Lewis]

grose used to be good but recent years has seen  them as  often quite useless

do check the air filter gaskets are not upside down 

Pete

[Sandy Gibson]

Had the grose for a while now and pretty sure there OK.  Didn’t have the filters on for the initial ( failed!) start.

[Pete Lewis]

have alook at the HT lead to the coil   can be very green inside 

check the points have not closed up 

check there is a carbon brush /contact in the head of the cap

does the rotor arm have a rivet in it ???

do the jets drop fully  when you pull the choke ??? and return when pushed in 

is there a chance on rebuild it is just set far too lean ???

Pete

 

[Sandy Gibson]

OK  It’s confession time!  I had the plug leads on wrong!

I have spent the last 60 years playing about with mainly Triumph engines and would have bet my bottom dollar that I wouldn’t have done that but it does let you see we can all make stupid basic errors if we get too complacent!

Thanks for your help, I’ll go and lie down in a dark room somewhere now!

[dougbgt6]

Well done Sandy, we've all done it, well, not Pete, obviously. 

Doug

[Pete Lewis]

i wouldnt bet on that 

but check the last twiddle.......... can be embarising 

Pete

[daverclasper]

On 23/02/2024 at 12:48, Sandy Gibson said:

Plugs are dry so no fuel getting through

I had a starting problem on Vitesse. Even after lot's of cranking with choke, the plugs were dry. Assumed it was a lack of fuel issue. Turned out, it was dirty/oil fouled points contacts.

I still don't understand, why the plugs were completely dry?

[johny]

Bit strange Dave but maybe the fuel was evaporating quite rapidly so not accumulating on the plugs. How easily does it start normally in cold temperatures?