Beast and the carb
- spookefoote1956
- Member
- Posts: 1836
- Joined: Mon May 01, 2017 7:32 pm
- Location: Wales Innit
Beast and the carb
I've fitted the Thorspark and managed to get it to fire albeit with the throttle full open. Could it be that the needle and pilot jets are the wrong size? The supplier kitted it as per Plumstead specs Pilot 30cc and Needle 106. Any advice gratefully received.
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
-
- Posts: 615
- Joined: Sun Nov 25, 2012 9:40 pm
- Location: Chipping Norton
Re: Beast and the carb
Fitting a Thorspark unit should not change the carb jetting requirements in any way. It is more likely you have a timing problem
Les
Rules are for the obedience of fools and the guidance of the wise
Rules are for the obedience of fools and the guidance of the wise
- Harry44
- Member
- Posts: 279
- Joined: Sat Dec 17, 2016 5:26 pm
- Location: SOMERSET UK
Re: Beast and the carb
I thought the "correct" main jet was 260. I have a new carb on mine and to get it running right I've put a 280 main jet and a 35 pilot jet but gonna try a 40 pilot as I still have a flat spot just above idle.
si is does non opportunus vos postulo a maior pango
- clanger9
- Posts: 1165
- Joined: Sat Jun 20, 2015 9:38 am
- Location: Chester, UK
Re: Beast and the carb
Have you checked the float level? Should be correct on a new carb, but you never know...
1989 Moto Morini Dart 350
1993 Ducati 750SS
1993 Ducati 750SS
- Harry44
- Member
- Posts: 279
- Joined: Sat Dec 17, 2016 5:26 pm
- Location: SOMERSET UK
Re: Beast and the carb
clanger9 wrote:Have you checked the float level? Should be correct on a new carb, but you never know...
Yes I forgot about that. My new carb it was miles out had to put a shim under the seat.
si is does non opportunus vos postulo a maior pango
- spookefoote1956
- Member
- Posts: 1836
- Joined: Mon May 01, 2017 7:32 pm
- Location: Wales Innit
Re: Beast and the carb
I might try raising the valve throttle needle
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
- clanger9
- Posts: 1165
- Joined: Sat Jun 20, 2015 9:38 am
- Location: Chester, UK
Re: Beast and the carb
I wouldn't muck around with anything until the float level is spot on. Most carbs (especially Amals) won't work *at all* if it's not correct.
An engine will usually start even if the mixture and jetting is miles out (it just won't run properly once it warms up).
The needle position just changes the full throttle mixture. It doesn't affect starting.
Assuming you've got a Monobloc, it's easy to check the float height. Just remove the pilot jet cap and push a length of transparent plastic pipe over the jet. Switch the fuel on and check that the fuel level settles in line with the bump on the float chamber.
If that's right (and the timing is even vaguely right), tickle it and it should fire.
If it chuffs & coughs, dies something is wrong with the fuelling.
If it spits back, it's lean and/or retarded.
If it kicks back, it's advanced.
If it won't do anything, take the plug out.
If it's wet, you flooded it so kick it over on wide open throttle until it fires. Then start as normal.
If it's dry, something is wrong with the fuelling.
Good luck!
An engine will usually start even if the mixture and jetting is miles out (it just won't run properly once it warms up).
The needle position just changes the full throttle mixture. It doesn't affect starting.
Assuming you've got a Monobloc, it's easy to check the float height. Just remove the pilot jet cap and push a length of transparent plastic pipe over the jet. Switch the fuel on and check that the fuel level settles in line with the bump on the float chamber.
If that's right (and the timing is even vaguely right), tickle it and it should fire.
If it chuffs & coughs, dies something is wrong with the fuelling.
If it spits back, it's lean and/or retarded.
If it kicks back, it's advanced.
If it won't do anything, take the plug out.
If it's wet, you flooded it so kick it over on wide open throttle until it fires. Then start as normal.
If it's dry, something is wrong with the fuelling.
Good luck!
1989 Moto Morini Dart 350
1993 Ducati 750SS
1993 Ducati 750SS
- spookefoote1956
- Member
- Posts: 1836
- Joined: Mon May 01, 2017 7:32 pm
- Location: Wales Innit
Re: Beast and the carb
Stupid question but I do block the end of the tube? Supposing the fuel does not rise to the appropriate level how do I alter the float height?
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
- Harry44
- Member
- Posts: 279
- Joined: Sat Dec 17, 2016 5:26 pm
- Location: SOMERSET UK
Re: Beast and the carb
http://www.ebay.co.uk/itm/RKC-SHIM-AMAL ... xyjFpSTDon
Bend the tube around so that you can compare the level against the dot under the word Amal. The fee end needs to be open so the fuel can find its true level.
Bend the tube around so that you can compare the level against the dot under the word Amal. The fee end needs to be open so the fuel can find its true level.
si is does non opportunus vos postulo a maior pango
- Expat
- Member
- Posts: 1033
- Joined: Thu Nov 12, 2015 2:22 pm
- Location: Tennessee, USA
Re: Beast and the carb
As Harry said,
Just hold the free end of the tube alongside the carb and an inch or two above the 'dot' on the float cover. Fuel won't overflow.......unless the float needle isn't shutting off, in which case fuel will be spewing out of the carb throat anyway
Regards, Steve
Just hold the free end of the tube alongside the carb and an inch or two above the 'dot' on the float cover. Fuel won't overflow.......unless the float needle isn't shutting off, in which case fuel will be spewing out of the carb throat anyway
Regards, Steve
Keep shiny side up.
These are my principles, if you don’t like them, I have others. (Groucho Marx)
These are my principles, if you don’t like them, I have others. (Groucho Marx)