Single carb on Mastiff AGAIN!

[AIRMANBEAR]

THANKS FOR THE TIP.... YOU MUST BE FROM CORNWALL OR DEVON... WHERE MY FAMILYS FROM IN 1620s..... IVE RIDDEN THERE OFF ROAD ..
I HATE THOSE 2 CARB SET UPS AND MINE AND G STARTED STICKING THE THROTTLE PLATE … AND HAD TO BUY ANOTHER SET WISH I AHD SEEN THIS ARTICLE FIRST .. TO WIND UP WITH ONE CARB … NOW IM HAVING TROUBLE WITH LOOSING SPARK OVER 2500 RPMS...……….? A MYSTERY SO FAR...on my SCORPION.. 1996…...ANY SUGGESTIONS..???
ED N.Y. USA …...

[breakwellmz]

As good as it performs, I feel i must be missing out on upper rpm power by so crudely reducing inlet breathing as well as reducing total carb area. The airbox is now much more `open` as well.
I`m thinking of possibly re-utilising the blanked-off  LH head port adding a small (24-26mm) CV carb., actuated  only by vacuum from the left hand port.  (a slave carb?)
No butterfly, cable, choke and maybe even a blocked off idle system (the starting, idle and low to mid speed response are really good with the pumper CV carb.
Any thoughts most welcome.

[DAVID THOMPSON]

we are all EARS keep us informed
Dave

not looking for big hp just some thing that runs NICE

wife keeps saying "sidecar" every time i go to work on any of the bikes

[breakwellmz]

Well here is the latest version.
Link port within head joining the two inlet ports has been blanked off so LH valve supplied only by what can be dragged through the 14mm ID copper pipe.
The engine feels freer(?) to rev without loss of bottom end, instant starting and solid idle, less banging on the over-run is a bonus.

[Puffs]

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[breakwellmz]

we are all EARS keep us informed
Dave

not looking for big hp just some thing that runs NICE

wife keeps saying "sidecar" every time i go to work on any of the bikes

Fitted a 150 main jet today to replace the 180 that came with the carb, only a ten minute job. They took a bit of searching out as they had an M6 x 1mm pitch thread rather than M4 × 0.7MM that Keihin CVKs have. https://www.ebay.co.uk/itm/Keihin-Carbu ... 2749.l2649
It just gets better! Far cleaner running on the main jet with no `baulking` on big throttle opening gear changes. I`ve been getting a reasonable 46mpg (Imperial gallon) up to now so i expect that to improve as well.

[DAVID THOMPSON]

found JET on eBay in USA and its ordered from same place you got it in UK
thanks Dave

ouch on the price by the time it gets here...
but where i live every thing shipped in is expensive

and we lost an other bike shop here no one has any money

and riding a bike year around here is hard due to wet really nasty winters

[Puffs]

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[breakwellmz]

The carb was intended for a Harley hence the 180 main jet it came with, i just did a bit of research on main jet sizes for a range of 650cc plus singles and made an educated guess!