Hi!
I am building a Locost with a Honda CBR1000 engine (3 years so far!) and am having grief with the carbs. I am using a Red Top pump via a Malpassi regulator (I have adjusted this to replicate the fuel height given by a bike tank). It starts, but only with choke, and even then it is easy to flood. Once warm it idles ok, but the moment the throttle is opened it kills the engine, or if I'm lucky it 'fluffily' revs up the range. The engine is standard (late model with the Keihin VP flat-slide carbs) with the addition of a Powerspeed 4-into-1 manifold and straight-through silencer and a Pipercross foam filter fitted to the base plate which was custom made from a Pipercross blank. Is there anybody out there who can help - or knows a man who can? I have not discounted a possible problem with one/both coils. If anybody is interested I have just made a fibreglass bonnet, with bulge, to suit this installation, and have a mould which can produce some more at cost (free if you can fix the bl**dy carb problem! Cheers.

I'm no expert on bike engines but if this was a car engine I would be looking at the ignition timing.

How is this managed? I guess it's probably an electronic system with a 3D map. In which case there should be a crank position sensor, a temperature sensor and some sort of load sensor - a throttle position sensor or MAP sensor or similar.

Check these are all present, working, wired correctly and plugged in.

Also check coils, ignitors (if you have them) and all wiring going to and from all components in the ignition system.

Try some new plugs first but bike electrics are usually very reliable. If it's firing I would look at fuelling. Clean the carbs out or fire some carb cleaner through them and see if it makes a difference. You might be better off with a bike fuel pump and no regulator, they only run when the pressure drops in the float chambers. Is that how the red top works?

Have you had it re-jetted to suit the new air filter and exhaust system??

Adam

Cheers Gents - just found out it's a duff plug lead (muppet)
I was always told to get the ignition 100% before playing with fuelling. Now it starts/runs ok'ish I can spend time on the fuelling. Any comments on Dynojet kits - I'm hearing some derogatory things. I know I'll need a fair bit bigger main jet. Anybody know of a rolling road with bike engine savvy?

Thought I'd fixed it!
Spent all Saturday trying to diagnose it. Two faults! Half of one coil was down (not the lead) - shot off to Bike Hut (Breakers) two s/h coils for £30. Beats 88.50+vat for one new one! Still playing up - looked at fuel delivery. Currently fed by Red top pump via pressure regulator. Set up temporary gravity feed (bottle + tube) Instant improvement, smooth idle and snappy response. Have now put in return line on fuel system, with restrictor (old main jet!) in return line to ensure carbs are fed. All is now sweetness and light.