Hi I am not at a loss as to what to do next with my 906 in terms of getting her to run OK. I have got her to run beautifully in the garage for anything between 2 and 20 minutes. Then all of a sudden she will only fire on one cylinder. (Horizontal). Pops and bangs through the exhaust when this happens. I have assumed this was to do with the Weber fuel height and pressure. Bike was previously laid up in dry storage for 10 years- no idea why (maybe this!) Replacement electric pump was previously fitted but no pipe work. New fuel lines and a new filter added by me.
Pump,is a facet low psi version (1-4 psi off the top of my head) whilst convincing myself I had a flooding issue I also fitted a Holley pressure regulator(1-4psi range). This is set right at the bottom of the range.
The carb was ultrasonic ally cleaned and a refurb gasket set used ( this included a new valve and seat for the fuel chamber part.
Sometimes it will only start on one cylinder sometimes 2, other times it will fire up on two then fall back to one which could happen in 30 seconds or 5 minutes.
I swapped over the coils in desperation but no change. Connections to it all clean and tight. Three way connector to it opened up, male side cleaned up and female side nipped up slightly to ensure good connection. The AMP connection was also a opened- some evidence the female side had been distorted a bit but still connecting to male blade side OK. ( have ordered a replacement just so I can be 100%). Connector block to ignition unit pulled off and reinserted- all seems fine.
I'm now at a loss as to what to check.
All I can think of is change filter as it may have become clogged up from debris in side tank ( inside actually quite shiny). Clean the carb -3rd time!!
Can anyone please suggest some ideas! I'm getting frustrated as when she does run she sounds great.
Best regards
Keith MM in SE London

Hi have you checked the valve clearances? If the are wrong when it's hot they may not close properly and cause a back fire?

Hi thanks Benelliman. A good suggestion. However, as part of the recommissioning of the bike I checked and reshimmed the valves. They are as close to perfect as possible. It's almost like there is a switch being turned on and off causing my problems. Which of course indicates an electrical issue. However, knowing the Weber have special issues I have focused on this. As I type I'm thinking if they were being flooded it would effect both carbs? Any thoughts readers? If it's not the coils or the wiring I'm now looking at the magic ignition box? Anyone know of spare I can buy?
Keith MM in a very wet and windy

check the bottom of the ignition switch, pull it off and see if its burned

Hi, you could try swapping the ignition coils over? If the fault moves to the other cyclinder then that would indicate a faulty coil? But if it remains on the same cyclinder this rules out the coil?
Good luck

Tried the coil switch over- no change.
Never even thought to check the ignition switch Higgy- sounds like you have experience of this wierd cause of the fault. I'm now onto it.

Keith MM

all grounds, all connectors and the ignition switch and kill switch need to be gone over


as a last resort check the plug wires


the wiring mod in the 906 f.a.q will go a long way to make it more reliable

Well this may be premature but I may have sorted the beast. After one of its regular ' I'm going down to one now' routines It bloody well ran on the other cylinder and stop on the previously ' good' one. Back to the carbs then!!!!. With the air box off I gently sprayed a little quick start done the offending throttle body. She would then kick back in for a moment. Quick blow down the main jet (the long one) and she ran cleanly again. Took the top off and noticed some bits at the bottom of the float chamber. Not sure how they got there as its a new filter. Anyway, yet another carb clean and a new filter and touch wood she has consistently run on two for the longest ever period. Took her out for a naughty spin around the block ( no MOT yet- hopefully Saturday) all went well. It's a long time since I rode a paso but she ran cleanly up to 8 k but there was never any great urgency or pull. Maybe I'm spoilt by 150 bhp of the multistrada. I have left the new fuel regulator on but it's way down at the bottom of its range. Maybe I need to open it up a bit? Next job is the replace the two wires coming from the alternator. They have been replaced with fAr too thin guage wire which has cracked insulation and looks like rubber sheathed cable from a 1930's house. Also get bloody hot. Wish me luck but it seems she is nearly fully rescued!

I can't be sure for the 906, but when I installed a pressure regulator on my 750, it ran best at just below 3 psi - around 2.8 -2.9 psi.

Thanks for that, this is really useful. I did purchase a pressure guage so I would have some idea where it was set. The high quality Chinese item I purchased proved to be a bit less than optimal I.e. It didn't work. Have ordered a different one so hopefully I can set it to something like your suggestion.
Best regards
Keith mm