Sounds like maybe a cylinder isn't firing meaning you're getting a load of fuel dumped into that cylinder. Would also explain the rough idle. Bag of spanners sounds also is a little worrying! If it was me, I'd not try and and run it again until I had done a little more investigating!

If it's pumping fuel out the plug hole then that carb is flooding,
I've just had the same thing today on a bike, it pumped petrol all over me!
Pull the floats off and spray the fuel valve and seat with carb cleaner that should sort it.
It will be worth putting a fuel filter inline as well, that will stop any more crap gettin in the carbs.

What I meant by bag of spanners was a shite exhaust note. The engine turned over fine when I checked the plugs for sparks.

I think it's the rear plugs, I'll swap them round tomorrow and see.


@dobbs

I'll get some carb cleaner tomorrow then! Not putting an inline filter in, I've heard they can cause problems at high rpm.

Not if you get a large one, it'll have enough capacity to hold full throttle for a while.
My FZR has one and ran 2 miles flat out at Bruntingthope air strip with no problems.

Fixed it!

I think it was a combination of dirty float valve filters and knackered old spark plugs.

Went to get some carb cleaner this morning and just asked if the autoshop had any ER9EH spark plugs in and to my amazement they did! £12.99 each though! But I thought sod it, I'm not waiting for some to come mailorder when I could have my bike back working today.

So I cleaned out the float valve filters, which weren't great. Then looked at the state of the petrol tank, after draining it, and it was spotless. Strange, but I think the dirt was just stuff that wasn't rinsed out properly when the carbs were ultrasonically cleaned.







After doing all that I thought sod it, I'll just stick these new plugs in. New vs old on the plugs shows the old were pretty damn old.



Got it all back together after turning the engine over by hand to make sure everything was okay and I wasn't missing a dropped/bent valve or something, and it fired up lovely after the carbs had filled with petrol. Idle was spot on once warm, there was no smell of petrol from anywhere, and the pick up on the revs was much better than before.

http://s1126.photobucket.com/user/olive ... 1.mp4.html

All in all, pretty happy it wasn't anything worse! Hope these new plugs last at least as long as the old heavily abused ones did.