1100M Fuel Starvation?!

[nickm]

Hi there,

My 1100M is fairly standard and has the 40mm carbs,, full akra system and a k&n with the small aperture rubber ring fitted.

Over the winter, the bike was laid up and I rebuilt the fuel tap with a tourmax kit. Anyway, after its winter lay up, I have noticed that on extended high speed riding (eg 6000rpm in top for a couple of minutes), the bike seems fine, but when you come to slow down, it drops down to three and doesn't wanna blip for downchanges. If you leave it idling for about minute, it then picks back up to four cylinders.

I have changed the vacuum hose from the tap for a new one and on the rebuild, sucking it gave the desired results. The tank is venting ok, as I've changed that. Bike has the correct iridium plugs fitted also, and I assume the coils are fine as surely it would drop on two cylinders if this was the problem?

So, I wonder if at 6000rpm its well in the main jets and there's some shit in the carbs (unlikely I think, as they were spotless last time I had them apart)?

Or is my tap Donald Ducked and are the rebuild kits poop? A new tap is 170 quid from robinsons!! Has anyone else had problems with the rebuild kits?

Thanks guys,
Nick

[nickm]

Here's the bike!

[gsx]

Running it on prime should eliminate problem if it is a fuel tap problem . Pingle fuel taps are about hundred large ones but . . . On , off , or reserve , sorted

[nickm]

Thanks. Running it on prime does seem to sort it, so I'm guessing it's the rebuild kit in the tap.

Looking on the internet, it seems a lot of people don't have much success with these kits? Has anyone rebuilt one with success??

[jaydee]

If the bike was lying up for the Winter, one of the main jets could have got a little gummed up with fuel starting to break down. It doesn't sound like a tap problem to me. The carbs may have been cleaned before the bike was laid up, but the fuel may have been breaking down in to a sticky resin which can block jets and affect the float needle operation also.

[wsn03]

I don't have experience of your bike, but I've had a similar sounding issue with blocked PILOTS - they are so small it takes nothing to block one. If you dont use fuel stabiliser the fuel in pilots turns to glue (small area) and can block them.
It affects cruising, tick over etc. Myself I'd just whip the carbs off, remove the pilots, soak in thinners over night, then blow them dry with compressed air.
Good luck.

[rusty]

I use a pingle tap on my 750 coupled with a decent fuel filter and its never been a problem only having on and off

[nickm]

Thanks for the replies guys. I swapped the fuel tap over from my other slingshot - I know this one is fine - and took it out again this evening. It was fine when cold, but once warmed up, sustained running at 6000 rpm in top and it fucks about again, dropping to either 3 or 2 cylinders - I can't really tell due to the wind noise.

When you pull over, it jumps back to four after 30s or so. Bike has new ish iridium plugs, so I'm gonna pull them when its cooled and see if they tell a story. Given that it seems to do it when hot, I wonder if its a coil or plug(s) breaking down?

If I can avoid taking the carbs off I will, as it still has the airbox and looks like I will have a fight on my hands to do it. Does the fact that it only does it when hot smack of electrical issues? Or should I just face the inevitable and get the carbs cleaned?!

Thanks guys!

[gsx]

If you can get at the float bowls try removing and filling with carb cleaner or drain the petrol and empty a tin down your petrol pipe .
Worked for me when no 4 was pissing about after a strip down , started it up and the cleaner gets dragged through everything , only a fiver and nothing to lose

[nickm]

Well, after reading about Profi Fuel Max additive elsewhere on here, I dumped some of this into the tank after filling up tonight and it seems to have sorted the issue after about 15 miles of riding!!

Hopefully, its shifted whatever gunge was causing the issue and fingers crossed it stays running well. Pulling the plugs shows its running a bit lean though with the akra pipe and k&n filter - I think it must be on the standard jetting still - so the next step is to get a factory pro jet kit and find a dyno... thanks for the help!

Anyone know any dynos good with carbs near Canterbury?!!