Surging

[darrenptalbot]

Ok, real problem with surging/ cutting out. 1999 R1100GS.

I've recently:

replaced the fuel filter
Replaced coil
Done valve clearances
Set TPS

It felt like a fuel starvation problem before doing the fuel filter. I now get surging/ cutting out usually over 3000rpm, or opening up throttle so it would get to 3000rpm if that makes sense. Once past 6000rpm, it's still there, but seems less

Anyone got any ideas, as I'm out of them now!

 

[darrenptalbot]

Ok, doing a throttle body balance.

Using a carb tune II, fine at low speed idle, but when I increase the rpm, one side mercury goes up, the other down! Any ideas?

 

[justabof]

Could it be a displaced throttle cable?

 

[Packer]

Are both butterflies opening correctly and return springs in good order?

 

[boxer]

If the cables are seated okay then the throttle bodies need balancing above tickover - 3000rpm?

 

[darrenptalbot]

Cables in place ok.

Butterflies seem to be ok.

I can't balance over 3000rpm, because when I open the throttle, one stainless things (mercury replacement) goes up, and one goes down. No idea why.

HELP!

 

[Ian J Hartley]

Difficult without knowing the order in which you replaced/adjusted stuff, and whether the bike ran OK in between.

I would be rechecking my valve clearances in case I had mixed up the gap on one side. The side where the stainless rod goes down would be the first to check.

Unless of course you are absolutely certain you have them all spot on.

Ian.

 

[MattW]

First - you have made sure that the throttles are on their stops at tickover haven't you (not held open by the cables)?

Assuming a '99 doesn't have the stupid one piece throttle cable like my '94, adjust the the slack out of the lower cables (making sure that you don't lift the throttles off their stops on a closed throttle) and with the engine not running, twist the throttle while watching the butterflies. Do they both start to open more or less together?

If they don't then you may have a problem with the splitter box

 

[darrenptalbot]

Ran ok after valves. Then a week or two later decided not to. Think throttles all done right

 

[Comfy Old Boots]

I had awful problem with a similar vintage boxer surging. I can't isolate the reason why but it runs fine now. Tips, valves and cable tension all sorted and running fine since.

 

[darrenptalbot]

I think I need to get it into Steptoe, as I'm running out of time and patience......

 

[Uncle Crumpet]

Ok, doing a throttle body balance.

Using a carb tune II, fine at low speed idle, but when I increase the rpm, one side mercury goes up, the other down! Any ideas?

Doesn't that mean you are losing manifold vacuum as the revs rise on that side, are you sucking air from a crack/split somewhere?

 

[darrenptalbot]

Doesn't that mean you are losing manifold vacuum as the revs rise on that side, are you sucking air from a crack/split somewhere?

Quite possibly. Any idea where?

 

[Comfy Old Boots]

Somewhere between the air box and fuel injectors. Get the bike up to temperature (spin round the block) and spray some carb cleaner/brake cleaner over the rubber gaskets that are between the air box and the fuel injectors. If the revs rise or fall (depending on the side) you have a leak.

 

[Steptoe]

Anyone got any ideas, as I'm out of them now!

HT leads .

 

[gspod]

Serviced mine - 1100 - just before the Stella, when I came back same thing surging like never before and cutting out when slow filtering, a right pain.

I blew out the air filter and of course all the crap from dusty trails came out and bike was back to normal.

I'm sure you've already done it but a simple check.

Good luck - I think my starter motor went this morning

 

[Uncle Crumpet]

HT leads .

Or just a shit plug breaking down under load.

 

[Steptoe]

I think I need to get it into Steptoe, as I'm running out of time and patience......

Oh dear, oh dear oh dear. Oh dear oh dear oh dear.

I'll let Darren explain.

 

[MattW]

Oh dear, oh dear oh dear. Oh dear oh dear oh dear.

I'll let Darren explain.

Come on Darren!

 

[Uncle Crumpet]

Dibs on throttle cable was unseated!