Lumpy when riding

[donk]

eh up all,

Just need to pick your brains!!. On a ride out yesterday it felt as though the bike was running lumpy, it kind of surges when held at a set speed. It goes when i nail it but as soon as i cruise again the surging comes back.

I bought the bike with a 2 into 1 and have recently gone back to standard, i never noticed it when the 2 into 1 was on.

Do you think i just need the carbs setting up/balancing??

cheers all

[Stratman]

If you've changed the exhausts then it will need setting up for them, esp.going from 2-1 to 2-2

[Mick B]

Mine seems to be doing this since I drilled a few holes in my exhaust.Loads of power when you open up but nudges back when cruising.I have noticed it is worse when the weather is cooler or damp so thinking it may be running a little lean.When its very warm its hardly there but when the temprature drops its very noticable when cruising in traffic.

[donk]

Oh mick, i hope it don't get any worse, i have just drilled 3 holes in each of my standard cans!!!

I think perhaps i should book it in and get the carbs done!!!

[sirch345]

If the spark plugs are good and the air filter is also, you could try balancing the carbs, if you've not done so recently.

Chris.

[Mick B]

Oh mick, i hope it don't get any worse, i have just drilled 3 holes in each of my standard cans!!!

I think perhaps i should book it in and get the carbs done!!!

Cant say this is the cause but its the only started since the pipes were done.My bike may have been on the lean side and drilling holes pushed it to far. Most people dont notice any problems to be honest. But the cooler the weather the worse it feels.

[Pete.L]

Sounds lean to me.
Surging on a steady throttle is always lean.

Pete.l

[Mick B]

Following on from this I have just found this pipe along side the bottom of my tank.I have traced it back to the underneath rear breather of the petrol tank is it supposed to attached to something or left open?
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[Phil-VTwin]

If thats the tank breather then it should be left open, however it is normally routed to the bottom of the bike with the fuel tank overflow and coolant overflow pipes.

[tony.mon]

Yep, normally bundled with other breathers to exit under the front LH side.
Drips onto the aftermarket bellypan if one's fitted, otherwise onto the road.
Tuck it away and forget.