After changing spark plugs, oil, oil filters, the bike starts up for 10mins . Runs on 4 cylinders and then changed to 2 cylinders and then dies...

I've checked the spark plugs, cleaned them, checked the fuel, coil packs and it's only running on 2 cylinders


Any suggestions?

Had a similar thing and turned out to be a trapped tank breather which starved the carbs of fuel. First dropped to 2 cylinders and then died.

If you have been changing plugs then the tank would have been off, so I'd just double check that nothing is trapped.

Checked.. It's not that

Have you done the HRC fuel tap mod?

skinnydog0_0 wrote:Have you done the HRC fuel tap mod?

i dont think so, why?

This mod can cause problems with fuel leakin ginto the carbs when the tap is in the off position, and i have had the diaphram in the tap block the outlet so it restricts the fuel and the engine dies.
If you have a vacume hose from the fuel tap to the rear right cylinder head, it is very unlikely you will have had this mod done. If you dont have this vacume hose then;
to check you will need to drain the tank and remove the tap and check that the diaphram is in the correct place and that the spring is present.

It is also possible that the vacume hose (if present) is collapsing when it gets hot, starving the carbs of fuel (this is probably the more likely than the HRC tap mod issues).

I take it the bike was running fine before you changed the plugs etc?

Incorrect pilot screw settings fouling the plugs?

Drunkn Munky wrote:I take it the bike was running fine before you changed the plugs etc?

Yes, i ended up taking the new ones out.. cleaned them put them back in, same thing happened.

and then i took the new ones out... PUT THE OLD ones back in and it works perfectly... took it for a good ride for half an hour and i broke down in the front of a petrol station.. had to get my bike trailered back home and i'm just sitting here wondering whats going on now....

Cammo wrote:Incorrect pilot screw settings fouling the plugs?

I dont think ive touched the pilot screws at all

What plugs are you using.

It's not unheard of for some of these 8mm plugs to be duds from new.