jerking and stuttering and loss of power

[rufus t glasgow]

After a fairly long ride I noticed a small flat spot and some jerking and shuddering around 4k.

I went for a wee spin today and the jerking and shuddering is more pronounced and starts from around 3k and carries on till about 7k.

My fazer had this problem in the past which cleared up after the carbs were cleaned.

Any ideas why the jerking and shuddering has came back?

[darrsi]

Have you been out in any heavy rain recently?

[Punkstig]

One of the spark plugs/ caps failing?

[rufus t glasgow]

Well, it was sitting out in the rain at Leeds festiva for 3 daysl before my long trip home!

[darrsi]

Might be worth draining the carbs i reckon, see if that helps.

[rufus t glasgow]

Might be worth draining the carbs i reckon, see if that helps.

that's what I was thinking, just wanted a second opinion.

[darrsi]

It's a quick and easy place to start.
If you pull water out you may have a dodgy seal on your tank cap.

[rufus t glasgow]

I drained a wee bit of fuel there, it ran clear then was a bit dirty, like rusty water, then clear again.

Took a spin round the block and it seem a wee bit better.

I'll disconnect the tank tomorrow and fully drain the carbs

[ChristoT]

Did you take the bike to the reserve recently? You may have pulled some crap at the bottom of the tank through. According to Exupnut, the best cure for this is a tank of high octane and a giving the engine a thrashing!

[rufus t glasgow]

Did you take the bike to the reserve recently? You may have pulled some crap at the bottom of the tank through. According to Exupnut, the best cure for this is a tank of high octane and a giving the engine a thrashing!

not on this roadtrip, I did a wee while ago. If it still persists after fully draining the carbs I may try the high octane/thrashing thing.

[unfazed]

Sounds like crap in the float bowls generally caused by water in the fuel which causes rust to form inside the tank. Since your bike was in the rain for a few day water may have also lodged in the top of the spark plug caps. This does not evaporate easily as you would expect when the bike heats up as it creates a seal and stays around the connection between the coil leads and the cap. Twist the cap off and maybe cut 10mm off the eads and spray the end of the coild leads and the rubber boot with WD40 before twisting them back on.
The reserve issue as mentioned by ChristoT is not a factor really with the fazer as it does not have a reserve tap, all fuel is taken from the same point low in the tank. Before draining the carbs change the Fuel filter and drain the tank. With fresh fuel in the tank drain the carbs and let the fuel run through for about 30 seconds closing the drain screw and opening it again after about 5 seconds during the 30 seconds on each carb. This helps wash any crap that may have stuck to the side of the float bowl during the initial draining.