Scarabeo misfires under wide open throttle..

[smille76]

Hi,

I have a 2005 Aprilia Scarabeo with the 2T carburated engine. Everything is stock on the bike, with only 1200km on the odometer.

Since last week I was able to do 75-80 km/h easily with this bike. However, out of nowhere since friday it will only do 65-68 km/h and I can sense like the engine is misfiring under full throttle, and power is not delivered in a smooth way on the higher RPMs.

The only thing that I've changed is that I filled my gas tank at a different retailer this time and it started to act strangely. Usually I put 89-91 octane, but at this service station, they were offering premium 94 octane gasoline so I tried it off.

Any ideas where to start checking?!

Thanks!

Smille76

[MotoringSpeed]

Don't do that.

http://en.wikipedia.org/wiki/Gasoline#Chemical_analysis_and_production

Specifically read the entry on Octane rating. It's the third down from that link.

Check your plug.

[OldGuy1]

While I admittedly don't know anything about Aprilia's my first guess would be contaminated fuel, but before I went to the bother of dealing with that I'd change the spark plug. There's always he possibility that plug failure is the problem and the change in fuel supplier's is just coincidence.

[smille76]

Thanks !

I solved my problem.....

First, I siphoned about 3/4 of the suspected fuel and replaced it with 89 octane from my usual gas station. Then, I changed the spark plug. It had seen better days. And finally, I cleaned the airbox and filter. It was a greasy mess down there, looks like the previous owner abused on the oiling part of the filter.

The engine now pulls strong and hard as before.

Thanks!!


SM

[OldGuy1]

Good, You're welcome.

[smille76]

Hi!


My problem has reappeared after about 2 weeks.

Here's a brief summary. Engine bogs down when WOT. I park on the side of the road. I remove the spark plug, (looks nice), put it back in, and when I resume my riding, no more bogging and top speed can be achieved.

I park my scoot at the store for 15 minutes and start back.....same thing, engine bogs down under WOT.....remove the plug, put it back in......no more problems.

Any ideas?Thanks!

smille76