Xciting 500 arbitrarily slow, doesn't rev up normally

[guile]

Guys, my Xciting 500 arbitrarily slows down. It sometimes doesn't want to rev up the way it used to...
It's about 40 degrees farenheit and very rainy here. Could that explain it?

Any ideas??

[BigOrange]

fuel injected or carb?  How old is the bike?  How old is the carb? How often do you ride it?  How many miles?  Does it need a valve adjustment?

[BigOrange]

I am going to guess it has a carb.  Piston / Diaphram needs to be replaced in Carb.

[guile]

fuel injected or carb?  How old is the bike?  How old is the carb? How often do you ride it?  How many miles?  Does it need a valve adjustment?

It's a carb X form 2006. I ride it daily. It has around 20.000 miles on it; valves were recently checked, but no adjustment was needed.

[Vivo]

I am going to guess it has a carb.  Piston / Diaphram needs to be replaced in Carb.

Sounds like it too...

[guile]

Can anyone tell me which parts I will be needing?

http://www.yorkcyclesak.com/oempartfinder.htm#%2fKymco_USA%2fSAA0AE_Xciting_500%2fCarburetor%2f2K03110005%2f2K03110041

[Vivo]

You really have to actually check which part is damaged...

[guile]

Thanks. Please explain what to look for. I'm not yet experienced  with a carburetor.

[sissy mary]

Lift the seat and take off the plastic carb access cover. There is the top of your carb. Remove the 3 or 4 screws that hold the cover/round bowl looking thing. There is your rubber diaphragm/slide. Look for tiny tear. Mine looked fine until I pressed very lightly around the diaphragm with a very small screw driver. By pressing on the rubber D I could see where it was torn about 2/3 mm. That's all it takes. I would take it to a dealer. It is only about a 10 minute job. U can do it your self, but sometimes you have to apply grease to the new D to make it stay seated in the recessed grove in the top of the carb to be able to put the cover/top of carb back on. It also has/is spring loaded. No big deal. But remember that it is there so you will not drop and lose spring. It's not a strong spring, but it can pop off and drop to ground. Also when u pull slide out, the needle jet will fall out when turned over. It's all very simple, but if u have never worked on a carb before, maybe it's better to let the shop do it. I think the part is under $40.00 They go bad due to the crappy gas we now have. Good luck.

[sissy mary]

Sorry, did not see your link. There are 4 screws to remove. Vacume piston comp. 1402-828-2601. $46.28 In the exploded view u can clearly see the needle and such. The needle and little plastic piece just drop down inside the the top part of the new VPC. Drop those inside the new VPC apply grease to outer edge of rubber D, slip/snap down into recessed grove in top of carb, place spring in middle of cover, replace gently to seat cover on carb, replace 4 screws and your done.  

[guile]

Thanks very much Sissy.

I went to the dealer and he took the diaphragm out and he did not see any faults. He thinks it has to do with a too lean mixture that in cold weather acts up. He tuned the needle fot a richer mixture around 4000 rpm. He said a richer mixture in higher rpm's needs a different jet.
I took it for a testride and although the engine feels a bit more lively it still won't pass 6500 rpm (+/- 80 mph). Coming out of a slipstream of a big truck it picked up all of a sudden and revved to 8000 rpm; a minute later it stalls again... (to explain the high revs: the X has a Malossi Multivar variator installed; almost 18.000 miles on it now).
It's a weird problem all in all; very unpredictable behaviour.

[sissy mary]

I don't know if the mallossi var has anything to do with it? But maybe the fuel pump is going out/not enough pressure? Maybe tech can measure pressure of pump? 

[BigOrange]

Have you replaced the diaphram before?  No. It is the diapharam.  I don't care how many miles it is still a 7 year old rubber component.  They wear out.  It is your issue.  Your gas mileage was great, right? On the flat no problem any hill even a small one like rolling a boulder uphill and no power.  It is the diapharam.

Replace it and go back to the original setting on the air fuel.  These machines are finnikey when you screw with the air fuel mixture.  Too lean burn the piston crown, too rich foul the plugs.  Clean or replace the air filter as well.

[sissy mary]

I agree with big o. I would also add a new fuel filter.

[guile]

Have you replaced the diaphram before?  No. It is the diapharam.  I don't care how many miles it is still a 7 year old rubber component.  They wear out.  It is your issue.  Your gas mileage was great, right? On the flat no problem any hill even a small one like rolling a boulder uphill and no power.  It is the diapharam.

Replace it and go back to the original setting on the air fuel.  These machines are finnikey when you screw with the air fuel mixture.  Too lean burn the piston crown, too rich foul the plugs.  Clean or replace the air filter as well.

Thanks for your reply. You convinced me to buy a diaphram. I will post the results as soon as I have it in ans installed.

I replaced the air- and fuelfilter recently so I don't expect problems coming from them.

The tech said he tuned the mixture a bit richer (he sais only half a millimeter). How should I put it in its original state? Up or down?

Thanks again you all for your replies!