Bogs down at 5000 rpm

[Ray Man]

This is my first post.  I have a 2006 Xciting 250 with about 17,000 miles.  Lately, when I accelerate, the motor bogs down at 5000 rpm.  I can open the throttle all the way up and most of the time it will take 5-15 seconds before anything happens.  Then it takes off like a cheetah.  I have changed parts in the variator, but now I suspect something isn't right in the clutch assembly.  Any ideas?

[zombie]

If it gets to 5k it really doesn't sound like a clutch issue. When you say it takes off like... Is that more of a take off than normal? I suspect carb issues. Thinking it leans out from a partially clogged main or fuel filter, and since you have the rpm's up it takes off lean, and screaming. also it may be a vacuum leak. Does it idle normally? or kinda surge at idle...

[JustWantToRide]

I'm with Zombie on this one - it sounds like the carb to me.  I would guess that your float is sticking.  Get e rebuild kit with a new float, new jets, and new seals.  Also replace your fuel filter unless you've done it recently.  If you don't know how to set a float level then get someone to help you or have a shop do it.  It isn't hard but it is crucial that it is set to the right level and the tangs aren't munged.

Poor man's temp fix.  If it started after hitting a hard bump then the float assembly might have shifted a bit to one side.  You can try tapping the carb from the left and riding it, then tapping from the right and riding it.  It doesn't work often - but it's free and easy.  After 6 years the carb could use a rebuild kit anyway.

[Ray Man]

A little more info.  Once the idle jumps past 5000-5500 and I am cruising, there is no throttle problem.  I can accelerate as before.  After it bogs down, when it does take off it is immediate.  Like having the rpm up and dumping the clutch on a standard transmission bike or car. Also, when I have the scooter on the stand, the throttle can run up to 7k rpm easily - no bog down. 

[JustWantToRide]

Still sounds like the carb to me.  Could be a sticky float (dirty, saturated, or misaligned), could be a problem with the diaphragm (dirty, corroded, cracked)...

Riding on flat ground - will it run through the rev's cleanly if you give it just enough throttle to keep accelerating?

Had it not been ridden in a while, did it get ridden in the rain or parked outside in really cold or damp weather?  Has it only been doing it on this tank of gas - can you add gas to see if it helps?  Did the problem come on gradually, or just suddenly start happening?  

When it does it - can you back off the throttle to stop bogging - and still accellerate (like at 3/4 throttle)?  After it does it and then clears, if you let off the throttle to let the revs drop back down to 5000 will it do it again?

Free and easy things to always check -

What does the spark plug look like?  An old weak spark plug or a loose cap *could* make it act this way.
Is your airfilter clean and seated correctly?

[Ray Man]

On flat ground, it is the same whether I accelerate slow or fast.

I ride whenever I can and it never sets more than I week.  It has been misbehaving for a few tanks of gas.

When it bogs down, it doesn't matter whether I back off the throttle and reaccelerate slowly or hold it there, the result is the same. 

Once it clears and I am cruising, I can let the rpm drop below 5000 and I am ok when I accelerate again.  It seems to bog down from stop or while slowing to 10-15 mph.

[zombie]

Well you started off thinking it is a cvt issue, so why don't you take it all apart to inspect/clean it all up. Make sure you get a new belt. Everything in there really... Rollers, and what ever else is worn. 17k don't mean much but 7 years does. There is a lot of plastic in there that degrades on its own.

[Ray Man]

Thanks, I will give it a try.  I will post back when I get 'er done.

[zombie]

Please do...

[BigOrange]

I have a very similar problem.  My scooter is quick on flat ground.  Bog's between 5 and 6000 rpms.  Local shop thinks diaphram wants to replace the whole carb.  Should I do, spark plug, air filter, and carb.  I am not handy enough yet to rebuild a carb.  I just want it to run better.  I love the new scoot 2007 Orange Xciting bought with 7500 miles put 800 in 2.5 weeks.  I had the seat redone will upload photos it is awesome went two tone marine grade vinyl.

[zombie]

The problem with the diaphragms is the Ethanol in fuel. They swell about 1/3rd larger, and loose responsiveness. The cheap cure is to buy another ebay carb for new parts, and swap it yourself. 3 screws total. One for the acess plate, and 2 for the carb cap. The trouble is it will happen again, Sea Foam in every third tank negates the problem or buy ONLY non E fuel... Marinas/airfields/race shops even NAPA sells c12 race fuel... Sea Foam is the cheapest way out.

[BigOrange]

I live in Arizona it is ethanol by 10% all the time.  I have similar problems. I too cleaned the clutch inspected the belt, new rollers, oil, seafoam each fill up 6-7 maybe 8 so far.  It probably needs new carb or rebuilt.  Should I plunk down the $250 dollars for a new Kymco OEM carb or buy a Cheap Chinese clone made with Kymco jigs in China.  I can buy a carb that looks identical to the Kymco for 1/3 of the price.   

[zombie]

That part is the tricky question. Get the OEM number, and search with that. You will find the manufacturer if it is NOT made in a kymco plant. For example the CDI's are made by Suitai. That will help find the cheapest price. If you only need the diaphragm, and a filter or whatever... Buy the cheapest one. Or you can seek out a rebuild kit from a scoot repair shop.

[BigOrange]

Oem carb Keihin 30mm Cvk.

Replaced air filter, new transmission oil, cleaned carberator, replaced diaphragm, slide and clip 3 holes in diaphragm.  Oil change and rollers couple of weeks ago.  New scoot now.  It is a Big Orange rocket.

2007 xciting 250 8300 miles 800 miles in last month.

Diaphragm was the game changer on the performance.  I  cannot wait to rid tomorrow.

[Ray Man]

Okay, it has been a while since I last posted.  I replaced the ramp plate, plate guides, and rollers.  Pretty much the same problem existed.  I pulled the driven pully and clutch.  I moveable driven face has three angled notches where the roller guides ride as the moveable driven face moves in and out.  The notches were galled quite a bit on the load side.  I believe this prevented the moveable face from moving in and out smoothly.  The wear is very significant to the point where the roller guides would get stuck on the head of the roller guides.  I have a new moveable face, seals, o-rings, and outer spring collar (it shows signs of wear) ordered.  The moveable driven face shows blueing around the angled notches as though it has been very hot.  This could be from the manufacturing step where the notches are cut out.  Parts should be in the week of 4/16/2012.  A will put everything back together and report on it then.