KymcoForum.com

thanks sid

i've ordered a new battery as a starter for 10.

I'm learning a lot, but this is getting expensive! 

Thanks for this, Spidrgr.
Interestingly, here's what just happened on my way home tonight:

0. As discussed, I left the bike at the office last night after it died, and when I tested it at lunchtime it still had poor power when I started it up.
1. I trickle charged the battery after lunch for 4 hours
2. I put the battery back in the bike this evening and it ran fine for 3 miles.
3. Then it died back again to low revs and low power. It stayed like that for about 4 miles whilst I rode slowly at lower revs
4. Then it suddenly picked back up again and worked fine for the last mile of my journey.

Mental. Could too much engine oil be the cause of this? Ie. when hot it expands and the power goes, then when it cools back down again, the engine runs ok? Anyway, I've drained some oil out, cleaned the spark, recharged the battery and replaced the fuel filter tonight so let' see what happens in the morning (UK time!).

Spidrgr to answer your questions:
1. I can't face reinstalling the original jet. I don't think it's this as the bike has been working fine with the current jet (if intermittently)
2. Restrictors in the air box...I didn't even realise these existed - probably one for later - I'd rather get it running normally first
3. The plug when I took it out tonight was black on the metal part around the white central "island", but the island was white, not black
4. Engine is losing revs. It's not as if someone was applying the brakes. Acceleration dies to super slow and top speed drops to around 28kph
5. oil level in the rear transmission - I replaced around 2000km ago, but you're right I will check this weekend
6. Rear wheel spinning freely when on centrestand
7. Fuel - I have thought this too, but I cleaned out the fuel lines, and fuel was flowing freely under gravity
8. Fuel petcock - Tested this a month ago and was fine, so don't expect this is the problem.
9. Does the engine regain it's power? Not after being stopped for a while. However if I recharge the battery, it will regain it's power after being stopped and the battery charged.
10. No evidence of gas leaking, plus have decent mpg still.

No oil on the floor
No oil evident inside the clutch/variator casing, and no oil on the belt
Never opened up the crankcase so can't comment there.
Air filter stock
Don't know what jet was in there before, but suspect it was actually the stock 80 (the last owner doesn't know if it was rejetted or not)
No obvious leaking around the drain bolt or oil filter.

Plug always looks fouled to me but I checked and cleaned it immediately before the oil change so I can't imagine it's clogged up that quickly? Is it possible for a plug to foul up in only 7 miles of running?

What's odd is that after the oil change it was running fine for 7 miles (say 30 minutes) then slowed right down. Now when I start it it's already in the "go slow" state.

Maybe it is the spark, but that would mean either it's set waaay too rich, or there is too much oil in the cylinder ie. failed piston rings. Correct? Or possibly weak battery - I did briefly charge the battery before I started the 7 miles. Does it make sense that it would produce a weaker spark after 7 miles of riding? I thought they charged as they went?

Maybe that's it? Any thoughts?

Valves - yes checked these. They're within service limits
Carb - checked, was clean. Replaced main jet with #82 (I have been trying to re-restrict as I think the last owner de-restricted)
CDI - not cut. Original
Belt - new.
Rollers - original 6.5g (I think). A bit dirty but I've given them a spit polish. Within service limits on diameter. Tried 5.5g but revved like crazy.
Clutch - not taken apart. Only taken apart the driven pulley of the cvt. Couldn't get the cluth nut off.

Bikes only done 5000k. Could all this be down to the oil type? Like I said it seemed fine for 7 miles after the change, then died again??

good news everyone. I've been playing round with lots of things on the scoot and now it's definitely broken.

Tried to replace the original rollers with new - that was interesting - the thing revs up to top revs super quick but still accelerates like a turd. also after about 40 miles it's died. I can drive it at around 5mph but any faster than that and the revs drop back to very low again.

Am taking it to pieces and putting it back together again but no idea what's causing the above. Anyone?

More annoyingly, this thing is still under warranty. I think it's been derestricted as it does 37mph (when working). That would invalidate the warranty so I'm trying to re-restrict it. I've replaced the original jet, checked the rollers were original, and now I'm looking at the variator boss.

I've got it out and it has no shoulder on it - it's completely smooth and it's 38mm long by 20mm wide - is this definitely a performance boss. ie. do all kymco agility 50s come from the factory with a shouldered boss? If so I think I've found how the bike was derestricted. Now the question is where the heck do I get an original shouldered boss from? Not so easy...

Any help welcome!

UPDATE: I've just taken it apart again and put the original rollers back in, which I think are 6.5g (I fitted 5.5g temporarily as above). Unfortunately I still have this problem with it not wanting to go over 5mph. If I rev it up, it just dies back down immediately with no acceleration, but I can creep up to 5mph if I take it sloooow. Looking at the driven pulley drive face there seems to be a big black ring of black rubber towards the outside of the face which I'm not sure was there before or not. Also just checked the belt and it's 15.7mm wide - below the service replacement limit.

Not sure if whatever I did last week has toasted the belt somehow.  Aaargh!
New belt ordered...

Thanks Kanbisk. I'll get the battery double-checked and maybe just buy a new one.
Any idea why the spark plug might have gone black so quickly?

ok. just replaced the whole carburetor with new. Still same problems. In fact even harder to start.
Finally got it running - idle problem might have been due to a loose throttle screw - now adjusted and idles ok but I have to have it at pretty high revs to keep it "idling". Not enough so that the clutch engages though.

That done, I turned to the spark. Just had a look at the plug which is only a couple of weeks old and it's black black black. Maybe from all my turning it over to try to get it started? no idea.

Below is an image of the spark plug. video to follow shortly.

In summary, I'm back to square 1 now. Got a running bike, but with no acceleration...

Next step change the battery? I had just been charging when I took it for testing. Could have been wrong. I'm thinking of biting the bullet and just taking it in to the garage.