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My scoot has about 6k miles on the odo. The handle’s rubber was probably mechanically damaged somehow (I already bought it like that) - the throttle grip is in good shape). Therefore I want original or an OEM replacement. Probably I will just buy it from the importer in my city, but I would rather replace it myself than pay for the service, as I like doing such stuff and have some experience.

I would just appreciate some “walkthrough” not to mess something up.

Problem solved. After applying 160 NM everything seems fine. I have only driven about 5-6 miles to test but it was only stop-wot-stop. The nut sits as it should. With the little heavier rollers I mounted (10%). Now the specs suit me more. Still I need to figure out how to make the clutch to engage faster (lower rpm), disengage later and be more 0-1 as the dry centrifugal clutches are. This wet multidisc has too much slip for me before fully locking.

Hmm I think I know now (I will test it tomorrow). I tighten the nut according to Kymco manual ~90 NM. But I found a YouTube wideo and than downloaded the j costa manual and it says not 90 but 160 NM for the j costa mount (same nut thought). It’s probably because the j costa bell doesn’t have the teeth on the bell which lock with the teeth in the crankshaft.

I hope it will solve the problem as 160 vs 90 looks like a really big difference.

Hello guys, i just changed my j costa variator rollers in my ak550 for a bit heavier ones (but also recommended by the manufacturer for this scooter).

After a very short test drive (maybe 0,1 mile) and 2 accelerations the tightening nut holding the variatior to the crankshaft got completely loose despite the fact I applied the top recommended by the service manual force (90 nm) using a dynamo metric wrench.

It never happened to me before in any scooter I owned

Any idea what might be the cause? I am thinking about applying blue loctite but its not mentioned in the service manual so it should not happen without it…

Hello Lads and Gents,

I just recently bought my AK550 and I absolutely love it (I've been riding a DT300 for the last 8 years with over 25k miles on it).

My scoot is equiped with the aftermarket J Costa variator, and I knew it has specific characteristics (high revs etc). What I didn't expect (however I should have, as I test driven a few AKs at the dealer shop before buying) is that the AK clutch catches rather high (on mine first signs of clutch engageing comes at 4500 rpm). The above mix results it the fact, that starting from dead stop or even accelerating ie from 15 MPH or 30 MPH (doesnt matter) comes with the revs going up to 6-7k (even if accelerating very softly).

Just to make it clear, I love the acceleration and 7k at WOT is something completely normal, however, it would be really nice if delicate starting from a dead spot or delicate accelerating would come with 1-2k less rpm.

Now the question: how is the best way to do it (I am ok with jeopadizing the performance a little, as the scoot has more than enough acceleration for me in every speed range). Would you start with buying heavier sliders for the J Costa? My first thaught was just softer springs in the clutch, but that i noticed this one has not a simple centrifugal scooter clutch but wet multidisc, so it would be way more difficult if no impossible in modding it to engage at lower rpm.

Thanks for all the tips and thaughts.

I check my valves every 2 inspections (10k km). For the first time the valves (exhaust) needed some minor adjustment yesterday (40k km). All the proces rook about 40 mins (with disassembly and assembly of the scoot).
Peter

Wheels, thanks for your reply. Thats not my case. The spark i under 5k miles and it is not really a high rpm drop, as when i am riding i.e. 70 mph on 6,5k rpm, then when i throttle up, the power is there and its ok.