ACE 50 - surely not this slow?


New Member
Hi there, first post, but been reading on here for a while.

I've just got a Skyteam ACE 50 for my son, but on test ride it's desperately slow. I don't mean 30mph slow - I mean it's struggling to get above 15mph on the flat! The bike just starts to die if the throttle gets anywhere near fully open. Anyone got any ideas?

It's brand new so I can take it back to the dealers on tuesday, but he really wants to just ride the thing after waiting over a month for delivery! Tried ringing the dealers this afternoon and they admitted they never test rode it as it was raining!
Ok, after doing some reading it seems that it's been known for these to ship with zero valve clearance. I'm going to check that in the morning as the lack of power maybe points there, although idle is fine.

Pulled the plug out and that looks ok I think, but too new to really tell. Definitely not oily - if anything completely clean so perhaps lean? Worth adjusting the mixture or should that not normally be touched on a new bike?

There's allsorts of plumbing between the carb and exhaust too, but not going to touch that yet....

Any other ideas gratefully received!
post a pic of the plug... I'm not expert admittedly but I'm sure someone can help out. if it's running lean I believe the plug would be white-ish off the top of my head. if it's brand new and from the dealership I would imagine it should be setup just fine? or is that too much to assume these days?
HI, If your Ace50 isn't running right and only a few days old.
Hear's a good word of advice,
Don't mess with it and void your warranty.
As you say the dealer didn't test ride it (which they should of done for your safety before letting you take it) then it should be returned to them in the same condition as you took it. Last thing you want to hear off the dealer is that what you have done is the reason it's not right.
You might be right, but I just want to get the thing sorted! Waited 5 weeks for it (when promised it would be two) and can't get it back to them until at least tuesday as they are closed sunday and monday, so probably won't have it back until next week. Honestly never had so much hassle with a bike purchase....and I've probably had 20+ bikes!

I won't do anything to void the warranty, but just want to check the basics.

This is the plug Spark by sagalout, on Flickr
My son went out on it today around the block. It was really hard to start from cold - would run for a second or two and then die. Eventually coaxed it into life. Used an iPhone GPS app to verify the speed. Slight incline (2%). Average speed 9.6mph, top speed 16.1 mph (coming back down the hill). He weighs about 65KG. Bike just bogs when you try and go into 3rd so obviously has no power. Gave the carb screw half a turn which improved it very slightly, but decided to just put it back and wait for the dealer to take a look as I don't have a carb diagram to know what's what.

I did notice that there is a lot of hot air being blasted out of the white valve thing on the left of the bike. It's also pretty much impossible to get the bike into neutral with the engine running. Have to turn it off, rock it back and forth and then it clicks up (with the engine not running). Is that just a case of needing a bit of use?

Bit disappointed so far, but hopefully these are teething troubles caused by a crap dealer. The actual finish on the bike is pretty good - better than expected actually, although the suspension appears to have no damping at all so that will be the first upgrade (after the engine is sorted)
stop messing with it, stop riding it too much, just take it back to the dealer and let them set the bike up right.
Yeah, I'm leaving it alone now - just wondering if the air coming out of the white pipe thing is normal?

I'm tempted to take the bike to a local dealer and pay for them to set it up. Lost all trust in the original place I bought it from. Not road testing a bike during PDI (but ticking the box on the service book) makes me think they are clueless cowboys
I had teething issues with my 125 cutting out. Dealer sorted it and 800k later going strong. Only just got round to sorting out lever and pedal positions to my liking. If you haven't done that yet, perhaps that could pass some time.
Neutral is hard to find on my new 125 too.. But getting easier each time, i think it's just new and should be better after it's worn in. Re the white thing blowing air, I have the same thing happening. Have a look what others have told me in "indicator help" a few threads below this.
Quick update on this. I ended up taking the bike to a local mechanic to have a look over as the dealer was closed on monday. He managed to get it running better after adjusting the valves (inlet had zero clearance) and setting the carb to factory settings and removing the restriction in the carb and EGR (they rang SkyTeam). It was still pretty slow, but would rev through more cleanly but still very lean. This got the bike up to about 22mph, 25 down hill, which was double what it was doing at delivery.

Rang the actual dealer on tuesday to tell them to pick it up and either sort it or refund me. They rang back yesterday to say they have found the problem, and its some silicon in the carb blocking the fuel flow. They've cleaned the carb out and now its pulling much stronger now but revving out at 30 so they are going to fit a new rear sprocket today to make it a bit more flexible. This does tie in with what Suus customs said with their Salt Lake Racer, so I'm really really hoping that when they deliver it back today my lad can actually ride the thing. This bike will only be for 12 months until he's 17 and one of them has already passed just trying to get the bike!

I do love the look of the bike though, and I'm half tempted to buy one for myself (a 125) as a project over winter. It would be a nice 2nd bike and completely different from my GS
Well turns out that was a load of crap from the dealer again. Got the bike back and it's pretty much the same as it was. They never got hold of a sprocket but I wouldn't describe it as revving out, apart from down hill. It's dangerously slow in traffic and there's no way I'll let my son on the road on it.

I'd already ordered a tooth up on the front sprocket so will see if that makes and difference, otherwise will have to try and get money back, or failing that get a bigger engine for it and keep it myself.

Looks like I'm going scooter shopping tomorrow :(
I hope it works out OK for you with the dealer.

To work out what sort of speed you should be able to get out of the 50....

If you go to this site and type Skyteam in the Filter box, you will get some skyteams to select from in the drop down box, pick the 50 and you can see a gear/rpm/speed calculator
It lets you key in new sprocket sizes so you can compare standard to modified.

You may also find the attached document interesting.


  • Ace Torque and Kw Graphed.pdf
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Those figures on the calculation site may be a little optimistic. As i was not really sure what tyre size to use for the standard tyre.

To get really accurate figures, the key is to measure the actual circumference of the tyre on the bike in inches and make sure it matches the calculated figure at the bottom of the page. Just fiddle with the first two tyre size numbers until it does :)

I am also not sure what maximum revs is on the bike, I just assumed 8500 as that is as far as the factory went when they measured torque etc.

Looks pretty accurate going by the Suus customs 39.5mph with the 13/38T.

Does anyone know what the stock jet is in the Sheng Wey carb on the 50? Was going to order a pack of jets to play around with but want to know whats in it at the moment (without opening it up)
is there any way to verify that the ignition timing is working ? that is at full advance at revs.if for some reason the timing is running retarded at higher revs, well there goes yer power and willingness to rev
Right, it's finally up and running properly now, making 35mph on the flat and still pulling 25 up a hill. I'd prefer a bit more acceleration so haven't finished tweaking it yet - think a better carb, exhaust and gearing should open it up a bit more but for now at least he can finally ride it! Took my son for a ride on it to show his grandad this afternoon (also a biker). Was nice to ride around with him, although I need a slower bike....maybe a 125 is on the cards for me as a 2nd bike!

Untitled by sagalout, on Flickr

by sagalout, on Flickr

by sagalout, on Flickr

by sagalout, on Flickr

by sagalout, on Flickr
Good to hear you got it sorted. The bikes look good together too.

What was wrong with the valve?
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