Skyjet SJ125-23 - impossible problem

[SkyJetDisaste...]

Hellow everyone,

Thank you for this site. I have a skyjet SJ125-23 and I'm baffled with one problem. Chinese bike I know, why bother? Yet we still get it (i regret it too much). Ok for the problem... I'll explain in brief to make it easy:

Nothing was wrong, I returned one day, and parked indoors. 2 days later, I went out, started the bike and let it warm up a little as it was cold.

Put it in first gear and and the moment it revved above 1, the bike switched off.
Started it up again and it switches on first time every time. But as soon as I rev above 1 or 1.5 whether in gear or not, it turns off (even in nuetral)
I took it to local bike mechanics and they do not touch chinese bikes and now I know why. But as he knew me, he gave it a shot (5 months long)
He cleaned the carbs
checked the sparks
Even replaced a new CDI unit
Tried all sorts of other things but he's baffled

I've spent over £1000 in total on the bike and a few parts and i just can't let it go.

If anyone can help me fix this problem, I am willing to pay them £50 (It's not much but I'm giving it with love so it's priceless)

This bike is like your first PC, it's dead and broken but I just can't let it go.

Thanks in advance and I hope I get replies soon.

Yan
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Someone please help me fix my SKYJET - Don't laugh

[P.addy]

[SkyJetDisaste...]

I'm in London (Forest Gate)

I really appreciate the offer
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Someone please help me fix my SKYJET - Don't laugh

[skatefreak]

Is it a mechanical or electrical cut?
Aka does it sound like the ignition is just cut so the engine sound just stops (electrical issue i would suspect)
or does the engine sound deteriorate/get worse/alter (engine running problem).

Maybe a sound recording?

You <40 miles from me, its exam season untill mid next month and if you'v not had any help i'll consider coming down (i maye not be thhaaatttt useful and no doubt will get lost heh).

Best regards

-Jvr

[P.addy]

youtube video would be great...that way we can see exactly what happens, possibly saving a trip!

[SkyJetDisaste...]

Thanks for the replies..

The bike's still at mechanics so I'll see if I can get a video done soon.

Sound: When revved, the engine sounds and goes off almost exactly like when you stall - but remember, this happens whether in gear or neutral.

So it's almost definitely not an electrical problem. He did say that sparks were check to make sure it's not electrical (if that helps)

I don't know much about bikes and repairs (i've changed speedometer and lights etc) but that's about it. Would it be worth bringing back home and give it a shot myself? What's the worse I can do?
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Someone please help me fix my SKYJET - Don't laugh

[CarlosCBR]

Could be the diaphragm in the carb having a tear in it. I had a similar problem on my CBR and i sprayed some WD40 in the carb and it has been fine ever since.

[SkyJetDisaste...]

Thanks Carlos, I will let the mechanic know this tomorrow. I really do hope it's something simple. Thanks again
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Someone please help me fix my SKYJET - Don't laugh

[Jesta_ZX6R]

Does it start up straight away after stalling or does it need a few cycles?
Also, have a look for the rev meter input wire, it might be attached to the coil or one of the wires connecting to the coil power lead, it could be possible that either this wire is shorting against another lead and loosing power that should be going to the coil into a close wire or there could be a fault in the rev counter itself, causing it to ground out or consume too much power. Try disconnecting it if possible, though that may require you to cut the wire which may not be the best option, especially if it turns out not to be the issue, though a simple crimp terminal repair job would fix it afterwards.

You could always check the voltage going into the coil when idling, then watch what happens when you rev it til it cuts out.

[SkyJetDisaste...]

Yes it starts up straight away every time once stalled/cut off.

Thanks so much for the replies and suggestions. I will definitely jot these pass this on first thing monday.
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Someone please help me fix my SKYJET - Don't laugh

[SkyJetDisaste...]

Just passed all these details on to mechanic today. Bank holiday and tuesday he was closed. I was passing these messages on honestly feeling that it's not gonna help but hey, fingers crossed and once again, thanks to ALL replies.

I will still try to get a video done if i manage to go down to the shop.

Cheers guys
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Someone please help me fix my SKYJET - Don't laugh

[N cee thirty]

[SkyJetDisaste...]

a cbr engine ib the skyjet? didn't know that was possible.

costs shouldnt be a problem because he's only gonna charge me on what gets fixed, so far there's been no charge except for previous work.

he's gonna give one last shot at 2 suggestions given on here then he literally said he's had enough, he can't figure it out.


I remembered one more thing if it helps and anyone knows what's going on, a few months ago when they first gave it a shot, the person working on it covered a part of it with his hands that's got something to do with the air (air flow, filter or something like that) and it revved up properly and didn't cut off.

Considering all the info given here, hoping this sheds some light on the issue.

Thank you all once again.
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Someone please help me fix my SKYJET - Don't laugh

[SkyJetDisaste...]

He tried the things suggested. He won't be looking at it anymore as he's said to ask someone who actually works with skyjets, chinese or other imported bikes.

In working condition, this bike is worth around £700-£900 from what I've seen online.

Can anyone suggest how much this would be worth in its state?
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Someone please help me fix my SKYJET - Don't laugh

[steven_191]

does it run at idle or cut out?

id would start by checking the fuel supply, air supply, check for air leaks. also check the plug gap rather than check that it just works. if the gap is too small the flow of air could blow it out or the oil could douse it.

because of the transistion from idle to throttle open id suggest the idle circuit needs checking too. but if it worked before and has not been touched im not sure. you could have some crap in it though if the fuel filter didnt do its job.

[N cee thirty]

whats the air filter like ?

on my cg when the airfilter fucked up,it would start and idle,but once i revved it or tryed to ride away it would just stall
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[cb1rocket]

sounds def. like a carb/fueling issue rather than electrical

[27cows]

It's not got an auto-choke, has it?
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The RXS100: vehicle of choice for Chuck Norris

[stirlinggaz]

hi,
the engine fitted to the skyjet is the 156FMI or similar, & its actually a cg125 clone.
the cbr125 engine is very difficult if not impossible to fit into the skyjet,sorry.
best off tryying to find a replacement engine, they can be had very cheap if you look around.
have a look at the engine model number, usually stamped down below the front sprocket,
these engines are fairly generic & are fitted to umpteenother chinese bikes.
there usually fairly bullet proof tbh, i owned a sky jet some time ago & put 6000 miles on it, with nothing more than a few oil changes within 6 months.
tbh, it wont be worth much in its current state, i paid 900 quid for a brand new one!
cheer,
GAZ

[Gazdaman]

[SkyJetDisaste...]

this is brilliant. You know, reading these replies makes me want to check the bike myself and learn a bit about how they work.

Ok, so I'll give that a shot, air leaks and HT lead (I'll have to check what that is too as mechanic has officially given up)

Thanks once again for all the replies. I really should get the video done but I won't be able to until I see the bike. it's at mates workshop so till then, I'm noting everything here.

thanks a million everyone
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Someone please help me fix my SKYJET - Don't laugh

[27cows]

I've had problems like this. You never let the feckers beat you. Never It's always great when you finally work out what the problem is.
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The RXS100: vehicle of choice for Chuck Norris

[SkyJetDisaste...]

Let's hope I experience the satisfaction of fixing this myself. It's hard to described how much hope I have in this matter. If you take "no hope" and multiply it by the number of chinese citizens, that would probably be close to it.

However, I can say I am looking forward to getting the bike back soon (gotta sort out a van - another downside) and start work on it myself grateful thankful to you guys honestly

Bikers are the most friendy and best people in the world no matter how rough and pissed they look on the outside
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Someone please help me fix my SKYJET - Don't laugh

[Jesta_ZX6R]

Where abouts are you? Someone close might be able to help, aswell as explain some of the points/jargon we're talking about.

[SkyJetDisaste...]