Help with a chinese 50cc scooter - Page 3

stevestrat · 25th February 2016, 15:23

I presume the bike is restricted? I've never had a restricted bike but is it possible its the restriction that is strangling it at full throttle

martinwest · 25th February 2016, 15:45

Hi Stevestrat
I don't know yet as its not been on the road but I have read up on restricted scooters and it slows the bike down by stopping the spark at a certain speed, I have tested it with a strobe light and there is still a spark when on full throttle may have to put it back together and try it so ware legal and see

neilb740 · 25th February 2016, 15:53

I have had the misfortune of working on a bike from the same manufacturer.

It looks like you have covered most things I would try, the only other thing I remember from my fight with the similar bike was that the HT lead was appalling quality.
There was what can only be described as a woodscrew sticking out of the side of the coil, you twisted the blank end of the HT onto it so it screwed into the centre core of the cable.
On the one I worked on this was full of water and rusty.

I didn't have the symptoms you described, this one wouldn't run at all, but if yours is the same it might be worth checking.

martinwest · 25th February 2016, 16:01

Hi neilb740
Thanks for the idea but its had a new coil and lead and the spark will jump about an inch and is bright and crisp with no plug or cap just lead to earth
I think Mr Bone is right petrol and matches but I bet knowing this bike I would have to get mythbusters to blow it up with C4

COLVERT · 25th February 2016, 17:26

Quote:

Originally Posted by Mr Bone

A perfectly jetted S3 triple at Pembrey in cold weather will a week later in similar temperature
at Knockhill (about 600ft higher) run rich and show a fuel mist at the carb mouth. Timing unchanged.
Saying that, its worth checking the spark is spot on first.
If its combusting in the crankcase there will be no need for matches.

Well there you go. A slower burn on a richer mixture which is still trying to combust on the inlet stroke. Hence the mist.-

COLVERT · 25th February 2016, 17:32

Quote.---colvert Hi
The timing is done by a fixed pickup on the flywheel and the CDI unit no adjustment available.

Opening the points gap slightly will advance the ignition.

Sometimes the weirdest things work. Nothing to lose.--

SideValve · 25th February 2016, 20:31

My money is on a dodgy ecu not advancing the timing correctly.

Having said that it might be better it never reaches full throttle -more chance of lasting the full year

A friend of mine used a 125 4 stroke for commuting, cheap as chips and actually very good for the 1st 6 months but pretty tired after that.

martinwest · 26th February 2016, 04:57

Hi sidevalve
Being the only thing that I cant fully check I have ordered a unrestricted one from ebay just to see if it fixes it if not I think the scooter will be going on ebay next week

martinwest · 28th February 2016, 15:07

Ok so after a lot of reading on the net I came across this https://en.wikipedia.org/wiki/Four-stroking

Turns out there was nothing wrong with it in the first place just needed to be on full throttle whilst riding and not on the stand. Oh well its now got some spare parts just in case it dose go wrong

Thanks for all the advice anyway

25th February 2016, 15:23	#21
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,566 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	I presume the bike is restricted? I've never had a restricted bike but is it possible its the restriction that is strangling it at full throttle __________________ Steve T4 Location Map

25th February 2016, 15:45	#22
martinwest Regular poster MG ZT + Join Date: Jul 2009 Location: Bedfordshire Posts: 88 Thanks: 10 Thanked 12 Times in 6 Posts	Hi Stevestrat I don't know yet as its not been on the road but I have read up on restricted scooters and it slows the bike down by stopping the spark at a certain speed, I have tested it with a strobe light and there is still a spark when on full throttle may have to put it back together and try it so ware legal and see __________________ [SIGPIC][/SIGPIC]

25th February 2016, 16:01	#24
martinwest Regular poster MG ZT + Join Date: Jul 2009 Location: Bedfordshire Posts: 88 Thanks: 10 Thanked 12 Times in 6 Posts	Hi neilb740 Thanks for the idea but its had a new coil and lead and the spark will jump about an inch and is bright and crisp with no plug or cap just lead to earth I think Mr Bone is right petrol and matches but I bet knowing this bike I would have to get mythbusters to blow it up with C4 __________________ [SIGPIC][/SIGPIC]

25th February 2016, 20:31	#27
SideValve Gets stuck in Rover 75 Saloon Join Date: Apr 2012 Location: Oxford Posts: 767 Thanks: 141 Thanked 204 Times in 141 Posts	My money is on a dodgy ecu not advancing the timing correctly. Having said that it might be better it never reaches full throttle -more chance of lasting the full year A friend of mine used a 125 4 stroke for commuting, cheap as chips and actually very good for the 1st 6 months but pretty tired after that. __________________ The Story So Far: Austin A35, Morris Oxford, Triumph Herald, Mini 850, Mini 1000, Austin Allegro, MG Midget, MGB GT, Rover SD1 2600, Austin Maxi, Rover 200, Rover 825, Rover 800, Bedford TK, Range Rover 3.9 efi, Rover 400, Rover 100, MGF, Rover 25, Rover 75 1.8, Rover 75 Connoisseur SE 2.0 V6, MGF 1.8i, Rover 75 Connoisseur 2.0 V6 Auto, Morris Eight Series E, Morris Minor 1275.

26th February 2016, 04:57	#28
martinwest Regular poster MG ZT + Join Date: Jul 2009 Location: Bedfordshire Posts: 88 Thanks: 10 Thanked 12 Times in 6 Posts	Hi sidevalve Being the only thing that I cant fully check I have ordered a unrestricted one from ebay just to see if it fixes it if not I think the scooter will be going on ebay next week __________________ [SIGPIC][/SIGPIC]

25th February 2016, 15:53	#23
neilb740 I really should get out more....... MG ZT 1.8 Join Date: Oct 2011 Location: Crewe Posts: 2,298 Thanks: 110 Thanked 362 Times in 237 Posts	I have had the misfortune of working on a bike from the same manufacturer. It looks like you have covered most things I would try, the only other thing I remember from my fight with the similar bike was that the HT lead was appalling quality. There was what can only be described as a woodscrew sticking out of the side of the coil, you twisted the blank end of the HT onto it so it screwed into the centre core of the cable. On the one I worked on this was full of water and rusty. I didn't have the symptoms you described, this one wouldn't run at all, but if yours is the same it might be worth checking.

25th February 2016, 17:32	#26
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Quote.---colvert Hi The timing is done by a fixed pickup on the flywheel and the CDI unit no adjustment available. Opening the points gap slightly will advance the ignition. Sometimes the weirdest things work. Nothing to lose.--

28th February 2016, 15:07	#29
martinwest Regular poster MG ZT + Join Date: Jul 2009 Location: Bedfordshire Posts: 88 Thanks: 10 Thanked 12 Times in 6 Posts	Problem solved Ok so after a lot of reading on the net I came across this https://en.wikipedia.org/wiki/Four-stroking Turns out there was nothing wrong with it in the first place just needed to be on full throttle whilst riding and not on the stand. Oh well its now got some spare parts just in case it dose go wrong Thanks for all the advice anyway __________________ [SIGPIC][/SIGPIC]