Problems starting my 50cc motorbike.

[Horsley6]

Bike: 2003 Peugeot XPS 50cc

So basically ive had alot of trouble with this bike and too much has been spent trying to get it working and im still stuck at square 1. Ive had, new crank, 80cc bore kit, 21mm carb (4mm bigger than stock carb), stator, cdi unit, sparkplug, HT leads, new bearings, gaskets, and a pod air filter.
All of the parts was fitted at my local motorbike garage. Its a very trust worthy garage so i know they have installed the parts correctly.

when i go to kick the bike the headlight glows and the buttons on the dash glow but the bike doesn't want to start. Ive tried bump starting the bike and had no luck either, it just sounds as if it wants to start but cant. Its got new petrol and 2 stroke in.

I took the spark plug out after about 50 attempts of trying to kick start it and the end of the spark plug was a bit wet with oil. Not a great deal but still, i had to wipe it off. It makes me think that the main jet is too high ? But i have only increased the main jet by 15% as recommended by the manufacturer of my 80cc bore kit and my carb.

Any info/help will be much appreciated.
Thanks,
-Lee.

[at106]

Have you checked the spark plug has a strong blue spark? If not change it and check the gap.

[Horsley6]

Yes it has a strong blue spark.

[MattWadz]

try bumping it with full throttle and no throttle?
____________________
Pitbike x2, Mini Moto x4, China Quad, 02' Suzuki AP50 > 03' MBK Nitro > 86' Suzuki GP100 > 02' Yamaha Jog R > 57' Honda Lead 100 > 95' Piaggio ZIP Rst 50 > 51' Suzuki TS50x > 83' Honda CB125TDE Twin > 51' Yamaha Aerox > 98' Kawasaki KX60 > 89' Yamaha DT50MX > 80's Honda QR50 > 05' CG clone > 125cc China Pitbike > 91' Honda MTX125 RW-L > 09' Peugeot Speedfight 2 LC LR > Lucky MX 140cc > Apache Tomahawk 50 Quad (current = 2010 Yamaha WR125R

[Horsley6]

Tried that aswell, The bike gives off a much deeper sound when i dont touch the throttle compared to when give it full throttle. I have also tried it with choke on and off.

[Alpha-9]

[Horsley6]

[Alpha-9]

[stevo as b4]

You need to check the basics again first. You say your getting a decent spark, and after trying to start the bike the plug is wet with fuel? If it's oily it would suggest that there's an ignition fault or a lubrication problem, although it's very rare for a 2stroke oil pump to over deliver oil than not deliver enough.

What is the compression pressure like? Get hold of a tester a screw in threaded type, and crank over the engine with the throttle open. I would say you want to see at least 110-120psi, if it's say 80-90psi, the it's probably never going to run!

I'd have the carb off again and strip it down, checking the jets are all correctly fitted and blow through them with an airline and all the pssageways to make sure there is no dirt lodged in the carb or jets.

Another thing to check is for a good seal on the carb to inlet rubber and reedblock housing to the cylinder. make sure all the gaskets are correcty fitted and check that the reed block is in good condition and that the petals all seal flat on the housing.

Lastly it is possible that you have a duff sparkplug that sparks ok in the open air but not under compression pressures in the engine. It's happened to me before with bikes and mower engines too. Try a new plug before you do anything else above.

I doubt there's any provision for ignition timing adjustment on the stator plate, so if it sparks strongly, then it's not ignition thats your problem, and assuming you have good compression figures, then your probably getting much too much fuel, which could be from something as simple as a sticking float or dirt in the needle valve etc.