woodburnyq50 Posted April 4, 2013 Posted April 4, 2013 hiya guys, can anyone help me diagnose the fauly with my yamaha aerox yq50.. i was out one day riding it no problem then suddenyl it cut out. after about 10 minutes of sittin at the roadside like a lost spanner it started again. ran for a bit and then cut out, it done this about 5/6 time and now it just wont start. anybody have a idea of what it could be? carb is gettin fuel and checked and changed spark plug. could you point me in direction of what the most likely roblem could be and how to go about fixing it? any replies are much apreciated
Moderator DirtyDT Posted April 4, 2013 Moderator Posted April 4, 2013 When it stops have you pulled the plug to see if it is still sparking? If it is then it may be fuel related. The carb may be getting fuel but is the cylinder? Clean the carb out. When it stops try taking the fuel cap off and trying to start it. Check the piston for signs of pinching - I am guessing there is 2 stroke in the bike. Also don't forget to say hello in the newbie section.
woodburnyq50 Posted April 4, 2013 Author Posted April 4, 2013 still got a spark, carb is defonately getin fuel as i checked, how would i check if the cylinder is gettin fuel? and how would i check for pinching on the piston? and what exacly is 'pinching'? sorry for the newbie questions, been mechanic for 4 year in military but never touched bikes or scooters, so not very confident quite yet
Moderator DirtyDT Posted April 5, 2013 Moderator Posted April 5, 2013 All diagnosis needs to be carried out when the bike has cut out. Once the bike has stopped 1 take of the fuel cap and try and start it 2 take out the plug - is it wet with fuel. What colour is it 3 with the plug out and attached to the HT lead, does it spark It is always going to be a process of elimination. Changing the plug and taking of the carb and fully cleaning it will never hurt. You need to determine what is working and what isn't when the bike doesn't want to run. This can't be carried out when the bike is running normally. 2 strokes are simple machines. A little fuel, air, compression and spark at the right time is all they need. Eliminate the easy things first. It could stop because a bit of grit is blocking a jet at times. It could be that there is a loose connection that fails when you go over a bump or turn the steering a certain way. It couple be that the carb float is incorrectly set so ragging it at full throttle empties the carb bowel ( which will then refill over time). It could be that running it at full throttle overheats the piston and this tightens in the cylinder (pinching). Intermittent faults are often a pain to diagnose so elimination and then replacing the cheapest parts is often the best way to go. Do you run it on good quality 2 stroke oil as it is a tiny piston and the engine has to do a lot of work.
woodburnyq50 Posted April 29, 2013 Author Posted April 29, 2013 well finaly got round to checking it and the spark plug is brand new and it is also bone dry.. through bad judgement i found out tht it does have a spark (was holding plug and didnt click on and tried starting it. and it also does not start with the fuel cap off. would this mak it a problem with the carburettor? incorrectly adjusted or something else.
woodburnyq50 Posted May 3, 2013 Author Posted May 3, 2013 well i managed to persuade local bike shop to take a look at the engine for me, free of charge, and found out exacly what my problem is.. turns out the oil pump had packed in and with no lubrication.. the piston and barrel is dead.. so need to source a new one. not buying from shop as 200 pound is to much. any links for what might fit from ebay? been looking at a 70cc big bore kit for 60 pounds
mike1949 Posted May 3, 2013 Posted May 3, 2013 You're most likely scratching your head and wondering why DDT suggested taking the fuel cap off to see if it would start. It's to see if the vent in the cap is blocked because if fuel is going out and no air is coming in it will create a vacuum in the tank, hence no fuel supply, comprendi?
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