Tgb r50x running problems

[Kenny1day]

Hi all, I've got a problem with my sons r50x, it's a 2011 which he has had on the road for two weeks, the other night he rang to say it wouldn't start when he came out of work, I drove up to him and had a quick fiddle didn't really do anything to it then kept the engine cranking till it fired. I told him to ride it home and when he got home he said it was fine for a minute then lost power and slowed down to 10/15 mph. The next day I took the bike out for a test ride and it was fine for a bit, then started bogging down again so I brought it home and removed and cleaned the air filter sponge, it seemed to of cured it but the next day he phoned to say it was doing it again and when he got home he said it bogged down so much it was virtually crawling back home! I've noticed now when you start it and hold the throttle open it will rev up, stay there for a second, then big down and cut out,when you hit the button it fires back up and sits there idling, any ideas off anyone what the problem is? Carb? Piston/rings? TIA

[Kenny1day]

Anyone??

[harry]

start with a tune-up, a  new plug and clean the air system
check/replace fuel filter .

perhaps clean the carb if your skilled at that .
don't forget to count the air screw setting/turns out
and don't move the idle screw.

a bad plug or cap & wire can act like a fuel issue or
get worse as the plug gets hot.

i don't mean to scold , and i hope you relayed this to your
son that riding it when it is having a issue like only going 15mph
is just asking for a major broken motor problem like a seized or
scored piston and cylinder or bearing & crank trouble.

oilyhans

[Kenny1day]

Hi thanks for reply, in between posting this and getting your reply I have cleaned the carb to no effect and stripped the engine down to find wear in the little end bearing and a severely scored piston and barrel, I have ordered new cylinder, piston and carb just waiting for them to arrive to fit hopefully that will cure it, oh and a new plug

[harry]

ok so what was the cause of the soft seize?  too lean or no oil?

make sure you check that oil is being pumped and open the bleed screw to confirm.
don't forget to lube all the parts with copious  amounts of 2 cycle oil when you reassemble it.
also add 2-3 oz of oil to the 1st tank of gas.

as a rule of thumb when tuning  i put my hand in the exhaust near (6") the pipe and if its too hot to
keep it there  your mixed too lean.  super tuning equipment(EGT gauges) basically do the
same thing but have a digital read out. if you have a digital  temp gauge  your looking
for (air) temps around 850-900f.

also check for air leaks in the intake system . you can have the right settings on the carb
 but a leaky intake system would allow too much air in the mix and make you lean .

oilyhans

[Kenny1day]

Thanks for the reply, where is the bleed to check oil is pumping? Is it on the housing on top of the engine?