Hi i have a 79 dt175 that is making a pinking sound at full throttle and melting pistons,at low to mid range throttle it goes fine, I have tried to richin it up by raising needle and adjusting float level and have tried retarding the timing. also have disconnected oil pump and run premix,but is still doing it,any other ideas thanks.
intrade,
Mar 22, 2:39am
how about you fit the correct spark-plug to start with!
hurricaneken,
Mar 22, 2:51am
yes have got correct sparkplug
intrade,
Mar 22, 3:05am
maybe it is worn out 2 stroker dont last as long as 4 stroker maybe you got piston slap that you hear at high rpm. i know of 2 stroker needing new piston and boors every 42,000km kawasaki 125cc are one of these. mate once only done 25,000 befor it was rooted.
budgel,
Mar 22, 3:53am
At full throttle it will be the size of the main jet that governs richness.
Check there are no air leaks between carb and engine.
hurricaneken,
Mar 22, 4:08am
hi engine has been rebored and new piston and rings, i have sprayed crc and brakeclean around engine and carb and nothing changed so dont think there is an air leak,only other thing i could think of was maybe the C.D.I was over advancing on higher revs! any ideas,thanks
hurricaneken,
Mar 22, 4:10am
STD main jet is 130 and it has a 150 in it,
hurricaneken,
Mar 22, 4:18am
I took it for a ride earlier and held it at full throttle for about a minute while it was making the pink noise,shut engine off and took plug out and it was a nice tan couler so am thinking not mixture.
bigfatmat1,
Mar 22, 4:35am
timing
hurricaneken,
Mar 22, 4:40am
ill see if i can find my spare cdi unit and try that thanks
planted4u,
Mar 22, 4:51am
Try spraying engine start around crank seals. It is running lean with such a large size main jet it has to have a air leak somewhere.
hurricaneken,
Mar 22, 4:56am
will try that but crank seals shouldnt be leaking as i replaced them 6 months ago
bigfatmat1,
Mar 22, 4:58am
the cdi isnt the only thing that controls timing btw its adjustable
hurricaneken,
Mar 22, 5:12am
yes i know it is adjustable and have retarded it but hasnt made much improvement
hurricaneken,
Mar 22, 5:22am
i think i might take it to the bike shop tomorrow thanks
doriandarby,
Mar 22, 5:29am
dont think it would be crank seals that would cause it.Sounds more like a bad air leak between the carb and cylinder.
hurricaneken,
Mar 22, 5:33am
i am thinking timing as engine start or crc sprayed around intake and crank seals does nothing,and plug comes out tan coulour like its spose to
1fordluva,
Mar 22, 5:35am
Main jet is to small,pinking at high rpm is it starving for fuel
Or a very bad leak,melting =air or fuel
hurricaneken,
Mar 22, 6:22am
ok will hook oil pump back up and get a bigger main jet and see what happens thanks
hurricaneken,
Mar 22, 7:18am
Hi head and base gasket are genuine yamaha but the piston is a mitaka which is really cheap.so the piston might be the problem as before i got it rebored it had a yamaha piston and it wasnt pinking i dont think but i only rode it a couple of times. not shure about smoke on startup but it is blue while riding
hurricaneken,
Mar 22, 7:25am
all i have done to engine so far is, rebored to .50 over,new mitaka piston and rings,new yamaha crank seals,had float level adjusted by bike shop,new head and base gasket,new float needle,exhaust was also decarboned and new airfilter. Im not 100% shure if it was pinking before the work was done or not as i only rode it round the block a couple of times. then decided to restore it and that was over a year ago and have just finished it.
1fordluva,
Mar 22, 7:46am
I presume you are mixing 98oct and not 91!
hurricaneken,
Aug 13, 7:19pm
yes using 98 from bp
Since the public registrations are closed, you must have an invite from a current member to be able to register and post in this thread.
Have an account? Login here.