Problems with my Poorly maintained 2002 DT only 6500 miles
-
Hi calum I am going to get a rebore and new piston etc for my DT 125 R ,which piston set is a good buy and which ones should I steer clear off
3 days ago Calum
You can't really go wrong with any of them. Throw a few names at me and I'll let you knowI personally always buy Wossner forged pistons.
But I'm running more than stock power
I have racked up 10K plus on cast mitaka pistons
And I've racked up 1K miles on forged. Can't say I noticed a difference
Only be careful with Wossner as the piston ring end gaps are always too smal
2 days ago Leftyno1
Thinking of going with the Mitaki piston, bike only had 6500 miles when I got it so disappointed to be working on it, interesting point that Piston was only worn on Exhaust port side , piston scored entire length and rings stuck in grooves on same side very strange.a day ago Calum
Not really sounds like what you would expect. The exhaust port will run a lot hotter than the intake ports. Sounds like it over heated to me. These bikes will do around 10K to the piston. More if you use decent oils and look after it. But sounds like heat seizure to me which would say you might want to look into the fueling/cooling. The colder weather will make a two.stroke run lean. So you need to up the fueling.slightly.a day ago Leftyno1
my bike is running in a constant 80 deg heat ( Caribbean ) so that could have been a factor, I took off the radiator cover to allow more air pass through, plus power valve was not working it was in closed position, could that have been part of overheating problem as under full throttle exhaust gasses can not get away ??a day ago Calum
Put the scoop on mate. Removing the scoop causes negative air pressure behind the radiator which in term means less flow and less cooling. 80 degress isn't too hot which could tell me its either a fueling thing.a day ago Calum
Curius about the power valve. Are you sure the powervalve didn't hit the piston?What bore size you on. If its an oversize then you need to modify the powervalve.
about 11 hours ago Leftyno1
Hi Calum it is standard bore original Yamaha piston which is 56mm ( think lol ) powervalve when rotated is not near bore as I thought it could be that maybe, running a 220 jet in a brand new VM28 Mikuni flatside carb,needle valve 1 notch lower snorkel out air bottle out on boot ( hole taped and sealed),reed switch removed from clock and placed out of clock, ,manifold above reeds sq rubber nose removed and filed smooth, exhaust is stock with a KH125 tailpipe ( on when bought ) and have only done 50 miles on it since bought [there was no air filter in when bought though and had not been run for a year, changed coolant also, thats it as they say.about 11 hours ago Leftyno1
I always thought the bike might be low on compression as I did not feel a lot of resistance at TDC, but I thought hell its only got 6500 miles so must be my imagination,oh exhaust was loose at manifold when i bought it oil all over exhaustabout an hour ago Calum
Oh dearThose bottles want replacing and putting back in
Put the main jet to 240
about an hour ago Calum
Put the snorkel back in. There is nothing to ne gained removing itStarting to sound like incorrect air/fuel ratio caused it to run lean mate
Amazed it ran for as long as it did if thats the case. Take the spark plug out and have a look at the colour
And this is starting to turn into a thread. Do you mind posting this in the correct section
This will not only allow others to chime in
But it was also record this information so that others can read it shoukd they experience something similar
2 minutes ago Leftyno1
No problems, will do cheers -
That head will want a gentle skim. I wrote a tutorial about how to get that done.
Get the barrel down to a specialist to get them to see whats what. Can't see from tbe photo but it might not be too bad.
I would make sure the oil pump works correctly, increase the oil slightly or bettee still go premiz.
-
Thanks for advice bringing all the bits back to UK at Xmas ,to a good Mechanic in my area for re bore etc.
The pre-mix idea is a very good one as I read on a blog about a guy who had 3 engine seizures before realizing it was the oil pump on his DT, In my humble opinion I think the previous owner ran the bike with no airfilter loose exhaust manifold which would in itself cause overheating plus PV not working and in shut position,
So on the bright side I think the CDI is OK as spark plug sparks
-
Okay,
Firstly CDI is not the only thing you can determine from the plug colour. I was thinking more fuel ratio since cdi does not control fueling. And cdi tends to be stock ignition curve.
Yes air filter will cause premature wear of the piston. But this would be evident in the reed cage and piston walls.
If it were me I would restore all the missing bits. Boost bottles snorkels and up jet it to 240 main jet.
I would replace the exhaust stud. I can't see why this would cause it to overheat though. I appreciate the scavenger process will suffer because of the harmonic resonance charge lost because of this stud. But then power would be lost too so it would only run a little hotter.
But whatever.
Keep us posted
-
Sounds like someone read on Facebook that they were all restrictions so removed them. Forums are the best for this sort of information and you have come to the right place.
The gain/loss might not be noticeable. Certainly the sound will bw different. But trust me when I say it's for the best that it be restored.
-
Cause there is nothing to be gained removing the snorkel, wat a load of bs. Put the right pilot jet in and set the mixture screw up right and there is loads of bottom to mid to be gained.
