First street bike for 15 yr old DT50 - What should we check etc.

Did a 10 hour road trip Sat to help a buddy and his sone get his first street bike. Being 15 he can ride 50cc on street. Had 3 to look at, Ruckus (Slow!), BWS (little faster) and a DT50 (a real bike, clutch and gears etc.) so we talked the new owner into the DT.

OK, I know a lot about everything on the DT except the engine. We are going to make the new owner do a complete lube, check, adjust before he goes riding, will likely walk him through a good carb cleaning etc. What I want to know is, what should we check motor wise? Bike has never sat more than winter storage, been ridden everyday last 2 years at least. Crank case oil is clean, coolant is clean, oil injection works well from what I can tell. I rode it before we bought it, I could get it to 50 mph with my 200 lbs fat ass on it, new owner is 15 and maybe 110-120 lbs. What should this bike do top speed wise. we want it to be able to hit 60 mph as that is the fastest rd. limit he will be riding it on.

Is the bottome end on these the same as the DT100? could we swap the barrel and piston and double the cc's? I think it would be safer if he can keep up with traffic etc. and the local cops wouldn't be pulling the head to measure cc's. Any and all knowledge on these little bikes is welcome. The plan is this son rides for this year and next then upgrades to the KE100 in the Stable when his little brother hits 14 and then he rides for 2 seasons and I buy the DT for my son who will be 14. Going to keep in all in the family LOL.

Cheers.

cool little bike ! the kid is a lucky dog !
my guess is it has more in common with the 80 surely being only a 50 it must have a shorter stroke than a 100
make sure the airfilter is in good shape 2 strokes really suffer from dirt/dust

Cool. filter is on the list, I didn't know there was an 80 so that would be the logical 1-up upgrade. I know alot of these 2-stroke Yamahas they hve the same bottom ends and a quick power upgrade is a top end swap. I will look into the 80cc and see. I see there are reeds available as well as performance pipes so we could start there for sure.

Maybe it's the father in me speaking...... but at 15 years old, I wouldn't want him doing 60 to keep up with traffic. Back roads at 40-45 tops would be ideal. Let him enjoy the scenic route!

LOL, I know Rich, more like 50-55 max is the real number. We are rural and the cars get pissed when behind slow vehicles and will pass in dangerous places to go around them. Scooters, farm equipment etc. I want him to be able to do the limit at least, but not more. I actually think with an air filter cleaning, carb cleaning and cable lube it will have just enough.

He will be able to ride to school ok, it is all 50 KPH = 30 MPH, it is if he wants to go other places where he will need to be able to go the 50-55 MPH. The good thing is the bike came with brand new 50/50 rubber, name brand and new Tubes so he is all set that way.

get new brake shoes as well when they get real old they can de-laminate its not pretty when that happens

Thanks, I am pretty sure the PO did the brakes but I will check to make sure they are new, they are not expensive for sure.