well after some thieving sod pinched my other dtr project i bought for me and my little boy to work on i managed to find a replacement on ebay at what i think is cheap enough £300 all things considered but need a bit of advice, its probabally been covered somewhere before but hopefully someone can point me in the right direction. the guy i got the bike of said his son blew the top end 18months ago, so was rebored, head was skimmed new top end and small end bearing fitted then bike was just left to stand as his son lost intrest so it hadnt even been ran in. i took it home give the carb a clean put some fresh juice and a new plug and air filter and it went straight away and all seems well. however theres a couple of things im unsure about. when i took the carb of i noticed a bit of damage to the carb warmer unions so i just disconnected them and joined the pipes to each other on the head however i noticed that the pipes seemed to be a bit bunged up with crap and gunk and one of the warmer unions on the carb was really blocked up pretty bad. didnt really wanna split top end before ive even run it in but could ther be an underlying issue causing this???? i flushed the radiator out and put fresh coolant in and water pump appears to be working fine just a bit unsure about potentially heat siezing it if thers a problem. also whats the crack with the powervalve is it right i may need to re profile the actual powervalve with a dremmel due to the reduced amount of clearance between valve and rings especially when hot?????
Depends on how over sized the piston is. If its on it's 3rd rebore then yes. However boring the powervalve is nonreversible. By the 3rd rebore the bikes covered its mileage and it'll need a compete overhaul. Since two strokes have short lives anyway. I'd rather have the barrel rebored and replated than mess with the powervalve.
You could have a leak with the water pump and gearbox. If not sealed correctly you'll get gearbox oil mixing withy the coolant. Temperature can increase. Happened to me and just using water than had mixed with oil my bike topped out at 100 degrees. A quick blast an I brought it down to 80. Still quite high. My rs runs happily at 70.
DTs run hot anyway mind.
If he 'blew' the top end then he risked getting metal in the bottom end which essentially means a complete engine rebuild anyway. To be fair for £300 expect a project. Sounds like a good bargain to Me. Especially when you want a project.
This sounds like a bargain bike so yeah as said don't be disheartened if you have to spend more time and money than first anticipated.
The gunk in the coolant could be from mixing 2 different types of coolant. I've been told the red and blue, when mixed will create a funky glue type stuff. I'd flush the system well and re fill with quality coolant/antifreeze and distilled water.
With regards to the Powervalve. I'd agree with the above that it's only when you go over a certain oversize. Some people say they have had it happen on lower but I've not personally. My bike does seem to run vey cool by comparison though.
