think urll find that the tzr had a slightly bigger bore size to the dt. i found this out after i brought a brand new barrel off ebay so i thought i being brand new its gonna have standard piston size so after i fittted the piston with the new barrel it ran fine untill i revved it up a bit it knocked like a brick in a bucket so i stripped stripped it all out again measured the bore and piston n they wer a fair bit out (cant remember wat it was now was ages ago) so i went to my local yam dealer n explained wat happened n he said yea that bore size is standard for tzr so i got me a tzr size piston fitted AGAIN n now it runs sweet as. very starnge as the barrel from the out side doesnt look like a tzr one (as far as i remember they look different but still fit all the same)
sooo short story u MIGHT av to bore out ur barrel to match the head? and i would think tht jetting would be fine as is ...and there prob aint no gain apart from bein a few mm os??? if anywon can confirm tht being slight os will make difference, iv got a barrel that is 2mm os in really good cond if ur interested?
-- Edited by DT-R_bradders on Friday 4th of February 2011 12:41:43 AM
yeah DT-R_Bradders spot on there with the bore being different, the tzr stroke is shorter (unless you have a 1988 3bn dt engine) so the bore was marginally bigger to suit. The head looks like it will fit on as i have one but with longer studs, also you would need new head steady brackets, the difference on the width of the combustion chamber wouldn't be enough to worry about really, its not really worth the effort as you can get the dt heads with all the same squish band designs(except maybe one), just get one without the groove cut around the edge as thats one hell of a restriction (some tzr heads have them too) can't quite remember but if you can get a 4fu head with out the restriction i think that had the best profile, theres a thread on hear somewhere about it
Im not sure if they fit or not mate, if it does then you will need the TZR 125 carb, and manifold i think mate! If it does fit you will have to also mess around with the gearin (sprocket's) to get it to be any faster than it all ready is........if im correct the TZR 125 barrel is better because the port's are higher or something like that im not really a grease monkey
Quote: Im not sure if they fit or not mate, if it does then you will need the TZR 125 carb, and manifold i think mate! If it does fit you will have to also mess around with the gearin (sprocket's) to get it to be any faster than it all ready is........if im correct the TZR 125 barrel is better because the port's are higher or something like that im not really a grease monkey
*you won't need the carb or manifold, its crank mounted induction :s *the main adavantage to the tzr head is it has a larger water jacket so can handle being thrashed that bit more and keep the chamber at a more constant temp as it has more area around it, which i imagine equates to less chance of detonation if you were to properly machine everything to get a actual functional squish band as manufacturers are way over tollerance for it to properly work as they have to allow for extra manufacturing tollereances on crank/piston/cases etc *if were talking barrel too the ports are pretty much the same but with less restriction on the transfers coming off the crank and also much neater cast, awesome if you want to port it as more to work with otherwise naf all!
the tzr parts are a better starting point if you want to do some serious machining and push the limits of this engine, otherwise as standard they don't have much over different dt parts you can get that are a straight swap
so i stripped stripped it all out again measured the bore and piston n they wer a fair bit out (cant remember wat it was now was ages ago) so i went to my local yam dealer n explained wat happened n he said yea that bore size is standard for tzr so i got me a tzr size piston fitted AGAIN n now it runs sweet as. very starnge as the barrel from the out side doesnt look like a tzr one (as far as i remember they look different but still fit all the same)
