rebuilt?

i just got a 1999 yzf400 on trade. the guy i traded of course told me that the bike had a fresh top end... seems to be the norm for anyone trying to get rid of a bike. so naturally i didnt believe him. anyways the bike ran fine, no clacks, no grinds, shifts well, starts well, etc.. so i traded him. i was looking at the motor and there are two numbers or codes reading 52r34 and 1368 engraved on either side of the head. not the factory cast numbers either but engraved by hand. also i noticed the number 35 engraved the same way on the cam guides. does anyone know what these numbers mean if anything? could the top end or head been rebuilt at some point, not necessarily when he had it?

The numbers were probably meant for identifying who's head it was from being sent in. But thats just a guess... The previous owner of the bike I have now said it hasn't been tore down or anything but when I went to change out the cam chain, the cam cap bolts had socket marks on them. so someone had the cams out at some point in time. But after about 275 hours on it, never had a problem with regular maintenance and checking every bolt and valve clearances. These yamaha's will run forever being properly maintained

that would make sense. im not really worried about it, just curious. as the bike runs fine. thanks for the reply

As the old saying goes, "if it ain't broke, don't fix it" lol. and not a problem, just tryin to help a brotha out :eek:

i dont know how common it is for a thumper to grenade the top end since im new to the 4 stroke scene but i always liked to throw a new piston at my two strokes before something really bad happened. nikisil's are expensive.

i dont know how common it is for a thumper to grenade the top end since im new to the 4 stroke scene but i always liked to throw a new piston at my two strokes before something really bad happened. nikisil's are expensive.

Its not very common at all, well it is if you beat your ride and neglect proper maintenance. :eek:

thats good advise to everyone! also you got any suggestions on a stripped out oil drain plug on the motor. found that little treasure when i changed the oil friday.

well there's a few different ways. You can re-tap it and put a slightly larger plug in it, or just get it helicoiled. I've even heard of someone using jb weld to put the threads back in it(don't do this). But the best way is to get it helicoiled... Wait, is it the plug or the hole where the plug goes in? lol

the hole

Ok, go with previous post, and disregard the question lol.. And I don't know why I asked that, the bolts are steel and the case is aluminum :eek:

cool i'll probably tap it. i dont care much for heli's. thank you for your help.:eek:

Go for it. Good advice would be to just gob grease on the tap to catch the filings. But that doesn't matter if the case has been split already. I made the mistake of tapping american threads in one of my old bikes :eek:

oh shoot

The engraved numbers are done at the factory. All of mine have had them, and none have been sent out for repair. They don't mean anything to anyone outside the Yamaha plant.

thanks gray

The engraved numbers are done at the factory. All of mine have had them, and none have been sent out for repair. They don't mean anything to anyone outside the Yamaha plant.

There it is! thanks for clearing that up Gray! :eek:

+1 on the helicoil. stripped mine last summer. No probs with the helicoil. Cost me $25. But, Get some one who has done it before. Some minor drilling involved, careful drilling.

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