I have here an engine and was told that it is a 1976 Yamaha 2 stroke 500cc dirt bike motor. I do know for sure that it came from a dirt bike cause, I pulled it off myself and saved the twist throttle to. I'm just not too sure on the year. It does say 496cc by the intake side of the jug. It has a compression relief valve on the exhaust side. the only number I could find on it was as follows.. 363-003428. I need to know a lil more about this motor for I take it to the machine shop. I'll post up some pics if I can figure that out, Laters.B-)
What engine is this?
- Thread starter moparman9598
- Start date
LOL.. wow!! i have a quoteable quote in someones sig.. rock on!!!
def prob a wr500... seems about right since all yammys are numbered higher than there actuall cc level
def prob a wr500... seems about right since all yammys are numbered higher than there actuall cc level
that is a 74 MX500 the SC500 was 73 and was silver, it has a comp. release a 4 speed gearbox a chain driven counter balancer and has more torque than anything I use to ride one up in Mi. hills, man it was a handful if thats the bike now its worth a small fortune
They are the same bike.
In fact my shop manual from 74' thst I used for my own 1974 MX lists all the MX models of that year and they refer to the big 500 as "SC MX 500"
The engine code he gave matches the SC500.
The pic I posted is from my own archives.
Well, I got my tax check finally on Friday. After that the next thing I did was take it to the local yamaha dealership that also does machine work. This thing is gonna be up and rolling this season. Thanks for the help guys and I'll be sure to let you know for sure what kinda motor it really is.I:I
Hey Paulie B you're right the machine shop called me today and said it is in fact a 1973 sc500. The problem now is that I need a piston that'll fit a 96mm bore, any ideas were I can find one? The machine shop said that weisco would have to special make one cause its so old.
any pics of that engine ?or a link ? this sounds like its gonna be a good build !!!I love builds ! some of them old two strokes were freaking monsters...years ago when i first got into motocross i had a 1974 ossa 250 trials bike, it was weird, kick starter was on the left side, it was an old spanish race bike i believe, i rode the hell out of that thing for years...but anyways !!!,,hahaha, im ramblin on here...that motor was a power house, could barely kick the damn thing over...i use to have to lean it against a tree and jump with both legs to kick it..i was young kid then, but still......i love the old two strokes, if ya can get parts. sometimes its hard
2 stroke technology is old. I mean, that engine my be from a '74 but, Nothing has changed in a 2 stroke engine in all that time.
The reason that all the pros and a lot of people are riding 4 strokes now is because they finally developed a 4 stroke that had the pick up of a 2 stroke so they are good to race MX. Before 4 strokes had great torque but it would take them some time to get up to speed. They were also heavy.
Now 4 strokes are quick and lighter (not going to say they are light b/c they are not).
Bottom line 2 stroke is old technology!
exactly...and everything is changing 4 stroke now not because of performance, but because of emission control...
4 stokes just became popular the past 4 or 5 years...before it was all about the 2 strokes! The bike makers had to design a 4 stroke that could compare to a 2 stroke because of states like CA that want a "cleaner burning" engine.
