Hey I'm new here just wanted to introduce myself,

I'm from Detroit, MI and just recently purchased my first bike from a friend last fall as a winter project. It's a 1975 Yamaha xs500 DOHC and I bought it in non-running condition, i replaced the coils on it, the plugs, completely rebuilt the carbs, new (used but in good condition) intake manifolds, and got the bike running. Now heres my problem...

The bike will start, and idle fine once its warmed up like any other bike, sounds great, has a healthy rev when in neutral but where i start to wonder what could be wrong, when i ride the bike it runs fine up until about 4k-4500k rpm's then the right cylinder cuts out, and it runs only on the left one, i thought maybe it wasn't getting fuel, so i rebuilt the carbs, still wasn't working, so i thought it wasn't getting proper air/fuel mixture due to cracked up rubber on the intake manifold boots, so i replaced those, still isn't fixed.. I'm thinking my problem lies deeper in the engine, like i need to tighten my cam chain or a bent valve or something? I have no idea where to look anymore i've fixed what i can and im about to just take it to a shop and have them tear it apart and fix it because im at a loss..

Any and all help is appreciated and if anyone knows a good place to locate xs500 parts please let me know because they're damn near impossible to find it seems

Thanks ahead of time!

Tony

Heres some pictures of it

I`m sure our resident wizard and general good egg will be along soon to welcome you (Mr Drewp)

he has a mine of knowledge and does`nt mind shairing it

for my pennies worth... is it electronic ignition or points?...... have you had the coils checked whilst under load?

i had a set of coils once that would only breakdown once the engine/bike was warmed up??? i have no idea why???if it`s points ignition... do they have a condenser?? ...has that gone west?

just a few ideas!

Only a suggestion, but try swapping the spark plugs over and seeing if the other cylinder cuts out.

Wow thats a 'stunna' you got there, I like, welcome to the forum Tony !

welcome nice retro yam and nice BMW too mate

Failte: Tony to the YOC

Me is likein your bike v much

Unfortunatly I have no help for ya with your classic !

thanks for the help and welcomes guys, the BMW is giving me some electrical problems but it is a lot of fun to own as well, I'll see about the points, it does have electric ignition but it sounds like hell so i just use the kick starter. I know people have told me yamaha points are notorious for going out so that could be a good place to start. Thanks again and I'll keep you guys posted as it comes along, riding season in Michigan is just about here and i finish taking my riders course tomorrow so I'll be legal and ready to go so i definitely want this working right!

Hi and welcome to the forum. 

Can't help you with the older stuff, does look like a nice example though. Good luck with it.

Vez.