oh no

[moorishone]

Ok guys I finally got to ride the bike today for the first time. It's pretty powerful and fun until I got it up to 60mph then it started sputtering and shut off while I was riding it. I know I need a new battery amongst other things. I've cleaned the carbs and the rest of my bike but I can't throttle past 7000 rpms even in 3rd gear. But why can't I go over 60 without it stalling? Any ideas anyone it's a 1979 yamaha xs400. Thanks in advance

 

[willem]

could be a bunch of things, but it sounds like a compression or carb adjustment problem.

might have to clean them again actually, it takes most people about 3 or 4 attempts before theyre actually clean.

set your valve clearance, clean the carbs, adjust the idle mixture, sync the carbs, put some new plugs in and try again

 

[moorishone]

Ok I did that now it's running good but it is smoking from one tail pipe could it be the plugs or the carb cause I'm getting good compression on the right pipe but smoking out of the left one any suggestions?

 

[Scorpio1963]

What color is the smoke blackish or blue.These bikes are old its not uncommon for the to smoke ,could be valve stem seal or worn rings or poorly tuned carb.If its blue run a compression check.If its black fine tune your carb.

 

[moorishone]

Bluish white and smells like gas

 

[Scorpio1963]

How many turns are fuel mix screws turned out?

 

[Scorpio1963]

white smoke is a sign of too much fuel,something is out of adjustment on the carbs.

 

[moorishone]

I counted 2 and 1/2 turns from completely closed

 

[Scorpio1963]

Have you set the floats to their proper level?

 

[moorishone]

Idk what I the proper level. I may have to readjust them

 

[xschris]

Bluish smoke means oil.

 

[Scorpio1963]

The float level should be between 26-28mm depending on if you have plastic or brass floats.I have brass floats and adjusted them to 27mm which seem to work good for my bike.
Chris he said the smoke is bluish white and smalls like unburnt gas,the gas fuel mix screws shouldn't be causing the problem at 2 1/2 turns with stock jets so Im assuming he has a float level problem.Could also be a choke problem also.Both of the latter is going to send to much fuel into the carbs.

 

[moorishone]

Wow thanks for the input. I fixed the smoking problem as soon as I changed the plugs it stopped smoking lol. But now it won't idle I'm having so many minor problems with this bike I'm getting frustrated.. I need a new battery or something I charge it then when I start it to run it the battery immediately drains down to no charge at all this is the best/worst first bike I can think of holy moly donut shop

 

[Scorpio1963]

My bike has been the same way a lot of minor things to fix on it but basically maintenance issues,then I have been struggling to get the exhaust sound I like for over a year.This is my 1st bike also but I have learned a ton of things about working on it.Alot of these finds are bikes that have been sitting for years which causes numerous problems to be ironed out on them.

 

[moorishone]

By the way thanks xschris the banjo bolt works great you did me a solid I appreciate it

 

[Specdog]

I need a new battery or something I charge it then when I start it to run it the battery immediately drains down to no charge at all this is the best/worst first bike I can think of holy moly donut shop

Bingo, there is your problem right there. Until you get a fresh battery you are wasting your time trying to run this engine. Once your new battery is installed, check to see your charging system is working properly.

 

[Scorpio1963]

@ specdog
If the battery is discharging while the engine is running providing the battery is good wouldn't that indicate the bike has a charging issue?

moorishone hook your battery to a charger,then start your bike and see if it stays running.Also check the voltage of the battery while the bike is running it should be close to 13.8 to 14 volts.