Motorcycle Safety & Driveability: 82 Yamaha Maxim XJ 550, motorcycle repairs, wet salt

Question
19829.1  

I'm a rookie at motorcycle repairs so please bear with me.  I have an 82 Yamaha Maxim XJ550 that is just refusing to start.  It cranks but there is no fire.  I can get it to fire for a few seconds with some EZ starter fluid if it is sprayed right into the carbs.  I have fuel delivery to the Carbs and have spark.  I don't really know how to check the carbs to make sure that there is air flow.  Could you help me with that or any other ideas as to why it won't start?

I've cleaned the carborator and and it started earlier this year.  It sounded "dirty" when running.  Almost like it had a really obnoxious wet salt shaker in it.  When it died again it made a some really awful noises.  The sound was an uncharacteristic rumble and only happened when the throttle was open.  The throttle would catch are run really high but then would drop off even though it was wide open.  

Any questions or if you need more information let me know.

Thanks a million,
-Christian
ca_appold@hotmail.com  

Answer
Christian,

Thanks for the question.

Sounds to me like you have some really dirty, really plugged up carburetors. Your bike won't start because most of the small fuel passages and metering orifices (commonly called "jets") are plugged up either with dirt or fuel varnish. When you spray in the starter fluid (which is actually just gasoline), you give the engine a momentary supply of gas, so it runs for a second. The "main" carb jets are probably still passing some fuel, that's why the bike runs when the throttle is wide open, but only for a while. Also, how old is the gas being used, is there water in  the gas, and is the air filter in place or not? All three things could affect how the bike runs (or doesn't run). But from what you describe, it sounds like plugged up carbs.

If gasoline is left sitting in carburetors for an extended period of time (say, a couple of months), it evaporates. But not ALL of it evaporates. It leaves behind a hard, varnish-like crud that can't be reomoved with any spray or long-term soaking. The jets and needles must be removed and replaced. If you try to "clean" them, you will change their size and once re-installed, your bike will truly run terrible. The carbs must be "rebuilt".

What you need is four carburetor rebuild kits (one for each carburetor). Each kit will include needles, jets, gaskets and other items to return your carburetor to stock form. Your dealer may have them or you can easily find them online. You must follow the directions EXACTLY in order to get them installed correctly. Carburetor tuning borders on black magic, and I strongly suggest you get the bike to a dealer for a diagnosis. If the carbs do need to be rebuilt, get a cost quote and weight your options. Yes, you can do it yourself. But if you do not understand why and how each carburetor part works, you might want to let a pro handle this one. If you plan on doing it yourself, get a book on carburetors/motorcycle repair such as the Motorcycle Restorers Workshop Companion. You can see it here:

http://www.amazon.com/exec/obidos/ASIN/1852603933/ref%3Dnosim/broughsbooks/103-7...

This will give you a basic understanding of carburetors (among other things) and the repair will make more sense to you.

Again, I'd get it to a shop to make an official diagnosis, and then decide if you want to tackle this job. But for the most part, it sounds like you have some badly plugged up carburetors. Make sure you put in fresh plugs and a new air filter before syncing the carbs at the end of the installation.

Good luck!

Bill Roberson