81 XS 400 will crank but won't start

[Bella Blank]

Hi, I just bought a 81 xs400. The previous owner said that it had sat for awhile and only needed a new battery and the carb needed cleaned out. I have replaced the battery, cleaned out the carb, sprayed starter fluid in the intake, and replaced the spark plugs.
Now it will turn and make a small combustion sound but will not start.
Any suggestions?

 

[Jeff0133]

Sohc...dohc?....kick or e-start?

 

[Bella Blank]

I believe it's a dohc. It has a kick and an estart

 

[16VGTIDave]

If it has a kick, then it is SOHC. I'm going to suggest searching here for carb cleaning advice. A full teardown and cleaning will be required. x3 unless the person cleaning them has lots of experience.

While the carbs are being cleaned, check the valve adjustment, change the oil & filter and replace the air filters. Also recharge the battery. Then, while the carbs are being cleaned again, inspect / replace the fuse block and clean all electrical connectors from front to back and apply dielectric grease to them. Don't forget the engine ground. And when the carbs are being cleaned for the third time, inspect the ignition system, trimming the spark plug wires and replacing the boots and spark plugs with new ones. If the engine has decent compression, this should have it running and ready to tune.

I know, I sound crazy... Welcome to the wold of vintage motorcycles!

 

[Bella Blank]

What oil do you recommend using? Also where is the fuse box located?
Thank you

 

[16VGTIDave]

Heh. An oil question, the internet's favourite! Ask a forum about oil, and you'll get 3 contradictory replies for every 2 members who reply!

But since you asked... I've been using Shell Rotella T6 5W40 Full Synthetic diesel oil in my DOHC and it likes it. It is one of the few non-motorcycle oils that meets the JASO MA spec (the new T6 also meets the newer MA2 spec) as required by our bikes. It is also about 1/2 the price of most full synthetic motorcycle oils, and is available at Walmart, truck stops, auto parts and farm supply stores, etc. If the T6 is too expensive, or you are mistakenly told not to switch and agree, Rotella is also available as " T Triple Protection", a 15W40 distilled dinosaur flavour. It just doesn't lubricate as well or last as long as T6 does.

The fusebox is under the seat. At least, that is where it was when your bike was built 3.5+ decades ago. Who can say what has transpired since then?

 

[Jeff0133]

 

[NewHavenMike]

Im not sure if its just a typo in the first post, but there is two carburetors on the bike right? There has been single carb conversions, but Ive read that its not the way to go.. Cleaning the carbs is not too hard, its just meticulous.

Obviously, I recommend removing the carbs and setting up a work area that is very clean. After you go through the basic cleaning of gunk in the fuel bowl and making sure all the jets and passages are clean, Make sure the float and needle are in good condition and that the floats are within the proper height specs. The float tang should rest easy on the needle without compressing the needles internal spring.

Before you put the fuel bowls back on, Id probably connect the fuel line up and make sure that fuel flows proper and the float needle does its job. You might want to think about inspecting the fuel tank for debris as well... Dirt and rust can get sucked into the fuel line and clog up the carbs instantly and youll have to clean it all over again. Just let some fuel run into a bottle and make sure its clean. Or you can use an inline fuel filter.. I bought a small clear one so I could see any debris.