20 Most Recent 1981 Yamaha XS 400 Questions & Answers

hi did you sort it as my 1981 yamaha xs 250 twin is not sparking but i dont now why

You probably need to replace it.... :-(

http://www.bikebandit.com/houseofmotorcycles/1981-yamaha-motorcycle-xs400sh/o/m8262#sch213650

Look at this schematic. Timing chain tensioners are self adjusting. When they have made their full travel, it's time to swap out the chain.

In the front of the motor you will find a round finned cover with a large bolt going through the center of it. Be sure to use a six point socket on the bolt (or you will strip the bolt head). They are usually over tightened. They only need to be snugged up enough to seal the oil in. Do not over tighten when you reinstall the oil filter cover. When placing the new filter in the cup , hold the cup in one hand with the center bolt sticking up , place the spring in the bolt first , then the washer (probably either missing or still stuck to the old filter) and the filter ,so the filter is pushed against the motor.

best way to find out, is to drain the old oil into a container, and replace it with the same amount. It is not very much, about 125ml in each fork. there is a small drain screw on the bottom of each fork.

The XS400 H (Special 2), SH & SJ (Heritage) US models share the same harness
Ride safe
Bike-Doc
Please mark this as very helpful (if it has been!!)

I hope that the starter solenoid has a B and an S on it. B goes to the battery and S goes to the starter. Chaz Moto DC

if either pointer or ( needle ) is damaged a new clock will be needed, allso check condition of both drive cables that go to your clocks remove with plyers or fingers if poss, then trace back to engine and front wheel, allso disconnect ,turn inner cable with your fingers the other end will turn if good. the end of the cable should be square ,and not rounded off ,allso oil cable from the top if stiff.

Here is a possible source in the USA:
http://www.cycletronics.com/home.htm

Check ou this link... http://www.xs400.com/forum/picture.php?albumid=169&pictureid=1767

Water in the HT lead and/or plug cap.

Ebay or an auto jumble.

its best to use a good oil especially on older bikes i use amsoil 20/50 it cost more but is best

bulb may be bad-testit for lighting--hard to tell just by lookin--may hav flaw in harness-inspecting takes time--make sure all fuses are sound

Try www.tradebit.com. It's not free, but most downloads are around 10 bucks. I have had a lot of success there, they have alot of stuff. Good luck!

Hi.

The symptoms are those of a defective CDI unit. Here the part. Ensure that spark plugs, coil and wiring and all the rest is OK before replacing CDI.

Regards.

Ginko

For some reason my first answer did not post. The problem is a bent shift fork or two. The forks move left and right to move slider gears to engage into other sets of gears. Don't expect to see the bend in a bent fork. A bent fork looks just like a good one. The bend is very slight. With the gearbox opened up you can manually shift through the gears to see the gear shifting patterns. Some shift patterns require two forks to achieve the shift. Some patterns require only one. You can look to see what yours requires. Below is a generic diagram of how the shift forks move slider gears.