Just bought a non running 81 XS-400 for Son's first street bike.

[hitechluddite]

Hello all, after cruising many internet sites all summer we came across a complete 400 barn bike with 3600 miles for $250. It was sold as a parts bike with a bill of sale. We ran the VIN through three different sites before purchase and they all came back clean. We don't have a key and are researching how to get one With my Harley a title is required but I would like to make sure it will run before going to the effort and expense of getting a title. It has good compression and the tank is solid it is a complete bike in very good cosmetic condition for the year.. We will remove the carbs, disassemble for cleaning and drain the tank later tonight. We have found some ignition switches on ebay and maybe the best route will be to just get a new switch to get it started then title it and get the proper key. Any advice and experience with these bikes much appreciated. My Son was very impressed to find his bike has it's own Forum!

 

[NewHavenMike]

Welcome. Whats the VIN prefix letters, what year is it?

The lock cylinders will have a 4 digit code. Ive found matching original keys on EBay just by typing "yamaha key 1234", or something along those lines.. Theres a few EBay sellers who will also cut a new key for you. You will need to message the seller first and give the bikes details and they will see if they can cut the key. Sometimes they will cut original blanks, its possible for you to find a used original key though.

Not sure about the laws in your state.

The major thing about all old machines is the maintenance. Having good compression is crucial to moving forward. Cleaning and rebuilding the carbs is a must. There are rebuild kits available and main/pilot jets too.

The motorcycle will give the best performance with stock components. This will make everything much easier when it comes to tuning and maintenance and just getting used to how the bike feels. If your bike has a mechanical regulator, it is a good idea to upgrade to a solid state unit. The new regulator will allow you to use a AGM battery which is better in every category for a battery.

It would be best to get new carb boots too. After the carbs are clean you will have to perform most or all of the maintenance procedures listed in the manuals.

 

[hitechluddite]

Thanks, Good info about the regulator, are there drop in units or will there need to be splices made?. We got the ignition switch out and I see the code on the bottom. I'm taking it to the local Yamaha shop tomorrow, if they can't get me a key the son has some ebay seller lined up.

 

[xschris]

Post some pics of the bike so we can see what your dealing with.

 

[hitechluddite]

Here’s what it looked like when we bought it.

 

[NewHavenMike]

Looks pretty good for a "barn" bike! Forks are in great condition. I would definitely replace the front brake line and rebuild the caliper and MC. Brake lines rot from the inside and they can be deceiving, plus a newer line wont expand like that one does. I have a Goodridge Black shadow line along with their fittings, very nice setup for what it is. Tires would be next and theres a lot of nice choices out there. You should be alright with the charging system as I failed to notice that you have a 1981 model year. I find that the stock suspension is a little soft so I installed progressive springs in the front. Check the rear swing arm for movement, they used nylon bushings and they wear out from not being maintained. You can buy bronze bushings that are much better. You can upgrade to neck bearings too

Those are just some small things you can do to get a better ride but arent totally needed. I wouldnt pass up on renovating the front brake though.

 

[hitechluddite]

Thanks NewhavenMike, Cosmetically it's pretty good but there is lots of issues as we dig in to it! Looks like the fusebox will have to be replaced due to corrosion and metal fatigue. We got the carbs all freed up and cleaned out and we have spark but even with starting fluid we can't get it to fire at all. Compression is good. I dropped by the local parts salvage shop today and he mentioned that the ignition module on these are known to be fragile and probably needs replaced. What say y'all who wrench these?

 

[NewHavenMike]

The original fuse boxes are crappy unless they are brand new. You can find new reproductions. Most of us change over to blade fuses. I use a small fuse box that takes mini ATM fuses.

Carbs will always need to be stripped down and thoroughly cleaned, always.

The ignition modules arent the best either, luckily, my bike has points. It is possible for you to revert back to points. Actually, I would recommend points because of ease of repair and adjustability and theyre cheap. There are some aftermarket electronic ignitions out there, Ive had them all. They all work well until they fail and youre stuck on the road. You can find factory ignition boxes, they will be very expensive and/or theyre about to break anyways. Ive seen NOS ones go for $500+

 

[hitechluddite]

He said he needed the last 3 digits off the module to match it up with what he had available and if he has one about $50 will do it. When one fails do you still get spark?

 

[xschris]

The only time I have even had a stock TCI box go bad it would miss on one cylinder at idle. Other that that it would work fine. Chased it for a while thinking it was carb related and being the bike was modified it would have been very likely. I put on one of my many spares and bike ran like new. What goes bad on these boxes can be fixed for cheap and easy if you can solder and find the parts. A member on the forum was able to rebuild his for a few bucks and it worked like new.

 

[hitechluddite]

I know on my 89 K100 Beemer you just shorted a diode and it would continue an aggressive timing advance curve to redline. What fails in these modules? He said jumpstarting them would kill them almost everytime...