I'd like to have a Yamaha air and oil-cooled, in-line four motorcycle. Anywhere from 650cc on up. But I can't seem to find a model history of the Yamaha Maxim and Seca (and Radian, one of those is for sale cheap near me). In fact I can't seem to find out what the heck Yamaha was doing in the 70's -80's with inline fours at all!

I'd like a bike that is easy to modify and work on. What are the quirks for the different models from the era? How hard is it to find parts for any given machine? Who has been chopping or bobbing the 80's Yamahas and
what are the biggest hurdles?

My current Kawasaki project, while nearing completion, seems to be made of unobtanium. The Hondas have been done and done, as have the GS models. What do the very attractive Yamaha motors have to offer? I just love the dependability and chracter of my Vmax, and I'm looking for more....

But I need a bike that is above all economical to find parts for. And..I'm glad to be here!

coffee_brake wrote:

I'd like a bike that is easy to modify and work on. But I need a bike that is above all economical to find parts for. And..I'm glad to be here!

Sounds like you need an XS650 twin then.

Maybe I should explain. If you want something easy, then go with what has a following. Parts will be plentiful and cheaper, and there will be more examples to look at when you are brainstorming where you want to go. Now, if you have mechanical and engineering/designing capabilities then pick something like an XJ series bike and show your skills off. Otherwise, look for a Kawasaki KZ650, Honda SOHC CB750, or a Yammy XS650...

+1

Parts aren't very hard to come by for the XJs, but they are NOT always economical. 4 Carbs instead of two, etc.

The longevity and popularity of the XS series 650 twin makes it about the easiest Yamaha to economically find stuff for. Plus they are MUCH easier to modify and work on than the XJs.

The XJ series were extremely bulletproof high-performance engines that were quite a bit ahead of their time when they first came out, well engineered but a bit complex.

Originally introduced as a 398cc chain-driven "sporty" bike for the Japanese market, the first XJ looked just like the 550 Seca that was brought here, sans fairing.

The "second generation" XJs introduced the idea of shaft-driven high-performance bikes, something that really hadn't been done before, and the Maxim pioneered the "power cruiser" genre.

Here's the history lesson: xjbikes.com/Forums/vie...14576.html

And here's the hard truth about the cost involved: xjbikes.com/Forums/vie...14581.html

If you're up to the cost and the "next level" mechanical skills required, then they can be VERY good candidates for being returned to fully operational condition, some quarter of a century later.

Plus they're an absolute blast to ride.

+2. I can vouch for the fact that costs can mount up quickly, especially if you have to buy genuine spares. I have been greatly helped by members of this site, though.

If you want an XJ (Mine was called an FJ in the US), I suggest buying a "Runner" and avoid bikes that "Just need a battery", "Carbs just need a balance" or "Was running fine when I put it away". Previous owners tend to be very economical with the truth!

As Fitz said, The XJs were Yamahas 4cyl/4 stroke bikes of the 80's, noted for quick performance and good handling (The alternator is behind the engine, not on the end of the crankshaft).

Don't forget though - the range is up to 30 years old!

+3 on buying a runner. Non running can be anything from bad plugs to bad crank or cams or valves or pistons, or.............well, you get my drift.

Thanks, that is the kind of information I was looking for!

I wasn't really considering a restoration, I was thinking more of modifying one aesthetically (while keeping suspension intact). The XJ's because my favorite motors are inline fours, and the XJ powerplant is handsome, something I'd like to own and show off.

My first project is a Kawasaki KZ440, a parallel twin for which spare parts are plentiful but new parts are hard to find. Plus the carbs are really hard to tune. The XS650 is much easier than the 440 to build and keep, but I was aiming at an inline four.

The 440 basically fell into my lap and I found out how bad the carbs are, and how impossible anything made of rubber is to find for this bike, after I brought the hulk home and began the work. Also, there are almost no standard or overbore pistons or rings available for it anymore. No more rebuilds! Unless you use pistons from a different machine and modify them to fit, which only the dedicated and/or mechanically adept are doing.
Once this 440 is back on the street, I thought an inline four other than the done-and-done CB750 would be an interesting and fun project.

I'd like to stick around here and look at what all of you folks are doing with your XJs, and what plagues these bikes. And, my eyes are open for a good deal on an ugly, running XJ in my area.

Thanks.....I appreciate candid info....

Two points you brought up merit a bit more discussion;

"Almost no standard or overbore pistons or rings available" this is also true of the XJ series, with rare exception or good luck. Rebuilds are often best accomplished by finding a lower-mileage motor to drop in.

Common Plagues:

Fusebox contacts crystallize and break or oxidize.

Carburetors.

Rust in fuel tank. (Not uncommon to have rust from day 1.)

Shim-over-bucket valve adjustment, often never done. Always do a compression test unless you want to buy into a rebuild.

Higher mileage shaft drive XJs have a ticking time bomb in their "primary" chain guide. (The primary chain runs the jackshaft for the starter, alternator, etc. It does not provide primary drive on the big bikes.) It is prone to "chunking" and the chunks end up in the shift drum. Replacement requires splitting the cases.

Starter clutch; problems more often on the bigger bikes: Slipping from being gummed up; or worn rollers or cracked housing which requires major surgery to correct as well. If the starter spins the motor every time then you don't have a problem.

Rear brake shoe delamination from sitting. VERY common, if overlooked can have disastrous results.

All good reasons to find a "runner" if you want to have any hope of doing it economically.

the KZ400/440 owners forum has lots of info for a cheap 2 into 1 manifold to ditch the lousy carbs on the stock bike. Maybe you should look into that? I designed one for my XS400J...

Welcome to the form Jenn.

I've picked up two XJ750's in the last couple of years for about $500 each, neither bike was in running condition. Cleaned the carbs checked the brakes, fixed some wiring issues, check valve clearances and now I have two good running bikes. (Working on the Nighthawk with my son) The biggest expense for each bike has been tires and recovering the seat. With the help of the good people on this form getting these bikes up and running is not hard at all. Good luck in finding one in your area.

No rebuilds for the XJ's either? Hunh...that's rough. Pistons/rings for any of them are rare?

I split the cases on this 440 to install a kicker. I NEVER want to do that again, especially on an in-line four. Then again, I have a bike lift now so maybe it wouldn't be such a nightmare as last time. Thanks for fair warning.

DWcopple I just received my 34mm carb today, the one that will be used for my single-carb setup. If I ever figure out why the darn thing is missing with the stock carbs....I hope to have a manifold like yours fabbed up for it soon.

I thank everyone for good solid information and not just blowing sunshine about the XJ.