1982 Yamaha XJ 750 Seca

Hi everyone,

I just got a XJ 750 Seca as a project bike. It is still in pieces and still have to get it running in order to ride it this summer.

That being said I am starting to look for ideas to modify this motor cycle.

The first thing I want to look at is changing the head light and the speedometer instrument panel to something more updated.

Head Light I know I found a schematic that tells you to jumper out a few pins in order to install a new headlight.

Any ideas on the speedometer? I have read nothing but problems when trying a different speedometer.

Here are some bikes that I like that I would love to make the bike look like.

Thanks

 

Read This First

Here's the wiring mods to remove the rectangular instruments

Don't do Pod Filters if you want to ride this summer.

 

My plan is to get the bike running this summer.
The motor was just overhauled.
I plan on putting the bike back together, and going through every maintenance step after it was put back together. This will help me learn what is what and where everything is.
Running it around the block a few times and to my parents house back and forth.
That way if the bike breaks down I'm close to home and its easy to pick up.
Next winter will be the bigger modification.

 

So it appears as if quite a few of the nuts and bolts are still loose. I have no idea what the previous owner has done/still left to do.
Rather than attempting to get it running half assed and not knowing what is done and what isnt, after all it is my life on the bike.
I now have to strip the bike apart and put it back together.

I see what you mean about pods. unfortunately I was really hoping to go with pods but now I see why you dont.

This is going to be a super slow and painful process. but hopefully worth it....

 

You have summed up life.

If any one of the three options below occur, then it will be worth it.
1. You have fun.
2. You learn something.
3. You have a working motorcycle.

 

This is my 16 step program that I will have tons of questions about eventually.

1) Tear bike apart
change the frame to what I want.
Get the frame inspected for cracks (heard something about the frame cracking where the motor mounts), repair where necessary.
2) Get Frame painted
3) replace brake pad front and rear.
4) get wheels painted, get the tires I want.
5) clean front rotor and ensure that the front housing for the brakes is good and sealed.
6) replace wheel bearings if needed.
7) attach shocks and wheels... replace rear shocks with something new and cool

** Should be a rolling chassis at this point**

8) get motor good as new, bore if needed. replace seals and such. Replace anything in the transmission.
9) paint the motor.
10) reshape and paint the gas tank.
11) replace all brake lines and throttle cables.
12) replace the controls.
13) mount the motor back on the bike.
14) change the lights, brake lights, head lights, turn signals.
15) Replace speedometer
16) Get a new seat.
16) put back together and ride!!!

I am doing this for a number of reasons

i) Safety - Why gamble with your life?
ii) Money - I see no point in spending money twice, once just to get the bike running, then again to get it the way I want.
iii) Maintenance - If I do all this now I know where the bike stands, aka everything is next to new. I do not have to constantly worry when the brakes need to be replaced, when the tranny needs works, when the engine might go.

This by no means makes me an expert and I will ask a ton of probably stupid questions that might seem obvious. I'm not too confident on working on the engine/tranny myself that is the one portion I might just get a shop to do, buy all the parts I want replaced and ask them just to do it.

Is there a good place to post my progress? or can I just use this thread?

 

The frame cracking that you heard about is not at the motor mounts. It's at the side stand mount, and it's not from stress, but from rust. The upper part of the cradle tubes were left open to to the elements (on purpose), and they tend to get thin and rust down near the sidestand mount. It's easy to check for, and also easy to fix.

Alter your steps a bit before you start spending money and making frame mods.
Make sure that the engine will run. If it won't run (it very likely will) you're going to be spending money on a replacement. Rebuilds are expensive due to a lack availability for some internal parts (like oversize pistons should they be needed).

 

Any advice as to what I should just automatically replace in the motor?

I am think just off the bat, bearings, seals, gaskets, chain.
Anything else you recommend?

 

As k-moe said, get it running first. But since it is already apart (how "apart" is it?), I'd go through the carbs first before reinstalling. Then check the valve lash (and replace the valve cover gaskets/"O" rings), check all the engine fasteners, change the oil/filter. Probably need a new battery too. Go through all the ignition/switch/relay electrical connections (cleaning/greasing/tightening). Then try to get it to run. If you get it running you can determine if you have any leaks. Fix the leaks. Then work on other major systems (brakes, suspension/steering, wheels, total electrical system, etc.) one at a time to keep your momentum going. When it is all done and running safely, then you can work on cosmetics

 

Nothing.

Inspect, measure, assess. Just replacing things automatically is a fool's game.


What I can say is if you need to split the cases for any reason, go ahead and replace the alternator chain guide and rebuild the starter clutch (after inspecting the roller body for cracks). The alternator chain guides will degrade over time and then fail, and the starter clutch rollers wear, so they might as well be replaced while the cases are apart.

 

Well when I got the bike the previous owner said the engine was rebuilt.

However he didnt use pre vut engine seal but rather that paste that you can use to seal up engines. The oil pan was off and some nuts and bolts were loose.

So I am going to go through the engine as little as I can, ensuring that the intake from the carbs is 100% clean.
Everything is good and tight.
Everything is sealed.

Once that is done I will mount the motor back on the bike.

Also I found out that the bike has what appears to be XJ 650 forks on the bike. this lowers the front end by about an inch. and naturally changes the whole geometry of the bike.

I am now on the hunt for 1982 front suspension...

 

are you sure you really want to do all that?
https://edmonton.craigslist.ca/mcy/6025644326.html

 

Link finally worked.

I already have a yamaha R6. I dont want another crotch rocket.

Why not...

It is alot of work but will hopefully pay off.

 

Given your description of loose bolts, I would not believe the PO.
Different people have different ideas about what rebuilt means.
I think your plan of attack is sound, but be ready to shut the engine down quickly if you hear any bad noises.

 

Hmm....
Change the bars, sell the body work and put a normal headlight on it and it could be a reasonable sports tourer for almost free.

 

I have minimal knowledge as to how to fix my own stuff. I know how to change oil, follow manuals all that basic stuff. I bought this bike as a project bike... not such a good project bike but i've put maybe 4 hours into the bike and already have learnt a ton.

Unfortunately my dog tore her acl. So this project has been put on hold.

I few things right off the bat that I dont like...

1) Front shocks are incorrect for this model of bike. Looking to correct. I believe the shocks on the bike now are from a 1983 Yamaha maxim (1/2" shorter)

2) front controls are heavily damaged - need to replace.

3) there is a bolt stuck where the carbs mount to the engine. trying to get it out.

 

I just picked up a Xj750 seca parts bike so let me know what you need ,buddy next door travels often to Calgary so if your not far away I can get stuff to you for the cost of BEER

 

alum will dissolve the bolt unless it is stainless steel
Videos of alum dissolves steel youtube

the controls are an easy clean what is damaged about them?

fork tube diameter
all of the XJ750 (except the XJ750-X and the XJ750RL) are 36mm, and

the XJ750X and RL models are 37mm.

and this
36mm tubes:
XJ550 M (leading axle)
XJ650 M, MM (leading axle)
XJ650 Seca (1982) (straight axle)
XJ650 Turbo (1982) (straight axle)
XJ750 M, MM (leading axle)
XJ750 Seca (leading axle)

 

Do the forks have two very short brake lines coming from the brake calipers and going to some funny-looking things that bolt onto each fork? If not then you are correct about them not being correct.