Considering Major Work

Hello Everyone,

Recently I have moved to Texas in pursuit of a job, and I got a new one working as an IP telephony engineer. I live on my own now and am out of the house! (woo!) Yesterday, my awesome family surprised my and shipped my bike down to Texas and I now have the black cat back! I have never been so surprised! However...

There has been a lot of work I have wanted to do on this bike, and I'll list off the things that are wrong with it currently:

Ticking at low RPM, maybe cam chain, exhaust gaskets
Shaking from the handlebars
Low Compression
Cracked Air Box
Starter clutch slip (use proper oil, have replaced starter and solenoid.)
Carbs in desperate need of tuning)
Rear break linkage bent
No Center stand bracket, so center stand hits the exhaust and now there are tiny holes in the baffles getting bigger every day.
Headlight cracked.

That is a pretty big list. So I was thinking about doing a pretty big rebuild this winter. I have always wanted to rebuild a motor. It would be a lot of time and money but I think it could be a nice hobby.

However, I'll admit that I'm nervous about doing such a large rebuild. I've done a lot of other projects successfully but this is pretty huge. I'm on the fence about this much work. Any advice or thoughts on the matter? I'd love to hear opinions.

Sidenote: It's a possibility that I'll be buying a new bike next spring but I will be keeping my XJ forever.

Sorry for such a long post, I appreciate all of the help!!!

Gato

 

first, do you have someplace to work on it? there's things on your list that are going to need parts laying all over the place and the engine internals protected
for a few days.
time and money, figure time X3 and money X2

 

I'd check/adjust the valve clearances first then do the compression test.

The following steps will depemd on your readings.

 

X2.

The ticking at low rpm is just valve noise I'd guess, XJ's like to tick a bit

 

the lack of ticking in a xj is more frightening. do some checks on the engine before committing to the rebuild. mainly if the compression test is good and your not burning oil then forget about pistons and rings, valve clearance check will give you an idea on the condition of the top end. unless a bearing starts to howl or the engine is trying to shake your filings out then with only 37,000 id imagine the bottom end is also in good shape.
why tear apart an engine when you don't have to right?

you have a lot to learn, a huge undertaking like an engine or ground up rebuild for a beginner will do one of three things,
1. you get part way through it and get overwhelmed and the bike sits in pieces for years.
2. You get it apart and back together again but you didn't take your time and made mistakes that may cost you an engine.
3. you take your time, you do your research, you ask one million and one questions to the experienced xj folks and you eventually get it all done and when you hit that start button it comes to life.

good luck.

 

Thanks!

I got the valves in spec about 3k miles ago. Almost time to do it again, and that was where I figured I would start. I did a compression test out of curiosity about a year ago and the numbers across all four cylinders read within 3 PSI of 122. I know that's below spec, but it's right at the bottom of the acceptable range.

Besides the tick, the motor has run like a dream, except one Achilles heal. The starter clutch! It will always slip when warm, so it makes it hard to stop anywhere.

 

Is 122 PSI the result of a test on a cold or warm engine?

 

It was a luke warm engine.

 

The difference between cylinders is ultimately more important than the overall numbers, unless they're truly low (and yours are fine.)

TOP END rebuilds (rings, pistons, etc.,) can get real expensive IF you can even find the parts. But you have no reason to pop the top apart. If you really want to get all deeply mechanical, pull the engine, flip it over and split the cases so you can replace the starter clutch and primary chain guide.

That alone takes a lot of doing, and even more doing to get it right.

 

1982 XJ750J Maxim Compression Pressure per book 156psi.....

As Fitz said you are fine, you have uniformity across all cylinders......

I have the same bike, I did a compression check & I was 125 psi across all cylinders....& my bike has been sitting idle since 2007....