Hello from Oregon!

Hello all, I've recently joined this forum as the new owner of a 1981 XJ750 Seca. It has 31,000 km and has been pretty well care for.

I wrench on classic cars but have never worked on a bike before, and I have all sorts of new things to learn. Hopefully with my prior skills and some assistance from the community here I can get this bike in tip-top shape for either the end of this season or the next one.

I think of motorcycles like aircraft and want to go through the whole bike before I sit on it, so if there is anything you can refer me to as far as an "intro" guide for new 750 owners, I'd greatly appreciate it!

Thank you in advance and I hope to post some pictures of the bike soon.

-Andres

 

https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

From there, make sure you can get it started, then move on to the brakes, then back to the carbs and engine.

 

Thanks, I'll be sure to read through that thread. Today I had a chance to visually inspect the bike all over. I think it's going to need a lot of work:

The bike runs and idles well (have compared the idle sound to other running bikes).
Haven't checked compression or vacuum yet.
Oil leaks throughout the block - seals are all cracked in some form or another. Mostly minor cracking but enough to cause leaks in several spots on the block.
Right front brake disc has major scoring.
All 4 carb boots are cracked near the circle clamp.
Wiring harness has been futzed with (I see a lot of crimp connectors and such especially near the tail end of the bike).
Looks like the E-brake is not functional.
Front brakes dont work at all and I see some kind of gel-like substance built up near the bleed valves for the caliper and anti-dive system.
There's some surface rust on the frame underneath the battery tray.
Bike seems to roll well but probably could use a bearing re-pack considering the condition of everything else on the bike.
Front fork seals have cracks in them and I see some light residue.
Front handlebars seem to move back and forth ok without any binding that I can feel.

Needless to say I have my work cut out for me!

 

It's been a while since I've shaed an update, but the bike is completely taken apart at the moment. I still need to remove the swinging arm from the frame before powdercoating, but that's about it.

While it's been apart I've been reading threads and trying to decide if I'm gonna go the custom route. I've basically decided I'm going to keep the bike basically the same as it was.

One of the shitty things that happened when I disassembled the bike is I cut the airbox because I figured "oh I'll just run pods". Needless to say it didn't take much reading to see that approach is really not the way to go. I only cut a small square out of the airbox to clear the frame without removing the engine, and a sizeable portion of it was already cracked so not a huge deal - I'm planning to fiberglass over the portions that are cut/cracked.

I also found that the bearing races front the steering head were badly scored, so those will need to be replaced. Based on guidance from other members in the community I'm planning on redoing all the bearings anyway. I plan to ride the bike quite a bit, so want to make sure all that is good to go...

Today I finished repairing the main wiring harness on the bike which is the first project I've completed since disassembly. The brown wire circuits (mostly lights it seems) had a bunch of crispy looking splices from a short circuit. I cut all the burnt splices in and soldered in new ones. I used doubled up heat shrink wherever possible. Next I'll be working through any wiring that's left attached to components, but aside from cleaning the connectors I doubt there is much work to be had there. Stay tuned!

 

Today I've been reading and watching mainly. I've started a spreadsheet to keep track of what I'll need to order, who I'll be buying it from, and what it will cost.
For the last part of the wiring harness project, I've opted not to go the fuse block route, and will instead be installing in-line blade style fuse holders. I don't see the huge advantage of having a fuse block on top of the air cleaner lid with a ton of extra wiring, so I'm opting to K.I.S.S. for this one.

Based on my disassembly order, the next order of business would be to start working on the engine. I've begun watching these video series, and studying the Haynes manual where engine overhaul procedures are documented:




Tomorrow I will write a checklist of things I'll need to replace on the engine and start compiling part numbers.

 

Backtracking on my prior post (Not sure what I was thinking lol) The engine is one of the last things to do before putting individual bits and pieces back on the bike. Right now focusing on suspension and brakes. Bad news is the prices I'm finding from Chacal are pretty spendy. I think I'll be over-budget just with brakes and suspension parts alone, so I'll try to salvage what I can. I'll absolutely be getting new brake lines from chacal but other than that I may have to source parts elsewhere. I can't afford to spend over 2k on brakes and suspension....

Today I took a look at the fork tubes, as I finally got the forks out of the triple-tree...looks like both tubes are slightly bent in exactly the same way. Puzzling because the prior owner had never been in a wreck, reported no issues with steering, and the bike has no body damage that I can see. I'll be looking for a set of inner fork tubes I guess.

 

I managed to find a complete front suspension setup on Ebay today - both front forks, and lower trip. Also has some front turn signal posts that aren't broken off like mine!
Also scored a full rear cowl and grab bar from the same seller. Not a bad day!

 

E-Brake?

Did you read the link provided by Kosel?

Slow down.

It's rare to need to tear an engine down, aside from a broken alternator chain guide or slipping starter motor clutch. Don't go there yet.

Clean the engine thoroughly (no pressure washer), and determine where the oil leaks are coming from. 99% of the time it will be the valve cover gasket, and maybe the shift cover or clutch cover.

Do valve clearanes, then perform a compression check.

Everything on the front end is rebuildable, so unless the forks are bent save the front end you bought for spares, or later resale.

 

Hi K-moe, I've been doing a lot of reading in threads where you pop up I know it seems like I'm moving fast, but my first post was in July of last year. I've done a lot of reading and learning since then. Yeah, I know the bike doesn't have an E-brake hahaha. Just wasn't used to the idea of a pedal operated drum brake on a bike at the time.

The fork tubes are both for sure bent, to the point where I don't need to roll them to verify. If it was cheaper to just get the upper inner fork tubes, I would....but it's not. I plan to swap over to this new set of forks, rebuild them if needed, put in a progressive spring and block the anti-dives off.

I've read through the information overload hour at this point, and go back to reference what I need as I move along. In terms of engine tear-down, the only real "teardown" I'd be doing would be to re-seal the cases (if needed) I don't plan on getting into anything else engine-related besides the valve shims, a general inspection of the bottom end, and maybe clean up the valves, cylinder hears, and seats while I'm in there. I think you had mentioned to another member that the wet clutches in these bikes tend to disintegrate after a while, regardless of how many miles are on em, just due to age, so that may be an action item as well. When I first inspected the bike, there was evidence of oil leaks below the valve cover gasket but I know how that typically goes on these bikes - it can go further than you'd expect.

I'm open to any advice you can provide. Still very much at the beginning of this project and my learning journey on these bikes overall.

 

First couple vids. This was the same day I bought the bike, last July I think.

 

My clutch is the same one that was in the bike when I bought it. @bigfitz52 reccomends replacing clutches that have sat, but I've not had any issues with that on any vehicle.

Regardless of where the oil is on the outside of the engine I still would caution against a teardown before making sure that it's not just a valve cover leak or some other easy-to-replace gasket. The alternator chain guide is worth replacing, as is rebuilding the starter clutch, but it's not worth opening an engine for if it's otherwise sound. If the head gasket or base gasket are leaking then go ahead and do it all in one go.

 

Understood, I know it's easy enough to do work on the engine with most of it still in the bike... so I'll go with the easy gaskets and test before I think about a full teardown. This motor doesn't have any issues with shifting or startup so I think we're good at the moment on those fronts.

Sorry for mixing you up with Fitz haha. I'm still not sure if I should go ahead and do the clutch or not - it seems pretty easy to do. I guess I'll decide once I ride the bike around a bit. This isn't going to be a commuter by any means so if things start to break down / not work so well I can live with that and address as things come up. My main goals are to get the big glaring safety issues or "known things" that should be replaced on the bike taken care of before putting it back in service. Seems like most things can be done without the bike having to be completely in pieces like it is now.

In other news, my front fork assembly came in today along with a correct rear taillight housing, tail light assembly, and grab bar. I was surprised to see the newer style tapered roller bearings and rubber dust boots attached to the triple-tree - prior owner must've gone down the same road at some point. Only thing I don't have is the races. If the bearings are good that would save me a bonus bit of coin! Also looks like he did a fork seal on one side but...not the other? One seal is a different style than the other, and the other appears to be "factory". This may be one of those things where I change the oil, mount the forks, test, and rebuild if needed later. They seem to be in much better shape overall than the forks I took off my bike, but looks can be deceiving.

 

Second video up

 

My Johnny Cash bike started with a frame and an engine , I bought it at a Walneck swap meet . The bike was taken apart , dude was selling pieces of bike ,when I showed up bought it for 120$ . I bought pieces from eBay , forum member Joe Eliff sold me rebuildable forks, and numerous other parts, Chacal supplied others as well . I already had many parts from my other Seca ...now Chicago weather it is way too cold to work in the garage . Not trying to hijack your thread just stating shop around , if possible buy a parts bike if you find one , or try to find a cycle salvage , Wisconsin cycle salvage, Cycle Recycle part two are two that I have gotten parts from in the past , most do mail order. Agree with Kmoe most engines will last 50k or more as long as engine has have had regular oil changes and not flogged to terribly. My yellow Seca the starter clutch was slipping when hot I finally , swapped out an engine I bought off of Joe Eliff...one day I will tear down old engine and replace starter clutch . Cheers .

 

Alright, so yesterday I looked over the frame again, and I'm not seeing any compromised welds or cracks in the frame so we should be go for powder coating.

I'm at the point where I need to start buying some parts from Chacal as I've got everything else I need, but I need to make a decision about how I'm going to get through the forks:

1. Do I rebuild these donor forks with a regular kit, rebuild the anti-dives if needed, and get stainless brake lines for everything, OR

2. Rebuild them with a progressive spring kit, block off the anti-dives, and forget about the stainless lines to the anti-dives as well (saves me about 90 bucks just in brake lines).

It seems to me I can get similar if not better performance out of my forks for MUCH cheaper if I just upgrade the springs and forget about the anti-dives altogether.

Anyone have opinions on this? I've heard the anti-dive units didn't really work all that well when they were brand new. No sense in spending hundreds on something if spring tech has evolved to the point where it doesn't really make sense to make them functional.

 

Save money on springs , buy a piece of 1inch pvc pipe ,cut an inch off and put this on top of the spring , and install top caps . I'm running 20 w fork oil , but I know the European 650 says 10w30 engine oil . As to the anti dive mine works on both of my Secas , cleaned them out and checked seals . As far as if you bypass them you will need a shorter " B" nut on cailper and will need to block off the port on the anti dive unit . I personally like "kool" factor . Cheers

 

I think you are referring to the union bolt on the caliper? If you disable/eliminate the anti-dive, you lose that brake line (from the caliper to the anti-dive), thus the need for a shorter (single-depth) union bolt.

The anti-dive system works "OK" when it is working, and tuned (note that it has an adjuster) for your riding style/conditions. Most bikes over a dozen years old or more no longer have fully functioning anti-dive systems, because no one attends to them and they get gummed up.....they still (may) "work", but poorly (top half filled with brake fluid....who ever changes that?----and bottom with fork fluid....and who ever changes that, either?). But....even in perfect working order, they are not going to give you a track-bike feel (nor was that their intent, I believe). They simply prevent excessive front end compression during hard braking, sort of like having a stiffer spring rate during braking, and normal rate the rest of the time.

 

Keep in mind that the factory springs are progressively wound. New springs from Progressive (the company) might be needed, but the anti-dive is good to have in working condition as well.

 

Frame and swing arm are at the powdercoaters right now. Forgot to give them the kickstand and center stand but might have those done later.

I am strongly leaning towards rebuilding the master cylinder. Since this is a 750RH it has the non-handlebar mounted unit. I've read through the procedure for rebuilding this in the Haynes manual, but it doesn't go into much detail. Does anyone know of a good thread on this?