1981 seca xj750rh rebuild

Hey guys, just wondering if ay one has a good method in dealing with this kind of thing? The rust doesn't seem to be too deep but im not sure what the best way to getting rid of it.

Cheers!

 

Aluminum foil, scrunch it up, get it wet and rub. It probably won't clean all of that ^^^ but you will be surprised how it will make things look much better.

Please post an "after" picture.

 

1- Replace it, new and used ones are easily available
2- sand blast and paint
3- wire brush and paint

 

you could try soaking in lemon juice

 

Here's how I deal with carb hats like that---

1. Get another

2. Throw that rusty one away


Dave

 

That looks pretty deep to me. I'm with Dave (hogfiddles) scrap and buy.

If you just want to see how it will turn out, take some light weight oil and 0000 steel wool. Plan on spending some time on it.

 

Sand blast and paint.

 

Save your sand and paint for something worth blasting and painting.

 

Yeah, unless funds are really tight, I'd replace (and I'm incredibly poor/cheap) - that's pretty damn bad.

I mean, you could soak it in metal rescue, sand it smooth, and paint it... But those hats can't be that expensive. And if there are any pinhole leaks from sneaky bits of deeper rust (or should they develop in the future under the cover of paint etc), the loss of vacuum would cause all sorts of problems.

 

Don't have to buy new, decent used ones are readily available

 

So available that $40 to $60 will buy you four, and the $1500.00 rack of carbs that they were originally sold with.

 

What you do is this: attend the Central NY carb clinic. When Dave isn't looking, sneak into the Legendary Hoard. Grab new cover. When chased by giant stone ball, remember to dodge poison darts and booby traps. Be sure that if you drop your hat while sliding under closing door, you must retrieve it dramatically at the last second.

Or you could use cola and tinfoil to polish...

 

Yeah, cuz I only have a few...

 

I use vinegar, soak parts for a few days and rust peels off.

 

Thanks for all the suggestions, I'm pretty keen to salvage all I can with this rebuild so I'm going to give the vinegar a go and see how it goes.

Will post after photos in a few days.

Cheers

 

I have cleaned some rusted parts with vinegar and I was surprised of the result. Just brush them sometimes to let the vinegar reach the metal underneath.
While replacement parts are available, trying to salvage what you have doesn't hurt.

 

Hey guys,

Im working on restoring a bike that has sat in a garage for 10ish years. Before I get stuck into the complete tear down I want to make sure the engine is all good and the juice is worth the squeeze so to speak.

So far I have drained all old oil out of the engine and replaced oil filter. I have the carbs dis assembled and cleaned, just waiting on getting new jets before I can put it back together and fire up the bike.

Is there anything else I should be doing before I just fire her up? And once it's going (if it goes) what should I be looking/listening for to see if the engine is worth keeping.

Cheers!

 

I'd recommend a compression test. I know somewhere on here there is the proper procedure. Check dry and after squirting a little oil in each cylinder to note the difference. Would give you a start but there is always the possibility the rings are stuck from sitting idle so long. My 2 cents any way

 

^^ THAT ^^

Throttle held open. TCI unplugged. All sparkplugs out to help the starter out since it's going to be doing all the work.

Also begin reading the links in my signature.

 

As a guy who's just finished doing this, note that the "stuck rings" thing can lead to a really dramatic difference. A motor I had sitting here went from 110/100/100/110 to about 130-135 per cylinder after a week of sitting with a couple tablespoons of k-moe's stuff (a 50/50 mix of acetone and ATF) in each cylinder.

 

Not my stuff. Grandpa told me.

 

Thought I should add some photos of the bike when I first got it to show everyone what I'm dealing with. Everything is in need of complete tear down clean, polish and replacement if I need to. My main goal is to salvage anything possible. To me it doesn't look like it's condition is too bad but I guess Ill find that out once I start pulling everything apart.

 

Has anyone managed to breathe life back into a battery thats sat for a few years? Has anyone seen a tutorial online that takes you through the steps of getting one running? I've got a charger but not sure what to do with the cells etc before I hook it up.

 

Junk. Go get another one.

 

This. You can "recondition" a battery to an extent (and reasonably well with the right materials) but it'll never really be reliable.

As our bikes rely heavily on having a good battery or they just won't spark, this is one of those places that you really don't want to try to save a couple bucks. Batteries are cheap, and if you end up with one that does charge and hold a voltage but cannot reliably deliver the needed power all the time, you'll be fighting electrical problems from day one. Not fun. You'll be joining the ranks of people where "My bike turns over, but only sparks AFTER i let go of the Start button!"

 

a

 

Done, ordered one today.

 

Thank the old one in to any place that sells batteries. There was a core charge paid when it was new so it would be brought back in for recycling. This is a federal program so you can both legally and morally take the old one in and get that core charge back (when you bought the bike you also bought the battery). No matter who you take the battery to, they will turn it in to a recycler, and the store will be compensated for the core charge.

 

Here's the results from 48 hours soak in vinager and scrub with a wire brush. The rust isn't all the way through but has definitely started to lift the chrome. Looks like I'm stripping the chrome too and will have to paint them.

The vinager soak worked really well as far as getting the rust off though. Will definitely use that technique again with other parts.

Any one got a good chrome stripping recipe I'm thinking I'll just soak in acetone

 

It's called patina nowadays. Your bike will get more likes on pinterest with it.

 

Got the new battery in so I can do compression tests but can't get the neutral light on for some reason so the starter motor won't run. Ill be trouble shooting with my Haynes manual tomorrow but if anyone has some common problems that might be causing it let me know.

 

You are getting it in neutral, just no light? Or can't get it into neutral?

If the former:

I don't have my wiring diagram handy, but test the wire from the neutral switch with a multimeter. Check if continuity changes when you put the bike into/out of neutral: you want to determine if your problem is that the neutral switch is working or not.

From there, it's just checking electrical connections from the neutral switch to the relay to find the problem, as it'll either be that the neutral switch itself isn't working, that there's a poor connection, or that the safety relay has failed.

In the mean time though you should be able to just bridge the starter relay with a screwdriver to activate the starter for testing purposes, but be sure the bike is actually in neutral first!

 

The neutral switch wire is the only sky-blue wire on the bike.
Two common issues are; someone removing the wire from the switch to bypass a suck switch, and a stuck switch.

Usually with the bypass you'll find the wire has been grounded to the oil pan, but someimes it's not done very well and comes off or ha bad contact.

Usually a stuck switch can be freed up by using Seafoam in the oil to clear out sludge buildup from around an inside the switch.

The switch is in a recess on the left side of the oil pan, just near the front of the kickstand mount. The wire runs along the left side of the oil pan, tucked up behind the lower left frame tube.

 

Thank guys,

I had a look at it today.

1. Found the sky blue connection and cleaned it all up re-connected it. Still no N light
2. The frame is in the way to actually unscrew the switch and clean it up so I took off the casing behind the shifter. Can't really get to it easily through there either. 'off to buy a new gasket'

@Moe can I just ground the blue wire and it will by pass the switch allowing it to turn over?

@Wintersdark I'm 99% sure I'm getting it into neutral just by feeling the half click but I'm getting no light which I assume is stopping the starter motor doing its thing.

Sorry if this is super simple stuff, it's my first build and all that

Cheers

 

You can be 100% sure by just spinning the rear wheel (or, if off, the power take off at the rear of the engine) - they'll spin easily if the engine is in neutral.

A problem with the switch is more likely, but it's always best to be sure of the simple things first.

 

Thanks for the info @Wintersdark got the starter motor going with a screw driver. Judging by the rego its been about 16 years since it last turned over.

Did the compression test with some odd and pretty varying results. I had all of the spark plugs out, carbs are off and put a teaspoon of oil down into the cylinders a few days ago.

Haynes manual says:
Standard 156psi
Minimum 128psi
Maximum 171psi
Between cylinders 14psi

I got:
C1=35psi
C2=0 (this had no reading)
C3=70psi
C4=35psi

So obviously they are all super low which has me thinking that:
a) The battery isn't at full power?
b) I haven't done valve clearance tests so this is effecting pressure dramatically.
c) This bike needs work way past my ability and I should rethink restoring it.

Any thoughts or ideas on what to do next? Im thinking a little more oil our penetrating fluid for C2 so it frees up but as far as the super low readings I guess im just hoping its not broken piston rings or something more complex.

Cheers

 

Low readings across the board could indicate a bad gauge. Know anyone with another you could borrow to confirm the readings?

 

The swich is a bear to take out while the engine is still in the frame, which is why I suggested puting Seafoam in the oil to clean the sludge out of the switch (this works about 90% of the time).
You can ground the sky blue wire to bypass the neutral safety switch, but do so temporarily.

 

Sure you're doing it right? Cranking until the pressure stops going up on the gauge, fully charging the battery for each cylinder? Readings that low seem like something isnt right in the testing process.

 

I vote for faulty gauge as well. Even with no rings on the pistons, and all the valves loose, there should be more compression than that.

 

Will the seafoam work if the bike is not running to mix and circulate the oil thru the filter?

 

I am also rebuilding an xj750seca and I would recommend saving everything you can. Also, buy one of those assortments of metric
fasteners for sale on Ebay. You'll avoid a whole lot of trips to the hardware store for a $20.00 + - . I also use the 50/50 mix of acetone and atf
to loosen up the rings, but I use a small oil can with a flexable tube/spout, sticking the spout into the plug hole and squirting a couple of
shots against the uphill cylinder wall so the rings get saturated all around. I let it sit for a couple of days before I turn the engine over for the
compression test.

 

Swap the neutral bulb out in the instrument cluster first. these are 35+ year old bulbs.

 

You wouldn't need to circulate it. The switch is at the bottom of the oil pan, and covered with oil when the bike is on the side stand.
It might have to let it sit for a quite a while. One of the things that helps to break the sludge up is heat. If you have a magnetic block heater it would not be a bad idea to use that to wam the oil in the pan. Once warm, you should work the transmission to see if the switch will free up.


Even if the neutral indicator bulb is burnt out the bike will start in neutral, but only if the switch and relay are working.

 

It is a brand new gauge, not ruling it out but would be surprised if its faulty. Ill try a few of the other suggestions before taking it back.

Definitely not sure im doing it right haha. I'm going to charge the battery for 12 hours and see if that makes a difference.

Yeah definitely saving and using all the parts I can, part because I'm on a budget part because thats half the fun! Just had a look at those fasteners... good idea. I've seen someone else suggest that 50/50 mix to free up rings so ill give that a go and soak for the next few days.

 

Thanks for the suggestion gents, will update when I give it some more time over the next few days.

 

After another attempt the results were slightly higher but not much at all.

I'm actually thinking its the battery... I bought the cheaper one and it sounds a little like its struggling a bit. Can I just hook the car battery up and give that a go?

 

Yup.

 

Band new compression gauges can be faulty, particularly the lower price-point ones.
Do your auto-parts stores have a tool lending progam?

 

Another attempted today after spraying a bit of CRC down the spark plug holes. It's an improvement but still not great.

C1 - 70
C2 - Still nothing
C3 - 75
C4 - 70

I might have to try the 50/50 mix I've heard a few people mention on here. Realistically will this give me the extra 50ish PSI I need?

I drained all oil about 2 months ago would that effect my compression this much?

As for Cylinder 2, I have no idea whats going on there, hopefully it frees up after I give it the atf and acetone soak.

Started to re assemble carbs today too so that will keep me busy until I figure this compression out.