XJ650 Starting issues

I'll take some pictures once I get home again. The rust inside absolutely. There's what seems to be rust of some sort on the seam but I can't easily tell just yet. Appears to be in very good condition otherwise

 

Images of the seam.

Besides that I don't see anything that looks like there is rust except on the inside, also with some varnish. So when I go to clean it I'll need to take care of that and make sure it doesn't flash rust after

 

The inside is what matters.
Water sits under oil and all. Rust sucks in your fuel.
Your outside looks like a light bog before a paint finish.

 

What did y'all use for plugging the various holes? I can't fab pieces of metal to block off ports so I'd have to come up with some sort of solution to block the holes. I was thinking Vinegar, since 5 gallons of evaporust looks to cost $100 and you can just ziptie some nitrile gloves or whatever to the holes. Should I get PTFE tape or something?

Sorry, what is "light bog"?

The black paint looks really good here and there's almost no dents in this at all, that I could probably get away with slathering this with some sort of paint remover and then sand down everything before doing primer and then following it up with a new coat of paint.

Then I'll just need to figure out how to get a silver emblem on this. Seems like the XJ650 Maxim petcock and gas cap are straight swaps, but, some people have mentioned the removal of the petcock ended up damaging the petcock which I'm a bit worried about, cause I don't want a different gas cap w/ different keys. I suppose I'd also need to buy a new sending unit gasket as well.

 

Spray on putty generally. It's what spray painters put on the metal to make it look rounder than the actual metal underneath. Seems to be called bog here. Like bogging it up. Go figure. Vernacular and all.

 

For the plate part I used some old computer case steel, some tin snips, a drill and a bit of tyre tube.

 

Looks like I could probably get some like, thin steel plates, cut them with my metal cutter snips, drill a hole, and get some 6 x 1.00 pitch screws, and use a rubber glove for the "gasket. That's about the best I could pre-fab lol

 

Ahh... I have xj750 seca tanks and I think the 900 tanks have the same issue with rust and water settling at the bottom rear of the tank.
Basically it rusts through at the bottom rear near the seat, like pinholes to start with.
I did end up welding (oxy/acetylene) the underside on one tank, with mild steel, after finding holes, before putting a fuel resistant lining inside

Not sure if it's the same with the 650 tank shape though.

 

My 650 tank is fine, I just bought a 750 tank (both 1982 Maxims) so I need to clean up the bigger tank before I can put it on the 650.

 

Keys.
The wafer locks are very simple to disassemble and if you have a play with the wafers and get lucky or get creative with chacal you'll be able to key alike the lot. As long as you don't move between key types. Yes they have different types ack.

 

That's why I'd just swap over my existing gas tank cap. Don't like having different keys for different parts of the bike.

I got a friend to 3D print some of the block off items (resin not fdm) soon that are posted here on the forum for tank restoration. Once I have those, I'll use like a glove as the gasket and be able to clean the tank out. I already ordered the paint and have an idea of how I want to paint the tank. (based on one bobber build for the XJ650 I saw online, they painted the tank and the aluminum side of the rims the same color, which actually sounds like a great idea, and reminiscent of Yamaha's MT line, I might do that. I'll have to see how my paint job comes out.)

 

I was just watching a video about the "cam chain tensioner" and how on one guy's XJ650 the cam chain was loose and scraping on the bottom of the valve cover. I read in the manual that the automatic chain tensioner needs to be serviced periodically, but then it didn't say anything on like, how to do this. I believe I have a 650J not a G, so I assume it should have an automatic chain tensioner. When I get to the bike tonight, I can use a caliper to measure the distance of the slack with a digital caliper

I went back over my images and saw the attached image. Should I be worried? Should I untighten the bolts and re-tighten them while I have the carbs off? Do I need to do anything else??

 

You are deep in now!

With the valve cover off, move the rotor (crank) a bit forward and see how much slack is in the chain. Move it a bit back and do the same thing.

They stretch. So the chain tensioner is ideal to a point but eventually the timing goes out of whack when the chain is stretched too far.

So check to see if it's tight. If not you can force the tensioner a click by removing the plug and pushing manually with a screwdriver or whatever will fit into the hole.

A master link in the chain becomes ideal when you decide to just put a new one in!

 

Before you know it, you'll be splitting the engine and doing a full engine rebuild!

It's fate.

 

Unfortunately I do not have the space to do a full engine rebuild.

If that were to happen, I'd be pulling the engine off and rebuilding it in my living room, on the second floor.

Or more likely, just buying a 82 xj750 engine and work on swapping instead

 

Once you start...
Don't get me wrong, splitting the engine and rebuilding it is much less frustrating than tuning those damn cv carbs.
I have fully rebuilt a 750 and 2 X 900s so far.
750 is now a redundant 820 sitting in my garage taking up space.
You see, there is a kind of addiction to this process.

 

In saying that, changing a cam chain should be in your toolbox of knowledge. It's pretty rewarding if it needs to be done and no engine removal.

 

I just don't have the space to pull the engine, I think I can only keep the bike in there till the end of the month where it is now.

I'll measure the slack once I get to where the bike is, maybe around 8:00 p.m. Eastern.

 

All right so I've taken a look at the chain, at certain points during the engine's rotation, the chain I can barely even move it. Then at other times in the chain's rotation, it looks like I can lift it off the middle riser by like, as a rough estimate, maybe 6 mm?

That doesn't seem that much.

So far I have replaced one of the intake shims that was extremely small, where I could only get the .03mm feeler through.

I went from a 295, to a 285. And it seems that brings me to exactly .11mm.

If I'm reading this right for the intake, that technically means it is, technically in spec. On the lowest end of that spectrum. I combined some feeler gauges together to get a more precise amount, in this case, .05 + .07, or .12mm And that would not fit. However, .05 + .06 would, or .11mm

Thinking about it, I wouldn't be able to go down to 280 on that shim, because then it would put me outside of spec

 

Your thoughts are correct.

 

This has now been addressed! There are the right amount of shims and gaskets for the throttle lever. I also used a brush to apply a small amount of purple loctite to the butterfly valve threads.

Probably going to have to come back tomorrow to finish up, but I should get the shims done and probably the bench settings for the carbs today. Fuel levels probably tomorrow, and then putting it back on the bike and carb sync tomorrow too.

 

All right, as you can see I got all the carbs together, and everything is tightened down and nice and flat, but I'm having some difficulty assigning the butterfly valves to be open at the same time. It seems like four wants to stay closed. Is it because the spring on three is too tight?

Rereading the Church of Clean, I guess since it's on the rack I'm going to have to, fully unscrew the number 3 alignment screw, And then probably unscrew the butterfly valve and then reseat it?

Edit: no, I did that, and it didn't change anything. I think the spring is set too far. I'm not sure what else it could be

 

As you can see, I have bottomed out all of the screws, and I can fit a guitar wire (30g) into #3, but each one is out of sync by like, a millimeter.

I could probably put two of these guitar wire thicknesses.

I have reseated all of these butterfly valves and have made sure they're the right orientation but it still is off and I don't know what I'm doing wrong

If I unscrew the throttle adjustment on the left it opens wider, not tightens up.

 

I am stumped. I'll take another look at it tomorrow

 

What method did you use to keep the carb rack in heavenly alignment when tightening down the rack screws?

The problem you describe is what can happen if one of the carb bodies was out of alignment during final rack assembly.

 

#4 butterfly closed, sync screw all the way out


#4 butterfly open, sync screw near bottomed


So just turn the sync screw so #4 matches #3

#1 carb synced to # 2, looks pretty close


so now turn #2 sync screw so the pair matches #3

 

Basically the same one that mezzmo did

 

I feel like sync #4 was fully bottomed out. 3 is tight against the guitar wire, but is not holding any other wire, the gap is too large

I did buy that 3/8 plate glass, but I think I would have to take the fuel hose off in order to lay them flat against the glass. Part of the carb rack will have to overhang, because of the top rows little metal hanger thing. I can't lay it flat against the butterfly valve side, because of the metal thing that juts out slightly

#1, #2, #4 are basically, very close to the same open state. #3 is slightly closed in comparison.

 

Send a pic of the butterfly side of the carb set, so the linkages are clear.
Maybe someone can spot a simple issue.

 

Btw, if it hasn't been mentioned yet.
You synch 1 and 2 and then 3 and 4.
Then you synch 1/2 and 3/4.

 

I've posted a few, they are the attachments. Unless you want me to take another from a different angle? I can do that tomorrow

 

Ahh didn't notice those.
They look good to me!
I wonder if you are just fighting between them though.

Unscrew the middle linkage all the way and pop out the springs, so you end up with 2 sets of carbs not connected.
Sync those two sets and then work on the middle linkage.

 

Then that's not the problem.....mezzmo's method is pretty fool-proof.

 

I have a video of me showing that I have the butterfly valves on correctly. (Yes I'll put locktite on them again)

Okay, I think I figured out a screw position that has slight drag on the guitar wire.

Once I finish putting this loctite on all the screws, I'll test again.

Once that's done, next step is fuel levels

 

All right, I think I have them all more or less at the same

 

With the new metal tips, they seat basically at 15.6mm.

There's no "middle ground" tilt because these do not have a hanger

I finally have the carbs hooked up to something, I've double-checked with a level that goes on top of the carbhats, and I have everything ready to go... Except I don't have enough gas.

 

With the fuel levels, it looked like one was way off, so I adjusted that and then it looked a little low, but I ended up noticing that number four looked okay, so I took out three and four and adjusted them to each other, about as close as I can get.

Now I'm going to set one and two to two and four, and then that should be good

If I'm understanding the instructions correctly, where the fuel should float, is roughly in between this little section

Also, I find that these hex drain bowl screws, take a lot more force to tighten than I expected. If I don't tighten them just enough the fuel will leak out, but it's tight enough that it makes me start to worry.

 

YeYeah the hex bowl drain screws seem to seep slightly for my tastes, as cool as they are. Gonna go back to the brass ones which worked.



I think I have the fuel levels right but it's hard to tell when either the hose or the drain bowl screw leaks and then the fluid in the hose decreases.



You can see here kind of what I'm talking about. When I check the levels individually, the amount is fine. And then I notice that something is leaking, and by the time I fix it, the fluid in the hose lowers

 

I think when I'm doing this fuel level check, carb 2 drain screw leaks, very slowly, even with the original brass screw.

Is it not tight enough? I inspected the hole and it looks fine, I don't see anything wrong with the threads

I took the drain bowl off, put the screw back in, and I don't currently see a leak from the drain screw, if I fill it with gas separately. Maybe it's just not tight enough and I'm anxious

I always make sure to back off a screw before I screw it in, until you hear that nice little click where it's set in place

 

Here's what I'm noticing.

The hoses can't be left on the drain nipple, or the gas in the hose backfills into the drain screw, even if fully tightened off.

If I drain the hose and remove it, the drain screw stops leaking.

I fully clean off the drain screw, with paper towel, leaving the aux fuel tank connected but the valve off, still having residual fuel in the line to the carb, so it should be "refueling" the carb via gravity.

So if I go off the initial measurements, before it starts to seep, I only really have the first carbs float level to adjust. Which just needs to be lowered by like 1 or 2 mm.

The only other thing I can think of, is why don't the drain screws have their own o-rings?

 

With some more finagling, I was able to get the carbs fuel levels, just about perfect. Four is perfect, and 1-3 are just touching the bottom range of the 3mm +/- 1mm. This is pretty much what it says per the manual, and to be quite frank, I would rather that float levels are a little bit lower than too high at this point. Dare I say good enough for an entire afternoon.

Found a little trick on the forum to getting the carbs back on the bike, and that was ratchet strap. I don't have any silicone lube and I'm not sure I could put red Molly grease on the inside of the intake manifold, so I got them in there by force of strength.

Getting the air box boots was a pain but required way less strength. They were still pretty malleable. The intake boots however, are like hard as a rock... When the carbs are off I did take a look to see if they were cracked, and I do not see any cracks.

In hooking up the carbs back to the bike and reconnecting the cables, I of course make sure that all of the cables are adequately attached, however when I'm testing the enrichment cable would I notice is that it almost looks like, by like a very extremely slight margin, all the screws are in there properly by the way, I triple-checked, but it seems like enrichment carb 1&2 get raised before 3 & 4. Not by much but enough that I noticed. I was really hoping to finish this this weekend, but fiddling with those float levels took the entire rest of the day.

Thankfully, the only things that I have left at this point, are doing the valve clearance, which I still haven't finished doing. I did do one shim the other day, but I need to finish the other 6.

I did look at the valve cover and I do not think it is warped.

Edit: technically I do have the fork to deal with, but I am right now more focused on replacing the shims and doing a carb tune, and then once I know that she's running again, then I'll do the fork

 

What I found works is I just push #1 carb into place then tighten it's clamp.
With #1 held in place the others will snap right in.
Loosen #1 and retighten once they're all in line.

I'm experiencing the same reviving a Seca. One float bowl was broken around the drain screw from over tightening and epoxied shut. I replaced that bowl. Now I have another one dripping.

 

That's what I had thought, I spent more time with it, so this entire process took longer, because I was worried that I would need to replace the bowls, and then worried that whatever replacement that I would end up getting, would have also had similar damage.

What I ended up noticing instead, is that there is a fine fine line, between the drain screw being tight, and tight enough, and it is like a fraction of a torque too small, that makes me worried it will over tighten. When it's the former, it is a very light seep. When it's the latter, it's fine. I would stop and check on it 10 minutes later, and there would be no leak, so the screw just wasn't tight enough. I don't like that. These things really should have some sort of o-rings.

The other thing I noticed is that, when I would measure the level of the liquid, even if I closed the drain screw, the liquid in the hose would backfill through the drain screw, so I'd have to quickly measure with the drain screw open and then close the drain screw and then drain the liquid out of the tube, or it would start to backfill through the drain screw. That doesn't make a whole lot of sense to me, but I guess something about static pressure? It made this entire process incredibly frustrating

Bending the Tang arm after draining everything and shutting off the valves and doing this again and then realized you have to bend it again and like it is so tedious and, honestly like I think I'd much prefer to do a valve clearance, even though being inside the engine at all makes me super anxious. At least with the valve shims it's just math

 

Post a picture of one of the drain screws. Did you buy them from Len? You should be checking the float level while the drain screw is open. and the fuel supply not turned off. One trick, which you can't do with a short piece of tubing wrapped with a rubber band, is to lower the tube and watch the fluid level. When the tubing is lowered, more fuel will flow into the bowl and you will get an accurate reading. Conversely, never raise the tubing, which will give a false reading because the fuel in the tubing will rise. Yes, it is the biggest pain to do.

 

Yes I bought them from len
Attached image was what I did as part of the process

 

I'm not understanding what you are describing here......what does the word "backfill" mean?

Oh, that's an easy one! Mikuni tried that with some of their drain screws, and quickly dropped that idea, as installing an o-ring on the drain screws reduces the diameter of the screw (normally an M6 size shaft) down to what the OD of the ring land is (typically about 4mm). Thus you're using, in effect, and M4 size fastener in a somewhat hi-torque application and----to make matters worse----drain screws almost invariably seize (a little bit, or a lot, depending on how often they are used), and now you're trying to use a lot of torque on a seized fastener (and probably not even using a JIS tool) and either the screw head gets mangled, or the drain screw just snaps right off at its weakest point....which is where the o-ring land is (was).

Drain screws work via a taper fit....the working end of the screw is tapered, and it fits into a matching taper in the bowl, and the interference fit between these tapered surfaces is what cuts off the fuel from the drain port. Overtightening the drain screw, at first, slowly grinds away and/or "expands" the taper in the bowl, and thus the drain screw has to be tightened more and more in subsequent uses until eventually the taper-fit fails or, as Simmy experiences, the bowl fractures due to over-torquing the drain screw.

When you encounter a cracked bowl, you know exactly what was going on in the past......

I won't go as far as saying it's a poor design.....I can't think of a better way of managing this situation besides using a much softer metal for the screw than what the bowl is made of (and then changing out the drain screw periodically......in other words, make the screw and it's taper sacrificial rather than making the bowl sacrificial). The "external head" allen-drive screw that we offer is designed to make seized screw REMOVAL much easier, as that is a much more common issue than wear in the bowl taper area. But few engineers think about how to ensure the integrity of design and parts for 45-years into the future, and even if some do, their solutions typically get nixed by management if there's an extra penny or two of savings that can be had by doing things in a "good enough for now" method.

And yes, it's a very fine line between tight-enough and too-tight with bowl drain screws......especially as age and use (or mis-use) works its wonders on the bowl metal.

 

The whole thing makes me nervous, but maybe I was being incredibly neurotic and tired from laying on the ground looking at float levels while huffing gas fumes

The carbs are back on the bike (those intake boots were solid as hell) but I think I need to take the #4 float bowl off (I think I have enough clearance with upgrading to hex screws) and use a caliper to measure the float tang and make the adjustment to #1. It's so so so close but I'm a perfectionist and it bugs me lol

 

Succinct!
No I'm not being droll.

 

If you have a tube with gas attached to the nipple, it leaks from the drain screw, even if you tighten the drain screw closed, gas in the tube flows out of the drain screw until you disconnect the tube entirely

 

That's where the ss hex cap screws come in.
Tighten it more.
Drain screws are normally just stoppers.
Generally you mess with them once and forget you ever did. Well generally.