Fuel Tank liner(?) issues on new shiny '82 XJ750 Maxim

Got her all together, bled the brakes. Had a chance to use kmoe's awesome vibratory sander method, which worked incredibly well.

She's up and running, put a few miles on her testing things out.

No pulsation at the brakes and no front end judder! Yay! Very happy about that.

This takes me to a couple fairly minor electrical issues (that existed before but where inconsequential compared to the judder):

Low speed very sharp cornering causes the bike to die completely, instantly. Like, kill switch fast, no misfiring. Not all the time, and it requires a fairly steep lean, but it's happened twice.

I have to have the kill switch off (as in running position) and the ignition On to start the bike - this is as expected, of course. But to turn the bike off, I have to turn off both the ignition switch AND hit the kill switch. Either alone will leave the bike running. I'd hoped this would be clear once I dug into the front end connections, but they all seem normal.

Not sure where to look first for these.

 

Spent some time pouring over wiring diagrams, and at the mess of wiring a PO did when he replaced the fuse box, and I'm at a loss for the problems above. However, I'm not too bent out of shape about it as I'm very certain I want to replace the entire wiring harness with new, shiny, custom harness and simplified electrical system (as I've said elsewhere, I'm really certain I want to yank out the Atari).


Moving on:

I've taken it into work now - a 50k commute - and have a couple concerns.

There's a ticking - I assume valves, as it's clearly ticking and RPM based - that's most noticeable when the engine is hot. It's very faint normally, and I didn't pay any attention to it in my first shorter neighborhood rides, but when I've had it up and running at highway speeds for a while, it gets a fair bit louder. Not "OMG MY ENGINE IS EXPLODING" loud, but definitely noticeable. Louder on the right side of the engine. Is this normal?

The engine starts very easily when hot. Tap the start button once, starts and idles immediately, runs really well (amazingly well for a 35 year old bike with 80,000kms on it!) which helps reduce valve-induced terror.


I know I need to check them as who knows when they were checked last, but as I'll almost certainly need to replace the valve cover gasket, the donuts, get a tool, etc, it'll cost me several hundred after exchange/shipping to get into the valves the first time and I'm pretty broke. Just wanted an opinion on whether or not it's likely safe to ride in the mean time or if there's anything else I should check with regards to the ticking when hot.

 

Both the 650 and 750 had a TSB regarding slightly loose tolerances for the camshaft endplay.
It's a regular ticking that increases along with the engine speed, and is most noticable from the right side of the head when the engine is hot.
It sounds to me like that's what you are describing.
Ignore it.
No harm is being done. The camshaft endplay is not so large as to cause any damage.

 

Ah that could definitely be it. It's decidedly noticable, but it's not.. smashy. Something that raised some concern, but didn't sound so bad I feared riding it home. Thanks!

 

tighten the 8 nuts holding the pipes to the head.

 

Checked em, all snug.

Can hear it here:

https://goo.gl/photos/36y4WAuh86dtSyuJ6

 

you're fine, go ride

 

That doesn't sound all that good to me.............maybe the valves are really loose, or???

 

Haven't checked the valves yet. Buyin to get the needed stuff is out of my price range at the moment, so couldn't say. Be about a month. Only does that when hot though.

There was a scarier rattle, but that turned out to be the choke linkage, so not a concern at all.

 

This is much more noticeable here on the right side vs the left side, so k-moe's TSB is still a possibility too.

It sounds "valvey" to me, but I am unfamiliar with these motors and don't get why valves would get noisier with heat (wouldn't things expand and STOP ticking?)

 

Ok, on my last trip to work (half hour commute) I pushed the bike pretty hard on the way home, to investigate the noise a bit.

It's definitely louder when the engine is under load - loud enough that I'm pretty concerned. Oraybe it's just paranoia making it seem that way, but she's a 35 year old bike with 80k on her... A little paranoia isn't bad

Any tips for investigating major problem issues and ruling them out for peace of mind, such as piston slap, or rod knock?

I need to do my valves anyways, and have to repair a stripped valve cover bolt hole in the cylinder head, so tearing down that far may as well happen anyways. What should I look for when I'm in there? Is it possible to rule out bottom end problems from there, or would I need to tear down everything to check?

 

http://www.earplugstore.com/

 

I have 2 Maxim rotors 25$ for both if interested

 

Nice! I got one already, though, as I said in the quoted post, so I'm good. Thanks for the offer though!

 

Shoot a video and we'll have a listen. It's best if you can do this on a day with very little wind, and give about 30 seconds (per side) of hovering on either side of the engine. All I really ned to hear is idle, but of you want to run her up to 2k and hold it for a few seonds too, that will help.

 

Will do; should have it up tomorrow.

In the mean time, I took this a day ago after a run to the local gas station, by taping my phone to my gas tank. I don't have a proper mount, and this allowed me to get the mic near the engine and out of the wind - excuse the bizarre visuals of the ignition in the reflection of the gas tank. Kind of a scary thing to do, and got some really interesting looks from a cop watching me tape the phone down =)

The ticking isn't bad here, but it is noticable. I'm also concerned with the nasty rattling noise at 3500rpm - it's very clearly audible in the video at ~15s to 20s. I can't get this to happen when the bike is motionless in neutral, only when it's actually running. It's not the keys; I tested with the ignition off and the keys out (bike will keep running if the kill switch is set to run) to be absolutely sure. Thought it was the choke linkage, as it's very rattly when the choke is off, but that appears to not be the case. Tough to feel/hold stuff while accelerating though, so it's hard to test things.

 

I've got another uploading right now that shows the ticking under load better. Should be ready in about 40 minutes after this post:



Hopefully this does a better job of illustrating why I'm so nervous about it.

 

Hmm. I was going to say camshaft endplay, but then you really got on it.

Needs further investigaton.

It definitely has the camshaft tick, but then there is that hollow ringing sound. Hollow ringing is not caused by camshaft endplay, or valve clearances.

Hmmm......

 

It's rattly at idle (slightly over 1k rpm), which goes away if you give it even a teensy tiny bit of throttle. Whatever is making the noise there may be what causes the scarier noise at 3.5k; will try to capture it when I get the video tomorrow.

I'm thinking of a guy who posted valve cover pics that showed the cam chain wearing on the valve cover. Will definitely look for a worn/loose cam chain when I open it. I'm just spitballing here though, as I have no idea what can cause that. Really hoped it was the loose choke linkage =\

 

well... err... I found it.

The good news is that it's a simple fix. The bad news is it's deeply embarassing, as it's such a simple thing and it's horrifyingly obvious, but because I only really noticed it when I was already riding and generally accelerating, it was hard to hear where exactly it was from.

I was taking the requested video, got to the right side of the bike, as I finished I noticed there was exhaust coming out of the bases of both mufflers. I bent down to investigate further, grabbed the muffler... and... well.



I'm going to go hang my head in shame now.

 

Oh good. I was worried that it might be a loose diverter plate in the collector.

Locktite, blue, everywhere that's not hot

 

HAHA ...we have ALL been there done that at one time or another...we overlook the obvious no worries great that it simple to fix. Cheers

 

So, as has been referenced in the daily Yamaha thread, I've been digging into an outrageous amount of lateral swing arm play:



Pulled off the swing arm, and yeah, the bearings are right done. Also is clear why the bearings are done: The left side spacer that sits inside the oil seal, between the bearing and frame, is missing. So, the only thing keeping the bearings in their races at all is the rubber oil seal. I've got new bearings and oil seals, will get a new spacer, but have a question:

The adjuster axle stub (the one with the 6mm allen head socket and ring nut) was on the left side of the bike, while the Hayne's manual says it should have been on the right side. Is the Hayne's manual correct? Does it matter? I'd assume it was just put together wrong, given the absent spacer, but just wanted to confirm.

 

Yes.

Confirmed!


Just think of all the other systems that the same level of attention-to-detail was poured into..........

 

Yeah; that's the misery and joy of old bikes. Can never assume the way something is put together is the way it's supposed to be put together

It's made more exciting because while the aftermarket repair manuals are very handy, they're not always absolutely reliable.

 

Swapped in my spare swingarm as it's bearings are fine. Reinstalled the axle stubs correctly, at specified torques.

Well, locknut is guessed at as I can't get my torque wrench in the locknut AND hold the axle stub with and Allen wrench at the same time and I figured a specification like 52 lb-in is pretty specific while 70 lb-ft is "snug that mofo down".

Swingarm moves up and down freely now, no scaryass sideplay. Can't wait to see how the bike rides now!

I'm pretty excited. Now I've fully disassembled and rebuilt (well, swapped, in the rear case) both front and rear ends, and both went pretty well. Feeling really confident about both now, so any future suspension related work should be cake.


Again, thanks everyone for all your help. It's been fun, educational, AND I've gotten a great running bike out of the process; the whole trifecta of "Is this worthwhile?"

 

So, as I mentioned in the daily thread, my Maxim appears to have spring a severe oil leak. Enough to go from full to empty in a day or two. I'm not positive of where it is yet (just noticed when I started her up to go to work) but it appears at quick inspection (in the dark) to be from the bottom of the left side transmission cover - no oil on the jugs or front of the motor, but a hell of a lot along the bottom of the left side.

Curiously, there was also a heavy "gassy" smell when I started the bike. Same method as always (full choke initially, immediately backing down to half) and I've never had that before. Not even "rich burning exhaust" but just gas.

Carbs don't appear to be leaking[edit: more than normal, 1 and 4 have slightly leaky boal gaskets but it's very minor], no smell of gas in the oil. Gonna clean it with brake cleaner, top off the oil and see if I can confirm where it's leaking from (and hopefully figure out what the deal is with the gas smell too) tomorrow morning.

 

Herm. Could be I panicked a bit unnecessarily.

Got home from work this morning, and checked up on my baby. Too much oil in it, which leads me to believe what happened last night was that with the oil light on, I popped the bike onto it's center stand and checked the oil.... but having just run briefly, the engine itself was full of (still sluggish, cold) oil, so it read low. I topped it up then and (*shudder*) drove my truck to work.

This morning, seeing it overfull, I drained the excess and got it down to a nice small bubble atop the sight glass, started her up and... sure enough, after a short time, oil light came on again. I know the level is good, but it's not done this before. Obviously, one potential issue is a hinky oil level float/sending unit. Is there anything else I should consider?

 

some of that oil might have got sucked up the breather tube to your airbox behind the filter, maybe look in there for a puddle

 

Hokay, back in the thread this stuff belongs in:

I've repeatedly thought I fixed my rattle, but alas, it persists.

I've gone through the bike multiple times, checking torque, making sure nothing's loose. I've just finished fully removing and dismantling my exhaust, replacing gaskets, cleaning it all out, checking for loose parts. Ensured the rear collector mount bolt (and it's full rubber mounting) is installed correctly. Opened up the rear end, checked brakes, changed oil. Not even the slightest bit of rattle in the collector or headers

Took it for a test ride before remounting my mufflers and without body panels and unnecessary chassis parts (painting stuff, still drying)... and still getting a metallic rattle at ~3000rpms.

I'm starting to wonder if it's the cam chain. I figure I'm about out of non-engine related causes. There's an automatic tensioner, but is there any way to know if it's working?

 

Take the valve cover off as if you were going to do a valve check turn the crank then turn it the other way and see how loose the cam chain is how far it turns before it gets tight.

when i did the valves on my bike it was how I knew I needed to adjust the tensioner.
yours is automatic and may need to be cleaned or the end replaced

 

Will check it once my helicoils get here. Have a stripped valve cover bolt hole (that previously held a helicoil) so I'm short a valve cover bolt at the moment, but it's not leaking and I don't want to disturb the gasket till I can get that fixed.

 

Pretty happy with how it's all going. Still waiting for the helicoil, though I'm seriously considering just clamping that corner (it's the front left bolt) with a c-clamp until I can get it fixed - I really want to get the valve cover off and check valves, cam chain tension and whatnot. Wish having that stripped hole fixed wasn't such a PITA.



She's come a long ways since March!

Finally replaced my flasher with an electronic one that's actually wattage independent (and adjustable!) and got the exhaust and such cleaned up.

Have a carbtune pro on the way, and looking to order a carb rebuild kit from Len on payday.

I've got three sets of carbs - the ones on the bike, and the ones from the second Maxim and the Seca. They're all the same HSC-32 carbs, but I haven't opened any of them. The existing set on the bike are running really well, so I'm assuming they're either synced or at least pretty close, and despite the apparent slight leak from the throttle shaft seal on #4 (can be seen on the pic above; but MAY just be from the bowl gasket - I think it's from the throttle shaft though) they seem to be set up pretty decent.

So, I'm thinking the best course of action for me is to tuck into one of my other sets of carbs, and do as good as possible a job on them, get them *perfect*, then swap out my existing carbs for the rebuilt ones. This way, I can keep riding while working on them[read: not feel pressured to do a fast job just to get carbs back on the bike during my soon ending riding season], have one set being cleaned and another set as a "let's look and compare" set though as I've never seen them run, there's always the possibility that things aren't correct on one or both of them. Install, sync, etc - then I've got the currently installed set to rebuild for my other bike (the Seca). That's the plan, at least.

 

I thought about this issue the other day when I came across this old thread, unfortunately you already had your exhaust back on. Post number 19 has the pics of the broken double wall pipe that was causing a rattle:

http://xjbikes.com/forums/threads/1989-radian-noise.34466/

 

That was something I was specifically looked for when I took the exhaust off. Was hoping to find that in fact as I've another set of headers available.

With that said, while I didn't find anything loose - I had each header off and shook them, then rolled/flipped them around a lot while wrapping them - it's not impossible that one is broken further inside but held by both ends so nothing was apparent when I shook them.

 

Definitely wasn't anything visible inside the ends of the pipes.

 

I believe the Seca carbs are jetted differently due to Seca having hotter cams. Somebody wanna confirm this? If so, it'd be best to use the Maxim carbs on a Max.

 

You are correct. Swapping the main jet end jet needle is all that's required though.

 

Righto, so I'll use the carbs off the parts Maxim, then.

Edit: Well, I'm not sure which set that is now. hah... Well, I guess I'll look at what jets are in each vs. stock jets. Needed to figure out what I have on hand anyways.

 

K-moe: I noticed in another pretty old thread, you noted that the cam shaft endplay ticking is due to the cam caps' tolerances, and that Yamaha would replace them but only if the customer complained (that is, it's not necessary, but it is a fix). I've seen posts previously on this, but hadn't realised it was the caps themselves vs. the cylinder head.

Did this affect all 750's of the era? Or was it just some? I ask, as having a fully spare motor, it may be worth checking. My Maxim's ticking is loud - likely due to 80,000k of tapping - so loud it's very noticeable when doing 120kph over engine and wind noise.

I'm thinking I could just try swapping out caps to see if I can find ones that are somewhat quieter, if it's that simple. Or just replace them, if replacements have the correct tolerances and are available(Couldn't find them in Len's Engine post, but may not be looking for the right thing)?

 

Well, got valves done, replaced a horrifically borked cam cap.

I was curious about cam chain tension in case that's the issue with the ringing noise. I did find this:


So there is occasional light contact - it's not worn in there to any noteworthy extent - can barely feel it at all. Chain feels pretty tight, though I didn't have time to get to the "resetting a potentially stuck automatic tensioner" procedure- can lift it a little bit off the guide, but just a little bit.

Think that could be the cause?

 

Posting it here for posterity too - what you don't want to see when you take off a valve cover:



Replaced with one from the parts motor.

 

turn the bolt to check valve adjustment then go the other direction and you will see the looseness of the cam chain.
that will give you an idea if the tensioner needs attention

 

The problem is I don't know how tight it should be.

There's some play when changing direction at the crankshaft before the cams move, but I don't know if that's normal or not. Will post video tomorrow.

 

Cam chain slack:



Normal? Too much?

I checked, followed the automatic tensioner "encouragement" procedure a couple times for good measure, then checked again - no change. It does feel very tight.

 

It does seem a little on the tight side to me, but I'm not sure what exactly the ideal amount of play is.

 

what you are looking for is how much lag turn there is when changing direction.

but when in doubt take it out and rebuild it
the chain does look tight as it should be in vidio

 

i doubt the chain can be overtightened the adjuster is spring loaded

 

Shouldn't be able to be too tight, as the tensioner is spring loaded. If that doesn't look loose, I'm happy with it. Certainly doesn't feel loose to me (but again, I don't know how tight it should be).

I figure if the cam chain being loose was the source of my noise, it'd be looser than it was and what while there's some marking on the top of the valve cover, there's no real damage there. A comparable amount as on my other two valve covers (checked today as well).



Reassembled the works with a spare valve cover and used-but-decent gasket and spare set of bolts with decent donuts. The gasket that was there was shot, and the donuts on the valve cover bolts where utterly destroyed - broken apart and crumbling.

I'm ordering a new set of donuts with the shim I need tomorrow, so I'll hold off installing the new gasket until I open the valve cover again for the final shim change, new donuts, fixed bolt hole, and all that. In the mean time, hopefully the spare gasket/donuts will do without excessive leaking. May as well clean up the original valve cover, get it painted up nice and shiny while I wait.

 

I'm sure you couldn't overtighten it with the tensioner, which would leave something like using the wrong chain, not having the cams torqued town correctly, or not having the cam chain guides installed correctly as the cause. From what I can see it all looks good so I wouldn't worry about it either. It definitely doesn't look loose. It's a little tighter than mine was when I replaced the chain ( as I recall) but not by much.