valves

alright guys i messed up once again. after i got done with my valve clearance job i made the rookie mistake and did not check the timing mark, i just put it at T.D.C tried to crank it and ended up hearing a clunk/crunch after it tried to turn over a few times and i thought oh shyt i just bent a valve. after i looked at the specs again it said the timing was supposed to be at 7 degrees B.T.D.C. Now i don't have a shop to take the motor out not even a garage i am doing everything outside and right now its cold that i dont mind but is there a way i can check to see if i bent a valve without disassembling the motor or would it be possible to take it apart with the motor still on the bike? i know theres not much clearance there but i'm running out of options and running out of money. the bike is an 85 yamaha xj700n.

thanks guys. big rob.

 

Did you pull the cams to do your valve clearances?

 

I'm about to check my valve clearances and im a rookie. Could you please explain what you guys are talking about?

 

http://xjbikes.com/Forums/viewtopic/t=1 ... xj550.html

 

and if you decide not to purchase "the tool" for yourself, http://xjbikes.com/Forums/viewtopic/t=29209.html

 

no i didn't use the tool i took the easy way out and just got some chord off of a test light that didn't work and blocked the piston from the spark plug hole it worked so i wasn't complaining. the motor did start after all of this it ran for a little bit then i hear the crunch/clunk so i killed it and haven't wanted to try to start it back up untill i figure out a way to look and see if the valve is bent.

 

no i never pulled the cams

 

If you check your valve clearances again you'll know if any are bent as the clearance will be massive...

Since the motor ran & you never pulled the cams I'd doubt a bent valve really though, but maybe I'd suspect a badly seated shim got spat out & hit the head

Hope there's not too much damage :/

 

well i just checked the valve clearance. it all checks out none are out of spec and seem to be the same as when i replaced them.

 

Good. The position of the crankshaft (TDC vs. 7 deg BTDC) when checking the clearances won't create a valve-bending situation.

Since it didn't spit a shim and you didn't remove the cams (therefore the cam timing should be OK) I kinda doubt it was able to bend a valve.

Pop the ignition cover off and turn the motor over, "forward" by hand and see if you can detect any signs of what might have happened (broken or displaced chain guide, or ???) You can use a mirror and a flashlight to peer down along the cam chain runs and check the chain guides.

In answer to you other questions, you can pull the head with the engine still in the bike; but at this point you have nothing indicating that it might be truly necessary. As above, you check for a bent valve by looking for sudden GIANT clearance gaps; and you don't have any.

 

alright thanks. one thing i did notice i was wondering about, on the cam and the sprocket the intake and exhaust are 90 degrees off if one is lined up with the marker the other one is 90 degrees off shouldn't they match up? i work on cars i'm still trying to get used to working on bikes so i'm not 100% on anything yet.

 

i think what i'm hearing when i turn the engine over is the chain. but when i turn it over by hand there doesn't seem to be anything wrong with it. the manual does not specify any tention specs any kind of free play or no free play at all so i'm kind of at a lost here.

 

Isn't it an automatic cam chain tensioner on these? If you can feel slack in the cam chain I'd say there's something amiss with the tensioner or guide as it should be not tight, but no free play/slack either.

As Fitz suggested it's worth getting a light and look down the chain run to check for any damaged or displacement of the tensioner/guide.

Just a thought, but did you by chance turn the engine over backwards (or worse, turn it over via the cams instead of the crank) when doing the shims? Not looking to insult your intelligence but stranger things have happened & if so I believe (but stand open to correction, so don't quote me until someone can confirm or deny it) there may be a chance your tensioner was able to pull up too tight & maybe damage a guide.

 

more than likely i did go backward a little on the crank no i never turned the cams but by a little i mean no more half a turn of the crank. but as i hear it more the noise does seem to be coming from the bottom of the engine and it definitely sounds like the chain. so i may have messed it up not sure. everything i do to this bike is my first time doing this is my first bike. right now my intelligence on bikes only goes as far as what i have already done, thats why i'm here to get help and learn.

 

i've been meaning to look down and see if i can see the guides but its cold and windy as hell out here so i haven't had a chance to get out there yet.

 

I fear you might have enabled the chain to overtighten by turning via the cams (shouldn't turn by them at all even a little bit so tensioner could have "nipped" up a bit)

I think if it was me, I'd check the guides for damage & then I would be tempted to remove the tensioner, check it's working & "reset" it then reinstall, release & see if it's any better. At least then a tight or loose chain is ruled out.

 

First off, you don't have to set the TDC to check your valves. Not sure what you're talking about there. Just turn the cam so each lobe is 180 degrees perpendicular to the surface of the shim.

If you removed your cams, then yes, you'd need to do the timing stuff. Otherwise, no.

If you didn't spit a shim, I doubt that you bent a valve because of the swap. UNLESS you put a shim in that was waaaay tTOO THICK----then the valve may stick out far enough to hit the piston.

Is is possible you dropped something into the spark plug hole?

Is it possible you dropped a shim down the chain tunnel?

CHeck also for a broken chain guide......especially the one way down in the bottom of the engine. Those are know to fail at this age.

Keep up posted on what you find.....

dave

 

alright its a good day today so i'm going to go see what i can do. I NEVER turned the cams i turned the crank. and i checked the clearance on all the shims they are all still in specs.
nothing i can think of could have fallin into the spark plug holes i tried to keep them in when i wasn't using that cylinder as a guide.
I only set it at tdc bc i thought that was the timing mark after i was done and trying to start the bike. i found out later the timing was 7 degrees btdc.

 

sorry about the delay with this. it has been raining with 20mph winds down here for the past week.

 

alright. there is only about a milimeter of freeplay on the cam chain. are you supposed to be able to see the front chain guide (intake side) from the cam down? if not that may be my problem i can see the guide on the exhaust but not on the intake. i used a mirror and a flash light and couldn't see anything but metal.

 

Metal as in the "backing plate" of the guide; or metal as in the inside of the cases, with no sign of the guide?

Look in the fiche: http://www.yamahapartshouse.net/oemparts/c/yamaha/parts under "camshaft chain" are you missing part #10?

 

metal as in just looking at the walls of engine. no sign of the guide.
I can see the damper chain 1 but no sign of the damper chain 2.
could that be whats rattling around at the bottom of the engine while its turning over? i don't hear anything or see any problems when i turn it over by hand from the crank. but when i tried to crank it thats when i first heard the noise.

 

Very possibly. The front guide just sits in depressions in the front of the head; if it wasn't engaged properly when you put the cover back on, or if you turned the motor over with the valve cover off, it's quite possible it got "sucked down" into the motor.

You should be able to drop the sump by simply removing the exhaust first (be careful of the oil level sensor and neutral switch leads) and have a look.

 

I notice you didn't say anything about seeing the chain guide that goes between the two cams gears across the TOP of the head..........

Is that missing? Gee... I bet I know where that went now----- Is it still there? Hmm....well, then we know it isn't that----

Dave F

 

Yeah sorry, I was distracted when I read your reply, will try to learn to not post when the dog's howling for me to stop the fireworks going off! Looks like there might be more to it than that from the progress anyway, hope there's no damage if it has sucked a guide in :?

 

drain your oil through a coffee filter. if you get chunks of anything, post a pic... one of us can probably identify what it came from.

 

His entire front cam chain guide has "disappeared." Highly doubtful it got ground up.

 

Well there's not much chance of it slipping through a coffee filter, you have to admit!

 

yea sorry guys i thought the damper chains were the guides. the guide between the two cams is still there didn't really think of that as anything but a bracket. i'm not familiar with all the terms of the 4 stroke engine yet. sorry for any confusion.

 

OK, so the funny-shaped guide sticking up between the cams is there, and you can see the rear cam chain guide looking down the back of the motor, but part #10 in the fiche is simply not there? And the motor ran fine before you serviced it?

If that is indeed the case, it's probably what's caught up down in the bottom of the motor. If it IS, then there is a good possibility that nothing else has been damaged--- YET.

If the front chain guide has suddenly gone missing then it needs to be found and replaced before you run the motor. If you didn't consciously pull it out, then there's a very good possibility that you knocked it out of place during the valve adjustment process (easy to do, but you're supposed to notice and put it back in its notches.) If that happened, it's not the end of the world. Drop the sump and retrieve the mangled front chain guide. It's a plastic/nylon/weird composite I doubt it could have damaged any real metal parts, except for maybe bend up the strainer but that will be easy to see with the bottom off the motor.

DO NOT turn the motor over except slowly by hand until this is sorted.

 

yes except the carbs giving me hell it was running. alright now what do you mean " drop the sump"?
yea the front and back guides are just 2 things i never even noticed. if they were a snake they would have bit the hell out of me because i never seen em.

 

The sump is also known as the oil pan, basically it's the bottom "cover" of the engine & it's likely where the guide will be hiding if it's fallen, so dropping it would entail removing the exhausts, un-clipping oil sensor wire & undoing the sump bolts in a "criss cross pattern" as Haynes like to say. When you drop the sump down be careful the dowels don't fall out/go missing.

 

also there's enough oil left in there to make a mess and you'll find all the sludge in there too

 

yea thats what i was afraid of. i need to find somebody that will let me use their garage i can't do this on the ground. well probably possible but a major pain in the ass.
Thanks guys as soon as i can find a place to do all this i will update the post and tell everyone how it went.

 

It can certainly be done on the ground if you don't mind working upside down. I don't have the luxury of a workshop or lift so any work I do is at ground level, it's not always easy but you can still do pretty much anything if a lift isn't available.

couple of things I'd advise if you do have to drop the sump on the driveway is lay a plastic sheet down to protect the concrete/tarmac & have a bucket of sawdust and plenty of rags available for any oil that gets spilt, and wear short sleeves & eye protection. That way theres no chance of a splash in the eye and you don't end up with a coat/shirt that's oily inside up to the elbows! (ask me how I learnt that on the first ever oil change I did! It was lovely and warm though... )

 

If you lean an XJ hard-over left, then right (90*) then drain again, you will drain SEVEN ounces of extra oil. This drains the middle-gear cavity and other hidden spots.

 

my only real concern with dropping it outside is my drive way is all dirt and gravel after i take it off one nice gust of wind comes along and blows all that nice dust and debris inside which will be hell cleaning back out.
oh yea i hear ya there i got plenty of those shirts so much oil on em now they'll never be able to clean again.

 

That's true, I guess that's one "benefit" of living in the UK... It's rarely dry enough for dust to be a worry :? I wouldn't expect it to be a problem though unless it's really dusty where you are... Or really windy...

And my new "favourite" place to collect oil & grease is my hair, it always seems to dangle in any spillage that happens however small!

 

This is great info on valves, thank You Fitz for your great photo's and info, I have recently bought a 83 xj650rj oceania model,Australia/New Zealand, It had been sitting for 10 years, the motor had the carbs off, still in the frame, wheels off, wiring harness off, the previous owner had been in the process of restoring.After a couple of late nights I put it together,I jumped started and got running very well considering, a real good buzz !!! , I have since compression checked and found 1 & 2 cylinders are well down at 90 psi and #1 had the wetest plug I have seen, this may have been some carb issues of course,#3 & 4 are at 130 psi with nice burning plugs, I checked the valve clearances and they were well over on inlets, My question is.. Before I change shims, would it be worth while removing the head to see if the valves are fully setting ?hence my loss of compression, They may have collected some corrosion over time.

 

Welcome so you have loose clearances? I'd imagine that standing so long with the carbs off the valve heads/seats have probably picked up a little corrosion so yes I'd say coupled with the low compression it's probably worth pulling the head & lapping the valves in/changing the stem seals.

Before you tear t down though try a "wet" compression test (add 1-2 TEAspoons of light oil to each cylinder & retest), if the compressions rise significantly then it's rings causing low compression (again probably due to standing more than wear)

Start a new thread and post your results there, congratulations on your find & best of luck getting her fixed up. Don't forget also to check your rear brake shoes for delamination & look for the tyre & brake hose date codes too (there's links in my signature for these).

 

Thanks for that, I have checked all of your saftey items, waiting on brake shoes to arrive, thats good advice you have given, too often forgotten. I used to race horses, when ever I would get a new horse, feet,teeth, blood, a bit smilar. The bike may bite harder if the tyres are stuffed !! also if the horse didn't fire on all cylinders,some may remove the head too !!

 

lol yeah, I've never heard of an XJ shot for a cracked wheel! 8O