82 xj 650 startng problem - surpise!

ok will run (rough) with fresh plugs for a few minutes, then no
carbs are clean, bench synched, mix screws set at 2 turns (except #1 stuck), floats set,

trying to get idle to plug YICS and vaccuum sync!

ok wierd part when tryng to start a second time it sputters and trys, then i noticed the pipes on 1&2 are warm but not 3 & 4?

switched 1 & 4 wires same spark at 1 but still weak at 4!? (same coil!)
pluck look black (rich) #1 dry and #4 damp?

:x

petcock was rebuilt,

new battery

(assume valves are done please unless this is REALLY a strong possibiility)
i have been reading tons here for last couple months just not posted, you guys seem to have it covered

no safety circuit stuff

this bike seems light and nimble compared to my honda cb750s really anxious to ride it!

 

have you done a compression test? this is done to establish a viable plant and that oil is not getting past the piston rings.

 

I.B.F. (In Before Fitz)
YES....Valves are THAT important. Unless your valves are in spec you'll never get it to run right. Do the valves.

 

I.B.F. (In Before Fitz)
YES....Valves are THAT important. Unless your valves are in spec you'll never get it to run right. Do the valves.

 

agreed ^. is #4 wet with fuel or oil?

 

valves aside- it ran last summer so we will skip for now. running right vs running at all are 2 very different things...

compression- yes checkd 110-115 across board sorry i meant to include that

#4 fuel wet foul #1 slight dry foul
I just dont get the R vs L side? dont share coil or carb?

thanks fellas

 

Probably not this, but is the enrichment circuit in carb bowl base REALLY clean?
Here is a post that covers it
xjbikes.com/Forums/vie...60246.html

 

Valves NOT "aside" based on what are actually pretty low compression numbers, I'd check the valve clearances.

CHECK. Then when (yes, when not "if") you discover that a majority of them are tight, get them in spec so you can actually adjust the carbs.

You can't just brush aside the critical first step in the process and hope to get anywhere.

 

the good...your bike will run with tight shims. the bad...if the valve clearance is not in spec you will not be able to sync your bike. the ugly...tight shims will blow the engine.

Gary

 

carbs are zestfully clean

 

great!^. now you can get the shims right and air leak test the carbs so you can dial in that beast.

Gary

 

um nevermind....its not the valves, but whatever

 

Dude; you're barely above running numbers on your compression, below about 90 the motor will barely run if at all.

These are "interference" motors, there is a lot of valve "overlap" and a few tight valves can mean the mixture is going in one side and out the other without ever having a chance to burn.

CHECK the valve clearances; then report back. No need to go doing anything radical yet like actually getting them in spec; just check them.

 

Enygma64, there are a handful of people on this board who's opinion I follow no matter what I've done or think I should have done, and one of those people is BigFitz.
You are clearly within your rights to toubleshoot however you feel best and in accordance with your previous experience...but, if you want to save time, save money, and get done correctly the first time...take his advice. Why reinvent the wheel?
Lastly, there are also a handful of people on this board who ask for advise then summarily dismiss it as frivolous for whatever reason...eventually most of those people have final post stating "I'm done with this piece of junk".
Checking and adjusting valves is remarkably simple...just follow the advise given..first time for me it took all afternoon...I'm now on my 4th or 5th go-round and with my 15 year old's help I can check-replace/record-recheck in about 2 hours.
I wish you success!
P

 

I just LOVE when people ask for advice and then don't take it because they don't like the answers that are given. Might as well just go figure it out for yourself and quit wasting everyone's time! Sooner or later you'll (hopefully) realize that the advice given was spot on and finally decide to listen to it.

 

glad you feel sarcasm isnt wasting YOUR time, moose

anyway found that the carb 'expert' who ultrasonically cleaned them switched the air jets around!

synched at 7" with yics isolation rod.
runs great high rpm, cant get idle to settle from 3k though. think its a vaccuum leak...

 

So what were the valve clearances when you checked them?

Dave F

 

It's not the valves, Dave, you heard the man.

Must have been the transposed jets causing the crappy compression numbers; you know how that works.

(IT DOESN'T YOU STILL NEED TO CHECK THE VALVES.)

The "hanging idle" is more likely a function of being out of sync; and you can't GET a truly good vac sync with out-of-spec valves.

But hey, what do I know anyway.

 

Oh, I am 100000% sure it's not the valves....... He made that perfectly clear - I'm just curious to know what the clearances were. It would help me to better understand what size shims I don't need to keep in the shim pool.

Dave

 

if you think giving me grief about my valves is annoying me have at it.

they're all within the tolerances bigpiss posted. i just dont feel all this extra posting is constructive. but if thats all you have to do, have fun.

funny how i post one thing every couple days and a couple people immediately reply... get a life

like a bunch of women eeeew did u here what she said...? lol

bye

 

Giving you grief about checking your valve clearances is NOT suppose to annoy.

It IS supposed to be taken as good advice; if it was me (as Pat mentioned) I would heed the good advice.

What don't you understand about free advice? People here have integrity behind their words. They want everyone who comes here to have a safe, reliable ride. . . this isn't a cyber-bullying site; it's an XJ Bikes site. A lot of people reply because they actually know a thing or two (me? I just like to see my dog's picture on the world wide web). I have learned things here that are priceless and have served me well.

Because the truth of the advice may come across as cold and hard doesn't mean you should take it personally. Embrace the XJ love!

 

You're giving us grief by not doing the NUMBER ONE maintenance item in any XJ manual you'll find...valve clearances.

So, the valves are all within the specs that were posted, but NO ONE posted any valve clearance specs.

You get replies from the same people, because some of us are on here way more than others. Another reason to heed their advice.

Please don't ever check the valves. We need more decent parts bikes with blown motors.

 

Unless you've got a 2-stroke, or hydraulic lifters, the valves need to be checked. The bike is new to you, and may have never had the initial valve check done.
Fitz has the tagline "Technical Writer" for a reason; he knows of what he speaks.
Take the advice you've been given so you don't spend a week chasing your own tail around trying to solve the hanging idle issue.

If you've checked them and they are in spec according to the Haynes manual then they aren't in spec. Haynes made several errors in the published manual, as did Yamaha (which is why your air jets got moved to the wrong positions). The correct valve clearances are printed on the inside of one of the sidecovers (I forget which ATM).

http://xjbikes.com/Forums/viewtopic/t=14827/postdays=0/postorder=asc/start=0.html

If the valves truly are in spec then we can move on to checking for vacuum leaks and other possible causes.

 

It could be a number of things. But the first step is the get the valves in spec.

You can't sync the carbs without it done.

Sounds like it could be any number of problems... Start a list check off the valves and go from there.



A pic I got from fitz when I first started here.

Heres how to do it...

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




Thanks to fitz.

If it hasn't been done yet.

 

1. Check check check check Valves valves valves valves..... Better yet don't check them .... When your engines seizes pull the shims that never needed to be checked and send the to me so I can throw them out since they will most likely be damaged beyond use.

2. Amazing....bigpiss, huh?!?!. A Gear Grinder rank and he's calling people names.... Especially after asking for advice, advice given....... And duly refuted. Did anyone

3. Funny, you only posted 9 things.... Two on May 8--within 9 minutes, 5 on May 22--some pretty close together, And then two today. Now, your gonna complain when people try to help by answering QUICKLY? Heck, ask another question--- I'll be willing to wait to answer it next year if it will help you feel better.

3. Women will HEAR what someone said

4 . Bye....... Ok, see ya.... Don't let the door hit ya

Good luck to you.

D

 

FYI - Those compression numbers are in spec for the 6000 ft in altitude where he lives. For altitude we have to do compression conversion, The conversion factor for those of us at this altitude is 0.83.

Make sure your throttle cable is sitting correctly in the bracket. It make be sitting high on the bracket.

 

Not one to be a killjoy and interrupt this Thread-Of-Happiness, but I feel that, for clarification purposes and---in tribute to the immortal words spoken in the classic, epic, pre-salad-dressing days of yore in "Cool Hand Luke" by Mr. Paul Newman---it should be said that in assisting in "Getting your mind right" I should gently point out that an oft-repeated statement expressed 'round these parts isn't quite the truth, the whole truth, and nothing-but-the-truth, and that statement is this:

And yes, I know that this gospel comes straight from the red-circled horse's mouth, Yamaha Motor Company.

But it ain't true, and it begins with the reality that you ain't "synching" the carbs, at all, no, nein, nyet, nope.

You're synching the engine via the adjustment (of the throttle shaft openings) of the carbs.

And I'm not just trying to nit-pick words; words have meaning, or, as a former president of Ford Motor Company used to say, "When I speak, each word weighs a ton". Words convey an understanding of what is going on, and the wrong words give a person the wrong understanding, the wrong visual, the wrong (in modern hipster slang) "optics" in their minds, and a wrong understanding of what is going on (and what you need to do to correct it) could easily turn a mind into that dreaded "terrible thing that's been wasted".


Synchronize: to cause to go on, move, operate, work, etc., at the same rate and exactly together: They synchronized their steps and walked on together.

http://dictionary.reference.com/browse/synchronize?s=t


Does setting all the carb openings to differing amounts mean that they "move, operate, work, etc. at the same rate and exactly together"?

Well golly-gee no, it doesn't. In fact, the process of "synching" does EXACTLY THE OPPOSITE, in regards to the carbs........it sets them up to "operate" slightly differently from each other. On purpose.


For what purpose, you may ask? For a good purpose, of course! So that you can equalize the power output of the cylinders, so that you can "synchronize" the horsepower/torque output of each cylinder, so that each cylinder will, in fact, "work, etc. at the same rate" (or power output).

And by the way, for you guys that are over-edumacated, you'll immediately recognize that the word "work", in this context, is really close to the physics definition of "work", that being of energy output over a unit of time. But I digress.......


Having each cylinder output 20 horsepower (20-20-20-20), rather than a cylinder output map that looks like this: 16-23-24-17 ----- and please notice that in both cases, the total engine output is 80 horsepower ---- but in the 2nd example, since each cylinder outputs a different amount of power, the engine will "fight itself" and run rough, perhaps misfire, beat itself to death, etc. Definitely not that "sewing machine smoothness" that we all adore and aspire to.

And beat itself to death, over time, it surely will. Having grossly mis-matched power outputs in each cylinder puts incredible stresses on the crank, rods, and bearings. If that thought doesn't bother you much, then do the following:

a) carefully remove your valve cover. Set all the bolts aside, labeling as necessary so you can re-assemble properly.

b) remove the camshaft bearing caps, just one or two of them. Again, put aside and label.

c) get your ball-peen or claw hammer out, and start hammering away, as hard and as fast as you can, on the cam journals. Try to do this at least 3000 - 6000 times a minute to closely duplicate what an unbalanced engine does to its rod and main bearings.

d) re-assemble everything and go ride your bike in traffic, or on a long-distance ride. It's all okay. These engines are built tough.


Now, why would an engine have a power output map of something kooky like 16-23-24-17, or even 19-21-22-18 (note this last one is a lot closer to being equal across each cylinder). Well, it could be that the pistons/rings in each cylinder aren't EXACTLY equal in condition to each other. Maybe one cylinder has a bore that is .02mm larger than the others, or maybe a larger ring gap on the top ring. Or another cylinder has a valve that isn't seating/sealing as well as the others.

Or, hey, how about this: the valves ARE in spec, but since spec is .11-.15mm clearance (on the intakes), suppose cylinder #2 intake valve is at .11mm clearance and cylinder #4 is at .15mm.....both within spec......but the different clearances results in different valve timing (when the valve opens and closes within the cycle) and thus a different power output from each cylinder.


What you want is a power output of 20-20-20-20, or at least as close to that ideal as possible.....and note that it MAY NOT BE POSSIBLE. Cylinder #1 has a slightly.....which is well within tolerance, mind you.....larger bore than all the others. It has a little bit more ring blow-by. It won't/can't develop as much compression pressure as the other three. So you get compression numbers like this: 131 133 139 137

Again, well within "spec". But cylinder #1 isn't going to EVER make as much power as the others, and short of taking the engine apart and "blueprinting" it, that "little #1 cylinder that could" well, in reality it couldn't, wouldn't, and it won't ever make as much power as the other cylinders.


So note that the "synch" process forces you ---- via adjustment of the carb throttle shaft openings, setting them all a little bit differently from each other ---- TO DE-TUNE THE POWER OUTPUT OF EACH CYLINDER DOWN TO THE LOWEST COMMON DENOMINATOR.......it's the educational system equivalent of "dumbing down" the students so that everyone gets a gold star.....

So in this engine: 16-23-24-17

you're going to have to "de-tune" each cylinder to 16hp, so that it ends up looking like this: 16-16-16-16


But in this engine: 19-21-22-18

you'll be able to achieve this output map: 18-18-18-18


Hey, that's an extra 8hp, which is nothing to sneeze at in an engine of this size, and truly a difference that you can feel.....


So why do you adjust the valves before you "synch" (really, un-synch) the carbs? Because out-of-spec valve clearances will typically get you this engine:

16-24-24-17 (which you can then "synch" to 16-16-16-16)

while valve clearances in-spec will allow you to get this result:

19-21-19-21 (which you can then "synch" to 19-19-19-19).


Look, you can't do anything about cylinder bores, ring clearances, valve seat seal, carbon build-up, etc. as part of any normal maintenance procedure (well, you could, but 99.99% of people aren't going to do a top-end job every 5000 miles). But you can adjust your valve clearances pretty easy. And doing so will allow you to flash a big toothy grin with "19's" all across the board, rather than a set of 16's on all cylinders, and unlike what you read on the internets, the "size" of numbers does matter, and bigger really is better-er.


So in conclusion: Yes, Virginia, you can "synch" even if your valves are not in spec ---- you can synch your engine to 16-16-16-16 instead of 20-20-20-20 ---- and negate lots of the fine engineering that Yamaha did for you and piss away 16 horsepower the fast and easy way.

Like they say on TV, it's your dime, Boss............

 

I think maybe it is a case of deflated ego
you buy a bike and you get all kinds of ideas of what
you want to do to it
then you come on here.. and get told you have to
do this that and the other thing before you can even think
about the other thing
it is like yeah yeah yeah.. I know what I wanna do.. but
when it comes to it.. Bigfitz and others stressing
to check the valves is no damned joke
the bike will not run properly without it being done
you can't run without walking
and when it comes to valves in Spec, that is barely crawling
this forum is the most amazing place on the internet
when it comes to knowledge and care for your bike
it is also sometimes the most comforting place on the internet
my bike runs great, because of the help I got from everyone
also this place can be the most entertaining out there
and I am going to go on the record to say it is a once a day
must go to site
you can buy a repair manual for 20 bux and you should
but the advice, and help on here is the best bar none
same goes for Len and his parts
or Hogfiddles and his shim pool

so spend the time, check your valves.. or have a bike that
will not run properly and no matter how clean your carbs are
you still will not get it to purr like a Main Coone kitten

 

i got my bike and it had about 25k on it. i thought hell maybe the valves are in spec. but i got more weary and weary and reading posts on this site to check them. and they were wacked out. i for one am glad i listened to guys like hogfiddles and bigpiss... sorry i couldnt resist chuckling there bigfitz

 

If ever there was a case for a "sticky" nomination, Chacal gets my vote!

 

I checked mine a few months ago and even I am weary and
want to recheck them
when the bike runs perfect

my favorite part is when BigFitz gets sarcastic and starts mocking
it is in this thread and the awesome
"I am done with this XJ" thread

 

Nice post Len, very interesting to read. I knew there is some latitude for adjustment, I could feel it and understand it, but not explain it. That sums it up.

Dave

 

So, just as starting a bike is important, we must also realize that stopping a bike is important.

SO......maybe it might be a prudent thing to mention that you should take a moment to check your rear brakes for delamination signs.

Well, that would be a moot point, of course, if one feels that the brakes are not an issue because it stopped perfectly fine last summer......

 

It was Wisconsin sand not delaminated brakes!