Think I may have a problem....

1983 xj550......just purchased as a project with my 17yrold son as his first bike.....has an extremely high 4000-6000 idle, that doesn't come down. Pulled the rack, did a "quick" teardown, not really finding anything glaring except a couple of intake gaskets that were bad, but had zero effect when corrected....Finally got the manual, and started from the begining. Started by checking the valves and have NO valve clearance...... .04MM is the smallest and not even close to going......how screwed are we??? Bike has 17000 on it, and these have probably never been touched.......any chance these are not smoked, and would it be possible for this to cause the idle issue?

 

Do the following:

1. Get Valves In Spec.
2. Full Teardown of Carbs ( nothing short of this ) - Church of Clean
3. Bench Sync
4. Vacumm Sync
5. Colortune the Plugs...

http://xjbikes.com/Forums/viewtopic/t=14827.html

http://xjbikes.com/forums/threads/in-the-church-of-clean.14692/

http://xjbikes.com/forums/index.php?threads/how-to-bench-synch-your-carbs.6366/

 

There is something in the Information Overload Hour about setting the idle... There is a screw to turn on the carb rack that may allow you to lower the rpms. But yeah,those valve clearances should be adjusted too!

https://www.google.ca/url?sa=t&sour...ggdMAA&usg=AFQjCNGGXBiR9vWcHasP4Ir2qWRaSDDYJg

Some light reading lolz

 

Ok, here is what I am figuring, someone please chime in and tell me if I am on the right track.

1) EX: .04mm gap, 270 now, get a 250
IN: .04mm gap, 270 now, get a 255

2) EX: .04mm gap, 270 now, get a 250
IN: .04mm gap, 270 now, get a 255

3) EX: .04mm gap, 265 now, get a 245
IN: .04mm gap, 265 now, get a 250

4) EX: .04mm gap, 270 now, get a 250
IN: .04mm gap, 265 now, get a 250


Any help is appreciated! Thanks!

 

r u sure you are measuring correctly......all measure .04mm...interesting.....hard to believe......r u following the correct procedure to measure.....???

17k miles on it.....& all valves are that tight......interesting ....

 

.04 will go through, .05 will not........followed the Clymer's manual word for word......guess it could be 117k.....doubt it though... was kind of a surprise

 

1 ex 270 to 255
1 in 270 to 260

2ex 270 to 255
2 in 270 to 260


3 ex 265 to 250
3 in 265 to 255

4ex 270 to 255
4 in 265 to 255

according to FSM

 

Thank you!!!!!

 

i do find it odd that all your clearances are .04.

on bike exhust is front of bike intake is rear you seem to have that correct
on shim chart top chart is intake bottom chart is exhaust


a 250 shim is 2.50 mm thick
a 255 shim is 2.55 mm thick
our shims come in .1 millimeter incriments and .15 mm incriments


what manual are you using?

seca or maxim?

 

Yes. ^^^

 

On all except #4, .04mm would go easily, .05mm would not go....... on #4, both intake and exhaust, .04mm had to basically be forced to go under, so it would be actually less......rechecked them again this morning with a different set of feelers, same results......wish the tutorial on here still had the pics viewable.

 

when you measure, the cam lobe ( pointing part ) needs to be 180 degrees opposite the shim...then take measurement.......

r u doing that with each valve......???

Each valve you measure, the cam lobe needs to be 180 degrees opposite of shim.......then stick your feeler gauge in between shim and lobe to take the measurement...

Photobucket broke the Internet.....remove their external linking....now they are holding us ransom......want $400 a yr to link photos....yeah....right


http://xjbikes.com/forums/threads/airhead-valve-adjustment-with-pics.14827/

 

still the same shim changes
until you hit 0.omm
all shims will put you at max gap so even if you are off a little you will end up in spec

at 17k miles he is still 3 maintance checks into the bike if it was ever done just short of the 4th, and his first check because he just got the bike.
Miles not kilometers

done at 3000 miles, then every 5000 miles

 

sorry

 

first as long as there was some clearance you should be good

high idle easy things first
First. idle adjustment knob at back of carbs is set to high. back it out
second throttle cable is to tight and/or needs lube and adjustment. do you see any slack in the cable? or end of cable at carbs is not set in cup
third choke/enrichment plungers are not bottomed out.

hard things now
vacuum leaks
intake manifold boots and caps on test port. could be cracked . you canclean them with carb cleaner and coat with black rtv (fuel resistant type) replace port caps.
test with unlit propane torch see if it revs up or carb cleaner. You can use wd 40 and idle should drop.

hardest throttle shaft seals 2 sets on each carb on test same way. fix is complete tear down of carbs.

 

ok i thought you were suggesting choping up the bike

flicker will be next to go the pay for dot com web site media storage.

 

google photos may come in to save the day.......hopefully ...so we can post pics here in the future with ease...

 

+1. Check the plugs gap, make certain the battery is fully charged and check each one for spark then compression test each cylinder.

Gary H.

 

Compliments of Bigfitz:

"Rotate the crank (forward, CCW) so that each cam lobe in turn is pointed "skyward" away from its bucket at a 90 degree angle from the surface of the shim, and check the clearance between the heel of the cam lobe and the top of the shim."


And just to add this as the 90 degrees stated is a bit confusing:

wamaxim asked:

"Fitz, shouldn't the step below state 180 degrees and not 90 degrees?

As usual a brilliant instructional aid. We are lucky to have you on this forum.

Rotate the crank (forward, CCW) so that each cam lobe in turn is pointed "skyward" away from its bucket at a 90 degree angle and check the clearance between the heel of the cam lobe and the top of the shim."

Bigfitz replied:

"I meant 90 degree angle to the (visible) surface of the shim; it would be 180 degrees from the centerline of the bucket but that might be more difficult to visualize. I was trying to explain that they shouldn't be STRAIGHT UP, as the buckets/valves are at an angle, that they should be straight up IN RELATION to the surface of the shim.

How about
"...each cam lobe in turn is pointed "skyward" away from the surface of its shim at a 90 degree angle and check..."

I'll go back and change it if you think it will be more concise that way, I'm always open to suggestions.

Technical writing is an art, I'm just an IT guy, but I did stay at a Holiday Inn..."

 

Thank guys, we did check the valves correctly then....in the process of ordering the shims, and all the goodies I need to put the carbs back together after we tear them down and soak them.

 

Could well be that the PO did the valves, but did them to the wrong spec. As they don't have all the same shims, that seems most likely to me anyways.


With that said, Plug, be sure to use metric, metric, metric. Careful to avoid inches all around, as once you start converting stuff, you introduce opportunities for error.

 

Yup, metric, metric, metric!!!! Got it......now I guess I wait till my parts arrive. Thanks for all the help!

 

Nah... That metric stuff is just sorcery...

 

Umm.. no. Metric is science. 1 ml = cm³. 1m = 100 cm. 1km = 1000m.
Imperial is based on arbitrary measurement taken from the body of a guy who has been dead a long time, arbitrarily appointed by a long dead god. There's your sorcery.

 

OK, I was being very unserious... but now that you mention it, all spacial units are arbitrary. A mm could be slightly longer or shorter but some French guys decided it was some arbitrary math problem... "the meter was intended to equal 10-7 or one ten-millionth of the length of the meridian through Paris from pole to the equator. However, the first prototype was short by 0.2 millimeters because researchers miscalculated the flattening of the earth due to its rotation"

SO if they chose another city or the planet was slightly different, the measurement would be different. Not much different than measuring the kings foot. The smart part was dividing by ten I guess .

 

units of 10 are easy to understand. money was loosely based on metric system by Ben Franklin. more people understand money counts than the metric system, but if they thought of it as money it would go a long way to understanding it.

machinist break down the inch into tens, hundred and thousands of an inch which is easier than 1/2, 1/4, 1/16, 1/32.....


i am sure there was a reason to make a foot divided by 12 inches instead of 10 inches.maybe the king had 12 toes

 

Barley corn.
How's that for sorcery.
I recently got a new job at Weinbrenner (they make Thorogood boots - go buy some, your feet will thank you).
I program, digitize and manipulate patterns for a CNC machine that cuts material used in boots. Anyhow, in my quest for grasping the fundamentals of sizes and grading rules in the footwear business I discover that shoe sizes were originally derived form barley corn units.

https://en.m.wikipedia.org/wiki/Shoe_size

 

Yeah, I got that you were joking. I was just taking the ball and running with it. Guess I ran too far. Again.

 

would that be from john barleycorn

 

Not at all

I'm in USA but work for a German company... We have to convert constantly

Just having fun with it

 

It's the fractions that really mess with my head... How do you divide fractions? Turn em upside down and multiply. Now that's dark magic!

 

We deal with thousandths of an inch off model (nominal)... so it's not bad.

 

Carbs totally spotless, new throttle shafts seals, idle mixture of rings, float levels set, bench synced......valves shimed.....hit the starter and a nice fairly even 1500 rpm idle....now to sync tomorow.

 

great job.....did you replace the fuel o-rings when torn down ????

Sounds like you just need to vacuum sync......& colortune......

Set idle to 1,050 RPM....not 1,500 RPM.....

 

Probably at 1500rpm due to not being synced yet.....as he posted that was still to be done.

 

he will want to run his XJ550 at 1200 rpm for idle while 1050 is spec 1200 quites the motor down helps get oil to the primary chain eliminating chain slap noise.
as advised by Bigfitz in one of his many threads

thats where I set mine and it makes a big difference

 

Yup, 1500 is MUCH better than the 4-6 grand I had before!!!! Lol.....screwed up with out going into detail, but unable to sync today due to three cracked intake boots....my fault 100%......followed the posts to repair, may be able to give it a go tomorrow......

 

Fractions are easy. It just takes practice. Do you know why using the inverse works? Part-part-whole. Flip it and you're working with the part you don't have, instead of the part you do have. The same thing that we do when figuring percentage of increase vs. percentage of decrease.

EDIT: I worded that wrong. My brain must still be on vacation. Carry on wihout me.

 

time to get the slide ruler out ...........ahh.........what's that the younger ones here are saying ......??

 

Synced and purring like a kitten.....now just need to get the mixtures dialed in......

 

And resynch after.

 

Ok gentlemen.......any tips on setting my mixture screws??? I am very familiar with 2 stroke outboards and 2 stroke MX bikes......screw in till idle drops, screw out till idle drops, set in middle of those two positions..........lol, finding out it is not the same at all!!!!! Don't have a color tune plug I have been reading about.......not sure how to go about it "by ear", not sure what to listen for......should I start a new thread?? Did go on about a 15 mile around the block ride today on it....my first ride since 1997....wow that felt good!

 

Set them at 2.75 tuns out from a soft seat and go for a good ride. Listen for popping on deceleration (leanness), or bogging on acceleration (richness). Pull the plugs when you retun and have a look at the gound strap coloring. The color change should be about halfway up the strap (it'll be a change in shinyness). Also look for signs of detonation (bits of aluminum on the insulators).
If you need to check the jetting you an do plug chops jus like on a 2T, but without the need to cut the plug; just take a few spare plugs with you, or break the outing up and clean the plugs between chops.
You could tune by ear like you are familiar with, but it's a lot more difficult to hear the drop on a multi than on a single.

 

Ok, guessing I still don't have idle mixture adjusted correctly....but...sputtering at steady speed on the road, can clear it by adding throttle. #4 plug is black, all others look good. Leveled the carbs while still on the bike and checked the float level on #4....dead on still.....so close, but still so far away........I can't imagine that the idle mixture screw would affect this??????

 

Good chance your synch is still slightly off... popping and sputtering are indication of this. Sounds like number 4 is likely culprit ... Just my thought , I know on mine after church , and setting synch I had a slight popping and had to adjust it in my case #1 was off ... Cheers

 

Thank you for all the help guys! Happy to report that between the two of us we put over 200 miles on the bike today. It is running like a scalded dog, and had zero hiccups or issues! Now to make the big decision of which oil to buy so I can finally change it.

 

No, after racking my brain, even ohming out the coils, etc, I decided to pull the hat on #4.....The slides were the only thing on the carbs I didn't take apart when I cleaned them....found the spring on the needle under the black retainer instead of on top of it.........guess what, made a HUGE difference! LOL!!!!