have been trying to start for over a week now

i bought this 82 xj550 last saturday, rode it for 100 miles back home, not a problem besides not wanting to idle at a stop (had to leave the choke closed to keep it running but if i did stall, i could fire it right back up). the next day i tried to get it to start, but it didnt. it started raining so i left it alone. the next day i tried again, and the next day, and so on and so forth. i've checked everything: nice blue/white spark on all 4 cyl., carbs are amazingly clean inside and out, bowls fill with gas, i have good compression, i have vacuum to pull fuel into the carbs, i made sure the carbs were all in sync. i have tried to crank this thing every day for the past week now to no avail. i have tried push starting it, jump starting it, starting fluid, pouring a little gas in the spark plug hole, new plugs. it just refuses to fire off

in the mean time i have been searching these forums trying to find something that would make sense of it. i am at my wits end. why would it crank and run fine one day and for the next 6 days not attempt to fire up once?

 

Thats weird to have happen like that, But you need four things to make that engine fire up. Spark you got that, Fuel you got that, Timing ??? Compression ???. I would check your compression first and then check to see if your timing is close. Pull the left crank cover and put a timing light on it and see if the timing mark shows up on every other flash of the timing light. Let us know.

Did you try starting fluid spray in the air box?

MN

 

i dont think i'm getting any fuel into the cylinders. none of the plugs appear wet, yet they smell like fuel, and the tops of the pistons do not look wet either. i've already tested the compression, 80psi on 1,2,4 and 70 on cyl 3. but i'm still stumped as to why starting fluid wont make it start. i took the boots to the airbox off and am spraying fluid into the carbs, closed throttle or WOT, doesnt make a difference...nothing

BTW, how do you adjust timing if it is off? ill get a timing light and check that within the next hour... i have a feeling tomorrow is going to be a beautiful riding day :cry:

 

i'd bet your timing is ok - or you wouldn't have been able to ride it home.

if it wouldn't idle without choke, then there's likely something wrong with the carbs.

are your plugs black and carboned up? did you ride all that way with the choke on, or did you just put the choke on when you came to a stop?

 

Although you say there is fuel in the carb bowls, it sounds like the fuel is not getting to the combustion chamber. Try switching the fuel tap to "Pri" so it runs all the time. Remember to switch back after though. It could be a blocked fuel filter (Inside the tank). Check fuel flows from the tap on "Pri".

 

timing mark is about 1/4 inch away from the T when trying to crank it. pulled the plugs out again after doing that and they are still dry. when i rode it home, i would open the choke while riding and have to close it when i came to a light. also earlier today, when i had the tank off, i turned the switch to "pri" and fuel came gushing out, and i hooked a hose to the vacuum port, turned it to "run" and sucked on the hose and fuel came out then too. two of the plugs i pulled out were NGK and they were black, the other two were autolite and they were a brown color. i'm assuming only two plugs were changed recently before i picked this bike up

 

i also noticed that my carbs were missing the smaller jet: <--the one at the bottom, not the tiny tube. i dunno if that is the idle jet that 98formula said might not be there, but it isnt. looking down into that passage i can see a smaller screw head way down in there.
btw, that picture is from a post that 98formula wrote on carb cleaning

 

Those are huge cabs compared to his foot!

 

Have you blown out the carb jets with compressed air? Did you flush the tank and put in fresh fuel??

 

i didnt blow out the jets, but i could hold them up to the light and see thru them. and i went thru a full tank of fresh 93 octane fuel on my trip back home. is it possible there are passageways in the carb bodies that might be clogged?

 

Your 550 has Mikunis, I believe you have a picture of Hitachis there.

Are you trying to start it with the airbox-to-carb boots out? It might be reluctant.

First thing to check would be your float levels (using the clear tube method) since you have the rack off the bike anyway. Be sure the enrichment wells and passages IN THE FLOAT BOWLS are clear. You should be able to shoot carb cleaner through them (watch your eyes.)

 

Doesn't his compression look low? Like REALLY low?

 

lol.

i also thought the compression was really low, but they are all pretty close, so i didn't think that was the issue.

is the kill switch off?

maybe wanna give the seller a call and ask them how they got it started?

 

I was writing that part off to a defective gauge or poor technique; and it was running.

Unless something bad happened on the 100-mile run home.

Let's back up to REAL basics: Engine have oil in it? New or old or ??

What exact method did you use for your compression test? Those numbers ARE rather low but the consistency tells us you may have used a faulty technique.

 

Do you have the bike on a charger/booster?? Not a trickle charger?
You checked ONCE for spark, but below a certain voltage, there is NO ignition.

Crank with throttle closed, light spray of starter fluid in airbox, all boots connected, after checking a spark plug again.

And +1 to all other advise above.

 

I'd test the coils just to be sure!
So she's cranking, but wont fire and turn over? Is the battery brand new?
Did you clean the enrichment circuits in the carbs? Is the Tank rusty? One spec of rust inside a port in a carb can cause these symptoms!
Just throwin some stuff out there. Questions that havent been asked. Hope you get her started soon!
-Chris

 

i didnt think if the kill switch was in the off position that i would be getting spark? the motor has oil but it is old. i figured since i would be messing with it again today that i would go ahead and change it. i had the right adapter for the compression gauge threaded into the hole, WOT and turned the motor over 4-5 times. i dont know how old the battery is, but ive tested it at work and it tests fine, even after sitting all day and using it to try to crank the bike the previous night. ive tried different chargers (trickle chargers, 2A charge, 10A charge, 15A charge, even tried starting it using the "engine start" selection on the battery charger) and i have checked more than once for spark, i check a few times every day to make sure there is still good spark. i'm going to try a different compression gauge today see how that works out.

 

just makin sure. my bike will turn over with the kill switch on "off" (it's not supposed to, but it does).

i'd ohm out the coils and maybe try some fresh plugs. if the coils are good and fresh plugs doesn't work, then you've narrowed it down to fuel, right?

based on the description of your ride home, it sounds like the pilot circuit is clogged up. (choke did something, and it ran with the throttle open, so those circuits should be at least functional).

based on the "it won't even start if i put gas in the cylinders or if i spray starter fluid" situation, i'd say it's a spark issue. . .

does it fire, backfire, or sputter at all? or does it crank and crank and absolutely nothing?

 

Before it ran and now it doesnt???? All good answers to this problem but what changed when he shut the bike off. Lets stay with the basics for a moment. Compression seems low so lets start with that. Take an oil can and squirt alittle oil in each cylinder and see what the compression comes up to. If he gets 120 or so on each cylinder that would be great. Then put your plugs back in and lets see wht kind of voltage you have when you crank the engine over. Let us know the readings and we can go further. The timing seems right if you are getting a timing mark close to the mark when you crank. That also tells me there should be enough spark going through the plug wires to trip the timing light.

MN

 

Try starting the Bike using Starting Fluid introduced to the Air Box.

If it "Pops", starts or tries to go ... you know the Bike is getting Spark.
You may have to coax it to start using Starter Fluid because the XJ-Bikes are extremely difficult to Start when really cold.

My Bike won't start unless I warm-up the garage a little bit with a Kerosene Heater and use Starting Fluid to get it to go.

 

i keep re-reading the orignal post and i noticed you said you didn't start it the first day due to rain. is this bike kept outside, or in a garage?

 

today i changed the oil, it was very black. i also puored about a tablespoon in each cylinder, put a rag in the holes and turned the engine a few times. my dumbarse grabbed the wrong gauge to go with the hose on the compression tester at work, so i had no way to test compression at that time. i put all the plugs and wires back and while the tank was off, i rigged up a hose that connected the nipples on intake manifold boot 1, 3, and 4, seeing as how #2 was connected to the petcock. this time i sprayed starting fluid in the hose that connected the three boots and attempted to fire her up and it actually tried starting! i tried again and gave the throttle a little twist and it started up, but it didnt rev high with the choke fully closed, i had to twist the throttle quite a bit before it would idle high. i let it sit for a few minutes running and then hopped on and went. same issue with coming to a stop, i have to choke it. i fooled with the idle screw and it just wont hold idle at a decent rpm. i'm going to come to the conclusion and agree with skeeter (and based on what most everyone has said on this post at least once) that i have a problem with fuel delivery from the carbs... a bad one

 

congrats! (i think?)

i take it once the bike is warmed up, it is easy to start (like before, if it stalls at a stop?)

 

yes, i have to have choke fully closed and it seems to start right up. i'll do some more homework on adjusting jets and what-not

 

Sounds like the low idle jets are clogged! take one carb at a time apart and use carb cleaner and forced air to clean all ports and jets! wear safty glasses when useing cleaner

 

I have 3 XJ 550s and the most likely cause is the enrichment circuit - I had a terrible time getting the enrichment jets out of at least 4 sets of carbs that were on my bikes - 90% of them weld themselves into the threads over time and if they are never removed from new forget it - you will strip the slot on top really easily. So the trick that worked for me was to wiggle a very thin (and I mean VERY THIN) wire from a wire brush in the hole in each jet in each float chamber until you clear the crud that is bound to be in there.... you will feel the wire gradually break through this tiny brass hole then you can squirt cleaner through and you should see it spray out the front of carb. After doing that you will be stunned at the difference - your bike will start with a flick of the starter and will purr like a kitten - i am sure

 

i pulled the carbs and checked the bowls, i held a pen light to the enrichment circuit well and light shined right thru :? i sprayed parts cleaner in it and blew compressed air thru it anyways. is there a method to cleaning the tube that drops down into the well?

 

You're going to need to pull the rack and do the carbs right, the shortcuts and "quick fixes" aren't going to work.

You now know you have a carb issue; you need to fix it right. The "choke" isn't a choke, it's an enrichment circuit; if you need to run with it on all the time then you're not getting enough fuel the correct way.

Something is clogged, plugged, or your float levels are way off, or a combination of all three.

You also need to check all your valve clearances immediately; I'm still concerned with the low compression numbers and tight valves will make an XJ very difficult to start even if the carbs are right.

 

Try using a heat gun to heat the body of the carb. This usually works but have had occasion to drill and use an EZ out on the remainder. Another important factor is to have a very sharp screwdriver. I like to use the one for carb syncing. It's strong as h*** with a big knurled handle on the end.

 

I think it may be a combination of carbs and valve clearances. Fitz definitely has a good suggestion with that!

 

yep, i'm going to check valve clearances this weekend probably... oh how i dread it

oh BTW, i overlooked the idle mixture screws in front of the carb hats, and i had to turn almost all of them 5-6 360* turns before they bottomed out...might have been affecting anything?

 

well, the clearance is tight, i cant get my smallest feeler(.008") in between the base of the cam lobe (not the apex) and the shim. what do i do from here? are shims something available at most yamaha dealers? do i just guess at what sizes i need for a starting point? and should i be able to get that bucket tool at the dealer?

and also, by the valve tolerances getting tighter, how does this affect the ease of cranking? is it basically like having a cam with very short duration? or vice-versa?

 

What about a plugged gas cap? I was skimming along some of the old posts and someone had a non start issue that was the result of a plugged gas cap.

It is a simple thing but could be the source of your problems.

Give it a try..

Rob

 

You should have started by doing a Compression Test before fooling around with the Valves.

If you have some latent issue that causes the Compression to be very bad, having adjusted the valves before finding out you have a scored Cylinder Wall or a Burned Valve will have been a generous waste of time.

You do not need to adjust any valve within specs.
Tight or loose valves will not alter Cam Duration.
For that, ... you alter the Cam.

Test Compression
Good: Continue.
Bad: Rectify.

Spark is good.
Compression is good.
Use Starting Fluid to see if the situation is Fuel or Ignition.
Runs a moment on Starter Fluid means FUEL Delivery issue.

Does not respond in any way to Cranking with Start Fluid means
you troubleshoot Ignition.

If after Testing Compression is Marginally low, ... Ck + Adj Valves.

Checking Valve Clearances on a "Don't Start Bike" is putting the Cart before the Horse.

Work on the Bike like you do it for a living.
The Don't Strart Bike will be parked in front of your toolbox.
The Work Order may only say: "Won't Start"
1. Fuel ... The first thing you check. It could be silly.
2. Sparks ... Next. Plugs, Check Battery and fuses.
3. Air ... Make sure the Air Cleaner + Box are clear.
4. Compression Test.
Shop Manager or Foreman will review the results and decide what to do after going over the results with you.

 

Rick is right about putting the cart before the horse.

In answer to your questions above, in order: You re-shim; yes Yamaha dealers carry them but will rape you, contact chacal; no, you don't guess, you remove the too-tight shim and read the thickness; then you choose a new shim based on what was in there, and its clearance compared to what it should be. There is a chart for that, it's in my valve adjustment article. http://xjbikes.com/Forums/viewtopic/t=14827.html And yes, the tool is probably available at your local stealership but you can get them pretty much anywhere else for le$$.

 

so the dealership said they dont have the tool in stock, unless they didnt know what i was talking about. i guess i should take a picture of it down there to them and see if they recognize it then. what are the clearance specs so i know which shims i need to remove and replace?

 

ok, here are the valve specs (i used the zip tie method). i did the SAE to metric conversion for you guys:

cyl 1 intake: .10/ 275 exh: .13 / 265
cyl 2 intake: .08/ 275 exh: .13 / 270
cyl 3 intake: .06 / 275 exh: .15 / 270
cyl 4 intake: .08 / 275 exh: .15 / 270

any thoughts?

 

well, after all the headache, i installed a new battery after replacing valve shims, and complete carb cleaning. i had to fool around with the idle mixture screws, but i finally got it to fire up. only thing is that i had to disconnect the headlight so it wouldnt come on while trying to crank. i could turn it over and as soon as it "popped off" one good time, the headlight would come on and it wouldnt pop anymore while trying to crank. i got a wild hair and unplugged the headlight and sure as hell, it fired up after a few cycles. take in mind the battery is brand new and has 12.82 volts cold. should i wire in a switch for the headlight to keep it from coming on? i have checked all wires and everything is tight and clean.