Spring Frustration - Need Advice

So I finally got a weekend of time to get my bike all put back together after a winter of tuning up various areas. I went through the carbs completely, replaced needles and seats, cleaned all the passages, even bought chacal's little drill bit to clear the starter jet. I checked my valve clearances and replaced the two that were out of spec. I got it all back together yesterday, and after getting the carbs as close to synced as I could with my homemade manometer, she was sounding pretty good. I went on a few test rides and was pretty satisfied with my work.

Now today I cant get it to start at all.

After changing out last year's gas and filling it with fresh, still nothing. It cranks and cranks but doesn't want to idle. I've gotten a few especially loud backfires paired with white smoke out of the exhaust. I was thinking it might be that my carb syncing is still off, but without an idle I cant really fix that yet.

I checked my plugs, and I'm thinking my problem may lie there. Spark is good to all four, but cylinders 1 & 2 are OILY black, while 3 & 4 are a bit on the lean side. 3 & 4 are where I replaced shims, both on the exhaust side. Am I right in thinking that I should next replace valve seals on 1 & 2, to cure the oil leak? If so, does anyone have advice on how to go about this? I looked around the site but that seems to be a HOW TO that has yet to be made.

Thanks in advance.

 

Try cranking the idle knob clockwise a couple times to see if it will crank and then back it out to get the idle right.

 

Yeah I was messing with the idle knob back and forth, it seemed to get it a little closer to wanting to start but still couldn't get there.

 

Make sure you are getting good fire. I know the back fire means you have some but, check all spark plugs for spark.

 

sounds like your enrichment circuit is clogged a little on3-4? My Maxim wouldn't start until cranking for a few minutes, turns out 3/4 of the enrichment circuits were clogged, cleaned them out and blammo, starts no problem.

 

Make sure that you aren't looking at gas soaked fouling instead of oil on those plugs.

 

Exactly. Once they're soaked, they won't fire, even if you clean them.

When you put the carbs back together, how did you adjust the float levels for your new needles and seats? With clear tubing and fuel, or dry?

 

I'm pretty sure the fouling is oil, when I tried to burn it off the plug with a lighter it wouldn't dry up.

I checked the float levels with clear tubing and fuel, everything was in spec there.

 

Fouling can't be burned off with a lighter, you'll need a hotter flame. I have had pretty good luck with a propane torch.

Since you have spark, try shooting a little starting fluid in the intake and see if it will fire. That will tell you if it is fuel related. Make sure your battery is fully charged. IF it fires, you are probably not getting sufficient fuel. Maybe your enrichment circuit isn't functioning properly.

 

I tried spraying in some starting fluid, but still couldn't catch an idle. This would rule out an enrichment circuit problem, right? I made sure to clean out that jet really well when I went through my carbs.

So if the fouling on my 1 & 2 plugs really is just gas and not oil(which I'm hoping is the case), then would the fact that my 3 & 4 plugs are NOT fouled mean that there is a problem with my carbs being out of sync that is keeping it from starting?

I really appreciate you guys helping me pin down this problem, keep the knowledge flowing!

 

Yes it could be a sync issue. Where did you set the idle mixture screws after you cleaned the carbs?

One other note: Once a spark plug becomes saturated you probably won't be able to effectively dry it out for immediate re-use. It may dry out enough to work again but it takes a few days.

Also-- the most likely reason there isn't a "how-to" on valve stem seals is that it's something you do as part of a full-on valve job, not as a "maintenance/service" item. As such, it's not something that comes up very often, as most folks doing a valve job know to replace them, and the actual process just involves basically pushing them on. However, it's part of a much more in-depth procedure (valve job) that most folks don't attempt themselves.

 

I didn't mess with the mixture screws at all, hoping they were set to what they needed to be from last year. But now that I think about it this means I'm assuming the PO had them set correctly, and that's probably not a safe assumption. So next step should probably be making sure I'm starting from an even setting across the carbs which is 2 1/2 turns out, correct?

 

Watching this thread closely. Good tips to be had.

Good luck muck.

 

2 1/2 to 3 after you sync the butterflies. I like Rickomatic's business card strip technique, once they're all set, take note of where your screws are now (by measuring as you are screwing them down clockwise), screw them all the way down and then back them out 2 1/2 or 2 3/4 and see how it cranks up, just keep in mind that your main idle knob may need to be adjusted clockwise to get it to crank. If it cranks and roars up to about 4k, back your idle knob counter clockwise until the idle is right, usually 1200 or so, then when it warms up, readjust as necessary. This worked for me, hope it helps!

 

Re: Spring Frustration - Need Advice- UPDATED

Ok, Im bringing back this thread after another weekend of work on the bike. I took apart the carbs again and replaced all the throttle shaft seals which I had neglected to do on the last go around. Bench synced, put the carbs back on and then did a real sync. Everything was sounding pretty good, so I took it for a little ride. Came back and checked plugs, WHOA DANGER lean on 3 & 4, black sooty rich on 1 & 2. Evened out all the mixture screws to 2 1/2 turns outs, still had the same look on the plugs from an idle. From there I started bringing the mixture screws on 1 & 2 IN half turn at a time, and the screws on 3 & 4 OUT a half turn at a time. After each adjustment I let it idle for maybe 5 min then checked to plugs again. Eventually I got to the point where the mixture screws on 1 & 2 are ALL THE WAY IN, and on 3 & 4 they are about 4 turns out. 1 & 2 are still on the rich side, but better than before. 3 & 4 are less white and getting tan. I know that I need to do a proper plug chop to see whats happening at a higher rpm, but my question is this: WHY IS IT that there is such a difference in the two halves of the engine? I checked for any air leaks by spraying some starting fluid at the intake manifolds, but there was no surge in the idle after doing so. At this point the only thing in the carbs that I HAVE NOT taken apart is the idle mixture screws. Could it be that the o-rings under the screws are leaking air and causing the lean condition? Is it possible that the coil on 1 & 2 is getting weak and not allowing for a complete fuel burn? It seems that with the mixture screws turned all the way in I really shouldn't be running rich on them.

I know I'm getting close to getting this thing dialed in perfect, if anyone has any advice on what to do next it would be greatly appreciated.

 

If you didn't have the idle mixture screws out, you didn't clean the carbs fully.

Have you checked the valve clearances?

Done a compression test?

 

Valves are in spec. I haven't had a chance to check the compression.

I just took the carbs off again and took out the mixture screws and made sure everything was clean and clear. I also took apart the enrichment circut and cleaned that again. Set all the mixture screws to 2 turns out. Carbs back on, re-sync. Also checked float levels with clear tube method, all check out.

Now I'm having problems with a racing idle. Seems ok until it warms up, then I'll rev the throttle and when I let go it takes way too long to rev down again. No sure what to do next.

 

Bad sync can cause hanging idle and sticky slides can cause that too. Did you polish the slide bores and did you bench sync?

The only other thing that can make things weird is vacuum leaks. Double check your carb manifolds and use raw propane to see if the manifolds are leaking.

 

I double check my crabs.

 

My Slides passed clunk test and I did bench sync. I did my final sync with my homemade manometer which worked pretty well for the most part, but I did have trouble getting my sync really steady and solid. I'd get everything lined up, then blip the throttle or something and they would go all out of whack again. It seemed like cylinder 3 would start to suck a lot harder than the others when this happened. The vacuum hose from the #3 manifold up to the petcock does seem a little old and stiff, perhaps that could be where I'm getting an air leak?

 

I'm having a similar issue with my XJ550. Did the valves, completely cleaned out, set the screws to 2 1/2 turns, put the YICS tool in and manometer on it to sync the carbs, etc., and the idle doesn't want to come back down. When we pushed down on the plate, the idle dropped to normal like it was sticking or being held open some. I'll check the vacuum hose and the manafolds also but could the throttle cable be sticking?

 

And what did you find? Were they crusty?

 

c_muck,

Silly question here but when you're syncing your carbs, are you using the YICS tool? I'm asking because I had a similar issue.

I found that the throttle cable was sticking some and since I found the chain to be the original from '81, I figured this was probably due for replacement.
The vacuum hose looked worn also so I replaced that as well.

After I replaced the cable, I took her out on the road and when she warmed up, she started idling at 4k (choke off and idle screw completely backed off).

I got her home, reset the mixture screws to 2.5 turns and started to re-sync the carbs. I forgot the YICS tool and wound up with same symptoms you were just stating, it looked like one carb was pulling way more than the others. I realized I hadn't put the tool in after I started to sync the carbs and she konked out on me. After putting the tool in and re-syncing them, she's been great.

I hope that helps.

 

the coils fire 2/3 1/4 so no there. spraying the starting fluid on the intake manifolds isn't good enough. You need to remove them from the cylinder. mine looked great until I had them off, it was obvious after removal there was no good seal, and I sprayed starting fluid and let raw propane surround them while idleing. and yes if the orings are shot you could be gettting a leak there too.

 

My motor doesn't have the YICS, thanks for the thought though.

Did you have any of the manifold bots shear off on you? I've heard enough horror stories on here about it happening that its going to be my last resort to try and take off the manifolds. I've got a new vacuum line and breather caps for my manifold, as well as new o-rings for the mixture screws all on order from chacal. If that isn't enough to solve my problems I guess I will have to wrestle with the manifold bolts to get at those gaskets next.

 

cmuck, those horror stories have an equal amount of good stories. I beleive the good reports come from bikes that aren't rusted. Mine came right out with ease, no rust on the bike though. if your bike is rusted, like the fork tubes, and the manifold bolts themselves, I'd be prepared for the worst. But once you have them off, you'll see how such a large area couldn't be ignored or ruled out.

 

any update on this?

I've got a similar situation.. the motor wants to race (up to 4K) after warming up and I've got to stop using the clutch to lower the idle at stoplights. taken the carbs off numerous times to polish the slide bores, re-align the throttle springs and square the rack again, and my richness problem is on 1&4. the problem could not be ignition coils though... they've been replaced

i'm losing ideas and this has been an ongoing problem the last month or so

** EDIT ** just to give a better picture I fired the bike up 10 mins ago. it idles perfectly when cold and NO choke at all. I feel confident in my carb rebuild because of this. however, when I go down the road blipping the throttle to get through all gears and come to a stop, the idle won't return back to 1050. rather it hangs to 3-4k

 

I did end up getting it running with a regular idle. It took making new gaskets for the intake manifold, as well as sorting out a PO-fault issue. Turns out I had 3 stock size pilot jets, and one pilot jet that was drilled out by the PO, more details in this thread:

http://xjbikes.com/Forums/viewtopic/t=31550/highlight=jets+different+sizes.html

Now that I have no air leaks and 4 pilot jets all the same size, everything is running great!

 

well suppose I oughta take the carbs off again. maybe I have a similar problem with the jets. during the carb rebuild I lost a jet after throwing the soapy water out in the grass. wind up purchasing two new ones from chacal and using two of the best looking ones. I'll verify my jet sizes are all the same and that can either rule out another possibility or find my fault..

no air leaks, shims spec'd, carb bench sync and running vac sync so I'm almost there... during the run earlier the idle would hang around 2.5~3 and like you mentioned in the other thread, if I push down on the throttle linkage shaft the idle drops so I thought the linkage was binding up. however, I've already squared things on the rack twice now so it can't be that

 

jet sizes have all the same size. independent verification by two other people sighting through the holes and the jets have been cleaned. anything else that could be holding the idle up?

spring has come and gone. i should RIDING in this weather rather than taking the carbs on & off so many times in one day. and by no means am I rushing. I've dealt with this problem for too long,,, with a full-rebuild it should be happy to serve me right.

took the pilot mixture screws out for the heck of it to check. they are all looking fine and dandy as well

 

I definitely understand your frustration, after going through so much it simply SHOULD work! Have you checked the gaskets on your intake manifolds? It's sometimes hard to tell if they are leaking or not, and it's easy enough to get some gasket paper and hi-temp RTV and seal them up for good. Also, it might be worth it to order some new o-rings for your mixture screws, they are cheap enough and at this point its worth it to replace anything else you possibly can until it works.

 

gaskets have now been changed for the intake manifolds which are also in excellent shape. mixture screws were all taken out for inspection and the rubber rings were soft and flexible. put things back together, did bench sync again with business card, did running vac-sync, and warmed bike up with a quick ride. still the same problem. my IDLE is too high.

the idle adjustment screw has been backed out all the way and vac-sync balanced out. i don't get why the motor insists on a high idle. another thing: when I give it a lot of throttle it bogs down and literally refuses to go beyond 60mph. so between the high idle and refusing to accelerate into the powerband, what's happening fellas?

 

feel as if I haven't gotten anywhere on this situation. i wasted 2 weeks sitting around waiting on a shim and then got everything put back together yesterday.

VALVES IN SPEC ==> check
RUNNING VAC SYNC ==> check. didn't have to change any idle screws

also note: float levels have been checked a while ago and they looked level with the bowl screws. my bike fires over and runs on the first try without any enrichment which surprises me now. seems like my upper engine rebuild has made the motor WANT to run and once it warms up I can't get the idle to drop below 2.5~3k rpms. it ususally takes 2 to 3 minutes of running to slightly raise the idle to this point.

in case you are wondering about plug colors; 2&3 are tan, 1&4 have a little carbon/sooty aftertaste. also, this should be titled "Summer Frustration - Need Advice"

 

If the float levels are "level with the bowl screws" it sounds to me like they're too high.

I can't speak for the Hitachi-equipped 650s' specifically, but BOTH of my 550s WILL NOT START COLD without using the "choke" until they fire/start to warm up.

You probably need to turn it down a bit more but can't; you may have "adjusted out" any further adjustment during the sync. If you start with the main knob too far out it's possible to adjust to the point where it can't back off any further.

 

okay carbs will come off yet once again...ACK! i knew it was coming when I discovered my adjustment screw is out beyond necessary. so you're saying I should start with another bench sync with the main screw in more? is there a limit too far?

since I will have the rack off, float level tangs will be adjusted everso-slightly to lower the fuel level in the bowls. all suggestions are greatly appreciated! thanks Fitz

 

You Bench Sync using the No.-3 Carb as Base.

Begin by getting the Butterfly of the 3-Carb adjusted to the "Feel" of a guarter-inch wide strip of 3X5 Card.
Adjusting the Idle Rod to have the Throttle Plate of #-3 Feeling the gap between the Throttle Plate and Carb Body.

Match 4 -to- 3.
Use the N0.-4 Sync Screw.
Do 1 & 2 to complete the Mechanical Bench Sync.

(Placing a thin, Nylon Flat Washer above the Spring ... Between the Spring and Shoulder of the Idle Rod will make the Idle Rod easier to manipulate.

 

Solid advice;

but RE-CHECK those floats using fuel and clear tubing so you don't have to pull the carbs yet again.

 

ya I'm leaning towards float levels too high. I am a little eiry about bending those tangs since I've heard others have a pain trying to get the right float levels after messing with the tangs. since they might be a shy high, I bend the tang everso-slightly UP towards the needle correct? i've got some other research on this printed off; just need to verify myself

at this point I'm running outta options since I've bench synced so many times and gotten to the point of checking afterwards with running vac sync and its nearly perfect. of course after doing float level changes I will do it yet once again for giggles and practice

 

welp back to where I started.

last night I was a happy boy. everso-slightly bent the tangs for float level to drop a little and was satisfied after checking using clear tubing. also, this time I turned the main idle adjustment screw almost all the way in then bench synced like Rick stated. put the rack back on and fired up. it SOARED so I quickly turned out the main idle adjustment screw and it was idling very nicely 1200~1350 or so. took it for a spin down the road. came back and the idle was creeping up again!!?!?!?! so out of the blue I turned main idle adjustment screw out more 2 to 3 half turns and the idle dropped to normal (better) 1000 ~1100 and I was pleased!! took it for another spin and the bike was much calmer the rest of the night!

fired it up this morning (had to use a tad enrichment choke) and it was idling nice. so after lunch I hooked up manometers (4 tubes) mercury setup and all four were outta wack. grabbed the screw driver and made changes to the butterfly screws for running vac-sync. now the idle increased and I can't lower the idle any lower since the main idle adjustment screw is out all the way again>.... ^%*$

what am I doing wrong?? is the main idle ajustment screw not in far enough upon initial bench-sync? last night it was just a few turns from practically screwed all the way in after completing the bench sync... now I'm outta play for the main adjustment screw since the idle has gone back up after vac-sync this afternoon...

**EDIT: am I correct to believe that the only way to lower the mercury level in the manometer for #3 carb is to turn the main idle adjustment screw. i know that all the others are married to #3 so that's my problem. the idle is too high still but I can't turn out the main idle adjustment screw anymore.

 

anyone else ever tried pushing down on the 3 screws when the bike is idling? when I do (even if its just one of the 3) the idle drops to a more respectable number say 1200~1400 now

 

here's a few pics for verficiation from someone else that my carb rack is in fact correctly assembled.. also note the main idle adjustment screw has a plastic washer for easier turning. I've about had it with this carb sync stuff. thought I had it perfect until the mercury manometers showed me differently. so I go to change each carb while its running and now everything is outta wack and idle won't turn down anymore... ONCE AGAIN!! ugh.. please help me out

 

update: come home from work with the cager. anxious to work on the bike. notice its low on fuel so I fire it up with intentions to ride back uptown and fill it up. to my surprise, it fires on a little enrichment, warms up and down the road I go. no problem. head back home, idle and throttle is fairly decent. no problem. only thing I noticed was I couldn't get it beyond 60mph or else it would bog. no biggie, I'm still in the fine tuning process right now.

get home, let it idle in the garage and try to lower the idle somewhat from near 1800 down to 1200 or so. it does so just fine. then after idling and playing with the main idle adjustment screw, the motor steadily increases and the idle is roaring near 4k rpm and staying at that point. WTF?!?!? no problem to and from the gas station (5 mile round trip) but once its sitting and not cruising the idle slowly increases

before you go and tell me its an air leak.. ITS NOT! I've checked numerous times around the air boots, intake boots, and throttle seals. i've taken the carbs off numerous times and re-did bench sync.

i'm tired of it and haven't gotten much response

 

From the looks of the sync screws it looks like maybe the rack isn't square.
Loosen the screws holding the carbs together and put the carbs on a piece of window glass or a mirror the thicker the better. That will square them up . Then snug the screws and check again. Finally tighten them and re-check. There is a thread around here somewhere that tells you how to align them correctly and much more elegantly than this drivel. I think it is in one of the cleaning threads.
Mine just did the same thing and it WAS a vacuum leak.
Check the stupid stuff. Like YICS plug missing a washer or the timing being advanced a bunch or the vacuum advance hose being on manifold vacuum instead of ported.
Don't lose heart the answer is there!
These things were invented by humans, designed by humans, and built by humans ( of course that means three strikes yer out). A human can repair it. No black magic required.

 

In that one pic you've got: 2; 6 turns... 3; 7 turns... That's not what you actually have the pilots set to I hope

It very well could be you're running rich still, if you don't require choke to start, somethings not right.
I HAVE to use choke when the motor is cold, ever if it's 40 degrees outside (Celcius) she won't start without it. Of course after it's caught and running I can back it way off and she'll idle at 1200.
After a couple km I can turn the choke completely off, and just have to sometimes hold the throttle open a little at stop lights so it doesn't dwindle in revs and die out. This is only until she's completely at running temp.

The idle adjust in that one pic looks like it's WAY too far in with all those threads showing.


As a side note, ty Rick for that nylon washer behind the spring tip, i'll be doing that next time the carbs are off.

 

you know i've always wondered that. rack is apart again and I will be using the table saw since we don't have glass lying around in the garage.

nobody has answered my question that I raised yesterday.. dad and I are thinking after last night that this may be my culprit

 

Yes, pushing on the screws will affect the idle speed.....that is exactly why when you sync you should turn the screw a bit then blip the throttle and let it settle back down first. Then adjust a bit more and blip the throttle then let it settle back down, etc...., etc..., etc.....

the screws are sensitive so then you 'blip' to allow everything to adjust to itself w/o the screwdriver pressure.


Dave Fox

 

The WHAATTT???

Ain't no "vacuum advance" on an XJ; ignition timing pickups are fixed and the trigger is firmly attached to the end of the crank; the timing is electronically advanced by the TCI unit. The only vacuum-op component (other than the carbs) is the fuel valve.

I don't believe it's a YICS motor is it?

--I still think the float levels are too high (starts with no "choke.")--

 

No vacuum advance hose that I know of. Never heard of it. I believe timing is non-adjustable.

 

between tightening the rubber manifold "deathly" bolts, squaring the rack yet again, and adjusting float levels to lower the fuel amount in the bowls, I don't have a hanging idle!! and by idle I mean 1000rpm its purring like a nice bike FINALLY! in fact, I also got rid of the boggish throttle around 5000-6000 rpm. now it'll run like a bat outta hell all the way up to 9krpm.

question about running vac-sync now to get the bike in top-notch performance: i know that closing the throttle (turning ccw) raises the vacuum thus raising the mercury level in manometer. opening throttle does vice versa and the mercury level falls. so currently I have carbs 1, 2, & 3 all evened out without even adjusting anything since I did that good of a job bench-syncing earlier. carb 4 shows mercury level lower than the others so my thinking would be to close the butterfly thus raising the vacuum and mercury level. when I do so however the main idle increases as well and throws the other three outta balance. guess my question would be why is this and how do I even it out with the others if my main idle adjustment screw won't lower the idle any more?

going out to check plug colors.. would that tell us more as well? pilot mixture screws are anywhere from 2.5 to 2.75 roughly. also, I may intend to purchase new main fuel jets since they are chewed up. bigfitz thought wolves had gotten ahold of 'em lol

 

balance 3 and 4. Then balance 1 and 2. The balance 1/2 with 3/4. At any given time, if the idle gets higher or lower than you want, adjust it with the idle knob. Then, continue with the balancing. I find most often that as I am balancing, the idle drops so I bring it up a bit when needed. I've never had it increase while balancing.. YMMV

Dave Fox