It ran fine after valve job - won't now!

[Guest]

Ok, what I did? I took my bike for a 2 mile ride this week after adjusting the valves, and it was smooth, no problems. Yesterday it started, but wasn't running very strong and finally wouldn't run for more than a few seconds at a time, which is where I'm still at as of this evening!

My first thought is that I let it get flooded with the temporary gas supply I've got hooked up, but I cut that off, left the plugs out overnight, and have cranked it quite a bit with choke on/off, throttle closed/open without any improvement.

My second thought is that something got wet when I rode it since it was drizzling lightly and the tank was off, but there is spark at all four plugs when I crank, so...?

I was all set to synch the carbs yesterday after spending half an hour or more trying to get the rubber cap on the mercury reservoir of my Motion Pro tool. I didn't notice until after I'd poured the mercury that the cap wasn't seated properly; great quality.

Anyway, any simple ideas what my problem might be now? I'm sort of to the point of just wanting to let it sit for a few days before I try again.

[Steve]

Really should not make any difference for what your problems are, but what bike are we talking about?

If you have just checked the valves, have you gone back to see if any of them changed? If you have changed a shim, it might not have gotten seated correctly, and the clearance will still be off. Check the valves again, just to be sure.

If your temporary gas supply flooded the carbs, your carbs need some work. The float needles should regulate the flow of gas unless your supply was considerably higher than the usual level of gas in the regular tank.

Proper starting procedure is usually 1/2 to full choke, NO throttle, key on, pull clutch, push starter button. If this does not work, something needs to be adjusted until it does.


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[cloudbreakmd]

Did you check for fuel flow to the carb bowls? Perhaps something as simple as the vacuum to the petcock working loose?

And is there a strong spark to the plugs?

[JMHJ]

83 850

The spark seems decent at all four plugs, sort of blue, but I wouldn't swear it's strong enough (I don't have enough experience to know what to compare it to).

I agonized over the valve clearances, and changed every one of the shims, some more than once to get where I wanted to be, so surely they're ok (?). I also turned the cam lobes over at least twice before rechecking the clearance, and I used the method where they're not all straight up, btw.

Half choke cold is usually good for me too, but it's been in the 30s here. About the only time it will even try to run now is with full choke and closed throttle.

I've got the tank off, and the vacuum source plugged, and the supply is sitting on the frame in front of the seat.

I may go out and give it another shot here in a little bit. Thanks for the replies. - Mike

[TheCafeKid]

Stupid question but does it have CVs on it?? Is the airbox back on when you started it?

[JMHJ]

Only running on 2 and 3

I don't know about the carbs. It's the stock ones (83 850), and the airbox is still on.

I got it to run a little just now, and only the inner two exhaust pipes are getting hot.

The left coil (1 & 4) has small breaks in the sealant between the plug wires and the coil body (the bike got a little wet in the drizzle the other day), but yesterday there was spark at all four plugs.

I had .09mm clearance on #s 1 and 4 intake valves after shim changes.

Maybe this makes the problem more obvious? - Mike

[TheCafeKid]

Well, Steve, who taught me how to do this proceedure, suggested to me that he'd RATHER have them JUST over the highside of spec, simply because they'd be beaten into spec in relatively short order. I wouldnt think one thousandth on the high side would cause a huge problem, BUT im not an expert on this either. I'd maybe examine those plugs again to see if they're getting spark at all now that the coils may have been exposed to moisture. Maybe those exposed spots are part of the problem, and mayhaps not. I'd also check to see that you've no air leaks in your airbox, and around your intake boots. These are common problems that can sometimes contribute to the problems you seem to be having.

[JMHJ]

Another thing I did between running good/not running was take the allen screws out of the intake boots and put the little adapters in (capped off) for carb synching. I changed back to the allen screws though on Friday, I believe.

I've got the battery on the charger now, and I will recheck the spark next.

[JMHJ]

Now running on 1 and 3!

I checked the spark again - it's there on all four; it was weaker on 2 and 3, but those plugs had some carbon on them after running shortly on those two cyls today (I wirebrushed all the plugs yesterday). I swapped the 1 & 2, and 3 & 4 plugs and put the wires back normally. Now it's running on 1 and 3!

I'm still confused. I will check back for replies after church. Thanks. - Mike

[paco13]

How did it run before you adusted the valves? Was poor running what you were trying to fix?

Start with some fresh plugs too, if just swapping plugs around changes things seems a couple are bad.
Make sure you have the wires correct too.

[bwringer]

In cases like this, I've always found that I didn't reinstall something right or I knocked something loose while reassembling.

I'm also wondering if the airbox isn't on quite right. You didn't mention removing it or the carbs, but it's incredibly easy to get one of the inner airbox/carb boots flipped under the wrong way precisely where you can't see the furshlugginger thing...

Also check wiring connectors to the coils (I've noticed these are rather vulnerable) and anything else you can find.


Having the valve clearances at .09mm won't hurt a thing. When one or two get too tight (zero clearance), it will definitely screw up the way the bike runs, but a little loose is fine. I've left them at .09mm - .11mm many times.

[paco13]

when you pull the plugs are they wet with gas or no?
what were you using for an aux. tank? Was it clean, water free?
What did you have for dinner last Thursday?

[JMHJ]

Thanks for the ideas. It ran ok before the valve adjustment, just had a little noise up there I didn't like, and also seemed to be a little short on power compared to what it used to be.

I didn't move anything while doing the valves except the cam cover, and I wire-tied part of the wire harness up closer to the frame to help me get that cover out. The plugs are fairly new, and I put a K & N in the airbox not too long ago also. I rechecked it after a week or so to make sure it was still seated up in there the way it was supposed to be. The weatherstrip could've used replacing though.

I started thinking after my last post that maybe fuel starvation could be my problem . I added gas through the fuel line with a syringe until it wouldn't take anymore. Now exhausts 1, 3, and 4 are hot, but not 2. It will run with no choke at all too. I was worried that my direct source of fuel without the fuelcock was like having it on "pri" which I thought you were supposed to avoid for more than a short time.

Maybe it's still not getting enough fuel somehow. Could that make 2 or 3 cylinders work but not the other 1 or 2?

I fiddled with the wire connectors at the coils too, and they seemed ok, but I can't tell for sure. I'll check back this evening. Thanks for any further input. - Mike

[paco13]

You should definitely confirm that all four carbs are getting/filling with fuel.
I was thinking that maybe some debris had entered and clogged something up with all the messin around.
Check and make sure No connections/wires were disturbed when you pulled the harness up out of the way.

[Steve]

Here is the part that got my attention:

I wirebrushed all the plugs yesterday.

Did you do that with a manual wirebrush or a wheel on a grinder?
With a manual brush, there is a chance that one of the wires came loose and lodged deep in the spark plug, and could be shorting it out.
With a grinder-mounted wheel, I have found that it tends to deposit a layer of steel (from the wires) on the ceramic, again, shorting the plug.

Splurge, spend the $8, get a new set of plugs.


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