Seems I have a problem with idle.

Re: Seems I have a problem.

To restate the latest sequence:

Synched with YICS blocked, idled at 1000
Pulled YICS tool, put plugs back in, put the tank back on
Started and immediately revved to 6000
Pulled the tank, put the gas bottle on
Checked throttle linkage
Checked spark on all cylinders.
No start

 

Re: Seems I have a problem.

if you used a paper clip to do a bench sync and never turned the idle knob down to lower the idle, there's a chance that 6K is what the idle is set for.
it might be set high enough to defeat the enrichment circuit.
try backing off the idle screw till it's off the linkage then go in till it touches and then in 3/4 to 1 turn.(that's a guess), no yics tool.
if you pull a vacuum cap and nothing happens, could be because that cylinder isn't firing.
sometimes a plug will fire outside the engine but not when it's under compression

 

Re: Seems I have a problem.

So, I turned out the idle knob.

Got it to start and idle at 1000.

And then it jumped to 3000. At least it's not 6K...

 

Re: Seems I have a problem.

Still misfiring on a couple of pots at cold startup, idle is adjusted to 1000 on the firing cylinders & then as the engine warms, the other 1 or 2 start firing and the revs shoot up would be my educated guess...

 

Re: Seems I have a problem.

Sounds logical.

What would be the next step from here? New coils?

 

Re: Seems I have a problem.

New plugs not coils!!! (unless you know something we don't, have you checked the resistances?)

I've found bad plugs can cause hard starting & on multi cylinder bikes can cause a miss until they warm slightly, plus they're a cheap option. What code number is on the plugs that are fitted?

 

Re: Seems I have a problem.

We're still waiting for you to tell us if one or more pipes are cooler. At least that will narrow it down to a particular cylinder(s)

 

Re: Seems I have a problem.

All the pipes run hot, as far as I can tell. #4 seems to be hotter than the rest, but that's about it.

 

Re: Seems I have a problem.

you can't wait till their hot, check the pipes as soon as you start it, while it's still at 1K.
don't even sit on it to start it, kneel down by the pipes and feel for heat as soon as it starts.
go get some new plugs.
then let the bike warm up real good,(3K idle, choke off) set the idle to about 1500, and start the sync again and try to keep that 1500 while you sync.
then go to 1200 and start on the mixture screws

 

Re: Seems I have a problem.

So, the plugs I have in it are B7ES. The parts catalog says they should be BP7ES.

Do I not have the right plug?

 

Re: Seems I have a problem.

http://www.sparkplugs.co.uk/pages/techn ... g-code.htm

The P is a projected insulator type, not having it could potentially result in less effective ignition of fuel/air mixture, especially on our bikes with their "super powerful" spark lol

 

Re: Seems I have a problem.

Awrighty. So, I got new plugs, NGK BP7ES. They do protrude into the chamber quite a bit more than the ones I had before.

I tried to start, and it spun, but didn't fire. I put the charger on, and it fired almost right away. That kinda looks like my battery is too weak to provide decent spark.

 

Re: Seems I have a problem.

One more time...

New plugs, fully charged battery. Kept charger on, just in case.

Started. Synched at 1000 (maybe a little higher)
Ran just fine at 1000 for a few minutes with the choke completely off.

I gave it gas, it revved and came down. Three times.

On the fourth it revved to 4000 and stayed there.

Seriously, what the hell?

 

Re: Seems I have a problem.

Maybe it's the 550 next to it that's doing this. They made a deal over the winter and the 550 wants to get ridden first. Yeah. That's it. Or, it's haunted.

 

Is your bike by any chance named Christine? 8O

Sorry but I'm almost out of ideas if it was definitely firing on all 4 when you set the idle....

Have you tried turning the idle screw down when the revs jump up? Maybe be an idea, Does it have any effect?

 

Idle screw is all the way out. I unscrewed it till it was loose and then just got it to start, so it's in the threads.

I'm back to wondering if there isn't something wrong with the valve train...

This is where people typically talk about how much they hate carburetors, but I'm not wholly certain that's the problem. I know damn sure with the amount of work I've put into them they were done right.

 

I think you still have an airleak somewhere...see also:

http://www.xjbikes.com/Forums/viewtopic ... art=0.html

 

So it's still able to rev to 4000 with the idle screw backed all the way loose (so it's not touching the throttle at all)?

That, to me, suggests sync far out. As in, needing bench sync far:? Strange as you running sync'd it...

An air leak *is* a possibility, but this would cause the revving symptoms only if there was extra fuel available too...

 

And... I'm a moron.

I just realized I forgot to plug the YICS just now, so the sync isn't really a sync.

 

You got that syncing feeling? :roll: sorry couldn't help myself