#1 & #4 carb pilots have no effect?

[Yard Dogg]

I synced my carbs today and had some issues I wanted to ask about. Keep in mind I haven't shimmed my valves yet and they need it. My compression is within reason, can't remember exactly what but it's real close the last time I checked 2,000 miles ago. I knew I couldn't tune the carbs perfect but I wanted to get it close, plus I needed practice. It didn't turn out any worse than before and I think I may have gained some power on the bottom end, so I did something right.

I'm just wondering if it's typical to get them synced, then as it sits and idles, things just go weird and it get's off sync again all on it's own. I'd make an adjustment, wait for the effect to stabilize, then wait a little longer and I swear this bike has a ghost.

The thing that spooked me the most was the lack of effect the pilot screws had on the #1 & #4 cylinders. I could turn them all the way in and all the way out and have very little effect on #1, and no effect at all on #4 until it was screwed out almost all the way. The tips are still on em and they actually seat quite nicely in the port holes. I think I might have heard the idle ramp up a little bit but I think it was wishful thinking.

Does anyone know what could cause this weirdness?

[tw1980]

Sorry I've been fighting same problems for 2 years.I just finished going threw each carb with a fine toothed comb.I soaked each carb 48 hours and then rinsed blew out with air then ran a pipe cleaner and q tips threw every hole.Runs good one day,blubbers,hacks,coughs and idles up and down the next.Sometimes the idle will just slow down for no reason.I believe the emulsion tubes are bad.I haven't been able to find a source for new or improved emulsion tubes for these carbs so unless I come up with a fix soon,I'm going to spring for a set of new CR carbs.Sorry I couldn't offer more help. Terry

[Ken Talbot]

I'm just wondering if it's typical to get them synced, then as it sits and idles, things just go weird and it get's off sync again all on it's own. I'd make an adjustment, wait for the effect to stabilize, then wait a little longer and I swear this bike has a ghost.

No, this is not normal. Could be a vacuum leak at one or more of the rubber intake manifolds.

The thing that spooked me the most was the lack of effect the pilot screws had on the #1 & #4 cylinders. I could turn them all the way in and all the way out and have very little effect on #1, and no effect at all on #4 until it was screwed out almost all the way.

This is not normal either, and points to dirty passages in those two carbs. Sorry.

[3Phase]

The thing that spooked me the most was the lack of effect the pilot screws had on the #1 & #4 cylinders.

Spooked? Try the Ghost Whisperer?

Does anyone know what could cause this weirdness?

What idle speed are you using when you try to set the mixture screws? It has to be sync'd correctly and idling slow enough to notice a ~50 RPM roll by ear. Higher speeds will make it difficult to catch the roll and so will an improper sync. That's why you sync the carburetors and set the idle speed first, then drop the idle speed down and set the mixture screws. If it is your carburetors and not a high idle or bad ignition then the pilot circuit is not working in those two carburetors.

Problems with #1 and #4 pair or the #2 and #3 pair of cylinders are usually ignition. Have you checked for loose or bad coil primary wire connections under the gas tank?

You could also have the infamous broken pickup coil wire. It makes the bike do very strange things when one set of cylinders only fires when the phase of the moon is aligned with your left elbow and your head is held at the correct angle.


Regards,

Scott

[Yard Dogg]

Well, I just had my coils out sealing up the plug wires, all my wiring checks out good. I'm really starting to want a top end rebuild. Riding season is coming up so it'll have to wait.

I'm going to shim the valves, make new intake gaskets and install them with copper spray, then try to resync.

I cleaned the living crap out of those carbs. I use gunk carb dip, which I am not impressed with. When I bought it I was expecting the yellow stuff that would melt your hand if you put it in there. Gunk was weak, it worked, but it took much more scrubbing than I wanted. I blew then out with air, but all those little passages for the pilot circuit were hard to clean. I may have missed some build up in there.

I'm thinking it's probably that and maybe leaky intake boots and valves adj. needed.

[Yard Dogg]

Could anyone maybe explain where those pilot jets run in and out of the carb body? It seemed like a bit of a maze to me, the rest were easy. I understand the enrichener, but when I was cleaning em, it did feel like I was missing something inside when I blew air through em.

Maybe there's a method one of you gurus might have?

[psycoreefer]

When I clean carbs this is how I go about it...
1. Pick a hole, spray carb cleaner in it. Watch which hole the carb cleaner comes out.
2. Plug the hole the cleaner was just coming out with my finger (or something)
3. Spray carb cleaner in hole #1 Again, watch where it comes out now.
4. Plug exit holes from #1 and #3, repeat #3.
5. Do this until when I spray in no carb cleaner comes out anywhere.
6. Do this with each hole on the carb....

By the time your done your hands will hurt, you'll have carb cleaner in your eyes and you should have sprayed cleaner through each passage from both sides!

If I find a hole that I can't spray cleaner in I try to figure out what it does/where it might go and work it until Cleaner goes through it.

[Yard Dogg]

I should have spent a little more time on it to do like you said pscorey. My trouble is I just painted my carbs I've said it before and I'll say it again. I love my midnight but that black paint is a pain in the azz. I don't think I'll ever own another blacked out bike.

I'm gonna give the paint a few more weeks to set up, it's been about 2-3 then I'll pull em and see if I can work out the plugged something somewhere.

[psycoreefer]

This thread has a flow diagram, maybe it would help?

http://www.xs11.com/forum/showthread...t=carb+diagram

Also take a look at this one..
http://www.xs11.com/forum/showthread...s&pagenumber=2

[Yard Dogg]

Thanks man, that totally helped. Now I know what needs to happen. I think I'll have to reclean, and like you said plug things off and load it up with cleaner.

[cywelchjr]

Another thing that can happen with these carbs is that the o-ring under the washer and spring on the idle mixture screw wears out and flattens out, and makes it almost impossible to to get any adjustment out of the idle mixture screws. You can get them from MikesXS pretty cheap, IIRC they come in pairs, so just get two pairs and replace them.

[Yard Dogg]

Another thing that can happen with these carbs is that the o-ring under the washer and spring on the idle mixture screw wears out and flattens out, and makes it almost impossible to to get any adjustment out of the idle mixture screws. You can get them from MikesXS pretty cheap, IIRC they come in pairs, so just get two pairs and replace them.

They did look a little flattened, but I figured the spring tension would keep em sealed. I really need to check out Mikesxs. He has a lot of stuff I need.

[Ivan]

Although my experience with motorcycle carbs is limited, I have only done about 20 sets thus far, one common thread is plugged pilot fuel jets. Double check that #1 and #4 pilot jets are clear and that you can see light through that tiny hole.

Other possibilities are that your mains are rich enough that your idle is set high enough to make the pilots ineffective. Yes main jets affect everything. Everything else just necks down fuel delivery at lower settings. If this is the case, and your bike is happy at full throttle under load at high rpms, then look into changing your pilot jet size.

The leaking air is a good theory too, but I assume by now you have checked that already.

Also, if your bike needs the valves adjusted, you need to fix that first. If the scoot runs fine for extended periods of cruise and your compression is fine (which you said) then logic says your valves could only be loose. That doesn't cause running problems until they get so noisy you wonder how many bolts are flying around in the engine. I had a Fiat that constantly needed valve shims changed, to the point I got a kit and too the tools with me if I was going more than 20 miles. Valve wear tight and tend to make the engine skip out when they heat up enough to stop sealing. Thankfully this is usually not a problem on our scoots, so I am on the fence as to if it is on yours. But, like I said, if they are tight, they need adjusted before you can ever get your carbs nailed down.

Hope you can glean something useful from all that.

[Yard Dogg]

If my pilot jets themselves are stripped, as in the screw driver doesn't like them anymore do you think it would effect fuel delivery? I just figured as long as the jet hole itself isn't muffed up then it should work the same.

I went to Yamaha Country, my local Yami shop, and that a-hole was trying to charge me 22$ for valve shims. I said , he said, well they're OEM. What a maroon. Why would I care if they're OEM. I just want a piece of metal.

I'm going to be hitting an OT job next week. So I think I'll place an order. New intake boots, mine are cracked real deep, I don't like it. 2 new pilot jets, 4 o-rings for the pilot screws, shim my valves, then sync and that should solve it. I'd love to do a top end rebuild but the warm weather won't let me, I want to ride.

[psycoreefer]

It shouldn't effect fuel delivery the metering hole is in the other end, however if you haven't taken them out because their stripped then its unlikely that you've really gotten those idle circuits clean.

The intake boots are cosmetic most likely, Mine are cracked deep too but its a three layer deal, rubber, metal, and then rubber on the inside so even if the outer layer is cracked all the way through you probably don't have a leak. Easy way to check is with a propane torch, unlit of course.

When your ready to remove those jets a small screw extractor works great, heat up the carb body a bit, and then the screw extractor will go right into that hole in the jet, no need to drill.