Two Carb Issues

[LuckyEddie]

1. I recieved some pilot jets from Mikes XS They have holes in the sides, what I am replacing does not. Should I solder the holes in the sides if the new Pilot jets closed?

2. I beleive that 2 of my carb diaphrams are bad. With the bike running at idle, I put my finger over the kidney shaped inlet port and on Cylinders 1 and 2 I could feel a slight pulsing, Cylinders 3 and 4 I feel nothing. When I rev it up 3 & 4 appear to be operating properly and 1 & 2 are sluggish and do not remain raised as much as 3 & 4. Also, at idle they synch up perfect but upon raised RPM 3 & 4 stay down and 1 & 2 go up on the Carb Tune.
I'm thinking that I will hit the diaphrams with the Plasti Dip Spray tonight.
Are my diagnosis and solution correct?

Thanks in advance for your input,

[dbeardslee]

Lucky - On the pilot jets DO NOT apply solder. The configuration of the holes may be different, but the flow is what's important. Assuming you ordered the right size, they should be fine.

On your diaphrams, you can check them by removing them and taking them to a dark place with a flashlight. Hold the flashlight up to the diaphrams and see if you see any pinholes in the diaphrams. I'm not sure plastidip would be the thing to use for a repair - Ken Talbot recommended Napa's spray rubber coating. Could be the same as plastidip, but why tempt fate?

[Crazcnuk]

You can also check them by lifting the slides up with your finger and then putting your finger over the kidney shaped hole to block the air.

The slides should stay up or come down very slowly. If they drop like a rock, then you have holes.

[LuckyEddie]

Thank you very much for the tips and / or guidance.
If all goes well I should have a little riding time tommorow before the rain gets here. Have a great weekend guys!

[John]

If I'm not mistaken

The pilot jets in all XS11 carbs should have the emulsion holes in them. The size should be 42.5 for all 11's also.
You may have had the wrong pilots in there to begin with.
A while ago, Wildkat had bought some pilots for her FJ11. The ones she got had the holes in the side, but the OEM jets didn't. The guy that sold them to her said they were a direct replacement. Needless to say the bike idled like crap, and low RPM performance sucked! She bought some more pilots, from a different source, with the holes and the idle is good as is the low RPM performance.

[TopCatGr58]

Hey John,

His bike is the 81MNS, and it's very close to the XJ's, and I remember some folks reporting on their Stock XJ's pilot jets that they did NOT have the aeration holes in them, and that they are designed different. If Eddie will look at the diagrams on MikesXS site about the difference in the pilot jets, he'll see examples of the non holed ones and the location of the metering hole within the jet, vs. the holed ones and a different location for the metering hole within the jet. Then he'll need to look at his STOCK jets more closely, to see if he can see the difference in the location of the metering hole in the jet. He may need to order the other styled pilot jets without the holes!?

I haven't looked at the microfiche listings and part #'s for the pilot jets for the 81MNS and the XJ to compare them with the other XS's.....YET!
T.C.

DOH, he has an 80MNS, not 81, but no matter, the 81 also used regular XS styled pilot jets, but I was right with the XJ using a different style pilot jet. ??Perhaps he either got a different set of carbs, or perhaps a PO put in the wrong type??

XJ Pilot Jet: 4G0-14142-47-00 (#47.5)

80 and 81 MNS: 256-14142-42-A0 JET, PILOT (#42.5)

[LuckyEddie]

Greetings,

I have returned to the stock jetting for now. I have had an issue with synching the carbs in that I can get them to line up just fine at idle, but when rpm is increased #3 & 4 stay down. I have ordered and am waiting for delivery of 4 new carb holders. The photo of the new carb holders show paper gaskets with the set. When my old ones were removed, there were none, Just squashed, crusty, but solid o-rings. Should there have been paper gaskets also?

Thanks,

[red bandit]

I didn't use any gasket or sealer. I let the rubber rib do it's job, and it does. Some on here use a gasket w/sealer on both sides. (leakaphobia) They came from the factory with out any gasket or sealer.

[dbeardslee]

Lucky - Stock there were no gaskets on the carb hangers, but the aftermarket hangers come with them. I recently bought a set from George Fix that came with the gaskets. I permatexed them with Ultra Copper on both sides of the gasket (a very thin coat) and they're working great. Look a lot better too.

Have you done a compression check on your motor? When you mentioned the inconsistent vacuum across your cylinders with the application of throttle my first thought was valve clearances. If your clearances have closed up it will make it run rough too. Do you know when the last time your clearances were set? Supposed to be checked every 6K, but it's one of those maintenance items a lot of owners neglect. JAT

[trbig]

I replaced the pilots on my XJ a couple years ago. The ones that came in had the holes, but the stock ones didn't. I just replaced them all so they were all the same and didn't have a problem.


Tod

[LuckyEddie]

I did check valve clearances before I ever fired the motor. they were all within specs. I have not done a compression test yet. I've been busy wrenching on this bike and 3 of my other bikes to keep them on the road and inexcusably I have overlooked that detail. Thanks for the reminder.

[LuckyEddie]

Yesterday the carb holders came and were installed. No difference in symptoms. The old ones were crap though.
I checked compression with a warm engine, WOT.
#1 - 160 #2 - 150 #3 - 135 #4 - 165.
Tonight I will check it cold and add a teaspoon of oil to #3 to see if it changes.

Synch done at idle - 3&4 remain down with raised rpm.

Synch done at 3500rpm - 3&4 remain up at idle.

All should remain the same through the rpm band.
Where should I start looking for gremlins?????

Thanks,

[dbeardslee]

Lucky -3500 rpm's is a bit fast for synching - should be done at idle (around 1k). On the compression test, readings should be within 10% of each other - #3 is outside of that limit, and #2 is just barely within limit. If it was mine I'd be rechecking the clearances. If they're still within spec your valves might need to be lapped. You could also be loosing compression past the rings, but I think the valves are more likely culprets. Another thing you might want to take a look at is the ignition side of things. I recently had a problem with Betsy where vacuum readings were jumping around all over the place. After setting the clearances, replacing carb boots, and no less than 15 trips into the carbs with no change I focused on the ignition. The problem turned out to be malfunctioning coils. Might not be a bad idea to run some tests with a DMM on your electrics. My $.02.

[thewiz]

I wonder what the plugs ...

look like, especially in 2 and 3? As a couple of others have suggested, I think it's generally good to try to eliminate the ignition first before getting into the carbs.

BTW, have you checked the PU coil wires with an Ohm meter? If that 2/3 PU coil is failing intermittently causing a 'no fire', there may not even be enough vacuum developed to lift the slides.

[LuckyEddie]

As for synching at 3500 rpm, that is not how I do it normaly. It is kind of a search for cause and effect.
The plugs are black and sooty on 1&2 and a darker tan on 3&4.
I will check the electrical side for defects.

Thanks for the feedback,