Popping back through carbs

[donebysunday]

XS1100 Carb popping

Hi ! I'm the new old guy.
I bought my first XS1100SF new in 79 always amazed me to 56K when I sold it. Just got an 81 XS1100LH and have the same as you but I think it's just one carb popping. Seafoam added to the gas has helped much but it's still there, I can tell the valves need adjusting, bike was not used much has 12K on it. I'm in Milwaukee, Wi. if I can help be glad to. Don };~)

[650mark]

hi don

mark in mesa here, formerly from the xs650 forums. it's been several years since i've communicated with you. hope things are going well with your "new" xs1100. i got my '80 special about 6 months ago, no more xs650's. these 1100's are a real step up, huh? it's amazing what just another 50 horsepower will do you'll find this forum very well run and a great source if tech info for your bike. some of these guys are extremely knowledgeable about the bike's weak spots and may help you avoid some of the common pitfalls of riding an xs1100. i've done some of the recommended mods to my bike and hope to put many miles on it without too much hassle. so far, so good. in fact, the xs1100 is right now my only bike

[RWrightPhotog]

Hmmm. Interesting read. My carbs are popping, too, after a rebuild and no sync or idle adjustment...

[skids]

Any time mine starts popping, I will look and find one of the rubber plugs on the carb nipples missing/torn/cracked.

I had crummy mufflers on my bike and no matter what I did with the carbs, I could not stop the popping through the carbs. If you have OEM exhaust, I would check the welds underneath the heat guards that are forward of the footpegs, especially if you have a special. Check your baffles. Check the crush gaskets at the header pipes. I think that popping through the carbs is usually not due to mixtures in the carbs, but more due to air leaks somewhere, like TRBIG indicated.

[s63921c]

carb popping

Well, I'm finally back at my issue-checked the valve clearances and they are ok for a 1980. I have been thinking about pulling the head and having the valves ground/inspected just for the sake of knowing they're ok/not sticking.
any suggestions on where to get the gasket kit/valve seals? I've also noted that some exhaust gaskets listed for the midnight special appear different than the ones I've been replacing them with-more like orings than the square cut style. It's good to hear one of you is nearby-I may need to look you up. Thanks to everyone who makes this forum posssible-this bike would have been long gone without you!

[CaptonZap]

Well, I'm finally back at my issue-checked the valve clearances and they are ok for a 1980. I have been thinking about pulling the head and having the valves ground/inspected just for the sake of knowing they're ok/not sticking.

A lot of times, a person who goes to that length, without being very knowledgeable about the procedure, ends up doing more harm than good. I don't know your mechanical abilities, but if you will do a leak down test, aka differential pressure test, you can find out if your valves are good. If you can't do that test, I would suggest that you give the complete valve job a second and third thought.
A top end lubricant, Marvel Mystery Oil, 2 stroke oil, etc, will prevent sticking, which has never been a big problem with these engines, to my knowledge.
The leakage or not of the valves can be checked with the leak down test.

The valves are getting harder to come by, and a lot of them get trashed because of insufficient experience on the part of the people messing with them.

CZ, member in good standing of the HSTVA. (Help Save The Valves Association)

[s63921c]

I appreciate the concern you have,and maybe I will leakdown test the cylinder just for the sake of it. As for experience with such procedures,I've been a car mechanic for more than 20 years and well experienced with valves. The bike really doesn't have that many miles on it,but my concern is that this cylinder has run lean in the past-maybe I'll take my bore scope home to check it too...I have used sea foam in the bike every year I've had it-that stuff is the only additive I believe in-it did wonders after the first time I used it in the bike. I should note that I never soaked the carbs as they are painted and I didn't want to wreck the paint. Never did the ultrasonic cleaning-don't know if it would affect the paint-I would guess it would

[crazy steve]

Grinding the valves on these should really be a last-ditch thing, for multiple reasons. First, the seats aren't replaceable, so if you have one that's damaged or heavily worn, the head is usually toast. Next, if grinding the valves and/or seats, you really need a very light touch because if you recess the valve into the seat too far you'll run out adjustment on the shims unless you custom-grind your own in thinner-than-stock thicknesses. Another issue has been a pretty short life of the reground valves/seats for some reason (maybe the OEM parts have a shallow surface hardening that's easy to grind through?).

Not saying it can't be done, but for the people here who have tried it, most have had poor results. Even Yamaha says to just lap the valve/seat unless it's 'severely' worn (their word). That's what most do, and there's been no reported problems with this method.

[Courtney]

And making sure that the plug for the pilot jet well is reinstalled.

MP

Que??? I have never had the rubber plugs in my 80SG, they just weren't there. Clarification from somebody please.

[crazy steve]

Que??? I have never had the rubber plugs in my 80SG, they just weren't there. Clarification from somebody please.

Look here, sixth pic down....

http://www.xs11.com/forum/showthread.php?t=35964

[Courtney]

We don't got no STINKIN' holes drilled in our carbs gringo!

[ccogswel]

Just went through a similar situation on my brothers bike. I was trying to sync the carbs and had issue's. I'll explain in a bit. But I had some popping on number 1 carb while adjusting the carbs to sync. Then I noticed that it would quit and got number 2 to 3 and 4 as I was trying to sync. And never could get it to idle right if with trying to sync it. What I had found out was this. Between trying to sync and adjust idle to keep it idling and all I had adjusted the idle screw so far in to make it idle that it was opening the throttle plates just enough to allow those little metering holes in the front of the bell. The ones for the pilot circuit. Their on the top inside of the carb. Like 3 of them I think. Anyways the throttle plates were opened just enough to allow extra fuel and would bog it down. Now your not having these issues but I noticed I had a bunch of popping going on. Well I adjusted the idle screw all the way out and turned it back in as I sync the carbs. I got it to idle after a couple minutes. And now she idles at a nice 900 rpm's. Would like 1000-1100 rpm's but she acts a little funny so I left it at 900. But to make a long story short after the sync I had no more popping. Just a thought to help you out as I didn't see you say anything about doing a sync. If you did my bad.

As for the noisy valve train you may want to try and adjust the timing chain tensioner. Just make sure you put your timing mark on your plate to the C mark before you try to adjust it. I did that on my brothers bike and it quieted it down alot! And his bike has 60,000 miles on it! Anywho? Hope I was able to give you some ideas too.... Good Luck!

[s63921c]

Thanks for the input-unless my leakdown test shows anything,you've talked me out of the valve job.Looked in the cylinders with the borescope last night-appear ok,but carboned up a bit. I did note the carb mounts are getting very
badly cracked and the caps spin on the nipples-replaced them with Yamaha parts when I bought the bike,but all that time and sitting hasn't done them good. My tighteset valve is .005" on #4 intake,other than that,they are all good. Any suggestions on where to get the carb mounts? some of the cracks are pretty deep and I don't mind spending the money or pulling the carbs to do it