Does this sound like a clogged pilot jet to you?

[JeremyL]

I have cleaned the carbs on my 79 XS11 and thought I did a good job but I'll admit it wasn't as thorough as it could have been. I cleaned all the jets and the emulsion tubes and even installed new plastic floats and 140 mains but didn't pull the carbs apart and dip them. The bike has a 4-1 system and that's it for mods. Plugs were a little white so I figured the 140's would maybe help that out and 137.5->140 didn't seem like a big jump to me. I left the 42.5 pilots in there.

Well the bike runs pretty good as far as I can tell. The reason I say that is because I'm not sure what to expect from it, I had a 99 Honda CBR 600 before so even this 1100 isn't as fast as my 600 was, but I don't have a problem with that. It still pulls very hard and is fun as hell to ride. My only problem now is that I have a little bit of hesitation when I'm pulling out or lugging it around (don't really lug it much unless I'm accidentally in a higher gear than I should be)... If I pull out from a stop the bike will kind of bog but still go and then around 3000RPM, which i'm GUESSING because my tach doesn't work, it takes off like a rocket up to redline.

I noticed the other day that when the bike was warming up that the #2 pipe wasn't heating at all like the other 3. But when I got back from a ride it was hot like the rest of them from what I could tell.

I'm no mechanic but I'm kind of wondering if that would mean that my pilot jet on #2 could maybe be clogged and causing the bike to run rough when pulling out then that cylinder picks back up with the main jet and the bike runs great again. Before I pull the carbs (AGAIN!! ) could it be anything else? Would an idle mixture screw make THAT much difference? I don't mind to pull the carbs again but with a new baby I'm lucky to have time to ride 1 hr a week, let alone pull and clean carbs, so I don't want to if I'm wasting my time... although after pulling them like 4 times now I'm getting pretty good at it.

[DGXSER]

Couple things to look at. First, did you clean the enrichment (choke) jet in the float bowls? If not, then if number 2 jet is plugged, it will not warm up correctly and will take longer to run correctly.

Below 3000 RPM is mostly the pilot jet circuit, so your on the right track there. However, when correctly tuned, you will still notice a difference when you hit the main jets at 3k. And then when you hit about 5k and your entirely in the mains, it REALLY hits the power band! I can be doing 70 MPH at about 5k, crank the throttle and hang on tight cause 80 is only a couple seconds away and 100 is coming on fast!!

[JeremyL]

Couple things to look at. First, did you clean the enrichment (choke) jet in the float bowls? If not, then if number 2 jet is plugged, it will not warm up correctly and will take longer to run correctly.

Below 3000 RPM is mostly the pilot jet circuit, so your on the right track there. However, when correctly tuned, you will still notice a difference when you hit the main jets at 3k. And then when you hit about 5k and your entirely in the mains, it REALLY hits the power band! I can be doing 70 MPH at about 5k, crank the throttle and hang on tight cause 80 is only a couple seconds away and 100 is coming on fast!!

I think I cleaned the enrichment jet in the bowls. It has been a couple of months since I cleaned the carbs. I think if I can just get this hesitation fixed I'll have an excellent running bike because once I rolled out on the road and hit about 5-10mph it just takes off. As long as I don't let it rev too low in corners I can ride at high speeds all day and it's fine. When I started the bike wouldn't go above 5000rpm and barely idled so I'm doing a lot better than I was.

Anyways, where are the enrichment jets?

[Cobia]

I had a similar situation with my XJ and it was the pilot jet causing it. It typically happens between 1.2k and 2.3k rpms.
In my case no matter how much I cleaned them and no matter how much adjusting I did, it would not correct it. In my case the PO had installed pilot jets that were a size too small. But that's not your case. Just take the carbs out and go through them again, totally. Take every jet out and spray in every passage with carb cleaner and the straw until you see it come out elsewhere.
Also, use a very thin piece of wire to clear out all the holes in all the jets. I use different gauge guitar strings for that purpose.
Good luck.

[DGXSER]

Enrichment jets, look in the fuel bowls, in the bottom you will see a small hole. That hole leads to the hole on the edge that the brass nozzle on the carb body slides into. In that hole lives a small "jet". Basically a restrictor. You need to b able to shoot carb cleaner through that hoel and out the one in the edge of the bowl body. It comes out almost if nto as fast as it goes in, so watch your eyes.

[11Rider]

That's right - watch out when shooting carb cleaner in that hole - it has a way of ending up in your face if you're not careful

[JeremyL]

Enrichment jets, look in the fuel bowls, in the bottom you will see a small hole. That hole leads to the hole on the edge that the brass nozzle on the carb body slides into. In that hole lives a small "jet". Basically a restrictor. You need to b able to shoot carb cleaner through that hoel and out the one in the edge of the bowl body. It comes out almost if nto as fast as it goes in, so watch your eyes.

Ohhhh, so that long thin nozzle that is for the enrichment? I always wondered what the point of it was. I don't think I really paid any attention to that so I'm going to try to pull the carbs today or this weekend and reclean again.

I was going to ride the bike to work this morning and it, like always, ran really really rough when starting up, even with the choke. The choke apparently worked some because without it the bike wouldn't even start, but I let it warm up for a good 5 min (at 65 degree) and it STILL was running rough and would die if you pulled the throttle more than half open.

Everytime I clean the carbs I find something that I didn't clean before... last time it was the emulsion tubes which were causing the bike to buck when you went WOT at high RPMs.

Thanks for the tips guys, I'll report back as to how it goes... hopefully it just needs a cleaning.

[JeremyL]

That's right - watch out when shooting carb cleaner in that hole - it has a way of ending up in your face if you're not careful

Hey, I meant to ask you this before but always forget... I keep noticing in your sig that you have a solo seat. When I get my bike running good that's one of the first cosmetic things I want to do. Do you have a pic of what it looks like?

[JeremyL]

sorry for the double post... can't figure out how to delete this post

[JeremyL]

Well I pulled the carbs off on my lunch break today... I can get them off the bike in 20 min -- too bad it takes 3x that long or more to get them back on.

Anyways, I didn't have time to strip them all down but I pulled the idle mixture screws and 2 are broken (and stuck in the holes ) and I had time to pull the one pilot jet out of the #2 carb with the cold pipe at idle. After I blew through it it was clear but the top of it is so damaged I don't know if I can screw it back in there again. It wouldn't hurt fuel flow but the parts that contacts the screwdriver head are chipped off so even if I got it screwed back in I probably couldn't get it back out. I figure I better go ahead and replace them all while I am buying mixture screws.

I was going to order the stuff from MikesXS but don't think I see the right mixture screws on there and I'm not sure if these are the right pilot jets or not:

Says 42.5 (what came out of mine) and for the BS 38 carbs.


Here is what mine look like:




Also, could the mixture screws cause the bike to run rough when pulling out or are they strictly just for Idle only?

[bikerphil]

Post #7 of this thread has a few sources for those idle mixture screws. MikesXS does not sell the proper mixture screws for the 78-79 carbs. The type of pilot jet you need is called a BS30/96 type which MikesXS does carry.

http://www.xs11.com/forum/showthread...ght=bikebandit

You can also try Georgefix, he should have kits that contain the proper mixture screws and pilot jets....

http://www.georgefixs.com/servlet/the-YAMAHA/Categories

[JeremyL]

Post #7 of this thread has a few sources for those idle mixture screws. MikesXS does not sell the proper mixture screws for the 78-79 carbs. The type of pilot jet you need is called a BS30/96 type which MikesXS does carry.

http://www.xs11.com/forum/showthread...ght=bikebandit

You can also try Georgefix, he should have kits that contain the proper mixture screws and pilot jets....

http://www.georgefixs.com/servlet/the-YAMAHA/Categories

Wow, $66 at georgefixs.com for FOUR entire kits? That's not bad. I actually need 4 gaskets (they don't leak but they look pretty rotted now), and I WAS have a problem with the float needles sticking so I was going to eventually order new float needs and seats. I have already replaced the main jets with new 140's and the floats with plastic ones. Seems like this kit would finish it out and $66 in one punch is better than nickle and diming myself by buying one thing at a time.

Thanks!

[latexeses]

Looks like the tip of that one needle is missing!!??

[ManagerMike]

Also, use a very thin piece of wire to clear out all the holes in all the jets. I use different gauge guitar strings for that purpose.
Good luck.

I use a torch tip cleaning kit for the same thing, many sizes of serrated wires with chisel tips. Ideal for clearing tiny passages which, now that I think of it, is what it is made for.

[latexeses]

lesson learned..Don't skip posts