fuel shutoff, replumbing, & individual filters

[xjguy]

You guys are quickly talking me into keeping my bike stock! By the way I am working on a fix for the leaking octopus. If it works I will share it. If it doen't, I'll keep my mouth shut.

[tsears]

pilot jet report

Hi Mike (and everyone following this thread ...),

I got my 42.5 pilots in today, and installed them in my 81 SH. Huge change - to leanish when I read the plugs. Also to get the idle right I had to unscrew the idle mixture screws (using colortune) a full turn and a half! Bike runs much more civilized now - strong in midrange and low RPM's - a little boggy at WOT (probably coz of 110 mains). I think I'll go back to the 128 mains tomorrow and see how it goes again.

While I was changing out the pilot jets, I did a little test. I have a length of model airplane fuel hose I got from a hobby shop (I use it for a float height tester - per a Tech Tip). I pushed it over the pilot jet hole with the 42.5 jet installed in one of the carbs and blew through it. Then I tried the same thing with one of the mystery pilot jets (rebuild kit pilot jet). I could definitely tell a significant difference. Mystery jet took a lot more airflow! (BJ joke skipped here)

The moral is, if you purchase the K&L carb rebuild kit for '81 XS1100, don't use the pilot jets provided - if you ruin the ones you have, buy new genuine Mikuni's - $9.99 for a set of 4 from Dennis Kirk.

Tim

[TopCatGr58]

Whatcha gonna do with the used jets?

Hey there Mike,
Well, sounds like you've almost gotten your jetting project figured out, and that you'll have a few sets of main jets laying aroung collecting dust. How much you want for them?? Since I'm running 110's and have white plugs, I can probably use the 115's at least if not even the 117.5's since I'm running 4-1 pipes and Indy filters also.

What's interesting is that I ran my bike stock except for the 4-1 pipes for many years and 10's of K miles, then did my topend rebuild, pistons were okay, even had carbon buildup inside of head. But after my rebuild and adding the Indy filters, just like your experience, my bike must be breathing way better than with the stock filter/box, and so also way leaner.

I drove it this way to XSEast this year, however the air temps were quite cool, and so hopefully that perhaps protected me from internal meltdown. Also, my carb floats may be set a little rich which also might have helped? On my recent run to Ken Krieger's place about 236 round trip miles,again cool cloudy weather, I got 37mpg with mostly 65 mph speeds, with just the occasional 4th gear 8.5Krpm burst to 100mph for fun and wakeup blast(testing the new 120mph speedo)!!!

[Mike Hart]

Hi T.C.

I just got back from a blast up Mt. Baker - still lean! 50 pilots next (47.5 is stock on XJ). Sure runs smooth though, very nice, but there's a bit more power to be had.

I bet you could go 117.5's and up one size on the pilots (how many turns out are your idle screws?)

I'm going to hold on to the jets - I have a plastic divided box I keep jets in, from both bikes, and I've seen how handy it is to have them on hand.

Herb Johnston is working on a K&N home made XJ filter (using the frame from a used filter), I might want to test that out.

Pics of Mt. Baker to follow - it was cold and foggy up there this morning in the snow!

[TopCatGr58]

Originally posted by Mike Hart
Hi T.C.

I bet you could go 117.5's and up one size on the pilots (how many turns out are your idle screws?)

I'm going to hold on to the jets

Okay Mike,

Guess I'll see if the local shop has some. Didn't you or somebody say that DK had them as well?? What kind of price should I expect?

Now, don't get to angry with me, my idle screws are still factory set and sealed, never got the courage to drill the tops out to get at them!! Right now, I don't really have a problem with the transition zone from idle thru to 8.5k, so would I really need to change the pilot jets?? Will keep you posted when I get the jets and test the plugs.

[Mike Hart]

I've seen mains go from $1.99 to $6.25 each. Big range! $3-4 is usual.

Well, just drill those puppies out, you're gonna need adjustability there at some point once you start messing with things

Generally, if you go up 3 sizes, yes you need to go one size up on pilots. You can wait for me to try it, that's my next step.

[dasuchbe]

THANK YOU GUYS

Well I adjusted the idle down, it runs real good now. Before I started all of this it would stutter at low idle. Now it is nice and smooth. There is a hint yet of smoke {{ but only if I let it idle for a bit}} and I do have a dribble from one side of the carbs when I let it sit with the petcocks on, but that is minor. All in all it is running a 100% better.

Next comes rebuilding the front master cylinder and getting those front brakes working.

Thanks for the info guys, it has helped loads.

David

[tsears]

mea culpa

I have an apology to make. I tore into my 80 SG carbs, the ones that I said right here on this list had 145 mains and 42.5 pilots AND STILL ran lean. Well it does run lean, but in reality it has 140 mains and the pilots are plugged off. I am sorry for the misinformation, really, I am!

This sort of bs is probably the reason I am 50 yo, divorced, am a renter, and unemployed.

I went ahead and set the bike up the way I said it was and now it runs like - very badly. Serves me right!

Can plugged pilots be unplugged and the carbs still set up to run well?

Sorry in Hayward,

Tim

[Bill]

Re: plugged pilot jets

Tim wrote:

Can plugged pilots be unplugged and the carbs still set up to run well?

The "book answer" is no. The Haynes manual warns against using any kind of wire to clear out the crud because it might change the size of the holes.

Fiddlesticks! On my last trip through the carbs I did just that. They work great. So, try clearing them with a small wire and some carb cleaner. If the spooge comes out easily, you probably won't have caused any harm. In any case, the pilot screw is the final adjustment for that low speed fuel circuit.

OTOH, if you need a drill to clear it out, you should probably replace the jets. When I did mine, I mangled one of the pilot jets when I removed it. I replaced it with one from a old set of carbs with no problems. If I were to do it now, I'd spend the $10 (or so) and put in a set of new ones.

Keep us posted and let us know how it works out!

[JP]

Some years ago I was having a conversation with Norm Kokes and he said his local dealer (one of the rare good shops) said not to run a wire through jets (I don't know which jets they were talking about). When Norm asked why, the dealer said there's micro filiments that cris-cross the openings to atomize the fuel. Norm told me that upon closer inspection there sure 'nuff was.

This is all second hand info. I wasn't there and I didn't see/hear it. But I don't think Norm was "giving me the business."

[tsears]

plugged pilots

Thanks for the info Mike and JP.

Well, fortunately (or not), by plugged I meant that there are these little threaded plugs capping the orofice into which the pilots screw. When I took out the plugs, nice clean 42.5 pilots were down in there.

When I opened up the pilot orofice, the bike stlill ran great at low to midrange, up to about 5K. But when I took it to my test hill for WOT tests, it starts cutting out badly starting after about 5k and just gets really bad, can't really get to 7k. Then when I back down, in the midrange, it pulls very nicely.

My gut feeling is that the mains are just WAY too big - 128's for the last test. I think I'll back down to 110's and try again. That is what my other, very sweet running bike has - and seems much more in line with what I've read from most people on the list, and is the next smaller set of mains that I have immediately available!

Tim

[Mike Hart]

Tim, I know you've had an intervening 'distraction'... but, if you have capped pilots, they belong in there. Don't base any rejetting on running without them. FWIW

[ratbyk]

Cone air filters

Mike, thank you for the tip on; "Y-ing" the fuel lines and installing a manuel shut off. Completed modification today. Looks good and WORKS!
Now here is a problem I found today that might affect you on these aftermarket "cone" air filters. Last Friday I picked up a set of Oval Cone type. Same as yours from the picture except oval in shape. I figured it would provide a little more filter area.
Well since then I have had the carbs off/on 4 times trying to make it run right. Still not there but I think I figured out the problem tonight. Will road test tomorrow.
The problem I think? Up inside the mouth of the air filter is a fairly large shoulder. I assume it is to stop you from shoving the filter to far onto the carb air horn. Anyway this large shoulder (I believe) is blocking off or partly blocking off 4 different holes in the mouth of the air horn. These holes (one being the air jet) are to provide atmospheric air pressure (air horn atmospheric pressure) to various circuits within the carb. The large one at the top of the air horn likely helps the diaphram rise and fall quickly for better throttle respones.
Tomorrow I plan on road testing first with just the rubber ram tubes from the stock air filter box. Once I have Ratbyk running right in this original configuration I will reinstall the the cone type filters and try again. If it craps out again I plan on using a new exacto knife blade and "relieving" the portions of this shoulder that match up with the carb air horn holes and try again to make it run on "cone" type filters.
Suggest that the next time you are working on your Yamaha that you pop off one of these filters and see if maybe this is your problem.
Ken/Sooke
78E Ratbyk

[Mike Hart]

Thanks for the info, Ken. Keep us up to date on your ovals. I really like the 'new' fuel plumbing, glad you like it too

I'll look at my cones next time they're off (in a couple days my new pilot jets should be here). Are your ovals from Emgo or Uni?

I think I see what you are describing, the cones didn't look like that, but then, I wasn't looking for it either. Will let you know.

My bike is running real smooth, good throttle response, just too lean, tho no surging or other lean symptoms, aside from lacking just a touch of power... oh I take it back - one other lean symptom, an occasional decel popping, but from my experience with Bandits, that's nothing to worry about (yet).

[oldnortonrider]

Re: "Ratbyk" posting;

The "place" to get the "right" cones , at the "right" price,
is www.aperaceparts.com . Part number: 005-121 ; $60.00 for four. Specify Yamaha XS1100 ; they do not have the stupid shoulder restriction. These are true K&N copies. I have ordered them before, and I am about to place another order for 4 more within the week.
I started to post the following info on the "Custom Kone" thread
a couple days ago ; decided to wait; will post it here now, instead : ....right now, I have, one, of the APE cone filters on my XS1100, and 3 Uni's. I had all 4 carbs with APE filters, for the last 2 years, until a few weeks ago; I rebuilt 3 Mikuni's for a fellow with an XS750, and he "talked" me out of 3 of the K&N "lookalikes". No problem , I could do without them until I ordered more. WUZ, going to order 4 more from APE, and suddenly discovered "PartsnMoreOnline". They had 'em, $10.00 apiece (I just needed 3), and free shipping. Got the PartsnMore cones in ,about 10 days ago. And discovered "the shoulder". Because of the rib/shoulder, that "Ratbyk" is right on, about, the hole going into the filter/element, is ONLY 41 MM in diameter. The insane part, being, that the carb circuit holes that Ratbyk is referring to, would certainly be restricted, if not, almost plugged. Whoever designed these filters, doesn't know the difference, between a carburetor and a footpeg.
>>More! stupid stuff! : the filter/hole diameter, of the filter, that PartsNMore is sending out for the XS's is 52 mm; it takes 54mm or 55mm, to be correct.
The outfit that PartsNMore is getting their filters from, make 6 different sizes, between 39mm and 54mm. Duuhhhhhhhh.
I ain't even goin' to send them back. Let them lose a bunch of customers , before they discover the problem, on their own.

I have ordered several different items from APE (American Performance Engineering, Burbank, CA) in the past 6 years.
These guys are A-1 . And their stuff is A-1. Generally, I talk to a fellow named "John", when I do my orders >>1-800-824-1825 .
They're still building, a complete online order site, for all their catalog goodies. The carburetor oval/cone filters, still need to be ordered by phone (I think).