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-   -   Fuel in crankcase? (http://www.xs11.com/forum/showthread.php?t=44484)

puskrat 08-12-2015 08:35 AM

Fuel in crankcase?
 
1980 XS1100G, bought about two months ago, still trying to get to shakedown.

Every time I get ready do to something, i find out about something else I have to or should do first.

Bike sat for two years. Needs new gas. Also, I want fresh oil before I fire it. First time on centerstand, I got a strong fuel smell and had thin fluid leaking through drain plug and somewhere else as yet unidentified. I have since concluded this is the infamous XS "gasoil". Now more than ever I want fresh oil before I fire it.

Local vintage medic warned me of possible overflow lines pumping fuel into the crankcase. Reading the threads on the fuel in crankcase problem, and the tech tip on O-rings from parts store. I'm not sure where to proceed. Is a petcock rebuild where I need to go? Is it a carb issue?

The previous thread I thought was helping me just stops without resolution. Lots of ideas and instructions, but no "I did it and it worked". It was a couple years ago I think.

I hate the repeat questions, but I havent seen this one answered yet, just asked. Help?

Thanks

Rat

MPittma100 08-12-2015 08:48 AM

Fuel in Oil
 
Gas in the oil indicates one or more carburetor float valves and petcocks are leaking. Need to rebuild petcocks and carburetors. When carbs are finished and reinstalled. you will need to sync them. Use only Mikuni parts in the carbs.

Change oil and filter prior to starting engine.

puskrat 08-12-2015 08:55 AM

Sounds like a definitive solution. Thanks, Pitt. I recognize that ID from the thread I mentioned. Appreciate seeing your input. IIRC, the idea was put forth to do a prelim oil/filter change with throwaway oil and after a quick run, do it again with keeper lube.

P.O. claimed to have rebuilt carbs before storing the bike. Could they have fouled somehow while sitting?

yamtom 08-12-2015 09:15 AM

po said what??
 
I dont know how well you know the po, but its a foregone conclusion, that many motorcycle sales are completed by po s that tell tales. If he says something, you must prove it correct before you rely on his word, end of story. Obviously, if its got gas in the oil, you have major work to do rebuilding carbs and petcocks. Most people get rid of octys if possible. A person of some skill can do these, but follow the guidelines closely on here, these guys are great for helping get a bike going safely.

puskrat 08-12-2015 10:12 AM

Thanks tom. I haven't torn into these carburetors yet, but my previous carb work, while not fun, hasn't left me with the dread that "major work" does.

How would I eliminate the octopi?

MPittma100 08-12-2015 07:02 PM

Fuel in Oil
 
Unfortunately, POs are full of BS on a lot of occasions. Some POs aren't really sure if a bike is running correctly or not. But they will say that it is.

After cleaning/rebuilding carbs, hook up a remote fuel source to them to verify that there are no leaks prior to reinstalling onto engine. Add 1 fuel filter to each pair of carbs. That is 2 filters total.

There are several causes of fuel system failures.

One is rust or other foreign material coming out of the tank into the petcocks. This can ultimately cause the petcocks to leak. Another cause is leaving ethanol fuel in the system for extended periods. Many POs or incompetent mechanics rebuild carbs incorrectly and are part of fuel related issues.

The XS11 carbs are sensitive to foreign material and the filters will help eliminate this problem. Rebuilding these carbs is sometimes overwhelming to the first time builder, but the satisfaction of getting them right is well worth the effort.

Start at the tank and work your way down to the carbs. Consider the complete fuel system in need of attention rather than just one part of it.

TopCatGr58 08-12-2015 08:25 PM

Hey there,

Well, your local mech/medic was a bit incorrect in that there are NO overflow lines on these carbs. There are alot of fuel lines due to the presence of the Octopus IF it is still in place. If so...then it is also not working right. IT is the vac. shut off valve AFTER the petcocks..the special petcocks are just gravity feed type.....they then flow into the Octy...and it's supposed to shut off the fuel flow when the engine is OFF=no vac. to the vac. valve in it...but that valve can get stuck/gummed up, or the metal behind it and spring can rust/corrode, etc.!

SO...there's a chance that the petcocks may actually still work....but they may have been left in the ON position which then leaked past the Octy....and THEN the carbs needle float valves also failed/leaked for a variety of reasons. The PO may have rebuilt/clean them but then stored with fuel in carbs/tank...and old gas forms varnish/gum which can cause the float needle valves as well as the Octy to gum up/stick and leak.

Then, when the float needles stick..leak the bowls fill up and overflow into the throat of the carb body...which then can flow forward thru the carb throat into the intake and then past the intake valve, the pistons/rings and into the crankcase=gasoil! :eek:

Most petcock rebuild kits for specials usually has the Octy rebuild parts also. But as was said....some folks thinks it's too much clutter and unnecessary complexity and so they remove the Octy....then just cap off the front petcocks nipple, and then run the petcocks directly to the carbs with inline filters...and then just remember to MANUALLY turn off the petcocks when they park for extended times. For just short parks....properly working carbs will shut off the fuel if the petcocks are left in the ON position.

Another leak source aside from the float needles are the needle seats and their O-rings. You can also test the petcocks by just removing the fuel lines from the octy, run to a catch cup/bucket and then test the function positions of the petcock handle...should flow in RUN and Reserve, not in OFF, and the prime position flows out of the FRONT capped nipple...redundant without the Octy. With the Octy....it provides a bypass to help Prime/fill the float bowls gravity feed way.

T.C.

Prisoner6 08-13-2015 06:03 AM

I think what first needs to be determined is:

Which model XS does Rat have? His profile simply says "1980 XS1100", and in his original post in this thread, he indicates the bike is a 1980 XS1100G.

In none of his posts do I see any other indication which model he has.

If it is a G (Standard)... then it has vacuum-controlled petcocks, and no Octopus to contend with (only Specials had the Octopus).

Rat, is your bike a Standard (bigger/more square-ish tank) or a Special (smaller/teardrop tank)? This is one possible way to tell (assuming the tank hasn't been swapped).

Once we know for sure, then we can discuss Octy vs. no Octy, and how to proceed.

Prisoner6 08-13-2015 06:32 AM

Quote:

Originally Posted by Prisoner6 (Post 470444)
I think what first needs to be determined is:

Which model XS does Rat have? His profile simply says "1980 XS1100", and in his original post in this thread, he indicates the bike is a 1980 XS1100G.

In none of his posts do I see any other indication which model he has.

If it is a G (Standard)... then it has vacuum-controlled petcocks, and no Octopus to contend with (only Specials had the Octopus).

Rat, is your bike a Standard (bigger/more square-ish tank) or a Special (smaller/teardrop tank)? This is one possible way to tell (assuming the tank hasn't been swapped).

Once we know for sure, then we can discuss Octy vs. no Octy, and how to proceed.

Also, do your petcocks have an OFF position? As delivered from the factory, Special petcocks had an OFF position, Standard petcocks did not.

puskrat 08-13-2015 07:52 AM

Yes it's Standard. Apparently *I* am special.
 
Sorry Guys. The profile was created when i didn't really know much about what was going on. Don't let that imply I know a lot now! My XS is an XS1100G, a standard, with no "off" position. That spleens why I had no context for working on the octopus, other than seeing references in prev threads to "the octy" I have a Yamaha Service Manual and have d/l'ed some references from links here on XS11.com, and am still familiarizing myself with my machine a little bit at a time. You guys have already been a big help, keeping me from making serious mistakes, and smacking me in the face with some reality. Keep it coming!

Humor.....My gf (also the landlady of my motorcycle storage garage) is a high school music teacher, and you all informed me of the petcock problem right before I went to her chorale reunion cookout. She asked how shop day went and to avoid the giggles, I had to use the term "fuel shutoff valve" several times rather than the more typical term.

I know to get Mikuni parts. I know a Mikuni model XX for an XS1100 (does the G matter in this case?) isnt the same as a Mikuni XX that goes on a randomjapcycle XXXX. How do i pick out what to get? Is that why Mikes has kits AND specific individual parts?

bikerphil 08-13-2015 08:02 AM

You can always call them 'fuel taps' to avoid embarrassment. Don't want those girls to think you are talking about roosters, lol.

Yes, the year matters when obtaining carb parts, the 78-79 bikes use different carbs than the 80-81's do.

Prisoner6 08-13-2015 08:32 AM

OK, Rat -

So, you have a Standard ... which means you have vacuum-controlled petcocks instead of the Octy.

THIS is the kit you will need to rebuild those leaky petcocks:

2X Yamaha XS1100 Petcock Rebuild Kits

BUT, as mentioned, you also have one or more leaking float needles and/or seats ... so, you will need to service/rebuild your carbs as well.

You should be able to buy the needle/seat assemblies HERE:

JetsRUs

Someone here will be able to help you determine the correct needle/seats that you need for your G (later carbs).

And yes, concerning these carbs, always use Genuine Mikuni parts, especially when it comes to jetting.

puskrat 08-13-2015 08:39 AM

thank you phil. If that's the only difference I should be able to piece together what I need.

The rooster thing has a certain irony at that school: A rookie teacher, known for her, shall we say, "sociability" had the French Club T Shirts printed with a large black silhouette of a rooster. She said she loved hers so much, so thought everyone should have one.

puskrat 08-13-2015 03:58 PM

Downloaded a Service manual that appears to be a 78-79 edition but with supplements for 80-81. The carburetor section Charts an XS1100 E, F, and SF. The E uses a different starter jet than the other two. and the SF uses a different carb. I read (I believe on this forum) the E is the European designation for the G) Does this mean I need the BS34-11 2H7-00 carburetor and the No. 40 starter jet specced for the E?

Thanks again for everyone who's helping and not tripping the stumbling newb.

puskrat 08-13-2015 04:49 PM

Never mind.
 
My hardcopy Factory Svc Manual tells me other information. Glad I didn't follow that rabbit trail far from the monitor.


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