Fuel in crankcase?

[Prisoner6]

Yamaha used the letters E through H to designate model years 1978 through 1981, respectively.

So, an XS1100E is a 1978 Standard. They added the 'S' to the model year letter to indicate a Special, i.e. SF, SG, SH ...

HERE is a jetting guide for the XS11:

Carburetor Facts - Models and Jetting

As Phil mentioned ... basically there are 2 different types of carbs used on these bikes ... '78-'79 and '80-'81.

Depending on what year carbs you have, and whether your bike is Standard or Special, there are subtle differences between each year, even within the 2 basic types.

I'm assuming your carbs are indeed '80G carbs, and haven't been swapped out for different ones.

There's a lot of 'swapping of parts' that goes on with these bikes, from tanks to seats to carbs to final drives to ... you name it.

[puskrat]

re: swapping of parts.

I was informed/warned about that. I got a lot of spare parts, which at first made me think "well he picked out only the right stuff for the machine", but now makes me wonder if he just tossed everything in their. guess I need to start IDing years models and carb bodies (among other) going back to the jetting resources for now. thanks everyone, have a great weekend, and be safe

[Prisoner6]

Hey, Rat ...

You can easily find out exactly which carbs you have ... look HERE:

Carb Identifier Guide

And HERE is a guide to the serial #'s and model ID's for our bikes:

Serial Numbers/Model Designations/Factory Colors

[puskrat]

Again, thank you, gentlemen. Tomorrow is my day off (aka shop day), and I plan to pull the carbs and diag the petcocks (I guess I know one is bad and need to know which) Printing the carb identifier, the rebuild tutorial, and the jet identifier to take with me. (wi fi doesnt reach to the garage, ugh)

[MPittma100]

Again, thank you, gentlemen. Tomorrow is my day off (aka shop day), and I plan to pull the carbs and diag the petcocks (I guess I know one is bad and need to know which) Printing the carb identifier, the rebuild tutorial, and the jet identifier to take with me. (wi fi doesnt reach to the garage, ugh)

The fuel getting into the oil gets there when a carburetor float valve is leaking. If a petcock is also leaking, that much more fuel gets into the oil. You need to verify which carb(s) is leaking. Make that repair. You should rebuild both petcocks regardless. If you have not rebuilt any of these fuel system parts before on this bike, it is time to do all of them. Do not leave ethanol fuel in the bike after rebuild for any length of time.

[puskrat]

on the stump

hate to be soapboxy, but I hope to not allow any ethanol in my tank period.

[puskrat]

Because it simply is not allowed to be easy

after looking into some oddball stuff, I found out from the PO my carbs have been swapped for 1978/79 models. Before you can do anything, you always have to do something else.


edit because reasons

[MPittma100]

Older Carbs

after looking into some oddball stuff, I found out from the PO my carbs have been swapped for 1978/79 models. Before you can do anything, you always have to do something else.


edit because reasons

No matter which year carbs you have. They all can eventually leak if not maintained properly. Sitting for years, ethanol gas, not so good PO rebuilds all contribute to failure. Get the right Mikuni parts and have at it.

[puskrat]

and so it goes

Guys....I'm about to get into the carbs......

I've 79 carbs on a 1980 G. Standard bike. My thoughts: the 79 carbs are jetted differently than the 80's. What changed to require the revision? How should I jet my 1979 carbs on my 1980 bike? Any other settings I need to be especially sensitive about? Should I just chip and melt and carbs that are on it and rebuild the "extra" 1980 units I got in my spare parts bonus bins?

[dbeardslee]

Guys....I'm about to get into the carbs......

I've 79 carbs on a 1980 G. Standard bike. My thoughts: the 79 carbs are jetted differently than the 80's. What changed to require the revision? How should I jet my 1979 carbs on my 1980 bike? Any other settings I need to be especially sensitive about? Should I just chip and melt and carbs that are on it and rebuild the "extra" 1980 units I got in my spare parts bonus bins?

My brother has an 80G with 78/79 carbs, and they work just fine. On the 78/79 carbs the pilot tower is plugged, and the pilots draw their fuel up through the main jet tower via a little cross shaft. On the 80/81's there's no plug on the pilot jet tower, so the pilots draw their gas directly from the bowl, hence the different main jet size. And the 80/81's had plastic floats while the 78/79's have brass. Never, ever put compressed air on the fuel or vent lines on the 78/79's while the bowls are in place, thinking that you're going to blow out the system. You'll crush the brass floats almost instantly.

Personally I like the 78/79 carbs better, but you do have to be more careful with the mixture screws. Never, ever screw those mixture screws down tight or you run the risk of breaking off a tip, and they're REAL boogers to get out once they've snapped off. The 80/81 mixture screws are usually capped, and you have to get the caps off before you can do anything with 'em. You also need a smaller screwdriver to get down in there to adjust the mixtures once you've got the caps off. Mixture screws on the 78/79's are exposed, and much easier to get at.

The way you need to jet those carbs depends on your intake and exhaust. How's your bike setup? Stock air box or pods? Stock exhaust, 4/2, or 4/1?

[motoman]

As usual, didn't read over the previous postings, so here goes. Actually FOUR types of carbs used on the XS11's. 78 had one type, 79-8-82XJ's had four type. Differences from 79-82 ARE: Standards had different jetting than Specials due to metering rod differences which required differences in main jetting. XJs had AGAIN differnt metering rods which required even diferent main jetting. Hope that made sense to those questioning. 81-82 had different float bowls with the drain seat screws on sides od bowls. This REQUIRED fuel levlels to be checked while idleing using a clear hose from bottom drains swung up beside tops of carbs. So, lots of differences there between year models and Special and Standard models. Do NOT confuse the jetting depending on yr. model of carbies.

[DiverRay]

OK here is what should work, and what you will need.
1. Do ONE carb at a time. You can pull the top and float bowls, but keep everything together so the parts go back into the carbs they came out of.
2. 4 new seats/needles from Mikuni source, USE ONLY MIKUNI!!!
3. If bad, replacement bowl gasket.
4. Probably need new jets, as I'll guess replacements are aftermarket. Go with stock jets for a '79 standard IF the jets in the carbs do NOT have the mikuni mark.
5. CLEAN everything, but DO NOT put carb bodies into a tank of carb cleaner! I use an ultrasonic cleaner with pinesol and water mix. Cleans everything pretty well.
6. Measure twice on the float levels, and both floats.
7. LIGHTLY seat the idle mixture screw! Use the screwdriver shaft to turn the screw so you don't overtighten it, then back it out 2 turns to start with.
8. Bench sync carbs
9. Bench test floats! put a fuel tank above the carbs, and make sure they don't leak. Leave it for about 1/2 hour, in case you have a float with a pin hole. BTDT

[puskrat]

and I shall.....

compiling the feedback....

Only recommendation I see on 79 v 80 carb bodies says go with 79s, even if it's not a strenuous opinion.

The jets are different because the system is different. That makes good sense to me. I'll inspect the bodies to be sure I'm in the right ones at the right time. Just need to make sure the number one is on cyl one, etc.

cleaning with pine sol; check

no compressed air through attached hoses. check

mikuni parts. recheck

one unit at a time. check.

I'm going to avoid ethanol like the proverbial plague (ethanol is theft - a dangerous thing to say in Illinois). BUT....if I'm out on the road and have to, I have to. Are there ethanol-safe O-rings That could be installed? Speculation has arisen my carbs may have in fact been rebuilt and then E90 sitting in the system caused the leakes.

[DiverRay]

Just do NOT put in E90!! The "normal" fuel here is 10 to 15% E, and my bikes run OK on it. I would NOT put E90 into anything except a race engine that was set up for it. You should not need any special seals, as the biggest problem from the fuel is it will eat the carb bodies if left too long.

[dbeardslee]

I'll add something on gas. The non-ethanol stuff I've heard of seems to be premium, which I assume is the 91-92 octane variety. There seems to be a lot of confusion when it comes to octane rating, and lots of folks seem to think higher octane means more explosive gas. In actual fact the octane rating is a measure of the compressibility of the gas, and unless you've got a high compression motor high octane generally causes more problems than it solves. It tends to gum stuff up. I run the lowest octane I can without getting pre-ignition, and for my 79F that's 87 octane. I've been running it with 10% ethanol since I bought Betsy in 2007, and haven't had any problems with it.

But if I could find non ethanol gas in 87 octane I'd be on it like a monkey on a cupcake. The information I've seen on gasahol seems to be that you can expect about 10% worse mileage with 10% ethanol than straight gas. Which seems wierd considering the powers that be would like us to believe it's making the gas go farther. Looks to me like we're just paying more for less.