How I shot myself in the foot on Fathers Day....

[Ken Talbot]

The octopus is a vacuum controlled on/off fuel control. The float valves, OTOH, regulate the flow of fuel into the float bowls. Flooding and fouled plugs can hap[pen if the float valves are not working properly, if the floats are set too high in the bowls, and if the main jets have been replaced with aftermarket units that are too large. When the octopus is working, it shuts off the flow of fuel when there is no engine vacuum and lets you not worry about turning petcocks on or off.

[manshack_one]

Ken, are you saying that it's ok to run the bike in prime all the time as long as you remember to turn off the petcocks?

[DiverRay]

IF the carbs are good, you can run on prime. I would NOT do that, as you are pulling from the bottom of the tank all the time, and tend to get more dirt into the system. Do a search on the "octopus", and you should be able to find the thread with the diagram on how to bypass the octopus.
I think you DO need to look at the needle/seat on ALL the carbs, and reset the float level a little higher, to about 27mm.

[manshack_one]

Well, I'd like for this bike to go back to as original a working order as possible so I found the routing diagram and just need to find some tubing to hook everything back up.

Does anyone know off the top of their heads what size the little float drain plug bolt is? Either I didn't have the right size wrench or I was cranking it the wrong way.

Also, when I pulled the plugs out they smell awful. I think the gas that flooded them out sat in there a long time. How do I go about de-gunking the cylinders?

[DiverRay]

The plugs on the bottom of the carbs are 8mm. The fuel line is 1/4", but it needs to be thin walled. IF you have a local auto parts store that has VW fuel line, it should work fine. I think the ID is about 6.5mm. I would drain the fuel, put in fresh HI TEST, about 2 gallons, and one can (pint) of Seafoam or Berrymans B12 chemtool.
You WILL need to pull the carbs off the bike and clean them. DO NOT try to skip this step, as it will cost you time and money in the long run. You should NOT need any parts, unless the needle and seats are worn. Check the "tech tips" from the MAIN PAGE, and print them out to follow.
You WILL need to know what year the carbs are off, as the '79 has a screw in seat, and the 80 has a push in seat. The 80 seat has an "O" ring, and it probably needs to be replaced if that is what you have. You can tell because the 79 has a 10mm nut that you turn to remove the seat, and the 80 has a metal "clamp" that holds the seat down with a screw.
If you need help, try and see if soimeone is close, offer beer, and they can probably give you a hand.

[manshack_one]

Great Idea.


FREE BEER and BBQ plate for anyone willing to help a new rider get his used bike up and running! I've got this weekend pretty much open but the one after is booked solid with my third child on the way the morning of the 20th.

Until then I'll keep pulling parts off the bike and inspecting them and reporting back.

[manshack_one]

Found out this afternoon when talking to a friend that I was checking for spark the wrong way. I'm a visual learner and it's not that you guys aren't helping me, it's just sometimes I need a picture. I'll recheck for spark tonight and report back. If that's working I'll move on to Air and Fuel.

[TopCatGr58]

Hey Manshack,

From what I can see of your carb photos, it looks like you have the 79 series carbs, I can see 2 sets of hoses going to the intake side of the right pair of carbs, the UPPER "T" fittings are the bowl vents, they need to be checked to ensure that AIR passed easily thru the "T" AND the hose connected to it, and the fittings on the airbox are also clear! IF CLOGGED, that alone will cause the carbs to start puking gas!!!

Secondly, the PO/mechanic "may" have bypassed the Octy because it wasn't working properly.....but could also have been because they didn't fully understand how it worked, ensuring that the vacuum hose that opens the valve is good, no leaks, and that the diaphragm inside is moving freely and not stuck/corroded! SO...before you decide to use the Octy, you will want to do some tests to see IF it's even working right. You can apparently get rebuild kits for it, but many folks just bypass it, just remembering to turn off the petcocks! I've run mine on Prime for the past 6 years, but this was AFTER I had cleaned and relined my tank, so running from the bottom(with inline filters) doesnt' worry me, and actually keeps the gunk from building up!

As has been said, the 79 uses the solid metal float valves, but they can still get a ridge worn in the tip, folks have commented about polishing them, etc., but it's best to get new ones from MikesXS fairly cheaply!

And, yes, face the fact that you will need to remove the carbs and take them apart to properly clean them to have a decent chance at good performance without other tuning problems! They are not as hard as some have made them out to be! I haven't looked at mapquest yet....folks know how good my geographic skills are , but there are a fair number of folks in Texas, but it IS a big place, hope you're near some of them, check out the Member's Forum searching for thread using "members Texas", and you'll find a list of who and where!
T.C.

[manshack_one]

Ok, I got this far tonight:



Another look:




I kind of winged it and unhooked the airbox so it would slide back, then loosened up the clamps on the cylinders side, then just wiggled it out and unhooked the throttle cable when it was out enough. I have no idea what I'm looking at but have a parts list so I can match up what you guys say with what I see. I did check the airbox and there was no fuel in it, nor was there any junk in the float bowls. I do have one float bowl drain bolt that is now stripped (how can you forget something like lefty-loosey/righty tighty?) and will not come off. I also pulled all the spark plugs out and man do they smell foul (pun intended). How do I clean those cylinders out (without dismantling the engine)? I'll have to buy some new plugs because these have a good thick layer of black stuff and I don't think they would fire.

One other question, the ignition wires are running to what I'm guessing is the coils, and if the cylinders are (left to right) in order from 1 to 4, then does the coil on the left fire 1 and 3 while the other one fires 2 and 4? Makes sense in my head but I want to be sure. Thanks again.

[Ken Talbot]

[i]does the coil on the left fire 1 and 3 while the other one fires 2 and 4? Makes sense in my head but I want to be sure. [/B]

Uh, no. One coil fires #1 and #4. The other coil fires #2 and #3.

[manshack_one]

So, as you ride the bike, the coil on the left fires 1 and 4 and the coil on the right fires 2 and 3? Does it matter which connector on the coil 1 and 4 or 2 and 3 are hooked up to?

[Bud Manley]

Your posting gave me the urge to clean the crap out of 1/2 my garage and pull the XS in from the barn. Tommorow I'll start on the brake system and look into my own ignition problems. I'll have to build a carb cleaning bench too.
Good luck.

[manshack_one]

Glad I'm helping! Be sure to take pictures to help us visual learners out here while you're working. Best of luck!

[mro]

Just a note.....

The fuel bowls....
Yamaha has different part numbers for em.
Looking can see no difference but could be related to the jet in the passage way in the bowl.
Would not hurt to try to keep each bowl with the carb it came off of........
asumming that a PO has not already got em mixed up


mro

[TopCatGr58]

Hey Manshack,

Normally you would clean the cylinders out when you get the bike running, just burning the carbon out with it running! BUT, if you haven't drained the oil yet, then you could put some Mystery Marvel Oil down into the spark plug holes, and SLOWLY crank the engine over by hand a few times and let it sit there a day or so! MMO is a good solvent that can remove lots of varnish/gum from the cylinder and the piston rings...in case they are stuck!

Then drain the oil cause the MMO can and probably will slip past the rings and get down into the oil. You'll want to put fresh oil in it anyways, cause old oil acidizes as it sits once it's been run in an engine!

Hope you've read the tech tips about the carbs, the special technique for removing the float pin WITHOUT breaking the float posts! There are photos there IIRC that can tell you what the different removable parts are. Save these photos, so when you get new bowl gaskets, you can match up the holes. Note the hole/tube in the float bowl, make sure it's clear and cleaner can spritz down thru it and come out the in the bowl!

In your first pix, on the fuel hose, I see a brass nipple, did that come off of the petcock? IF so, folks have reported being able to just tap it back in, but you might want to put a dab of JB weld around the outside of it before tapping it in to help reglue it in place!?

Make sure you have a nice variety of sizes of screwdrivers, you'll want one that snugly fits the pilot jet in it's tower farthest away from the float pin. The tower is capped with a screw! The other screw on the tower closest to the float IS the main jet! There's a washer under it, and then the brass main nozzle/needle jet emulsifier tube that slides UP THRU the TOP of the carb, NOT out the bottom! Yes, you need to take the tops off, notate the springs, inspect the rubber diaphragm for pinholes, and place in a safe place, do not clean with carb cleaner on the rubber!!! Best to remove the floats FIRST before flipping the carbs back over to remove the tops!

Under the float is the float needle valve that sits in the valve needle Seat! You unscrew the seat, and there is a screen on the bottom, it's delicate, will pop off for cleaning! Soak ALL JETS, Nozzles, and other solid metal parts in cleaner if you have it!

After soaking and cleaning the floats, put them in ALMOST BOILING water, and have something that you can use to push them down under the water and check for air bubbles=leaks! No leaks, then good to go!

Don't separate the carbs from the rack. Check the fuel and vent T's with carb cleaner to make sure they are flowing freely! You can use WD 40 on the fuel "T" on the outside where it fits into the carbs to lubricate it so you can pivot it up and down to see if it still fits snugly. IF loose or wobbly, then the outer rubber portion may have dry rotted, and broken off? THEN you would need to pull the outer carb from the rack to remove and replace or fix the "T" fitting!
I'll stop now, there's more, write back if you get stuck!
T.C.