ACK!

Hi all. I recently bought a great '81 XJ 750 Seca that had sat. Spent hundreds getting carbs rebuilt by a yamaha dealer. Ran pretty good afterwords, I found that #2 cyl was running rich -- pulled plugs, cleaned and regapped, #1 and #2 esp 2 were fouled. 3 and 4 were perfect. Now getting a little fuel in oil again! I get spark on all cyl's, a few questions:

Can I evap any fuel out of oil by leaving cap off, esp when hot? It's not a lot but I know it's in there. I just don't want to go through the long wait of the small town yammy dealer and pay them hundreds for a couple small adjustments.

I've been reading your posts about the fuel screw on carbs, which screw do I adjust? I'd rather give a couple tiny twists to the 1 and 2 carbs.

I trust that the carbs are really rebuilt, it ran pretty good when I got it back, I could tell the left side wasn't running as good as the right side, and the #2 cyl esp was running soso.

Another q: What's the diff between car plug wires and motorcycle wires? Can I use car wires for the bike?

I feel weak asking these q's but you guys are so great. I hope some day to return the fav.

BTW, the other day, my oldest daughter (18) the difficult one, asked for a ride. I took her all over hell's half acre, on the way down the highway with her on the back I started into a wheelie (by mistake). She wants to take an ABATE course. SH**. That makes two of my four kids now with the bug. Wifey doesn't understand. The two do...

Hasta!

 

awesome........just teach em waht they need to know to survive it and u will be doing well. Gas in the oil........hmmmmm sounds like maybe a valve is slighlty burnt,or the rings are really shot. could be wrong hope it isnt. maybe check the compression with a tester after warm up. pour a teaspoon or 2 in each cylinder and recheck. if it goes up significantly its rings. if not probably valves. there may be a seal leaking somewhere maybe the really good tech guys can clue u in on that issue. but gas in the oil is usually through a component of compression.

 

I'm mildly surprised you found a dealer to work on it at all.

I've not heard of people doing such a thing; probably better to drain and refill the crankcase with fresh oil. Before you do that, however, it might be a good idea to find out why the gas is getting in the oil to begin with. Conventional wisdom says that running a gas/oil mixture will thin the oil to the point where it won't provide adequate lubrication to the crankshaft bearings.

To the best of my knowledge, there could be one or two likely culprits. First, is that the petcock might not be shutting off when it's supposed to, allowing gas to flow from the tank into the carbs. If the float levels are set correctly, then they might keep the crankcase from flooding. On the other hand, if the float levels are set too high, as I suspect they are, the needle valve isn't getting the chance to close fully or at all. Fuel then flows freely into the combustion chamber, past the piston rings and into the crankcase.

I'd check the float levels at the very least.

That I do not know; Chacal would be able to answer your question. Then again, he also sells plug wire.

Weak? On the contrary.

"The fool doth think himself wise, but the wise man knows himself to be a fool." -- As You Like It, Act V, Scene I

Sounds like you need to take the wife for a ride. :mrgreen:

 

The fuel in the oil combined with your rideability symptoms leads me to think float levels too, probably not all 4 carbs but that may be the culprit with 1 and 2 fouling.

At this point I think it's safe to assume the shop didn't get it 100% right and you're going to need to double-check their work.

Rather than just starting to crank screws, I would run through the carb adjustments in order. Check the float levels first, using the clear tube w/gas method. Then check the sync on the bench, reinstall and do a running vacuum sync, THEN you can tweak mixture screws (if necessary.)

 

Dig thru your receipts and see if you got new needle and seats.
You should be able to pull the front drain yourself, and re-fill.
Hey, what oil are ya runnin" ??

 

Automotive spark plug wire is usually resistive, where as motorcycle plug wire is non-resistive (the resistance in motorcycle circuits is built into the spark plug cap, rather than into the plug wire).

 

Welcome and be grateful. She wants to start off the right way, by taking a class. That, my friend, suggests she is highly intelligent and/or was led to this wisdom by a wise person (my assumption is you).
If you want to further your good feeling about the daughter's intelligence, look up the Hurt Study by Dr. Harry Hurt (no joke). Read the findings and notice how smart your daughter is.
Glad to have you aboard, now try and keep the front wheel on the ground eh? Especially with a passenger (that is how my father broke his neck, true story).

 

What you need is a repair manual (Haynes) or the XJ CD... practically everything you need to know is in those manuals....

The fuel air mix screw your are talking about is located on the top front of each carb. Stock setting for those screws is 2.5 turns out counter clockwise (after screwing then in clockwise all the way)...

Maybe someone can post a pic of the top of the carbs showing the fuel/air mix screw.

If you had a repair manual you would not have taken your carbs to the dealer, and probably would have done a much better job rebuilding / cleaning them.

Like mentioned the fuel bowl floats can be a problem and you can easily check their level with out taking them apart. At the bottom of each carb is a nipple that is opened by a screw that's right besides the nipple. Insert clear hose into the nipple, bend the hose up besides the carb, start the bike and open the screw to see how far the fuel goes up the hose. A good fuel bowl level is just below the float bowl mounting screws area (7/8th of the bowl should have fuel in it).

Also check if your fuel petcock is leaking by setting the flow of the fuel petcock to "ON" and taking off the fuel hose off the petcock, if there is no fuel leaking then your petcock is good.

Good Luck!

 

ask lots of questions on here. There is alot of people on here that know there xj bikes. No point In going to a stealer ship for them to fix your stuff

 

But he already has. And he paid for it. And it apparently wasn't done right.

You should have paid North of $300 to have the carbs done. If someone had $300 of my money and the job wasn't right I'd be back telling them to fix it.

 

true but if they really don't know what they're doing they will probably just continue to make matters worse. It already appears as though they don't have a clue...

 

I completely agree, take the carbs back and tell them that they are incorrect. I'd raise hell. there isn't a shop (not a stealership) in my area that wouldn't take so much pride in their work as to not redo the carbs, for free. Shop I use to work at did, actually, both shops did.