About Ready to Give Up......

[CMA1]

Hi all,
I do not give up easily, but I almost took the SF apart with a sledge this week!!!!

I have done all kinds of fixes and rebuilt according to the tips on this site. I have Searched the archives until I am 'computer blind' and still can't get this POS running right.

I studied all the carb threads and related items... this is what I have done...

Rebuilt carbs, floats at 25mm, new everything! I rejetted according to the guide with 142.5 mains (open MAC 4 into 1 header) INDY breathers (necks do not appear to block the orifices in the carb throats, they are EMGO)
Started on Sunday ... smoke (grey/white indicating rich)
Would idle for a few seconds, then die.
With throttle would rev (smoke like a bad BBQ) then an exhaust backfire as I let go of throttle and it would die. Starts again though.
The petcocks I replaced with Pingle Hi-Flow/and adapters. I plumbed the lines through filters with a 'balance tube between the lines.
Its getting fuel no problem and carbs are shutting off fuel as they are supposed to.
I can't keep the darn thing running though and the indicated rich symptoms are confusing me.
Question: should I put the mains back to 137.5 OE and try from there?
I put new plugs in and they are black... have new ones to go in again.
Everything else seems ok...coils, pickups and wires etc.
Have just about given up

Thanks in advance....
Larry

[TopCatGr58]

Hey there Larry,

I just read where someone stated that the EMGO were the ones that caused air flow restrictions. Try removing the filters and see how it runs, if better, then you know it IS the filters!

During the rebuild, did your carbs have that channel connecting the main to the pilot circuit? Did you put the rubber cap back on over the pilot jet in the bowl? If you do have that channel, and you don't have the pilot jet capped, you may be getting too much fuel thru the bowl, instead of thru the main/pilot jet supply tube?

What other fixes have you done? Ignition? Checked your vacuum advance? How about the carb slide diaphragms, any holes, are they sliding easily? Just some thoughts, ideas?
T.C.

[MartyA]

Couple of things come to mind:
Try lowering the level 1mm. Assuming everything is clean, no old gas, etc., it sounds rich. That backfire might be unburned gas igniting.

Try without those indy filters, just in case.

Worn needle.

Needle jets not round.

Turn mixture screw in 1/2 turn.

Stuck choke (enrichener).

How's the battery / coils / spark / timing?

Can you bypass the fuel filters, just in case? Thinking carbs are set too rich and you might also be runnng out of gas if the filters do not permit enough flow.

[2fast]

carbs

You could always do what I did. Send them to someone that knows XS carbs blindfolded. I sent mine to Merriam Cycle and they came back perfect with a static setup. All I had to do was sync em up which is pretty standard and easy. Best money I ever spent.

[tab1324]

I'm with you...

I keep nearing the point of giving up on mine too, but it's only April and prime riding season isn't quite here yet (at least in Minnesota).

Keep with it - I've been through my carbs 3-4 times now, still back-firing, and won't stay running. Mine looks rich in all but cylinder #3 which looks lean. From what you describe (white / grey) I would think that's a lean condition, not rich.

But I'm no mechanic.

Good luck, keep us informed.

Tom B.

[ratbyk]

Cone Filters

Larry, as TC suggested. Remove those cone filters and road test.
Mine ran like crap with them on. Away to rich, removed them and zoom zoom. Never put them on again. Shipped back and got my money back.
Ken/Sooke

[graybird78]

don't give up

hi to all.
don't give up yet.it took me three times to get my carbs right. did you all completely dissasemble the carbs. i mean everything. i did and was amazed at what crap i got out. must have spent one night soaking all those little jets.next i used lots of air to blow through all those passages.then spent way to much time getting floats adjusted.make sure each float is balanced or same height on each side mine were not. then i made sure each float moved freely found a couple that were hang up on brass inserts that float pins go through. then i made sure after float bowls on, floats were still working. blew with my mouth in fuel inlets to check flow. also tipped carbs upside down blow air again to make sure no air flow. haven't had any problems so far with carbs and 2 tanks off gas. alittle tip when reassembling ,use carb cleaner to assemble any o-rings so the seat properly.carb cleaner acts as a lubricant. also use on air cleaner boots to help with assembly. i also adjusted idle mix screws with bike running, to acheive best idle .had to reajust base idle to keep it low to hear idle adjustments. one last thing i did was adjust pickup coils to .008".that helped with starting and idle too. just don't give up. i know how frustrating it can get been there.take abreak have a beer or 2 have a smoke if so chose, then go back at it . sorry for the rant just trying to help. we are all rooting for you.and were here to help if we can.

[CMA1]

Thanks guys for all the suggestions and the encouragement.
This is just ticking me off! I have spent way too much money on this thing (like a lot of you I guess) and have only put a couple hundred kms on it (last year).
I used to work on car carbs exclusively when I was younger and I am pretty sure they are clean... went through them twice before I reassembled... they are clean. It's not like I am trying to rebuild a Space Shuttle here, they are only carburetors... right????

I have tried twice this morning to respond here to most of what you all wrote, but the website 'times out' on me before I can finish... LOL I am not real quick with the keyboard ....

So, as soon as I get a morning here that is not raining (I am working outside) I am going to pull the carbs, recheck floats, and jets and then try to restart without the EMGOs on there (I did try that on the weekend) again.

Thanks again, I'll let you know what happens for sure and what I find ... if it's obvious .

- Travel safe, Larry (the sledge is right beside the bike !!!)

[Hepcat]

Just be careful to read the directions before you go putting carb cleaner on the rubber. I know at least one of my cans of carb cleaner says to remove all plastic and rubber as it will dissolve it. It makes o-rings gummy if soaked...personal experience. I wouldn't hesitate to use something like WD-40, silicone spray, or penetrating oil or something that won't degrade the rubber.

[Yamhammer]

If you rebuilt carbs using K&L (I think) kits check pilot jets,they put wrong size in kits. I went through same thing.

[skids]

I don't have experience with the emgo cones, but I know that people have had problems with flooding while running and with over-richness when the breather tubes are not venting the bowls. I think the vent tubes (78 and 79 carbs) normally pull a slight vacuum, above the gasoline surface in the bowls, when the tubes are hooked to a stock airbox. If you have plugged them off you will have big trouble.

The other thing to check is the condition of the pipes. Pull off the heat shields near the foot pegs and check for cracked welds. Jetting changes will not help a crapped-out exhaust system. Bad baffles can also have bad effects on engine effeciency.

If your plug fouling is occurring in the low rpm band: Did you use the original pilot jets? Aftermarket jets run WAY richer (depending on the make, I am sure). Using bigger mains in a 79 will cause more fuel to enter the pilot circuit as well, and I have seen this first-hand with a colortune. In fact, screwing the pilot screws almost all the way in was necessary to keep it from being too rich! You may want to try one size smaller with the genuine Micuni pilot jets and see how she does. I really think that the cones would mostly affect the mid to high rpm ranges of leanness because of the way resistance is porportional to air velocity.

If your fouling is occurring at the higher rpm ranges, one thing to make sure of is that that pressed-in main air jet is clean. It is pretty tiny. That is the one that allows air to enter the sides of "emulsion tubes" (your main jets screw into those). If it gets plugged, that emulsion tube will draw fuel at a higher rate.

[strom]

2 years and 2000$ poorer I now have a remote chance of maybe getting the bike legal, if everything works.
I know the sledge feeling.
How are your cams?
TCI?
Pick-ups and wires?
Mine didn't start without air filter.... had to put on cone filters or airbox. But my cam timing was messed up then.

LP

[DEmily]

CMA1,

Just about everything the other guys are speaking to, I went through with my 79 SF. I have been to the sledge level and back several times. I experienced the flooding and popping back as you have. I had the after market main jets which cause some of my problem. I replace them with the original jets and it seemed to do better. The next thing was the hoses that use to go to the breather. I put on the cone filters and pluged up those hoses. After unplugging them, it made a world of difference. However, when under load it would begin to load up rich again. I them cehcked my coils and found that they were not firing correctly all the time and were much weaker than they should have been. I replaced the coils and bingo! Like a new bike! About made me pee on my self when the bike took off down the highway!!
I am still dealing with an oil leak, but these guys helped me a ton and they know their stuff. Don't give up, the bike is seriously worth the time and money once you get her right.

Good luck
Dan:

[Mike Hart]

EMGO is the correct cone

the EMGO cones are the right ones (if they fit! they come in different sizes). There is some other brand that Ratbyk had that interfered with air passages. Anyway, EMGO work just fine.

[CMA1]

This picture won't likely last long as it is hosted from eBay (if it will post here at all) it is the bases of the K&N individual breathers... they look like the EMGOs where they mount to the carb throat...

I bought the EMGOs after reading Mikes "Mother-of-all-threads" on replumbing and jetting the XJ.
I will be trying the restart, today or tomorrow after I gop through the carbs. I did use the dreaded K&L kits before but I bought all new Mikuni jets and hardware. The only thing different was the pilot screws. 3 Of mine were broken... soi filed the ones from the K&L kits (because they were too pointy and different pitch!) maybe that is part of the problem (?)????
Which rebuild kits are recommended by the group if I go that route again???
Thanks again
Larry