Engine overheating revisited, 79 special

[rob carroll]

I've started a new thread thinking once the thread has left the first page it may slip into an orwellian memory hole. I'd like to follow up on the good advice given and let you all know I don't take for granted the time and thought youv'e shared.

I've been unable to comunicate in real time and just as well because I probably wouldn,t think of the right questions fast enough. I've actually very limited time and little access to the computer in the motel lobby. Hell, I don't even have a computer and used my Son's e-mail address to gain this forum. I'm sure glad I did though. It's been very interesting and informative to watch the development of this thread. XS11 is a great concept and a stroke of genius. I'm indebted to the originators, facilitators and participants.

The following is a list of questions which your advice has generated. I'm looking forward to clarification from anyone so willing.

1. If a pilot screw tip were lodged in the carburator would it be immpossible for that cylinder to fire at idle to 3500 rpm?

2. If too lean a pilot circuit mixture is capable of fouling a spark plug in a short while does that mean the spark plug is permanently disabled; or does it mean the plug can't fire properly until the mixture is corrected?

3. If you use a shorter and reshaped pilot screw that must be compensated for with a lighter adjustment how do you get it right without fouling the plug again?

4. Should a good gas tank cleaning leave the inside of the tank spotless?

5. Are inline gas filters superior to intank filters?

6. What kind of damage can running lean or running rich do to the 1100?

7. Are there superior grades of gas and vacuum lines to others?

8. How many miles can I expect between fuelups on the 79 special?

9. Approximately how many miles can I expect with the reserve portion of the special tank. (bike is stock)

10. The speedometer on my 79 special sticks at random mph. the odometer works fine. Iv'e replaced the cable but nothing has changed. I read a post about carefully lubricating some small bearings in the guage itself. What would be the best lubricant and is there other probabilities for this condition?

11. The oil indicator light remains on all the time. The oil pressure is fine and the sending unit supposedly tested fine. What else may cause this?

12. The tachometer is jumpy. Is this normal?

13. The plastic electric start button is missing on the 79 special. There is still a spring in the botton housing. I can use a paper clip to depress the spring and start the bike. Does anyone know where I can find any! button to replace it with?

14. I have an emergency kick start that doesn't fold back. Can I purchase a folding kick starter that fits this bike?

15. Is the 79 special a dependable bike or is it overly tempermental?

Topcat,

Yes it's been along time since Iv'e ridden a bike but Iv'e many years experience. My son has 3 years experience. I'm looking forward to the ride home. We will be trading off between car and bike. Don't worry we will be ever present; I know how dangerous any ride can be. By the way I gave the mechanic a service manual disc to work on the bike. Also I do have the original tool kit . I want to thank you for your attention. youv'e been great.

GNEPIG,

Thanks for your thread killer post. You put it all together for me. When I get a chance I'll post a bit about the journey home.

Thanks to all

Rob Carroll

[egsols]

2. Usually rich fouls plugs

3. Its all about adjusting and readjusting

4.Yes

5. Use both.

6. Lean worse when running.

7. Yes, go to a good bike shop for real fuel lines. Cheaper ones can break down and send carp into the carbs.

8. Depends on how you ride, 100 miles usually on a special tank.

9. Don't recall, I like to fill up before its too late.

10. Light oil, 3in1, for bushings not WD40, light grease on gears.

11. Oil light also used as tail light warning. Check tail light, if its not working that's your problem, could also be bad ground to tail light or rewired brake like circuit.

12. Only on the ones that are going.

13. Search this forum I think MikesXS has them.

14. Not aware, but would be cool.

15. The 79 Special, IMHO, is the best bike ever made, reliable, fast, good looking, kinda reminds me of me, but seriously if taken care and respected it will not let you down. I think the existence of this forum provides the proof!

16. Take my advice with a grain of salt, I'm not a guru and there is an abundance of XSelent info on this site, so search away.

[psycoreefer]

I've read in searches that the folding kickstart lever off of an xs750 or xs850 fits well, but you will need to grind a little of the kick start shaft that sticks out of the side cover to make it fit, because a bolt goes through just like on the brake and shift levers to hold it on.

Also, the oil light on my special comes on at random. Everytime I check the sender seems fine. My best guess is that I've got a wire somewhere that sometimes grounds against the frame making the light come on. One thing you can try is replacing the tail light bulb even if it looks good and works. They are cheap and it could be a "almost" bad bulb.

[boyat68]

Rob:

"1. If a pilot screw tip were lodged in the carburator would it be immpossible for that cylinder to fire at idle to 3500 rpm?"

Taking a WAG at this; (I have never had a screw tip lodged) I would suspect that the cylinder would fire as there is air being sucked in as well as some fuel from the pilot jet. However the balance would not be able to be set in relation to the other carburetors. This screw opens the plenum to atmospheric air.

[prometheus578]

"A few more answers."

Lodged needle tip: No fuel at idle. (It escapes me now at what RPM the transitional ports come into play.)

Rich, not lean, causes fouling. Depending upon why a plug is fouling... and how badly. If a plug is fouling at idle, at higher RPM with a correct mixture, the fouling can be burnt off. (I wouldn't rely on this always happening.)

Idle mixture screw is a precision fit. I doubt one could grind a new tip on it with any accuracy where it wouldn't allow too much fuel to get past. Should be replaced.

Fuel filters: Oft times, people sticking siphon hoses and such in the tank knock off the "tower" filters, allowing rust and crap into the petcocks, etc. Use both types of filters.

No damage from running rich, other than carbon build up.
Running lean can burn holes in the tops of pistons. If this question is in regards to the cylinder with the idle mixture tip lodged in the hole...You're not really lean... you have no fuel going in there at all. But even so... as it's only at idle, I wouldn't worry about it too much. You don't spend as much time at idle, as you would at high temp-high speeds where lean conditions would really hurt. It still needs to get fixed.

Fuel Line: Reinforced rubber seems to be stock. Reinforced Nitrile is better. Tygon is better. Automotive vacuum line (used for fuel line) is useless.

Speedo lube: Disassemble and lube. Don't just pop open the back and stick the straw from a spray lube in there and start blasting. You'll get lube on the inner face of the glass.

Oil Light: I don't believe this model had the oil light/brake light set up. I really don't think that it's practical to test oil sending units directly. When there's no pressure, the light is on. When there is pressure, a diaphram moves and an electrical connection is broken in the sending unit and the light goes out. Thesending unit provides the ground for the circuit. If one disconnects the sending unit, you've taken away the ground and the light should go out. If it doesn't.. then inspect the wiring... you're getting a ground from somewhere else.

Tachometer gets it's juice from the charging system. Now, assuming that the inside of the tach isn't gummed up and sticking, this indicates a charging issue. Maybe not a charging issue, but a connector issue. Check all wiring involved. Check for fuses and connections. Check all grounds. Fuses can look good, but after all these years can be bad. Pull all fuses... sometimes the metal caps on the ends have come loose and are faulty. Radical drains on a weak system due to bad wires, faulty grounds, etc can cause erratic tach swings. (My tach used to swing wildly and then die when I used my left turn signal)

Do a search for starter button, etc. Someone found a source. I used the horn's button till I found a replacement. ( I swapped buttons... not "tried to start the bike by honking the horn". Geez, some people!)

Our kick start levers aren't supposed to fold. They are not to be stuck on the outside of the bike. To the left of the oil filler cap, you hopefully should see a large wing nut. The kick start lever is stored behind the engine, held by the wingnut, and only brought out when needed.

As dependable as all the rest... meaning.. very dependable.

[trbig]

Just to add my 2 cents on a few of these...

#2. I don't exactly know what happens to a fouled plug. (I realize it carbons up) Years back, a buddy and I both had Yamaha dirt bikes. His was a 460, mine was a 250. If his ever fouled a plug, it wouldn't ever work again for his bike even after sanding/wirebrushing/sandblasting... but it would work in mine. So???? Something was happening to it.

#5. Inline filters are just an added measure. These carbs can get pretty unhappy when they start ingesting little bits of sediment or rust. While the in-tank filters should deal with this for the most part, those filters go bad and crack and break over the years. Being inside the tank, it's not something you would normally see. If a small piece of this screen were to break off and lodge at the narrower openings such as a float valve... then the carbs overflow. Hopefully the XS fuel would come out the air filter... but it may get dumped into your oil.. washing the bearings out and ruining the motor. Maybe it just clocgs one of the jets. Either way, it's carbs off for cleaning time. Inline filters are pretty cheap insurance to keep these "bits" out.

#6. Running rich will carbon things up and get poor mileage. Lean conditions make things run way too hot, making pipes blue, and possibly getting the combustion chamber too hot to where it starts pre-detonating the fuel. It's just generally too hard on the longevity of these motors. They like a SLIGHTLY rich condition to run best.

#13. Partsnmore.com has those starter buttons, but there's a minimum $35 order.

#15. While many of the bikes from this era were wore out at 50k miles, MANY members report having over 100k and a few with even 200k+ on the motors. There's not too many bikes made even today that could say the same. It is an old carb operated machine though. It will require some tinkering to keep running right. With proper storage in the winter, this will help considerably. If you don't mind spending an evening messing with the carbs, tightening up a loose bolt, adjusting a cam chain, or minor things like that occasionally.. then you will be very happy with your choice. If you are looking for a bike that you can just ride and put away and never do anything to... the XS might not be your best choice.


Tod