New to the Forum

[SouthernGrey64]

I just recently joined XS11.com (this is my first post) but I feel like I know a lot of you just from reading your posts over the last 11 months. Before I begin I want to say thanks to all of you for the enormous amount of help you have provided!

I am the original owner—bought the bike new in January 1980 from the Yamaha/Harley Dealer in Chattanooga. Rode it until 1993 (that was the last tag date-10,570 miles) where it sat in my basement with a half tank of gas until August of 2015 when I began restoring it. The bike is in pretty good shape since it was not exposed to the outdoors. With the information gleaned from this forum and bunch of money, I was able to complete (well almost complete) the restoration mid-May 2016 and ride it for the first time in 23 years.

Here are the things that I did in the restoration:
• Rebuilt both front and rear brake master cylinders and calipers (S/S pistons)
• Replaced brake hoses with S/S braided
• Replaced tires with Dunlop Elite 3 Bias Touring (MM90-19 on front anMT90-16 on rear)
• Replaced handlebar grips
• Removed rust from tank using Evaporust
• Rebuilt the petcocks and replaced filter towers (original filter mesh fell apart in my hands)
• Rebuilt the octy
• Replaced fuel lines with clear Tygon LP-1200
• Installed 2 in-line fuel filters
• Replaced vacuum lines and vacuum boot caps
• Checked valve clearance and corrected two valves that were out of spec
• Replaced battery with Sealed Lead Acid (AGM) type (22Ah, 350 CCA)
• Checked out ignition coils—primary and secondary resistances within specs
• Checked pickup coil wires for breaks with DMM–resistance checked out OK even wiggling the wires
• Checked the TCU for voltages—checked out OK
• Cleaned all of the electrical connections (fuse clips still tight in Fuse Panel-will replace it later)
• Replaced spark plug caps with LB05F and XB05F NGK caps
• Cleaned carburetors and reset float levels using clear tube method
The carbs were a mess but after triple cleaning them (installing and removing 3 times) got all four cylinders to fire. Diaphragms had no pinholes and were reusable.
• Set idle
• Synchronized carburetors with Morgan Carbtune Pro

I met up with my best friend at my 55th High School Reunion last October (2015). He has been riding his bike ever since he returned from Viet Nam. I told him I was restoring my bike and he invited me to go on a trip with him and some of his friend in the spring of 2016. We had planned to ride up to the Blue Ridge Parkway the day after Memorial Day.

I was all excited about going and then just a few days before the trip I was out on a local ride and the bike quit on me about 20 miles from home. It lost power (felt like it dropped a cylinder or two), began backfiring, and when I pull into a side street it just quit. I was able to restart it and it rode just fine for about 15 more miles and did the same thing again. I restarted it and got it home OK. I had to back out of the trip as I didn’t want to get hundreds of mile away from home with an unreliable bike. There will be other rides once I figure out what’s going on. Unfortunately, I won’t be able to work on it for a while as other duties call.

When I do get back to working on it, I will recheck the pickup coil resistances, TCU voltages, and ignition coils with my DMM. The only item I haven’t checked is the spark plug wire itself. That could be causing the dropping of cylinders. Need to look at it at night to see if there are any sparks. Any other suggestions would be appreciated.

[kboehringer]

Welcome SouthernGrey

Welcome Georgian.....

There are more than a handful of members on XS11.com from your neck of the woods.... I'm just south in PTC.

You might want to consider trying to make the XSSE event. Lodging at the Iron Horse may be unavailable but there is lodging close by at a number of other places. Heck of a great time and several of us will likely be riding our 11's together. Assuming we can keep up with Jeff & Marty.

[SouthernGrey64]

Correct Float Level with Clear Tube Method

Thanks Kurt for the invite to XSSE but as you can see I have a gremlin or two to work out before going on a long trip. Would love to go if I can just get the bike running with some confidence.

I do have a question about the float level on a 79SF. I am not sure I have set it correctly. I made a set of barbed drain plugs and set the float level by the clear tube method at the base of the washer on the float bowl. This is the correct level on an '80 model with plastic float but is it also the correct setting for a '79 with brass floats? I couldn't find confirmation on this anywhere.

[Radioguylogs]

Pick-ups are a frequent offender

Seem you already considered that misfiring problem could be the pick-up coil wires under the LH aluminum engine cover (where it says "Yamaha")

It's a common problem, especially on pre-1980 bikes.

My SF had that problem when I bought it.

You can measure the resistance at the connector near the fuse panel (looking for 720 Ohms), and/or you can easily pull the cover and put tension on the wires. They will stretch into an hourglass shape if the inner conductor has broken.

The kill switch is another common problem, but all of the cylinders would die at once; unlike your symptoms.

Seems you already know your way around -good luck.

-Mike

[Prisoner6]

... I do have a question about the float level on a 79SF. I am not sure I have set it correctly. I made a set of barbed drain plugs and set the float level by the clear tube method at the base of the washer on the float bowl. This is the correct level on an '80 model with plastic float but is it also the correct setting for a '79 with brass floats? I couldn't find confirmation on this anywhere.

It certainly sounds like the bike's been keeping you busy!

Specified float height for '79SF is 25.7 mm
Specified float height for '80SG (or '80G, for that matter) is 23 mm ...

And that is measured with no gasket in place.

Do you have a manual? If not, you can go to the following link to download the manual ... it's free!

Look in the "Resources for riders" section on the right side of the page:

Ringler

WELCOME to the XS11 Forums!

[mack]

Gas Cap

The tank is vented through the gas cap. Take it for a ride with the gas cap unlocked and just sitting closed. See if it stumbles and quits again. You may need to clean the vent.

[jetmechmarty]

I'm not far away.(Dahlonega) This shouldn't be that big a deal. I'm sure we can get that thing ready for XSSE.

By the way, folks, the Ironhorse has plenty of space. Just bring your tent and sleeping bag. I went to the Moto Guzzi rally last month and they had about 75 tents set up.

If that bike spent that many years in the basement, the fuel cap is a likely suspect. The filter is rotted and if the rubber seal isn't cracked, the tank won't vent. Both my XS650 and XS1100 Specials suffered this problem.

Consider sending me a PM. We'll exchange info and get this thing going.

[SouthernGrey64]

Thanks to all for your answers. It is great to have this kind of support.
Yes, I do have the Factory Manual for the '78E, '79F and '79SF—picked up one in 1980 right after I bought the bike.

I have some time today to look things over again and get back into fixing the bike. I will recheck pick-up coil wires, voltages and check out the gas cap again. I did replace the gas cap rubber seal. It was cracked. But I didn't check out the gas cap filter. Didn't know about that. Also, want to pull the plugs and see what they look like.

Thanks Marty, I will PM you later after I check out some things today.

[jetmechmarty]

... and check out the gas cap again. I did replace the gas cap rubber seal. It was cracked. But I didn't check out the gas cap filter. Didn't know about that.

That's the smoking gun. If the filter rotted, the tank was venting through the cracked seal. Once you replaced it, it can not vent. The engine starves for fuel and it quits.

[mack]

well

you have done an extensive restore to date. What ever is wrong is something very simple. Do the gas cap check before you get lost in other needless problem searches. Always look for simple first. These want to run no how bad a mechanic you are. Nothing personal, just saying they will run under the most adverse conditions. Show it some love and it will respond ten fold.! Your almost there. it will be something simple you overlooked. Gas cap venting is a classic.

[SouthernGrey64]

The results of today's tests (Part1)

The first thing I did was to check out the gas cap that Mack and Marty had suggested. Thanks guys for that suggestion! I took the cap off the tank and tried to blow through the vent. It was stopped up. Took the cap apart and it was full of crud and rust. Removed the little washer, the filter, and the gasket and cleaned them up. The washer and gasket are reusable but the filter (I think its foam) is trash. Any suggestion for a filter replacement. Soaking the metal parts in Evaporust now.

I then checked the spark plugs. #1 was black , #'s 2, 3 & 4 were very light grey (almost white) with a smidgen of tan on the nose. I don't think I have the carburetors set correctly yet (#1 too rich and rest too lean). I'll recheck them again after I return from a test ride tomorrow.

I then did the resistance and voltage checks again. I think they all look within range. I'll post the results on a new post as I ran out of room here.

Thanks again for all the help!
Linwood

[SouthernGrey64]

The results of today's tests (Part2)

Here are the voltage and resistance tests that I ran today. They look within range to me. Please let me know if you agree or not.

Voltage Checks—
Battery Voltage—13.57 Volts

TCI Voltage Check—Voltages on Large Connector with connector plugged in and Ignition Switch on:
Grey wire to Ground—12.01 Volts
Orange wire to Ground—12.02 Volts
White/Red wire to Ground—12.01 Volts
Black/White wire to Ground—6.25 Volts
Red/White wire to Ground—12.01 Volts

Resistance Checks—
Coil Primary Resistance @ coil—
Left Coil (Orange wire to Red/White wire)—1.4 Ω
Right Coil (Grey wire to Red/White wire)—1.5 Ω

Coil Primary Resistance TCI Large Connector—
Left Coil (Orange wire to Red/White wire)—3.2 Ω
Right Coil (Grey wire to Red/White wire)—3.2 Ω

Coil Secondary Resistance—
Left Coil (Cylinders 1 & 4)—15.61 KΩ
Right Coil (Cylinders 2 &3)—15.63 KΩ

Wire Continuity Check—Between TCI Large Connector to Coil Primary—
Orange wire—0.2 Ω Grey wire—0.2 Ω Red/White wire—1.8 Ω

Pickup Coil Resistance @ TCI 4-pin Connector (Connector removed)—
Cylinders 1 & 4 (White/Green wire to White/ Red wire)—743 Ω
Cylinders 2 & 3 (Yellow/Green wire to Yellow/ Red wire)—761 Ω

[jetmechmarty]

The first thing I did was to check out the gas cap that Mack and Marty had suggested. Thanks guys for that suggestion! I took the cap off the tank and tried to blow through the vent. It was stopped up. Took the cap apart and it was full of crud and rust. Removed the little washer, the filter, and the gasket and cleaned them up. The washer and gasket are reusable but the filter (I think its foam) is trash. Any suggestion for a filter replacement. Soaking the metal parts in Evaporust now.

What I did was cut out a small piece of Scotch Brite to replace the filter.

[SouthernGrey64]

Thanks Marty! Great idea.
Linwood

[TopCatGr58]

Hey Linwood,

The gas cap vent is classic. Your symptoms are that it runs a while, then quits. Sits, and then starts/runs again. Yes, vacuum locking the fuel flow at the gas tank can cause this. BUT the bike heats up as it runs, and another item that can go bad is the Ballast Resistor, that little shiny metal cylinders just under the left side of the gas tank on the engine head area. It heats up when running, it can develop a crack in it, and then if it heats up too much, it can separate and cut out power to the coils, killing the engine, until you stop, sit a while and it cools down a bit and then shrinks/makes connection again, power to the coils again and the bike starts again.

So....take your DMM with you on your test run and when the bike dies, pull the connector to the BR and test for resistance, but it will probably show an open circuit...no continuity!
You can then also make a jumper wire that can plug into the BR wire harness connector to TEMPORARILY bypass the BR and see if the bike starts and runs. If it does, that can help confirm the BR being bad. BUT do not run with it for more than a few minutes...otherwise you can fry your TCI .

T.C.