79 xs1100 SF not starting! newb to these bikes.

[BirdsbobberXS]

Hey guys! New to these bikes and also to this site! So bought this 79 Yamaha xs1100SF from a kid that had it bobbed out but needed some work. Was running when I bought it but not good.

First things first.
Thought it had a carb out of adjustment issue because it would lose power when I was accelerating and ultimately just die. Let it sit for about a month while cleaning Carbs. Battery died during this time. OK...no problem, let the battery charge up and tried again with freshly cleaned carbs. No go..she would just crank but not even sound like she was trying to fire. Thought maybe she wasnt getting fuel. Took off the spark plugs and saw that they were wet. Good sign getting fuel, bad sign is fuel is not getting ignited. Read all kinds of forums on here to see what steps to take on these old queens. Checked spark plugs and saw that they were firing on 2 and 3 but not on 1 and 4. Maybe a bad coil so I read some forums and checked the coils using a multimeter. Got around 16 on the secondary and 3 on the primary. Coils seem to be ok. Still not running. Did the 1/4 in wire cut to get rid of some corrosion and still a no go. Decided to check the next logical place at the P/U coils. Read some more posts and started looking for faults. Found my blue and reddish orange pick up wires broke under my timing cover. BOOM! Thats where Im at as of now.

Question on these pick up wires. Should I replace the whole pick up coil and wiring? or just fix the 2 wires? Also would this broken wire and one wire almost split in half cause my bike to not start? Any help would be greatly appreciated guys! Thank you!

[motoman]

Hey guys! New to these bikes and also to this site! So bought this 79 Yamaha xs1100SF from a kid that had it bobbed out but needed some work. Was running when I bought it but not good.

First things first.
Thought it had a carb out of adjustment issue because it would lose power when I was accelerating and ultimately just die. Let it sit for about a month while cleaning Carbs. Battery died during this time. OK...no problem, let the battery charge up and tried again with freshly cleaned carbs. No go..she would just crank but not even sound like she was trying to fire. Thought maybe she wasnt getting fuel. Took off the spark plugs and saw that they were wet. Good sign getting fuel, bad sign is fuel is not getting ignited. Read all kinds of forums on here to see what steps to take on these old queens. Checked spark plugs and saw that they were firing on 2 and 3 but not on 1 and 4. Maybe a bad coil so I read some forums and checked the coils using a multimeter. Got around 16 on the secondary and 3 on the primary. Coils seem to be ok. Still not running. Did the 1/4 in wire cut to get rid of some corrosion and still a no go. Decided to check the next logical place at the P/U coils. Read some more posts and started looking for faults. Found my blue and reddish orange pick up wires broke under my timing cover. BOOM! Thats where Im at as of now.

Question on these pick up wires. Should I replace the whole pick up coil and wiring? or just fix the 2 wires? Also would this broken wire and one wire almost split in half cause my bike to not start? Any help would be greatly appreciated guys! Thank you!

Simple answer to both questions: No and yes. Cut the wires and strip back just a short distance(1/8th of an inch) slip a shorty piece of shrink tubing over wire first, then use a shortened piece of naked butt connector and crimp it on, then slip shrink tubing over it and shrink it. This procedure overall works better than soldering wires together. Start it up, and it should get it hitting good on all four cyls.

[TopCatGr58]

Maybe a bad coil so I read some forums and checked the coils using a multimeter. Got around 16 on the secondary and 3 on the primary. Coils seem to be ok. Still not running. Did the 1/4 in wire cut to get rid of some corrosion and still a no go. Decided to check the next logical place at the P/U coils. Read some more posts and started looking for faults. Found my blue and reddish orange pick up wires broke under my timing cover. BOOM! Thats where I'm at as of now.

Thank you!

Hey there,

Brant/Motoman already covered the PU coils. The bolded text above is what caught my attention. You have a 79 SF which came OEM with 1.5 ohm coils and a 1.5 ohm ballast resistor. The 3 ohm coils were added in 81 along with dumping the ballast resistor, so that the TCI still saw a total of 3 ohms on the trigger side. SO...the PO has swapped out the OEM's for "something" newer, either 81 Yamaha oems, or Honda VF1000, or aftermarket high output types which are the better/best that you could have if they are that! But just wanted to make sure that the PO knew what he was doing and bypassed the ballast resistor. IF he didn't then the coils would only be getting ~9 volts during the actual running phase and that could also contribute to weak sparks!!! And the TCI would also be seeing 4.5 ohms....a bit too much, but won't necessarily burn it up compared to if it only had 1.5 ohm coils and no ballast resistor.

Also remember that the coils fire both plugs at the same time, so to test for spark you have to have both plugs connected to the head so that the energy can pass from the coil, thru the first plug, thru the engine, then back up thru the other plug and back to the coil! IF not properly connected to make a complete circuit, then you won't see a spark even though it may actually be working properly.

T.C.

[BirdsbobberXS]

Simple answer to both questions: No and yes. Cut the wires and strip back just a short distance(1/8th of an inch) slip a shorty piece of shrink tubing over wire first, then use a shortened piece of naked butt connector and crimp it on, then slip shrink tubing over it and shrink it. This procedure overall works better than soldering wires together. Start it up, and it should get it hitting good on all four cyls.

Thank you for getting back to me so quickly Motoman and TC. So yea I figured shrink tubing would work the best especially since its more oil resistant than elec tape. Gonna do the repair probably today.

I also noticed that TC when I got my readings so I assumed that they were after market or from a newer bike. I had read on the forums what they should be. Question. Where are the ballast resistors located on these bikes?

Sorry bout all the questions and long stories. Love the bike and cant wait to ride her again!

Thanka guys!

Bird

[3Phase]

Question. Where are the ballast resistors located on these bikes?

Welcome to the site, Bird!

The ballast resistor is underneath the fuel tank on the left-hand side of the frame up by the steering head. It'll be the bare metal ballast resistor thing with the two Red/White ignition wires plugged into it. It's nothing but a big, stonkin', resistor-in-a-can and it will probably burn your fingers if the engine's been running for a while so don't just reach in and grab hold of it!

[cajun31]

look at this listing

it is a good picture of the ballast resistor.

http://www.ebay.com/itm/1980-Yamaha-...dW6Dyx&vxp=mtr

[TopCatGr58]

Here's an image from the Dyna Coils Mod/Repair thread that shows it in place on the bike. It's the silver thing above the head hanging below the frame rail and the gas tank rubber mount.



T.C.

[BirdsbobberXS]

Thank you!

Thanks for the quick and informative responses Phase, Cajun and Tc! You guys are awesome. Im loving this site already!

Question though. So I'm thinking as previously stated that I have either after market coils or ones from a newer bike because of the around 3ohm readings I was getting from the primary wires. So if this ballast is still hooked up which I think it is, will it cause and issue to my TCI or even fry my wires? Seems like it would have a long time ago but hasn't.

Bird

[3Phase]

If you really do have 3 Ohm coils and the ballast resistor is still connected then you should disconnect it.

The TCI will be just fine with ~4.6 Ohms, nothing bad will happen to it but the ignition coils will have problems. With that much resistance cutting down the current the coils won't be able to build up a decent voltage and fire the spark plugs.

[BirdsbobberXS]

off topic question but will help in the long run

Thanks for the info 3phase. How am I going to know for sure what type of coils I have? A little of topic but how do I post pictures on the forums so that I can better show yall my progress or issues? Do I use an html type drop box site or?

Bird

[bikerphil]

how do I post pictures on the forums

You can use a free hosting site such as Photobucket, copy and paste the IMG link here in your post.

[3Phase]

Thanks for the info 3phase. How am I going to know for sure what type of coils I have?

You told us you measured the coils in your first post.

... Checked spark plugs and saw that they were firing on 2 and 3 but not on 1 and 4. Maybe a bad coil so I read some forums and checked the coils using a multimeter. Got around 16 on the secondary and 3 on the primary. Coils seem to be ok.

So, where did you measure the coil primary resistance?

If you measured right at the coil primary connections -- Red/White wire and the Orange wire for the #1 and #4 coil or the Gray wire for the #2 and #3 coil -- then they are indeed 3 Ohm coils and you don't need the ballast resistor.

If you measured somewhere else it may have included the ballast resistor if it's still connected.

[BirdsbobberXS]

coils and photos

Thanks 3Phase and Bikerphil! I definitely took my readings at the coils primary wires while they were disconnected so when I get home Im going to disconnect the ballast resistor and hopefully do the P/U coil wire repair in the morning. Thanks for all the help guys! oh and would anyone happen to know the thread that talks about doing the fuse box mod. The old style fuses look sketchy for a bobber and I want to improve that part.

Bird

[bikerphil]

and would anyone happen to know the thread that talks about doing the fuse box mod

Yup...

http://www.xs11.com/forum/showthread.php?t=14052

[BirdsbobberXS]

fuse box

thanks biker phil!

Im pretty sure I'm starting to get on yalls nerves with all the questions.