Need help with tuning...
Thread Starter
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Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
Need help with tuning...
I have a 1973 Super Glide. I purchased the bike as a basket case and recently got it back together. The bike runs but not as good as it should.
The previous owner got the bike from his father and he told me that the stock cam may have been changed to a high performance cam. It also has a SU carb on it.
Here are the problems...
Black soot on the spark plugs (fouling)
Grayish black smoke from the exhaust
Runs rough at take off and vibrates
I ride it down the street and back and then shut the bike off. The plugs are so fouled that it will not restart. If I clean the plugs, it starts right up.
Here is what I have attempted...
Adjusted timing... the points backing plate is turned clockwise as far as it will go. I dont have a timing light but if I turn it the other way, it gets worse.
Adjused carb... Its set at one turn out, seems to run best between 1 and 1 1/4 turn out
Adjusted pushrods... pretty sure they are good.
Adjusted points gap... pretty sure thats ok too
I'm not sure what else to do at this point. I have been working on bikes for quite a while but I am certainly no expert.
I always try to work on my bikes myself but I'm really tempted to take it to the local shop to see what they think.
Maybe one of you guys have had the same problem and can help me out.
Thanks
Lee
The previous owner got the bike from his father and he told me that the stock cam may have been changed to a high performance cam. It also has a SU carb on it.
Here are the problems...
Black soot on the spark plugs (fouling)
Grayish black smoke from the exhaust
Runs rough at take off and vibrates
I ride it down the street and back and then shut the bike off. The plugs are so fouled that it will not restart. If I clean the plugs, it starts right up.
Here is what I have attempted...
Adjusted timing... the points backing plate is turned clockwise as far as it will go. I dont have a timing light but if I turn it the other way, it gets worse.
Adjused carb... Its set at one turn out, seems to run best between 1 and 1 1/4 turn out
Adjusted pushrods... pretty sure they are good.
Adjusted points gap... pretty sure thats ok too
I'm not sure what else to do at this point. I have been working on bikes for quite a while but I am certainly no expert.
I always try to work on my bikes myself but I'm really tempted to take it to the local shop to see what they think.
Maybe one of you guys have had the same problem and can help me out.
Thanks
Lee
Last edited by 73HDFX; Jun 13, 2011 at 03:20 PM.
Road Warrior
Joined: Dec 2007
Posts: 1,286
Likes: 64
From: SoCal
The fact that your points plate is at an extreme position is a red flag.
I hope you have an HD manual to help you set your timing.
Behind the points plate are the advance weights. Check them out. they should be properly lubed, not wearing at the pins they pivot on and easily able to move to full travel and return to the retarded position easily as well.
Replace the whole assembly if there is anything funky about it.
If they are moving freely and are lubed okay, replace the advance springs so you are starting with new ones.
Once you have the advance mechanism working properly, set your timing following the instructions in your genuine HD shop manual.
So now you have an engine that is in sound mechanical shape (good compression) with the valves adjusted correctly (if you are sure they are) and the ignition timing set properly, now turn your attention to your carburetor.
I hope you have an HD manual to help you set your timing.
Behind the points plate are the advance weights. Check them out. they should be properly lubed, not wearing at the pins they pivot on and easily able to move to full travel and return to the retarded position easily as well.
Replace the whole assembly if there is anything funky about it.
If they are moving freely and are lubed okay, replace the advance springs so you are starting with new ones.
Once you have the advance mechanism working properly, set your timing following the instructions in your genuine HD shop manual.
So now you have an engine that is in sound mechanical shape (good compression) with the valves adjusted correctly (if you are sure they are) and the ignition timing set properly, now turn your attention to your carburetor.
Road Captain
Joined: Apr 2010
Posts: 692
Likes: 34
From: Texas
Definitely would do a compression test on both cylinders. I am guessing rings.
Just a couple of thoughts - put a simple Crane Hi-4 electronic ignition in - easy install, but you may need to change out coils, too on your bike. Statically timing it for the hi-4 is a breeze and usually pretty darn close. There are other electronic ignition modules out there that are just as good and cheaper, I just have experience with the Crane.
And install a CV carb - that will eliminate a lot of carb related issues and make for a more dependable bike. I went from a Super B to a CV and the difference was great.
Just a couple of thoughts - put a simple Crane Hi-4 electronic ignition in - easy install, but you may need to change out coils, too on your bike. Statically timing it for the hi-4 is a breeze and usually pretty darn close. There are other electronic ignition modules out there that are just as good and cheaper, I just have experience with the Crane.
And install a CV carb - that will eliminate a lot of carb related issues and make for a more dependable bike. I went from a Super B to a CV and the difference was great.
Tourer
Joined: Jun 2008
Posts: 306
Likes: 7
From: Somewhere, PA
+1 on the CV carb. If you go that route, I usually have good luck with them on Shovels/Pans in the area of 190/48 jets with the idle screw around 2.5 turns out to start. There are various options for press-in or rubber-based flanges to mount to your intake. I prefer the press-ons but people have varying opinions. Also, if you decide to throw a CV on the old girl make sure you also use a support bracket to help with the weight, or an intake leak is likely to happen in short time. You can buy support brackets that mount to the center bolt/nut at the cylinder base or at the top of your rockerboxes.
Good luck...
Good luck...
Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
Definitely would do a compression test on both cylinders. I am guessing rings.
Just a couple of thoughts - put a simple Crane Hi-4 electronic ignition in - easy install, but you may need to change out coils, too on your bike. Statically timing it for the hi-4 is a breeze and usually pretty darn close. There are other electronic ignition modules out there that are just as good and cheaper, I just have experience with the Crane.
And install a CV carb - that will eliminate a lot of carb related issues and make for a more dependable bike. I went from a Super B to a CV and the difference was great.
Just a couple of thoughts - put a simple Crane Hi-4 electronic ignition in - easy install, but you may need to change out coils, too on your bike. Statically timing it for the hi-4 is a breeze and usually pretty darn close. There are other electronic ignition modules out there that are just as good and cheaper, I just have experience with the Crane.
And install a CV carb - that will eliminate a lot of carb related issues and make for a more dependable bike. I went from a Super B to a CV and the difference was great.
I have a new Accel coil, wires and plugs.
I have a SU carb on the bike, from what I've been told, that is a CV carb.
I do have another question...
My coil is an Accel Dual fire coil. Is that the right one.
Last edited by 73HDFX; Jun 14, 2011 at 02:58 PM.
Road Captain
Joined: Apr 2010
Posts: 692
Likes: 34
From: Texas
The SU Carb is not a CV carb - at least from what I understand.
Dual fire is the stock Harley setup. I may be corrected here, but in dual fire, both cylinders fire at the same time (so it should not matter which port on the coil you plug your plug wires into). Accel makes numerous coils including both single and dual fire.
http://store.prestoliteperformance.c....html?cat=1109
You might want to check your coil's part number against their catalog.
Dual fire is the stock Harley setup. I may be corrected here, but in dual fire, both cylinders fire at the same time (so it should not matter which port on the coil you plug your plug wires into). Accel makes numerous coils including both single and dual fire.
http://store.prestoliteperformance.c....html?cat=1109
You might want to check your coil's part number against their catalog.
Tourer
Joined: Jun 2008
Posts: 306
Likes: 7
From: Somewhere, PA
The top end was just rebuilt. Not to say the rings arent leaking, just that they are new.
I have a new Accel coil, wires and plugs.
I have a SU carb on the bike, from what I've been told, that is a CV carb.
I do have another question...
My coil is an Accel Dual fire coil. Is that the right one. I'm not sure what single fire and dual fire means.
I have a new Accel coil, wires and plugs.
I have a SU carb on the bike, from what I've been told, that is a CV carb.
I do have another question...
My coil is an Accel Dual fire coil. Is that the right one. I'm not sure what single fire and dual fire means.
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Outstanding HDF Member
Joined: Aug 2010
Posts: 2,386
Likes: 15
From: The City Of New York
+1 on the ignition change. I don't think SU is CV. On my '78, I had the Dyna S sender with the matching coils into dual plug heads. S&S Super G, .40 over, Andrews cam. Machine would pull stumps out of the ground.Clear up the timing issues first, then work the carb tuning. My buddy had an SU on his '74 and nothing but problems.
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Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
The SU Carb is not a CV carb - at least from what I understand.
Dual fire is the stock Harley setup. I may be corrected here, but in dual fire, both cylinders fire at the same time (so it should not matter which port on the coil you plug your plug wires into). Accel makes numerous coils including both single and dual fire.
http://store.prestoliteperformance.c....html?cat=1109
You might want to check your coil's part number against their catalog.
Dual fire is the stock Harley setup. I may be corrected here, but in dual fire, both cylinders fire at the same time (so it should not matter which port on the coil you plug your plug wires into). Accel makes numerous coils including both single and dual fire.
http://store.prestoliteperformance.c....html?cat=1109
You might want to check your coil's part number against their catalog.
This is the webpage that says that SU is a CV carb.
http://www.sw-em.com/su_carbs.htm
I've used SU carbs on other bikes and they are user friendly and easy to tune.
I will check on the coil. Thanks for the info and link.
Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
I understand about the coil now...thanks
I also understand about the electronic ignition.
I need to get it running correctly first before I start throwing that kind of money into it.
I also understand about the electronic ignition.
I need to get it running correctly first before I start throwing that kind of money into it.