Harley Davidson Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
29 Posts
Discussion Starter #1
I have a 1990 Sporty 1200 that sat for some time. I finally got it finished and together and decided I wanted to start riding it again. I started by draining the gas, replaced the fuel line, cleaned the carb, changed the plugs and gapped to .040, replaced the plug wires with screaming eagle, ran it to heat it up and proceeded to change oil and tranny fluid.

It runs strong, starts pretty easy and idles pretty decent once warm. While driving it does not like to be under 2,000 RPMs, maybe closer to 1,500. It sputters, rides jerky and wants to die, I have to pull the clutch and rev or get up to 2,000 or more. I did not change the fuel filter because I couldn't find one at the time. This shouldn't be the prob though, if anything it would sputter when the gas is higher demand at more RPMs.

I guess my question is, would setting and checking the timing help this or could it be something else? I have a screaming eagle electronic ignition module. After runnung at low RPMs and give it gas, it likes to backfire once or twice. I am new to bikes and bike mechanics, but willing to get my hands greasy. Is setting the timing easy enough or should I take it to someone with experience? I do have a Harley service manual that seems to cover it.
 

·
I {Heart} Hookers.
Joined
·
31,321 Posts
I have a 1990 Sporty 1200 that sat for some time. I finally got it finished and together and decided I wanted to start riding it again. I started by draining the gas, replaced the fuel line, cleaned the carb, changed the plugs and gapped to .040, replaced the plug wires with screaming eagle, ran it to heat it up and proceeded to change oil and tranny fluid.

It runs strong, starts pretty easy and idles pretty decent once warm. While driving it does not like to be under 2,000 RPMs, maybe closer to 1,500. It sputters, rides jerky and wants to die, I have to pull the clutch and rev or get up to 2,000 or more. I did not change the fuel filter because I couldn't find one at the time. This shouldn't be the prob though, if anything it would sputter when the gas is higher demand at more RPMs.

I guess my question is, would setting and checking the timing help this or could it be something else? I have a screaming eagle electronic ignition module. After runnung at low RPMs and give it gas, it likes to backfire once or twice. I am new to bikes and bike mechanics, but willing to get my hands greasy. Is setting the timing easy enough or should I take it to someone with experience? I do have a Harley service manual that seems to cover it.
No external fuel filter on your bike. There is a screen in the tank, found by removing the petcock.

You have a lean condition.

It's either due to a vacuum leak, (Carb to intake gasket or intake to head o-rings/clamps) not enough fuel (air/fuel screw needs to be turned out) Too small of a pilot jet or partially blocked...

But probably from sitting, the accelerator pump diaphram is beat.
 

·
Registered
Joined
·
29 Posts
Discussion Starter #3 (Edited)
Once again Dave you have helped tremendously! Thank you as always. Just replaced the accelerator diaphram, o ring, and spring. Went ahead an replaced the vacuum line to the back of the carb. Haven't ridden it yet, but from idle to fast throttle acceleration it does not skip a beat, very crisp, no backfire, and returns to normal idle, like it should. :thumb

I have only one more question on this matter. The diaphram is a little different on the top and bottom. The rivet that goes through has a larger flat side and a smaller roundish side. The way it came out was with the larger flat side against the accerator rod (top side). There is a complete rubber side on 1 and the other is kind of a webbed material rubber coated, like a tight cheese cloth. So with the larger flat rivet side up this makes the webbed side on the top as well.

The diaprham that came out had the large flat side up but the webbing was down. The only reason I ask is because when I took the old one out there were pieces of rubber that had deteriated (just like you mentioned) and they were sitting in the reservoir below with some other cruddy looking gas. I thought maybe it was that way so if it did break apart it'd stay in the reservoir instead of continuing through the carb. Hopefully it doesn't make a lick of difference and I am all set as is. Sorry for the long posts, just trying to explain in as much detail. I'll head out for my test ride now and run it hard.
 
1 - 3 of 3 Posts
Top