Question about Harley Davidson XL 1200 C Sportster Custom Motorcycles

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Sportster sputtering at take off

Had a new tank put on. new spark plugs. also had o rings on carbs replaced. rode 30 miles, sputtering at take off

Posted by Anonymous on

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  • 125 Answers

You said you had your carb. o rings replaced. I am assuming that that means the carb. was taken apart. If that is the case, check and make sure that the little rod that is on the side of the carb. is stuck into the accelerator pump. This would cause a sputter effect you mentioned during take off. Also check your vacuum line to the carb., small cracks could be affecting the flow of fuel from the tank.

Posted on Mar 16, 2015

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Posted on Jan 02, 2017

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SOURCE: dies when hot no spark carb gets gas plugs are dry start when cool

It sounds like the coil getting hot and breaking down. Check for bad grounds also.

Posted on May 31, 2009

  • 56 Answers

SOURCE: 1989 tw200 yamaha won't start

G'day egdbcs . lets see.You say good spark,so i'm presuming you are doing the old sight test.Try bending the arm on a know good sparkplug about 5-6mm,earth the plug and kick'er in the guts(crank it over)Be very carefull , high voltage danger.If there's still a good spark it's safe to say that there will also be a good spark under pressure in the combustion chamber,speaking of which you should also do a compression test,anything over 100psi should be ok. as i'm not to sure of the extent of the re-build,hopefully the valves were lapped and checked for straight and true and valve seals replaced,if you notice oil on the tip of the spark plug you could have a leaking valve seal or oil seal .Try putting a small amount of fuel directly into the combustion chamber ,tighten up the spark plug ,install the plug cap and.......Yeah ..You guessed it ..."kicker in the guts".If all the abouve are correct and true it should fire up.If it runs for 5-10 seconds then stops you've got some sort of fuel starvation problem , could be dirt in the carb,blocked idle jet ,or air passage or even the needle could have come off it's clip,believe me with an old bike like yours anything could be worn and loose inside that carby.The only other thing to consider is the timing.There may be a good spark but is it happening at the right time inside the engine???. I'll leave it all in your capable hands EGDBCS.Hope this helps to solving your worries. Chow for now......Tilleydog..

Posted on Jun 03, 2009

  • 115 Answers


if your motorcycle is dynamo or contact point,check and allign its timing or replace the condenser..,but, if it is a CDI,then replace the CDI itself.

Posted on Dec 04, 2009

  • 4565 Answers

SOURCE: Have a 1999 Sportster 1200C that recently died on

it sounds like you have trash in your jets. The bike sitting for two weeks is not long enough to cause the problem and neither is the crossover fuel line in the front of the tanks. The cross over simply allows fuel on the right side of the "hump" in the tank to get to the left side where the petcock is.

Now, the petcock could be your problem. In 1996, H-D went to the vacuum operated petcock and have had troubles with them since. If you'll look on the backside of your petcock, you'll see a small tube that supplies vacuum to the petcock. Check and make sure this tube is properly connected on both ends.

If it is, you can loosen the petcock to drain the fuel out of the tank. Catch the fuel using a large funnel and an empty fuel can. Take the petcock out of the tank. Inspect the screen. One the backside of the petcock, there is a square plate with four small screws holding it. Remove the screws and carefully take the plate off. There are several small parts in there. A diaphragm, a needle and a small spring. Take the diaphragm and hold it up to the light and carefully stretch it. Look to see if a hole is in the diaphragm. If so, replace the diaphragm. When you reassemble the petcock, make sure all the fuel passages are clear. Personally, I suggest replacing the vacuum operated petcock with a high quality manually operated petcock such as a Pingel. I've seen too many people stranded with a full tank of fuel but none in the carb due to these petcocks.

Good luck

Posted on Sep 29, 2010

  • 167 Answers

SOURCE: My 2002 V-Star 1100 Classic

I can't solve this(there are litaraly hundreds of things it could be) BUT I can give you a way to narrow it down a bit.
I'm thinking it may not be running on all cylinders and an easy way to check is to start the bike from cold(do this test in the first few seconds after starting from cold DONT BURN YOURELF),put a bit of spit on your fingers and quickly touch each exhaust header in turn, to see that they are all warming up equally together.This will narrow down if your problem is related to one or more cylinders.
If one or more of the pipes is cold/er than the others then you know which cylinders are causing the problem.
If you find that this is the case- one or more of the headers are cold then.
Remove the spark plugs-Keep in order.Examine the plugs-used plugs tell a story.How do they look?clean?black & sooty?Are they all the same colour?
Re-fit plugs to caps,sit plugs on metal of rocker cover,press starter - cheack for spark on all plugs.DO NOT HOLD OR TOUCH PLUG/CAPS WHILST CRANKING-WARNING - HIGH VOLTAGE- CAN KILL.

I can also suggest a few common problems that bothered the v-stars/viragos.
They were notorious for open circuiting their spark plug caps on either cylinder.Having the coils tested will confirm this. If you have a multi meter let me know & i'll guide you through testing them.

Air leaking at the inlet manifolds-where they bolt to the cylinder-test this by spraying with wd type spray with engine running-if engine revs change-has air leaks(sucking in wd & affecting mixture.)
They even pop the carbies out at the front some times & **** air there.
The inlet manifolds also have hoses & plugs on them(for checking the carbie balance/vacume fuel tap)Check all these for splits & tears-common depending on the condition of the bike/milage/fuel used.
This will not solve your problem but may help you to isolate where your issue lies.

I hope this is somewhat helpful & I'm happy to help if you need after following these suggestions
Kind regards Andrew Porrelli

I hope that this is in some way helpfull.

Posted on May 11, 2011

Testimonial: "Thanks very much for that information. I plan to continue working on it this weekend, and I'll definitely use these ideas. Take care...Danny O."

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The diaphragm petcock operates by vacuum.
Sometimes, the vacuum line comes unhooked, cracked or broken.

Check the vacuum line.

Also, the diaphragm petcock sometimes dies, and needs replacing.

The reserve DOESN'T operate by vacuum.

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Hi Michael, and the usual suspects are:
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