my sportster began knocking then died, where should I start?

Question

I bought a sporty for my gf, got about 20 miles and it began pinging, then knockinging, then died. It seems like it lost compression since it rolled pretty easily in gear.

It had been sitting a long time before I bought it. I put fresh gas in it and thought It could wait until I got home to put fresh oil in it.

Does this sound like it could be lifters, piston, or valve problems? Yes, it's getting spark and gas.

It is a 1986, 883 with a 1200 kit

Answer 1

The year of the bike makes a difference. It sounds like a push-rod problem.

Answer 2

sounds like a stuck valve, if the oil hadn't been changed in awhile and the bike has been stood it could be that oil had solidified on the rocker shaft and caused the rocker to stick.
This will cause the valve to stick open and the piston crown will hit the valve destroying both..
Then you have no compression and no engine.

It is also possible that the bike was knackered before you bought it and the guy selling it might have put something in the oil to make it thicker to disguise the knock that was already there.. then you running it home could have resulted in total detonation of the engine..
Either way this sounds serious and requires a total engine rebuild.
Autopsy:-
First check Drain the oil and run it into a pan through a sieve with a magnet in. This will show any iron or steel particulate in the oil. the sieve will capture the larger bits.
Flush the oil tank and the engine through with kerosine or flushing oil.
Remove the filter and wash the outside. Cut open with shears and wash over a pan with a sieve and a magnet in kerosine.
this will show up any metal in the filter
Check all particulate for rust particles, this could indicate the problem existed before you took ownership of the bike.

remove and retain spark plugs photograph using a camera on macro with flash, look for a sparkly finish or metalic deposit on the insulator.
Clean grey or off white indicates normal..
Black or brown indicates contaminants
powerdery white indicates pre ignition

Drain carb into a glass jam jar also check filter trap in petcock in the same way.
Take sample of fuel from tank and check in same way.
Water seperates out of fuel and sits on the bottom of the glassjar, dirt will also settle here look for rust detritus etc.
Air filter remove and brush clean onto a clean white paper sheet using a dry paint brush. check for holes and damage
.
RETAIN ALL BITS FOUND

Now check the engine. Crank engine without filter and place hand over bell mouth of carb to check for suction.
Place fingers in spark plug holes and check for pressure compression, the engine should produce a fair quantity of both. now you can start pulling it apart.. Get a manual read and if confident get on with it..
oh and good luck..

Answer 3

You say bike has been sitting along time?

Start with intake seals, check timing and spark, eliminate the easy stuff. but,

probable cause - worst case- you blew a head or base gasket, very common on a bike of this year, did you let it completely warm up? did you accelerate hard? was it running fine then started the noise?
on a bike thats sat for awhile, you gotta ride it almost as if it were brand new, keep the RPM's down, don't lug the engine, allow it to warm up to operating temp, change the oil at 1000 miles, 2500 and 3500 miles. then go into a regular scheduled maintenance of your preference. but stick to it.

Answer 4

Hay, it does sound like the valve train except the pinging part.
the previous two answers are correct. (It's my thought that unless you are attached to the bike for some reason) in the USA you have 30 day's to return it under the LEMON LAW, I just thought I would mention that. Well best of luck in what ever you decide.

Answer 5

if your gonna keep it go ahead and tear down the top end, if you can work on a lawn mower you can work on a Harley top end. New top end is about 1,000 bucks if you do all the work. just have the heads done at a shop and replace the pistons rings wrist pins and keepers and pushrods yourself. easy job

Answer 6

Valve problem? amay be warped? from tomuch heat like low oil? bad problem have shop look at it...