Hoping for help on a 587 no-start.

[Sandman251]

Hoping somebody will take a crack at this. Picked up a 93 single carb 587 GS last fall. Just got around to playing with it this week, but can't get it started. Installed a new starter which was missing. Brand new battery is fully charged. Brand new spark plugs. The motor turns over great with no unusual sounds. Compression is 140/140. Both plugs appear to be getting nice Spark. Tried premix down the plug holes first then in the carb and no start. I turn it over for about 10 seconds and get a couple of small surges like it wants to start but it won't. So in a nutshell, I know I have compression, I know I have fuel and I'm pretty sure I have sufficient spark. The word I got is that it ran when it was professionally winterized 4 years ago. What's left besides timing?

 

[AKnarrowback]

Chances are timing is just fine unless you know someone has messed with it.

How do the plugs look?

If they are dry you are probably not getting fuel. Keep tinkering with a little fuel in the plug holes to get it to kick.

If they are wet it could be flooded. Hold it wide open while you crank on the starter. When I set up the 580 sp machines out of the crate I would use the choke until I heard the motor pop the first time and then use throttle only to get them started the first time, they were easy to flood by holding the choke too much.

Is there fuel in the water seperator/filter up by the steering column? If not that is also a good indicator as to why it's not starting.

You say it was winterized and sat for a while. You could also be fighting fogging oil trying to burn off. Again, how do the plugs look?

If it ran good when it was parked and has been sitting for four years I would guess it is just being stubborn coming back to life. The carb and pump might have to be taken apart and cleaned/rebuilt, also make sure the old gray fuel lines get replaced if it has them.

 

[mikidymac]

The plugs are your key, are they wet, dry, oily?

 

[Sandman251]

thanks for the reply. When it didn't start right away I was trying to take fuel , carbs, fuel lines, and filter out of the equation by adding fresh premix. Like I said, the plugs are brand new so they only show evidence of unburned unburned premix.

 

[AKnarrowback]

A trick I carried over from sleds is doing the drop of fuel in the spark plug hole and using that to kick the motor over to "prime" the fuel system without pulling the rope 50 times at the start of the season.

If there are brand new plugs with unburned fuel on them, "wet" plugs, then I would say you might have flooded the engine already. The solution is hold the throttle wide open and crank on the starter. If it's flooded it will take a little cranking, the engine will kick every once and a while but eventially start running rough and clear out. The process should take a minute or two if things go good.

The big question though is did the fuel system start to fill up? Is there fuel in the filter?

You could be fighting a flooded engine from putting fuel down the plug hole but not have any fuel in the system to keep the motor running once it gets going.

You are correct in that a mechanically sound motor with good compression, spark, fuel and air will run according to engine theory. It sounds like the unknown here is fuel. The question is do you have not enough or too much (short term rich/flooded condition).

If you put gas down the hole and pulled the choke my bet is it is flooded.

Look at that filter for fuel.

 

[funsummerahead]

If you have good 140 / 140 compression, good fuel - even if down the carbs or plug holes and good spark I would think it is an airflow issue. Either the rotary valve has the wrong timing or the exhaust is clogged. With a helper crank it over and put your hand over the exhaust outlet to check the exhaust to see if air is coming out of it. It could be that the water box is clogged up from a mouse nest restricting the airflow. They generally don't go in there but a machine sitting 4 years it's a possibility.

 

[Sandman251]

That's an interesting theory about exhaust restriction. Hadn't thought of that. So, if the exhaust system is clear it sounds like I'm going to be down to timing. If I understand the system, these machines cant just "jump out of timing" right? What I mean is there would have to be some sort of mechanical failure in the RV/shaft/gear.

 

[jts32]

I would suspect timing. If you have an inspection camera (cheap at Harbor freight), stick it down the carb and verify the RV is turning. I've had skis that tested great compression, but had a stripped RV gear from a screw falling down the carb.

 

[funsummerahead]

jts32 is right.
Either the rotary valve for timing is off -
1 someone put it in the wrong place.
2 the brass gear on the crankshaft that drives the rotary valve is damaged and it's no longer in the right place or not even spinning.
3 or you have excessive rotary valve clearance.

 

[Sandman251]

So this thing is still giving me fits. The RV is spinning and appears to be positioned properly. I set the mag piston to TDC. I can feel the position of the RV with my finger. It feels like it's right where it should be, or at least within a few degrees. I had a brand new CDI and installed it. It appeared to improve the spark color a little. But it was still very strong. I made sure the exhaust was free and unrestricted. The thing will still not fire on premix. I'm losing my mind. I have always been able to figure these things out. And anyway, even if the timing was off, shouldn't these things fire up on premix in the cylinders? Ugh. Somebody help me. Where do I look now?

 

[funsummerahead]

You need a manual. There is a lot of really good info for checking this in the manual. If the rotary timing is off more than about 5 degrees it may not start. The timing is pretty delicate and checking it with your finger just won't do. It won't start with premix down the plug holes if the rotary valve timing is off as it won't seal and keep the fuel air mix in the cylinder, it will blow back out of the carb and act just like you describe. If the rotary valve clearance is too big and worn it will do the same thing. Download a free manual at seadoomanuals.net for your year and model and look up the timing.

 

[Sandman251]

You need a manual. There is a lot of really good info for checking this in the manual. If the rotary timing is off more than about 5 degrees it may not start. The timing is pretty delicate and checking it with your finger just won't do. It won't start with premix down the plug holes if the rotary valve timing is off as it won't seal and keep the fuel air mix in the cylinder, it will blow back out of the carb and act just like you describe. If the rotary valve clearance is too big and worn it will do the same thing. Download a free manual at seadoomanuals.net for your year and model and look up the timing.

Thanks for your response. It is exactly the explanation I was looking for.

 

[mikidymac]

What CDI did you buy? A lot of the aftermarket ones are bad out of the box.

On the compression was the engine full of fuel or oil? This can cause false high readings.

Finally if everything else checks out you are going to have to pull the rotary cover and...
1. Check the rotary clearance per the manual.
2. Check the rotary timing per the manual.
Neither of these can be eyeballed, you have to measure precisely per the manual.

 

[Sportster-2001-951C-Stock]

No start sounds like not enough fuel, could be too much though.

Pull the plugs and crank it, while looking for "fog" shooting from the plug holes, hopefully if yes, it's pre-mix if it's there and if you do, it's probably too much. More cranking with plugs removed will clear it out. If no "fog" there may not be enough fuel, install plugs and squirt a few nice squirts into the carbs and try again. See if it pops and runs for a second or so.

Eventually if you add enough, you'll smell raw fuel around the exhaust, might be getting or is flooded at that point, remove plugs and repeat from above.

If the carbs are dry, as in not getting fuel due to internal corrosion or fuel line air leaks, you'll only get a couple seconds of running with fuel stored in crankcase.

 

[AKnarrowback]

On the compression was the engine full of fuel or oil? This can cause false high readings.

I pegged my compression gauge at 300psi after a few rotations on my oil flooded gtx. I have also used a little oil down the spark plug holes on a low compression motor to start it and get me back to civilization on two occasions. A little extra fluid around those rings can change things.