96 sportster one cylinder missing intermittently

[tbutt130]

I have a new to me sportster. Got it on the lake today for the first time. Initially it seemed to run fine and pulled great (38 mph on the gps). Then the rear cylinder started missing and I couldn't get it on plane. After a while it worked fine again but only for a little while. I limped it back to the dock. Any suggestions?? Thanks

 

[Dr Honda]

What do the spark plugs look like?

 

[tbutt130]

Plugs look black. I tried swapping the plugs but that didn't help.

 

[shakedown]

Try new plugs as well as trim the plug wires back a 1/4", then screw the spark plug boot back onto the trimmed plug wire

 

[Dr Honda]

:agree:


Sometimes you can get a little corrosion in the wires.

But if they a VERY black and wet... then you may be ruining rich. you may want to give the carbs a good once-over.

 

[tbutt130]

Changed the plugs. Seemed to help some, but it is hard to tell with the new cavitation issue. In neutral, the back cylinder seems to miss intermittently at idle, smooth out as I advance the throttle, then miss again further up in the rpm range. In gear, seems to pull pretty evenly up until it cavitates. I have it back home now with my tools, so I will trim the plug wires next and see if that helps.

 

[tbutt130]

By the way, how important is the flywheel guard? My boat is missing it and the flywheel kicks up a nice mist if there is any water in the hull. I was thinking that this was not helping my power issue since it could cause the engine to ingest the water??

 

[tbutt130]

Tried the trick with the spark plug wires. Seemed to make a difference. It seemed to idle more smoothly for the 15 seconds I ran it (boat is out of the water). Once I get the wear ring issue squared away I will float it and see if it makes a difference under load.

 

[harley2rde]

make sure you don't have a fuel leak at the fuel filter . had one do that over weekend and seal in filter housing was allowing air in fuel system causing misfire at times .

 

[Dr Honda]

The miss can be from running rich. Even if the plugs are good, on a 2-stroke, it needs a good load to clear out sometimes.


Just a thought... make sure your high speed needles are closed. (toward the top of the carb, on the opposite side of the throttle cable) They have a little plastic cap on them so they are only 1/4 turn adjustable. I would pull that little cap off, and make sure they are closed.


As far as not running a cover on the PTO... it's really not a big deal, but you will wind up spraying a little oil and grease out, and it will get all over the engine compartment. OR... if anything breaks loose, it could fall into the moving parts. I have one sitting in the shop. PM me if you need it. (I'll sell it to you for $5 + ship)

 

[tbutt130]

I took a close look today at the spark arrestor, it was filthy and quite clogged. This may be causing it to run a little rich as well. I won't really be able to troubleshoot it any more until I get it in the water.

Is there any way to run these on land? I see the hose fitting on the back of the boat, but I understand this is for flushing. Can I hook a hose up to this and run the boat out of the water?

 

[Dr Honda]

Yes, you can run them on land, but it's hard on the carbon seals, and without a load... you don't get a true run. So... with they kind of problem you have... running on the trailer isn't going to tell you anything.