Power loss!!

I've had this bike for 3 years and been riding the heck out of it with no problems....until recently. Have noticed a progressive decrease in performance over the last 2 weeks or so culminating in not being able to go over 70mph last night on my way home from work. 65-70 is usually where she really starts screaming well past the 110 mark. The bike has been hesitating a bit just off idle then running seemingly well, until last night. First thing this morning I checked and replaced fuel line and inline filter, no change. Pulled spark plugs...#'s 1,2 and 4 look beautiful, 3 was sooty and a little wet. Is it possible something stuck in my #3 carb and it's running really rich in that cylinder? Can only one side of a coil go bad? #2 plug looks to be firing just fine. I'm long overdue for valve clearances/synch/tune but its been running great until recently. Any ideas??

 

Sure. How many miles did you put on it in those three years?

You may have just burned a valve...

and hopefully not holed a piston (or two...)

 

Time for some long overdue routine maintenance. Clean carbs and sync, adjust valves , change plugs , oil and clean air filter. Preventive maintenance is you bikes best friend. Its the next best thing to a good helmet and jacket.

 

I'm just a little ashamed to admit that I've put 20000+ miles on it without looking into the valve clearances but as I've already said the bike has run great from day 1. It gets regular oil changes I'm very picky about where I get gas at and I run a can of seafoam through it about every 5th tank. I figured out #3 is either dead or very weak. Compression is good across all 4 cylinders, spark seems to be good on 3 so I'm leaning toward a carb issue.

 

try a new plug. be easier to check.

either plug isn't working INSIDE the cylinder or carb is flooding out.

could also have a bad connection at the plug gap inside the wire.

 

You might have something "Simple" to deal with.
Diaphragm Pistons failing to rise completely do to Aluma-Oxidation Film on the Diaphragm Piston Bore.

You need to conduct a "Clunk Test"

You and a little kid can Scrub the Bores and make them clean,, again, without removing the Carbs.

Get a Sheet of ScotchBrite Gray & White .... Scrub!

 

man check those valve clearances at least!!

 

Valve clearances and carb synch are on my list. Put new plugs in and its running better but spittin white smoke that stinks of fuel out of the tailpipe now. It was 104 degrees outside when I was messing with it so I'm gonna wait til its a little cooler to polish piston bores and "clunk" test. Thanks everyone.

 

You're 4X intervals overdue for a valve adjustment. Keep pushing it and you WILL burn a valve.

 

Pulled the carbs, polished piston bores. Passed the 'clunk' test beautifully. I was surprised to see that the carbs were pretty clean inside. Checked the diaphragms for holes and cracks they looked good. Blew carb cleaner through every passageway I could find, everything seemed to flow well. Still have the same problem. Checked coil resistances and they were good. 1,2 and 4 plugs still look great, #3 sooty again. At a loss again. Gonna park it until I can do the valves, carb overhaul, synch and tune.