97 M900 - rough running

[greenohawk69]

I did not start my bike since July 2016 and in the meantime, and recently performed the following:

* removed vacuum petcock
* removed vacuum line from intake manifold
* plugged / capped vacuum hole on intake manifold
* installed 5/16" fuel line

Bike started with the choke and would run, but once I dialed back the choke eventually to off, it would run slower and then stop.

After I started it again and pushed the choke off and used the throttle to keep it running. At low throttle, it started to cough a bit out of the open airbox (new K&N filter). Goosing the throttle a bit more, it revved higher and did kick out a little plume of black exhaust.

This was done in the driveway and not riding the bike due to slight weeping of tank drain plug.

Prior to the above changes, it would start with the choke, run and then rev higher and I would turn down the choke and then off after it warmed up.

Suggestions?

[greenohawk69]

When I re-installed the exhaust, I did install new gaskets into each port - there were none when I removed the exhaust this summer.

[koko64]

Not starting since last July is the key. There is every chance your carbs need a clean and service including unclogging the pilot jets and cleaning the float needles and float valves. Quite common with modern fuels waxing up or jelling over time. I would run fuel stabilizer when storing fuel in your bike. There are threads about how northern hemispherians can winterize their bikes. Even down here where we seldom see 30 F I start my bike weekly and run it hot. We ride all year around and seldom need to winterize our bikes. A big issue up your way and carbed bikes suffer most.

[greenohawk69]

It was stored in my garage prior to that for over a year and it started and ran fine. This time, I did store it with Stabil Marine and had run it through. Tank was empty from July until 3 days ago.  Thought I might have a potential problem with the carb. 

I'm from a cold weather state.  ;

[koko64]

Flooding carbs can give similar symptoms. What do the plugs say. Goop can also cause flooding when it gets under the float needles.

[ducpainter]

It does sound like the pilot jets are munged up.

If you think it would work, I'd try putting a few miles on it while running the choke to keep it from stalling. It might come out of it.

I wouldn't be looking at plugs quite yet.

[Howie]

Fresh gasoline and filter too.  You can burn the old crap in a car.

[ducpainter]

I also wouldn't hesitate to put a little Techron in the fresh fuel. It won't hurt, and it might just clean things up.

[greenohawk69]

Fresh gas is in the tank. I'll try the Techron also. I'll run it some more too. Thanks.

[ducpainter]

Let us know how you make out.

[greenohawk69]

Ran it for about 15 minutes. Started fine with choke and dialed back and then idle was low and then engine stopped. Started again with no choke and held throttle to keep it running. Revved it a bit higher and heard some popping out of the exhaust. Attached pictures of exhaust - changed in color is after I sanded it to a shinier silver.

[ducpainter]

Not sure what you're trying to show with the pics...but...

I don't think 15 minutes is going to do much.

If you can get it to ride reasonably well using the choke...put a tank full through it.

I understand the better living through chemistry thing, but it isn't instantaneous.

[Howie]

Or just clean the carbs.

[ducpainter]

That's always an option.

We don't know his motivation level...or his climatological challenges.

Whatever works.

[greenohawk69]

Motivation is fine. Lol  Drain plug has a slight weep that I need to fix with sealant I just got. The pics of the exhaust were to show color changes and if it someone was able to see if a definite rich or lean condition.