Topic: F2 started losing power and sounding weird

[Floshenbarnical]

Rode it in the highway for a total of probably 20 mins. Stopped at the grocery store to get a sandwich, made it 1/4 mile until I started losing power and the exhaust sound was weird, kind of lower and slower and growly. Bike was still moving, just about, stumbling and hesitating forward but I parked it on the Main Street in front of a busy restaurant and will be back to trailer it home later.

What’s my best diagnostic path? I’m a little overwhelmed. It’s not fuel starvation because I opened the drain screws. It’s not air starvation because I have appropriately oiled k&n pods.

I let it cool down and started it again, so it runs … idle is just really sluggish and RPMs have to be kept up w the throttle. My guess is that a cylinder isn’t firing but I’m overwhelmed and lost. Any advice for what to check in what order would be great.

[scottly]

Do a "spit sizzle" test on the exhaust pipes to see if one or two are cooler than the rest.

[PeWe]

Might run on only 2 cylinders if one point or its condenser is not working anymore.
(Normal behavior by time)

If you have an extra spark plug.
Try that on outside, pull one at the time and test outside plug against valve cover. Any sparks?
It works 1:4 and 2:3
If both of one of the pairs are not working.
Check that point.

You can swap condenser connections and see if problem follow.

The spit test as scottly wrote to be done first.

[Floshenbarnical]

I remembered I did just hit a service interval recently and didn’t regap my points

[scottly]

That doesn't explain why the bike suddenly quit running right. Do the spit test and go from there.

[Tracksnblades1]

You can take a wet rag and touch each header pipe to see which cylinders are firing.

The cylinders that are firing will react differently to the wet rag than the dead cylinder (s).

It’s the similar to the spit test. You just don’t need as good as aim…

[Don R]

 If you have an inline fuel filter, remove or replace. They will look fine but plug up.   

[Floshenbarnical]

If you have an inline fuel filter, remove or replace. They will look fine but plug up.   

I do not

Will be back at the bike in the next half hour. Will report back

[MauiK3]

Check the battery and charging system.

[scottly]

Check the battery and charging system.

Why, given the reported symptoms, would you go straight to suspecting the battery and charging system??

[scottly]

Will be back at the bike in the next half hour. Will report back

Any news yet?

[Floshenbarnical]

Check the battery and charging system.

Why, given the reported symptoms, would you go straight to suspecting the battery and charging system??

Lmao, my thoughts exactly

You could fry eggs on all four pipes. I shan’t, because they’d fall off the sides and ruin the eggs.

So all the cylinders are firing. One or two of them just aren’t firing well. It starts and idles fine, but when the bike is power it gets upset. Idle is a bit spotty but more stable than slow or hard acceleration/ cruising.

It’s feeling spitty and hesitating/ surging. Works same with choke on or off. Spark plugs are textbook, although the threads of #2 were a bit sticky from a tiny bit of oil. Might be from when valve cover gasket was leaky

Points are a little cloudy, but the gap is textbook. Didn’t check the timing because I forgot my timing light. Might file points tomorrow and adjust timing of the fact that I suspect it’s carb related:

Looked in my tank and there’s a bit of rust sediment on the bottom again. Also noticed some fuel leakage from drain tubes so I SUSPECT that some rust residue has gotten into one or two of the pilot jets, and is also causing one of the float needles to stick.

So tomorrow I’ll take off the carbs and blast it all out

Again

And throw some acid in the tank

[scottly]

Before you take the carbs off, do the "clear tube" test to verify the actual fuel level in the float bowls.

[cfairweather]

It sounds similar to a problem I recently experienced and it acted like the bike ran out of gas.  The gas cap was not venting properly due to a thick piece of felt behind the first vent hole.  I disassembled the cap and removed the felt.  I also turned the vent plates where the holes were 180 degrees apart to prevent gas from spewing out. 

[Floshenbarnical]

I have been laid up with COVID + strep + ear infection all at the same time so only just gotten around to tinkering on the old girl.

Yesterday I:

- Filed and gapped points
- Removed and inspected spark advancer
- Set timing
- Set valve clearance
- Pulled, cleaned, bench synced carbs (bowls full of fuel, verified w clear tube, jets and passages and accelerator pump all clear)
- Replaced spark plugs


Now the #$%*ing thing won't even start. I even walked it to the top of a long hill and tried bump starting it, and nothing. It turns over fine, moves through all the gears. All the electronics work, lights etc.

However.

The day this problem occurred I did change the ignition switch. Stupidly I forgot to disconnect the battery, and when I connected the final terminal on the ignition switch there was a spark and I blew my main fuse. I replaced the fuse and the bike started.

Then an hour later the aforementioned power loss occurred.

I'm wondering if this short that occurred may have damaged something like a coil or a condensor? I must admit I don't really understand how all that stuff works to be honest. How would I diagnose that?

[rotortiller]

Check the fuel flow out of your petcock. It has screens.

[BenelliSEI]

Both styles of ignition switches I use connect with a multi pin connector. What are you using. If that switch is the last thing you changed before these problems started I would be looking at it more closely……

[Floshenbarnical]

It's a 3-pin connector, identical to the old aftermarket one I had. I guess I'll check the connections and go from there.