Engine sound is not right no power

Took the bike out for a ride tonight. Have not ran it in 3 weeks. The engine did not sound right. It sounded muffled. When I roll back on the throttle there is no real acceleration. It started right up. Where do I start looking?

 

Assuming you made no changes, it sounds like either a fuel delivery problem or restricted air flow. You might pull the air filter and make sure you don't have a critter nest. It has happened. Also, at the bottom of your post you mention redoing the interior of the tank. What did that involve and how long ago.

 

See if the backpressure from both pipes feels equal when you rev it. Sometimes a muffler can rust apart internally and get blocked...usually it'll discolor the pipes involved too..

 

I did a POR-15 on the interior of the gas tank last year. Rebuilt the Petcock this spring. I do have an in-line fuel filter. I will check that.

The bike does have the original exhaust. I have some blueing on #3 and #4. I thought that was from a lean mixture. I fixed that issue. I will check the back pressure on the two exhaust pipes.

 

Back pressure at exhaust pipes seemed equal when I rev the engine. No blockage on air filter. It was clean. Replaced the fuel filter and put new gas in the tank. No change in performance. I also noticed when I downshifted there was not the deceleration I usually get. Could I have a bad cylinder? I Think I will check that I have spark in each cylinder and do a compression test. Any other testing suggestions would be appreciated.

 

Check to see if your getting fuel from all carbs, check to see if all your butterfly valves are working properly.

 

Hmmmm. Fuel or air starvation would not affect the deceleration. Thought you might have had some POR break loose in the tank. It does sound like compression but why from just sitting three weeks? Best bet is, as you say, check plugs and do a compression test. No miss in the engine, such as you would get with a stuck valve?

 

cole990 do you think the timing chain adjuster could be an issue? On mine its self adjusting...might be a stretch. But I think your probably going somewhere with a valve issue.

 

Could be, I guess, but only if it was loose enough to jump a tooth and screw the timing. Do I have this right - bike ran fine, parked three weeks with nothing done to the bike, then ran like crap?

 

Maybe your only running on two cylinders. Wire to a pickup coil bad or a bad coil? Had a 1980 XS11 that had bad wires to one of the pickup coils and it ran but ran poorly.

 

Check spark to all cylinders then compression test.

 

Compression may not be the tell all..... I had extremly low comp, but valves where 100% and had spark I was my carbs in the end. I had similar symptoms to Hecktichaze's.

 

What you are most likely dealing with is that wonderful concoction known as ethanol. Most stations sell it as 87 octane.

When the bike sits for more than a couple days. The fuel in the bowls evaporates leaving a gummy mixture. Also why everyone finds that brown gummy mess in the carbs when they rebuild them.

Once you start running the bike again. The gummy mixture gets sucked into the carbs. You can use either STP fuel system cleaner, or seafoam, and 89 octane to help clean the carbs as you ride, or pull the carbs and flush the passages with carb cleaner.

If you regularly let the bike sit for more than a couple days between rides. It is a good idea to use quality 89 octane fuel along with some form of fuel additive (Stabil, Seafoam, etc...) to help control the gum, and varnish build up. Unless you have change your petcock over to a true on/off/res style it is not possible to run the bowls dry.

Ghost

 

If you are not running your bike regularly put Stabil in the tank. It will stop the gummy build up and helps get rid of any build up that is starting. And it has no effect on the opperation of the bike.

 

Have you checked the valve clearances yet?

"Serviced" the carbs?

If not, start there. Valves were to have been checked at 3000 miles and again 5000 miles later. You're either 500 miles, or 5500 miles overdue (if they were ever checked.)

 

You can't count on a particular octane being ethanol free, some stations mix it into all grades. You should search for a gas station that specifically states 'ethanol free' gas. Save that you can put ethanol remedy in with the gas to prevent the separation that causes the gum & varnish-And if you can find the time ride at least every 3-4 days for at least 10-15 minutes.

As far as your issue I'd say bigFitz has it right, you need to check those valves-and either before or after or both do a compression test. We are all just speculating in the dark w/o the comp test.

But just to guess I don't think your problem is fuel related if you have significant loss of power and compression (engine) braking. I was thinking your main jets might be clogged, but now I'm leaning towards broken/burnt rings or a stuck/burnt valve. I imagine having fuel issues would effect engine braking, but I don't think it would be significant enough to notice.

 

Bike was running good before it sat for a few weeks. Valve clearances were put in spec this spring. Carbs were serviced in the spring. I have a good spark in each cylinder. I will try and do a compression test tomorrow night. Hope I have not burnt a valve or burnt/broke a piston ring.

 

Just to be sure I am doing the compression test correctly. Is it done with a cold engine, semi-warm, or hot?

Procedure:
1. Pull both connectors on the TCI
2. Remove all spark plugs
3. Install gage in one cylinder
4. Open throttle all the way, hit the start button
5. Crank a few times until gage reading does not climb anymore.
6. Record measured value
7. Repeat for all 4 cylinders
8. Go back and put a little oil in each cylinder and run the test again

Can I hook up my trickle charger directly to the battery while connected to the bike? Can you crank the bike with the trickle charger connected and on or do you remove it from the battery when cranking?

 

OK I did a cold engine cylinder dry compression test.
Results:
#1 - 152
#2 - 151
#3 -152
#4 - 150

These results looked in spec. Do I still need the wet compression test with the oil in each cylinder? If each cylinder goes up in compression significantly I could have ring issues?

Could we be going back to the carbs being gummed up because they sat with our great fuel? Can I try running some new fuel thu with StarTron or Stabil and see if it clears up or am I pullling the carbs off again and cleaning them? Any suggestions or other tests would be appreciated.

 

No need for the wet test, those numbers are excellent, your rings are good, as broken, burnt, or stuck rings could never generate even half that compression, and your valves appear to be adjusted correctly. The lack of variance in your numbers also signifies your mill is in good shape. Warm is the best way to test compression, but your #'s are good anyway.

Since you did say you have good spark, and you did test your coils resistances to be sure right? Then yes it's beginning to look like you have carb issues. You could always try the carb cleaner route, UCL in the gas, and squirting C Cleaner into the carbs with the bike running, BUT if there are any fully clogged jets or passages, neither will fix it. Like any good fluid it will just go the path of least resistance and bypass your blockage. Your probably going back to the church. Have you done a plug chop to see what your plugs tell you?

To your trickle charger questions yes, yes, not a concern if it's solid state (ie not from the 70's)