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)

 

This bike only sat for 3 weeks then played up? It must be something simple....when running, are one or more of the headers cooler than the others?

 

I was dealing with the same issue every time I had to leave my bike sit while I was on the road for up to 2 weeks at a time. I used seafoam at 1oz/1 gal. It will clear up the mess from the fuel after 1, or 2 tanks. If you want a faster option. Pull the carbs, and shoot the passages with cleaner.

Merc.
Most of the big name suppliers (shell, marathon etc..) that carry top tier fuels limit the ethanol to the 87 octane. The off brand suppliers is where you need to watch out. And now with the new biofuel blends it will get even more fun. Diesels may run on corn oil. Gas engines do not.

Ghost

 

I will do a resistance test on the coils this weekend. I did not notice one of the headers being cooler than the others. I'll check. I drained the gas tank and put a high octain fuel in with StarTron. New inline fuel filter. Still no real power and off on the engine sound pitch. I guess I need to make a decision to try the Seafoam or pull the carbs and start cleaning again. If I run with the Seafoam for a tank or two I won't damage anything will I? Thanks for all your input.

 

Check the spark plug caps and be sure you don't have a loose resistor core (they screw in, inside the cap.)

Just for kicks, fit a BRAND NEW set of correct, properly-gapped spark plugs.

 

I checked the resistor cores in the plug caps. When I inspected the inside of each plug cap I only found two that had a slotted insert that must have been the resistor core. They were both loose so I tightened them. The plug caps that had the resistor core installed had a deeper boot then the other two without the cores. The two shorter booted plug caps without the cores did not have any threaded hole to install a resistor core. Is it installed in the wire connection farther up in the boot? Did not make a difference in performance after I did tighten the two cores. I did check the primary and secondary coil resistances. They were:

right coil - primary 2.5 ohms, secondary 22.7k ohms
left coil - primary 2.6 ohms, secondary 27.9k ohms

From the Yamaha manual it looks like the maximum resistance on the secondary was 13.2K ohms, so both are out of spec.

How can I get the colortune to work if the coils are out of spec?

I went to install new plugs and found #4 sooted up. #3 was not looking to good either.

So am I looking at new coils, wires, and plug caps along with pulling the carbs again for a cleaning?

 

The OE plug caps don't look the same there should be a pair of 'long' caps and a pair of 'short' caps, and they do not have any resistor higher up the wire. Sounds like a part swap, what kind of plugs are you using (resistor or no). Those are bad #'s on your coils secondary for sure-you did do the test from plug wire end to plug wire end with no caps attached right? If not repeat the test that way, but even so the higher resistance in your left coil suggests a problem.

With that much resistance they will still generate a visible spark, but that is usually all it is and not sufficient to ignite-the reason is the pressure they're under. When you pull the plug it doesn't have to fight 140psi air/fuel mix to spark, under Normal conditions it MUST be strong to ignite the mix. Good bet most of your problem is related to this. Your carbs might actually be ok and not need a new trip to the CoC.

Your primary resistance looks ok though so your issue could just be the wires. At this point, assuming those results are correct, you have two options, do surgery on your existing coils and hope that fixes it (basically fit new plug wires by splicing into the coil (note: if you are familiar with electronics this is not hard otherwise it is a hard job), or you can replace your coils, & wires and likely be good to go. Used is cheaper but no guarantee of quality, there are some new A.M. sets that will improve performance over stock.

 

I used the non OEM Dyna coils that chacal sells. But I also replaced all my caps.

 

I thought these were original coils, wires, and caps. There are two short and two long plug caps. Original Japanese company name on the caps. I think the long plug caps had the screw in resistor. Maybe it is just an adapter for the spark plug. I measured from inside each cap. That was what I saw in the Yamaha manual with the primary disconnected. How do these caps come off? It looks like a molded connection to the wire. If I can get the caps off I will take a measurement at the wire ends.

If you use the Dyna Coil you must come up with a new mounting scheme correct? You would also have to make up a connector on the primary side.

 

You didn't get a bad load of fuel by any chance? Water in tank?

 

I don't think it was a bad tank of gas. I think the bike sitting for 3 weeks just gummed up the fuel system. I don't know what I am going to do to store it this winter. I have run my 4th tank of high octane and StarTron through and it seems a little better response on the throttle. The engine evens sounds more like it should. The problem now is I pulled the plugs to take a look at them and #4 was black soot. Not oily. So with the coils out of spec and now I am fouling plugs I am just going to pull the carbs and go through them again. I am also going to look into some coils, plug caps, and wires.

 

Forget the high O it won't do any good and is totally not needed. If #4 is the only sooty one then your looking at dirty carbs, pilot mix is off, or a bad synch, or a combo-plus obviously your coil might be an issue as well. Be sure and double, maybe triple check things before you decide they are bad, I had a high idle I was sure was an air leak and I had just forgot to readjust my idle screw after doing the carbs.

As far as for winter you need to run good 89 octane with UCL (SeaFoam, StarTron, STP UCL) or similar through it and then either drain your bowls or leave em with the UCL's in and run it every week or so. You can also use fogging oil which will keep it corrosion/gunk free for months w/o running it.

I know this seems like a puzzle that just won't come together, but it will and once it does and your consistent with your maintenance and fuel issues you won't ever have this problem again. It's just a symptom of an old machine, bad fuel, and needed maintenance.

I started with a too lean 550 (were talking lilly white plugs and not able to idle in stop and go traffic w/o overheating), which progressed to missing at low rpm's and 35mpg, to now being spot on, tan plugs, 53mpg, and a 12.9sec 1/4mile-spec says top speed should be 113mph, I hit 117mph (at Hallett motor racing circuit, too paranoid to do it on the street) measured by GPS. I have smoked several 2000+ year model 600's with a 528cc based on 1981 technology, so hang in there--you can do it.