Power loss at 4000 rpm?

[trolle]

I have now finished installing the Omega digital ignition control, I have adjusted the carbs (new needles and other stuff last year) and the electric system is OK. Never the less there is a very distinct loss of power around 4000 rpm. This is especially notable in strong headwinds (>10 m/s)  in the fifth gear and I have to go down to fourth to get past 55 mph. As soon as the engine is running past 4200 rpm in fifth, there are no problems. The problem arises both with a cold and a warm engine. The ambient temp. was 40-45 F

I pulled the plugs to see their state. They looked a bit pale, i.e. the mixture might be a bit on the lean side.

I need some advice before I start pulling my carbs apart.

Other than this, the Omega works like a dream: No failing sparks at any level of rpm; for the first time in four years the engine is completely steady when idling, no stuttering and there is much more power for acceleration.

greetings from a norht with varying cloud cover and  tolerable driving conditions (dry and 42F)

trolle

[Justin B.]

Maybe switch the wires back to the stock ignition just to eliminate the Omega as a possible culprit?

[trolle]

I have thought of that as the first step in my error finding procedure. No the second step, because I checked the ignition time setting and adjusted it, which did not make the powerloss go away. So my next step will be switching back to "normal" and trying that out.

BTW in my search for possible solutions, I came upon this:  http://www.theultralightplace.com/bing.htm

greetings from a north with varying cloud cover and  tolerable driving conditions (dry and 42F)
 
trolle

[nhmaf]

When you adjusted the timing, had the full advance mark appeared in the timing window by the time you reached 4000 RPM ?   If it had done so, and the
timing at idle was correct, I would suspect either an air leak somewhere in the carb boots to the intake or possibly a jet that is sticking (though also a
misaligned or punctured diaphragm in the carb could also account for this).

Please keep us posted as to what you discover !

[MrRiden]

Classic indication of a leaky diaphragm. However do not overlook checking your spark advance is at full advance as you reach 3,000 rpm with a reliable timing light connected to a power source that is not the bikes battery. Valves adjusted? Head torque? floats not set too low? you might also try raising the needle jet a notch if all else checks out.
rich

[trolle]

Thanks for the advice. I will start out with the easy things: Checking diaphragms and needle positions - I installed new diaphragms, needles and nozzles last year, and new floats. If that does not help I will go on and check the valve settings (I am quite anal about those, as Rob would put it) and when the tops are bare,  torque the tops of course.

I have considered raising the needles one notch, as the plugs looks rather light in colour, but this may be due to a better burn caused by my new high performance coils giving a better spark and not a too lean mixture, although my new airfilter might let more air through than the old one. My logic or my intuition tells me that raising the needles will result in more power as the increased amount of gasoline will "fit" the better spark and the increased amount of air. Having no measuring tools I have to go by ear and intuition.

Any comments on my "logic"

greetings from a sunny and windy north with wet roads and temps of 40F, mediocre riding conditions

trolle

[Rob Valdez 79 R65]

Are you running a OEM factory spec air filter?  If not, then some fiddling may be in order.

Do you still have those inline fuel filters on the bike?  Are they fresh and flowing well?

Have you performed Justin's suggestion of removing the Omega from the equation?

[trolle]

Hi Rob

Are you an early riser or a night bird?

The filter is probably made to OEM specifications - it says so on the box anyway, and I have no reasons to distrust the manufacturer.

The only filter in the fuel lines is the one sitting in the tank above the petcock, and although I have not checked it resently, I do not think it has been clogged.

I am rather busy at work these days, so I have not had the time to do all these fun things to the wh8la2 yet, but if the weather allows it, I will spend some time in the garage this weekend.

greetings from a still sunny and slightly less windy north, where the roads have dried and the riding conditions improved

trolle

[Rob Valdez 79 R65]

I was looking at your website to determine which air filter you use (flat) and I saw the photo with the inline fuel filter.
I guess that was an old photo, no longer applicable?

I am a night-owl that works 2nd shift.  I get off around midnight.  Last "night" I turned out the lights at around 6am...

[trolle]

Hi Rob

May be I should bring my site up to date  [smiley=nopity.gif]

I checked the diaphragms and their placing - they were OK. Thursday next week I am going for a round trip of 400 miles so let's see how things are then.

greetings from a grey and moist but warm, 43F, and calm north, conditions demanding careful driving

trolle

[trolle]

Update of measures: Moved the needles up one notch and checked the valve settings, they were OK, a loose .15 mm on the exhaust side and a firm .10 on the intake. Took the wh8la2 for a short spin down the highway to test the power. Conditions were dry, 42F and a very strong headwind above 12 m/s. When we reached the 4000 rpm the throttle was wide open, but it did not feel like a drop of power, more like the top. After a few 100 meters the headwinds subsided a little and I was able to bring her up to 6000 rpm.
 
Then the ignition disappeared (due to a  connector which worked loose and resulted in a major backfiring) and it was time to switch to the "beancan", no real difference, so I think that the Omega is aquitted. 650 cubic cm and 50 HP just is not enough to accelerate a 185 cm, 90 kg driver from 50 mph to 82 mph in fifth gear and in strong headwinds in an acceptable time. There is a flat spot around 4000 rpm which must be circumvented by going down one gear when accelerating the bike from 50 to 82 km/h under those conditions. (82 mph being the speed limit on our motorways or freeways [US])

On the return, with the wind in my back, I of course had trouble keeping the old gal below 140 kph ~ 88 mph.

After this short ride, 30+ miles, I checked the plugs to see their colour, which was a nice tan, not too light and not too dark.

Tomorrow I will make the final adjustments on balance and idle and fix the loose connection.

greetings from a percipitating north - bad riding conditions

trolle

[trolle]

The backfire referred to in the my posting above opened the left muffler all the way along the welded seam! It must have been rather loud [smiley=1drink.gif] [smiley=rifle.gif]

I hope my problems are solved by the way: The missing power  was probably due to the loose connection, which may have enhanced the natural? flat spot around 4000 rpm.

For those of you who wonders, why the left muffler and not the right as well? the answer might be a hanging choker on the left side, due to a worn cable, making the mixture richer on the left side and therefore more combustible.

Well after this experience my need for more exact tools than my ears, which may be damaged by the loud banging of my backfiring engine, became so great, that I had to drive to the nearest bigger town, where such tools are for sale. The shop lies 39 miles from my home and 35 of the 39 are on a motorway with very little traffic. (the result of a political deal made by a couple of very astute local MPs in the nineties, giving me and several others a perfect testing range).

On the way out I had a fair headwind and of course wind from the back on the way home. This time every thing worked precisely as I wanted it to. A steady 84 mph on the way out and a steady 90 mph on the way home. At one time I touched 103 mph still having power in excess. No signs of wobbling or other vices. Made the final adjustments of the idle and throttle, and exchanged the busted muffler with an old spare.

Well, I changed the needle position back to second notch because I found the gasoline consumption a bit high (170 miles on a full tank).

And what did I buy in this shop? One ignition test lamp (stroboscopic) and one compression testing device. The former showed that the ignition is OK and the latter has not been in use yet.

Status till now: Everything works as it should, the causes of the problems may be found and even though the wh8la2 looks like sh*, she is a very wellbehaved lady.

greetings from a precipitating (not again!  [smiley=drowning.gif]) north with bad riding conditions = wet and cold roads

trolle

I am getting good at keeping my own threads alive [smiley=happy.gif]

[nhmaf]

Trolle,

Your posts are often informative, and always entertaining -  I mean this in a complimentary way !

Good luck with replacing the mufflers - what are you planning to replace with ?

[trolle]

  I have just written the most funny and entertaining posting and then it disappears, just because I needed this link:


http://www.bmwandguzzispares.co.uk/bmw/products/product.php?f=i&code=BA_15_20_YA_60&shnew=New&model=R45/50/60/65/75/80/90/100%20(2%20valve)&shnewcode=15&part=Stainless%20steel%20fasteners&sub_part=S/S%20brake%20parts&modelcode=20&partcode=YA&source_code=BA_15_20_YA_60&spPage=1

Well that is life.

What I wanted to say was this: Having no children at home, a reasonable salary and a wife, who after a trip to our capital returned with the words: "I couldn't find anything to buy" I can afford to buy a lot of not very necessary things for the wh8la2, like new mufflers when the old ones look dirty, new electronic ignition although the old beancan is no more than three years old and works just like it should, superflous tools like the ones mentioned in my last posting and so on. The point is that I have not had a real hobby before and with the r65 I have found something which at the same time satisfies my love of problem solving and my penchant for dangerous but controllable situations.

Back to reality: I have a pair of old mufflers lying about, and they are quite usable. The only reasons for exchanging them with new ones was that the right on was newer than the left and that I found a new pair on Ebay, that I got at half  of the store price.

This leaves me with a problem! Now I have to by a new pair because ...

greetings from a wet north - bad driving conditions, dark, wet and cold

trolle

[Ed Miller]

Do you have that HPN (...I think that's the company....) catalog?  There's a way to spend money.