Topic: cb550f running at 10mpg

[Bru-tom]

Good call on the 1000 coils. Better would be GL1500 coils. Modern, reliable and you can get 3 for a song.
I had a brand new, ill-fitting Emgo air filter. If you have one, throw it in the neighbor's yard and get an OEM. Night and day.

thanks for the heads-up.

would this also require a ballast resistor as Deltarider mentioned? i guess the best thing to do is measure and see. I have done a ton of reading about coils and leads and discharge time of original and aftermarket performance coils, i think with the higher output voltage, ballast resistor and 5k plug cap to increase discharge time, it will be a nice upgrade with the new points iv ordered

[spotty]

when i saw the title of this thread i wondered if maybe you had accidentally put a vmax engine in.....

[tlbranth]

Good call on the 1000 coils. Better would be GL1500 coils. Modern, reliable and you can get 3 for a song.
I had a brand new, ill-fitting Emgo air filter. If you have one, throw it in the neighbor's yard and get an OEM. Night and day.

thanks for the heads-up.

would this also require a ballast resistor as Deltarider mentioned? i guess the best thing to do is measure and see. I have done a ton of reading about coils and leads and discharge time of original and aftermarket performance coils, i think with the higher output voltage, ballast resistor and 5k plug cap to increase discharge time, it will be a nice upgrade with the new points iv ordered


I'm quite sure you won't need a ballast resistor with GL1500 coils. Guys have used them on GL1000's and CB's direct. Good thing to check though 'cos I've been wrong before. I'm pretty sure you'll need to do some 'customizing' to get them mounted. I'm sure there's someone here on the forum who's done it.

[TwoTired]

My understanding is that Goldwing coils hav 2.4 ohm primaries.  These will draw twice as much current through the points, which will shorten their useful life.

Further, these are actually 6V coils that only run on 12 V during engine start on the Goldwing, after which they operate with a ballast resistor dropping the voltage down to 6V or so for normal run operation so they don't operate too hot.

Can you get way with a direct swap into an SOHC4?  Probably.  Does it follow good engineering practice?  I'd have to say no.  There's going to be some trade offs, like point life, taxing the charging system, and possibly shorter coil life due to higher heat operation.

I'd do it in a heartbeat after the apocalypse to keep the machine operable.  But, if proper parts are still obtainable, not without additional alterations.

Cheers,

Cheers,

[scottly]

My filter set up is a custom one. I have modified the plenum intake to house a custom filter box. I have removed it entirely and there is no change in this rich condition the surface area is exactly the same as original, so with no filter attached it should break just as well as the original setup would....

Sooty spark plugs ARE NOT caused by ignition problems! No fire, no soot. Once carbon fouled, there will be no spark, but the original cause is an overly rich condition, not an ignition problem. Since you have a "custom" filter, this would be a likely suspect. Please post a picture.

[tlbranth]

 I looked at the ignition wiring diagram in my GL1500 shop manual and saw no ballast resistor but the primary resistance is 2.6-3.2 ohms. My CB750 shop manual doesn't specify primary resistance so I'll defer to 2T.
If the 1500 coils will only work with a resistor, I'd just buy 2 Dyna coils. Oh wait, that's what I did. They bolt right up and you can get the primary resistance you need.

[scottly]

Terry, I'm guessing that the GL1500 isn't a points ignition.

[TwoTired]

Terry,
The stock SOHC4 coils are 4.8 to 5 ohm primaries that are switched by points.

Dyna offers coils in both 3 ohm and 5 ohm primaries.  The 3 ohm ones are intended to operate with their dyna ignition triggers.  But then, 3ohm and dyna-s draws too much power for use on SOHC4 bikes smaller than the 750.

Fyi

Cheers,

[dave500]

check the plug cap resistance,bad ones WILL cause sooty plugs full stop.

[BomberMann650]

5km per liter

11miles per gallon

Figured out why your fuel milage is low..

Pesky metric conversions :p

[robvangulik]

5km per liter

11miles per gallon

Figured out why your fuel milage is low..

Pesky metric conversions :p

Liters are consistent around the world, whereas gallons are different depending on where you are...

[Bru-tom]

Hey guys. Sorry for the late update.

Okay, I ordered an new OEM Tec ignition assembly for the bike, it arrived and it’s beautiful points shoes have grease and oil is applied to the felt pad☝️



With a few other bits, no more squeaky brakes



Ok, so I sorted the timing out, it’s spot on; advance mechanism serviced etc. bike still runs rich.

The new intake boots are there to make it easier for me to remove the cars from the engine easier. I think that’s where I’m headed, again🤦‍♂️

My plan, before I remove the carbs, it’s to run some velocity stacks I have laying around, and observe the fueling issues then. This will eliminate all intake - to - carb questions. If all else fails, I will remove carbs and confirm float levels in the bowls with the tube method to eliminate that aswell.

I went to a meet yesterday and an old chap asked what changes did I made. So I said, only intake and exhaust. Both of which should have made my bike run leaner if anything. But, the exhaust is also a non stock item. An item that this bike never ran with nor was jetted for. He said lots of the local guys overlook the tube diameters the local suppliers stock and often go with a smaller ID🤷🏻‍♂️ so, that would surely cause a rich condition if all else is stock!?


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[Robbo]

What spark plugs are you using?

How many turns out do you have each of your carb air screws set to?


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[Bru-tom]

What spark plugs are you using?

How many turns out do you have each of your carb air screws set to?


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I am using D7ES as I have 5k resistor plug caps...

I have 2.5 turns out from bottom


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[Robbo]

What spark plugs are you using?

How many turns out do you have each of your carb air screws set to?


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I am using D7ES as I have 5k resistor plug caps...

I have 2.5 turns out from bottom


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Okay good so the D7ES are stock.

The air screw setting should be 1 1/2 to 2 turns.  With being so rich I can understand you having set them to 2 1/2 turns to try and compensate.

So another couple of questions for you...

Are the plugs black dry sooty carbon or black and wet?

Did you have the same issues before you changed the airbox and exhaust pipes?




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[dave500]

the carb slides aren't in backwards are they?

[Bru-tom]

Okay good so the D7ES are stock.

The air screw setting should be 1 1/2 to 2 turns.  With being so rich I can understand you having set them to 2 1/2 turns to try and compensate.

So another couple of questions for you...

Are the plugs black dry sooty carbon or black and wet?

Did you have the same issues before you changed the airbox and exhaust pipes?

If I turn the screw even farther out, it makes little to no difference🤷🏻‍♂️

Plugs are black:



That’s from a 10min ride🤦‍♂️

If I really try hard to think back, and I don’t think I really paid much attention to this back then, but I can’t remember 🤦‍♂️ I do have a video somewhere that I will look for with my mate riding behind...

[Bru-tom]

the carb slides aren't in backwards are they?

Please confirm which direction they should face if I remember correctly, when I did the bench synch, the flat part of the slides faced then engine? They also have slots so they can’t really be reversed, not?


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[calj737]

I know you stated you got the jets from Harisuluv, but would you mind pulling the IDLE jetsand confirming their actual size and brand?easy enough to do with the bowls off.you could also verify the MAIN at the same time.

It is possible Haris sent you wrong jets, or inadvertently had a set of drilled jets from another set of carbs and passed them along. Not usual rom him, but he is human after all.

[Robbo]

+1 what Cal says above.


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[Deltarider]

Boy, this is a difficult one... assuming you are running the brand new ign. plate. Forgive me for asking the obvious.
Are you sure resistance to the plugs is around 5kΩ? You don't use resistor or carbon core wires, do you? BTW, personally I don't like my plugwires to contact the frame (or ground in general).
At idle does turning fully in and out the airscrew of one carb give any change in rpm? (It should).
If the overrich problem stays even after removing the airfilter, IMO it can only be too much fuel drawn.
That could be caused by a too high fuel level, main jet O-rings that don't seal well or overwide slow jets. 
One turn is 360^o right?

[dave500]

the carb slides aren't in backwards are they?

Please confirm which direction they should face if I remember correctly, when I did the bench synch, the flat part of the slides faced then engine? They also have slots so they can’t really be reversed, not?


the cutaway faces the filter,the slides are lefts or rights and can be installed incorrectly.


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[Bru-tom]

I know you stated you got the jets from Harisuluv, but would you mind pulling the IDLE jetsand confirming their actual size and brand?easy enough to do with the bowls off.you could also verify the MAIN at the same time.

It is possible Haris sent you wrong jets, or inadvertently had a set of drilled jets from another set of carbs and passed them along. Not usual rom him, but he is human after all.

Will do that as soon as iv tried the velocity stacks i have  i spent the whole day cleaning them yesterday so its only fair that they get a bash

how would i got about measuring such tiny holes though? if they were drilled to a large diameter that is...

[Bru-tom]

Boy, this is a difficult one... assuming you are running the brand new ign. plate. Forgive me for asking the obvious.
Are you sure resistance to the plugs is around 5kΩ? You don't use resistor or carbon core wires, do you? BTW, personally I don't like my plugwires to contact the frame (or ground in general).
At idle does turning fully in and out the airscrew of one carb give any change in rpm? (It should).
If the overrich problem stays even after removing the airfilter, IMO it can only be too much fuel drawn.
That could be caused by a too high fuel level, main jet O-rings that don't seal well or overwide slow jets. 
One turn is 360^o right?

yep, brand spanking as seen in the pics above. i will confirm the plug caps measure 5k, they were brand new when i rebuilt the bike. i did see once, when i brought the bike into a dark garage that i did see the occasional spark jumping off the wires onto the frame. i want to replace the plug wires sometime and join new ones, epoxied into the coils... i will try insulate them as best i can in the meantime and see what happens. they all have the same burn pattern though, its impossible for all of them to burn the same if there is a spark issue periodically, right?

the air screw does change the way the bike runs. i will try make adjustments this afternoon when i install velocity stacks and give feedback. I will also recheck the main jets o-rings.

yep, one turn is 360 deg..

[Bru-tom]

the carb slides aren't in backwards are they?

Please confirm which direction they should face if I remember correctly, when I did the bench synch, the flat part of the slides faced then engine? They also have slots so they can’t really be reversed, not?

thank you. i will confirm later

the cutaway faces the filter,the slides are lefts or rights and can be installed incorrectly.


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