Bike won't sing

[Bob K]

My bike runs really well. It idles solidly, it climbs really well, it starts perfectly,it's a bit cold blooded.
On the flat and level it runs about 30 ( maybe 33 mph) which is fast enough.
But ,
It sounds crummy. Like its' straining. The plug comes out light chocolate colored
and yet, it runs better on the flat and level at like 85% throttle.
Is this the engineered-in rev limiter? Timing,mixture? ideas?

 

[zwebx]

what engine?
was it a new plug that you used?

 

[Fabian]

If you are doing 33 mph on the flat, your bike is singing a lot better than mine.

Sometimes my bike is flat out at 5 mph and it's well and truly working it's guts out.

 

[Deleted member 12676]

liking 85% throttle means the main jet hole needs to be slightly enlarged with a micro drill bit or replace the jet with a slightly larger one.
What oil to gas ratio are you using?

 

[Bob K]

I'm running 32:1. And I replaced the leaking chinese plug with a NGK. It ran better when I put in the NGK.
I'll have to try opening up the main jet. I have no idea what is in the carb at this point in time.
I understand these carbs can use Delorto jets. Anyone have a preferred vendor?
Just in case I mess up this one. With the ethanol they put in the gas around here I really do not like
the long term stability of solder as a repair.

 

[Bob K]

I have been doing little more than riding my bike and it runs the same as always, which is good. After searching the forums for carb tuning, I am wondering.
Is it better in my case, just to turn down the needle tip a .001"( or so to start) to richen the top end? I really do not want to affect the rest of the power band
as it is "spot on". I have a low restriction aircleaner and a SBP pipe with extra muffler. Ideas, opinions,experience?

 

[Deleted member 12676]

top rpm running is the sole property of the main jet. the needle is from crack of throttle to 3/4 throttle.

 

[Bob K]

top rpm running is the sole property of the main jet. the needle is from crack of throttle to 3/4 throttle.

I hear what you are saying. However, as these carbs are not well supported with needles
( like a nice mikuni , say ) I was thinking it might be an option. Otherwise, its' just a bigger main jet
and drop the needle to maintain the rest of the crack to 3/4 jetting which is very nice.

 

[Bob K]

Let me re-phrase this.

After searching the forums, I have found that a bigger main jet upsets the idle and mid range on stock carbs.

Lets be real, on these stock carbs everything affects everything. I guess I am on my own here.

I will measure the tip of the needle and turn it down .001" and see what happens.

I will not move the needle up or down.

Lets see.

Next week , results....