Topic: Pertcock question

[anotherCB]

I have a problem when accelerating hard with my K7. When I rev 1st gear to red line, immediately shift into second, the engine "bogs" down when continuing to accelerate. If I wait a few seconds before accelerating in 2nd, everything is fine. Could the problem be a clogged petcock, resulting in less than normal flow of gas into the carbs? The accelerator pump works, I checked and see a "squirt" of gas in all 4 carbs when opening the throttle. Thanks everyone for your input.

[Bankerdanny]

If you can pull redline in 1st it seems unlikely to me that the issue is a clogged petcock. If you weren't getting sufficient gas flow I would think that it would show up at the upper rev range even in 1st.

At any rate, with the fuel line disconnected and the tap on do you get a steady stream of fuel out of the line?

[anotherCB]

The difference is that when I start in 1st gear, I have most likely been standing before so the bowls are full. Then by the time I shift to 2nd, they might be partly depleted and not totallly refilled. When I wait 5 seconds before revving up in 2nd things are fine.

I get a staedy stream, but i have no comparison how much of a flow there should be. It's definitely more of a flow than a trickle. Does anyone have a "flow rate", like so many cups per minute or something like that?

[TwoTired]

In technical terms, "bogs" doesn't make the list.

But, my guess is your accelerator pump has a problem.

Got any spark plug deposit info?
Got any tune up history info?
Got any induction/ exhaust modification info?

As for flow rate, what is your MPG?  It has to flow as least that well.

60 MPG @ 60 MPH uses 1/60 of a gallon per minute.  If I did my math right...

Cheers,

[Bankerdanny]

The difference is that when I start in 1st gear, I have most likely been standing before so the bowls are full. Then by the time I shift to 2nd, they might be partly depleted and not totallly refilled. When I wait 5 seconds before revving up in 2nd things are fine.

I get a staedy stream, but i have no comparison how much of a flow there should be. It's definitely more of a flow than a trickle. Does anyone have a "flow rate", like so many cups per minute or something like that?

I can ride normally for a few munites with the tap off before I start to hesitate from lack of fuel. A single redline pass should not be sufficient to empty the float bowls absent a big bore kit and much larger jets. Also, as you shift revs fall and vacuum with it, which should slow the draw on your fuel supply.

I agree with TwoTired that is sounds more like an accelerator pump issue than fuel flow.

[anotherCB]

Good points guys! Here some more info:

I am using 120 main jets (original I think is 110 for the K7), Pod filters and the Yoshimura 4 in 1 from motogpwerks. Plugs look as they should, light brown, no deposits, ignition is the original with points which I adjusted recently. When riding hard, I get about 40-45 mpg.

When I take off the air filters and open the throttle, I see that the accelerator pump works and that it squirts gas in the carbs, however i have no experience on how much there should be. I recently rebuilt the carbs completely and didn't find anything wrong. Bike was a daily rider when i bought it.

[TwoTired]

Plugs look good. throttle response bad.   Accelerator pump weak.

But, with pod filters it could be pilot circuit lean or slide needle taper wrong.

[anotherCB]

How much should the accelerator pump squirt out? Is there a video somewhere?

Coming back to the math, I think it should not be based on 60 mpg at 60 mph, because there needs to be enough gas flow to sustain high speeds. To keep the math easy I assume 120 mph at 30 mpg, which would come out to 4 gal/hr or 4/60th of a gal per minute (4 times higher than what TwoTired listed before). This is roughly 1 cup per minute, if I did the math right.

[anotherCB]

Ok, I have some more input. I don't think the petcock is the problem, I am pretty sure now I am running way too lean. Since I didn't have larger jets handy, I used masking tape and covered 75% of the pod filters, in other words restricted airflow. This makes the bike run richer since more gas (larger jets) or less air should have similar effects. Results were promissing, the bike ran really well!

Now my question is how much larger should I go on the jets? Original for the bike are 115 mains, currently I am running 130s. When I cover the filters like in the photo, bike runs well. Exhaust is a 4in1 Yoshimura copy. Should I go to 140s or larger? Thanks all!