Single Carb Conversion Testing - Part 2: Single Carb setup with Stock Jets...lets bust some Myths

Рет қаралды 510

7 ай бұрын

Setting up the Single Carb manifold as well as an easy way to check for manifold leaks. For Part 2, the single carb is setup using the stock 122 main and 41 Pilot so we can bust some myths on if the one carb can do the job of the duals since the cylinders don't fire at the same time. We will also see if it's the manifold that increases the low RPM torque or if its that the carb will need to be re-jetted.

Пікірлер: 11

@GarysnewYT 7 ай бұрын

Hi There Steve, All of these tests are very interesting. I appreciate all your work. Thank you very much.

@StevesDIYs 7 ай бұрын

Thanks man 👍. Yep, it turned out to be very interesting for sure. All the best ! Steve

@samizdat113 2 ай бұрын

I subscribed. Great content. Auh-ryte

@StevesDIYs 2 ай бұрын

Thanks ! All the best ! Steve

@maxwellleckie960 7 ай бұрын

Where did you find these claims? They're only partially true under the right circumstances. Carbs don't only supply fuel and air for the intake stroke but also during the other strokes. The manifold doesn't just have some or 0 pressure so on on a graph looks like a sin wave. As intake closes, air will still come through to correct the pressure from atmosphere and vacuum causing fuel to release and retain in the manifold which is factored into the main combustion charge next intake cycle. Since viragos are 60° v's, they arent evenly firing/ balanced. On a graph the amount of dead space between intake strokes is 120 for rear and 240 for front (clockwise rotation on diagram). Which for a carb tuned for 1 cyl would net lesser fuel for one and even less for the other. since they don't have the usual post-intake fuel. This is why you have one cyl leaner than the other. So, the single carb: 2 cylinders advice rings more true on even firing engines like a parallel twin, or v4, rather than a 60° v. But even then no single carb tuned to a single cyl will ever fire two without fuel charge loss without re-jetting due to the 'fuel after intake' principle I just mentioned. You would see the torque change after rejetting the single, but would need a dyno to really actualize. Good testing but poor starting claims though, keep it up. I love watching tests I didn't have to do myself.

@StevesDIYs 7 ай бұрын

Thanks man and thanks for the details as others reading the comments can get more detail on as to why the two cylinders pull fuel differently 👍. The fact or fiction items come from various Virago forum posts I’ve seen over the years as folks talk back and forth on why a single carb and manifold can perform as good as the duals. I’ve wondered about the single carb setup myself as I’ve always run the stock duals (rejetted, intakes and exhaust opened up, etc…but still dual carbs) so doing the tests confirmed I like dual carbs better. I’ll probably do some more testing with different designs just to see, but it did confirm several of the speculations by folks were incorrect. Thanks again and all the best ! Steve

@robosborne6514 7 ай бұрын

That's interesting & really good to know How many miles - kilometres do you get out of your motorcycle. I'm only getting 200ks from mine.

@StevesDIYs 7 ай бұрын

Thanks 👍. My stock 1981 750 gets the same as you mentioned…right at 200 km (125 miles) before hitting the reserve under normal riding conditions. The bobber that has air pods and an open exhaust (I re-jetted the dual carbs to account for this) only gets about 165 km before it hits the reserve fuel. In Part 3 of the carb testing, we’ll see something similar on the drop in fuel economy since I had to re-jet the single carb to be able to get the AFR low enough to run the motor.

@robosborne6514 7 ай бұрын

@@StevesDIYs ok Kool, thanks so much for the reply, appreciated,.

@minerma 7 ай бұрын

I can't wait for the facebook engineers to react

@StevesDIYs 7 ай бұрын

Lol ! Yep, I’ll say the comments will get interesting for these videos…especially the Part 3 one as it shows the testing and comparisons for the single carb manifolds. I actually left the checks for the manifold leaks in just so that question wouldn’t come up as well as put the dual carbs back on after the testing in Part 3 to show that the motor hadn’t changed any after all of the tests. All the best ! Steve