Re: I found something cool I think Need a k&b expert

GallopingGhostler Sun Sep 11, 2022 3:31 pm

davidll1984 wrote:How much does this one weigh? Nos compare To exact same size from different brand made!!?

http://sceptreflight.com/Model%20Engine%20Tests/K&B%2045%20Sportster.html

April 1988 Model Airplane News wrote:Checked Weights: 13 ounces (369gm) bare; 15.9 ounces (450gm) with muffler; 16.2 ounces (459gm) with muffler and firewall mount.

David, you'll have to check out the engine reviews on http://sceptreflight.com/Model%20Engine%20Tests/Index.html. I did some quick checking with the .45 - .46 engines. The Fox .45 Schneurle was lighter and so was the Enya, but the MDS .46 and OS Max .46FX were heavier. If article doesn't mention weight with muffler, then assume it is weight without muffler.

The K&B .45 Sportster is not the lightest, but is not the heaviest either.

The older .45 cross scavenge engines are lighter, but they have roughly half the power.

davidll1984 Sun Sep 11, 2022 4:49 pm

More informations on this engine it has a funny working carburettor:huh: that works this way. the k&b sportster is equipped wit a automatic mixture control .this is the type in which fuel is metered by the rotation of a tube surrounding the jet tube the jet tube has a tapered slit jet and the concentric outer tube which move wit the throttle barrel that has a radial hole that uncover more of the slit as the throttle open The jet tube incorporates an outer disc which can be rotated a few degrees either way by an eccentric screw to adjust the mixture compensation at half (part) throttle this system seems effective and must work just fine when it's adjusted at the right position

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Oldenginerod Sun Sep 11, 2022 8:22 pm

I think the carb is the same principle as a Perry which also uses a "mixture disc", although the perry just has a manual adjustment with notches in the housing to align, where the K&B has the eccentric screw. In my examples the carb adjustments work very well.

davidll1984 Mon Sep 12, 2022 10:29 am

Oldenginerod wrote:I think the carb is the same principle as a Perry which also uses a "mixture disc", although the perry just has a manual adjustment with notches in the housing to align, where the K&B has the eccentric screw. In my examples the carb adjustments work very well.

Yes it is in fact very similar but has fewer components and the mixture disc is well identified + -

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But different at the same time the operation of each is similar but different the two models must have the same characteristics and give Good result look close inside the rotating barrel is a tube in the middle

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GallopingGhostler Tue Sep 13, 2022 3:50 am

I haven't gotten around to figure out how the idle mixture disc apparatus works. On other engines (OS, Enya, Thunder Tiger, Magnum, HB, Fuji, Norvel, etc.) use a simpler idle bleed hole adjustable by a side screw to choke it off. My OS Max .10R/C doesn't even have an idle adjustment, just a filed spot inside the throat opening of the rotating barrel element, yet it has one of the most amazing reliable idles ever of a small engine. (At only 3.1 ounces weight with a movable exhaust baffle instead of muffler, it is one of the best engines to upgrade a half-A RC).

I do have one engine with a Perry carb, a well worn out Enya .15-III TV.

Fox uses a slightly different method.

However, I haven't mounted any of my Sportsters yet in a RC plane to harness its work, to really know more about the disc.

Ken Cook Tue Sep 13, 2022 2:44 pm

The carbs work well and adjusting them is simple. The screw doesn't have to move very far to achieve a difference.

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