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Originally Posted by Ruune
(Post 7464616)
in this case, both aerodynamic and fluid dynamic laws apply here. Smooth surfaces have less drag coefficient, due in part to reduced turbulence generation and reduced exposed surface area. The only advantage that a less smooth surface could provide would be increased atomization. Due to the velocity of the air moving through the engine at operating speed, this is a moot point. The vaporization point of nitromethanol in a vacuum environment (carburetion) is typically below the operating temperature of these engines anyways. This will vary, based on lubricants and additives.
Lastly, from the point of entry (carb venturi) to the cylinder, the fuel/air mixture is under vacuum. That is unless you're running forced air induction (supercharger). So, the mixture is being pulled- not pushed. The rest of the flow theory and things I will leave up to you guys :cool: |
Originally Posted by kyle133
(Post 7463823)
then why do people who build full size race motors spend so much time port matching and polishing intake runners on race motors?? :rolleyes:
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Originally Posted by JAMMINKRAZY
(Post 7463513)
That crank in your pics is an OS Speed crankshaft. It is drilled and THEN filled as 22racer said. The drilling is what does the real magic in that it lightens the crankshaft making throttle response more crisp. The epoxy just fills the empty void created by drilling, and brings crankcase volume back to what it was before the drilling. Simply adding epoxy to the crank ramp will not do anything other than further decrease case volume and slightly obstruct the flow of fuel/air mixture if you go too far with it.;)
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today i change my glowplug to an os p3,change my fuel(tornado)change my fuel tubing,clutch springs and i tought that its gonna be the end of my problem tuning my engine,but nothing changes.:cry::cry: still dying when i try to start,sometimes it will start then idle on top of the box then rpm goes high and flames out,then sometimes the rpm drops then flames out again,this is the first time i encountered this kinda problem on my go engine,or maybe should i change or clean my pipe?im using the dynamite 053 on my go 7port oh btw im using a a 7port sleeve on a 5port crankcase,but still using the 5port head.i read on this forum that the 5 and 7 port share the same crankcase.pls correct me if im wrong..thanks!
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The R21 crankcase used on the GX and previous generation are the same for 3, 5, and 7 port motors. So, the sleeve will work for you.
it sounds like you have an air leak. Ensure that your exhaust gasket doesnt have a tear in it, check the rear of the crankcase (remove the rear bulkhead, clean the surface and inspect the seal). Also, if your carburetor gaskets are reddish in color, replace them with the new black nitrile gaskets. This goes for the high speed needle, low speed needle, the base of the carburetor neck, and the seal that goes inside the hole where the carburetor neck fits in. lastly, check your carburetor pinch bolt. make sure it has black seals on it as well. Guys... if you're having tuning problems, start here. We've had none of these kinds of issues with the new GX engines, using the black synthetic nitrile seals- none. They're that solid. Question- if I were to put together packs of seals that included all the ones you need to replace on older motors, would you guys be interested? |
Originally Posted by Ruune
(Post 7467806)
The R21 crankcase used on the GX and previous generation are the same for 3, 5, and 7 port motors. So, the sleeve will work for you.
it sounds like you have an air leak. Ensure that your exhaust gasket doesnt have a tear in it, check the rear of the crankcase (remove the rear bulkhead, clean the surface and inspect the seal). Also, if your carburetor gaskets are reddish in color, replace them with the new black nitrile gaskets. This goes for the high speed needle, low speed needle, the base of the carburetor neck, and the seal that goes inside the hole where the carburetor neck fits in. lastly, check your carburetor pinch bolt. make sure it has black seals on it as well. Guys... if you're having tuning problems, start here. We've had none of these kinds of issues with the new GX engines, using the black synthetic nitrile seals- none. They're that solid. Question- if I were to put together packs of seals that included all the ones you need to replace on older motors, would you guys be interested? |
im using the older version.
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Originally Posted by jeremiah23
(Post 7467617)
today i change my glowplug to an os p3,change my fuel(tornado)change my fuel tubing,clutch springs and i tought that its gonna be the end of my problem tuning my engine,but nothing changes.:cry::cry: still dying when i try to start,sometimes it will start then idle on top of the box then rpm goes high and flames out,then sometimes the rpm drops then flames out again,this is the first time i encountered this kinda problem on my go engine,or maybe should i change or clean my pipe?im using the dynamite 053 on my go 7port oh btw im using a a 7port sleeve on a 5port crankcase,but still using the 5port head.i read on this forum that the 5 and 7 port share the same crankcase.pls correct me if im wrong..thanks!
did you put in new piston & rod at the same time ? how easy is the motor to turn over cold & warm ? does the v spec carby u are using have a plastic heat shield around the neck were it goes into the crankcase ? if so check that it hasn't gone brittle & cracked. as ruune said change all your seals to the new nitrile seals & your exhaust seals as well. is this 7 port sleeve out of your old 7 port u were having trouble with this time last year ? |
nope, i bought the internals bnew and im nearly done with the break-in procedure,but it still leaves a little bit of metal pinch on it,my os carb has a new thermal insulator which i bought last week.
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Originally Posted by jeremiah23
(Post 7468174)
nope, i bought the internals bnew and im nearly done with the break-in procedure,but it still leaves a little bit of metal pinch on it,my os carb has a new thermal insulator which i bought last week.
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Originally Posted by jeremiah23
(Post 7467617)
today i change my glowplug to an os p3,change my fuel(tornado)change my fuel tubing,clutch springs and i tought that its gonna be the end of my problem tuning my engine,but nothing changes.:cry::cry: still dying when i try to start,sometimes it will start then idle on top of the box then rpm goes high and flames out,then sometimes the rpm drops then flames out again,this is the first time i encountered this kinda problem on my go engine,or maybe should i change or clean my pipe?im using the dynamite 053 on my go 7port oh btw im using a a 7port sleeve on a 5port crankcase,but still using the 5port head.i read on this forum that the 5 and 7 port share the same crankcase.pls correct me if im wrong..thanks!
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Originally Posted by JAMMINKRAZY
(Post 7463513)
That crank in your pics is an OS Speed crankshaft. It is drilled and THEN filled as 22racer said. The drilling is what does the real magic in that it lightens the crankshaft making throttle response more crisp. The epoxy just fills the empty void created by drilling, and brings crankcase volume back to what it was before the drilling. Simply adding epoxy to the crank ramp will not do anything other than further decrease case volume and slightly obstruct the flow of fuel/air mixture if you go too far with it.;)
tested my epoxy ram filled crankshaft earlier today, simply fill the crankshaft without lightening process is not a good mod at all, unnoticeable power change but the runtime reduce... now only can get just a liltle over 7 minutes per tank... it used to be over 9 mins. got to grind off the epoxy..:D |
Originally Posted by RedlandRacing
(Post 7470088)
update;
tested my epoxy ram filled crankshaft earlier today, simply fill the crankshaft without lightening process is not a good mod at all, unnoticeable power change but the runtime reduce... now only can get just a liltle over 7 minutes per tank... it used to be over 9 mins. got to grind off the epoxy..:D |
Do i need to adjust my idle stop screw when changing to a smaller restrictor?
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