Good info... I haven't rode in weeks due to the weather being shit. Today I am tuning my carb. I have just put in the 105 main, needle clip in the middle position and the air screw 2 turns out. I am now going to go work on the intake manifold.... I'll let you guys know how my bike goes later tonight.
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*Old ass Suzuki RM50
*88 VL Berlina 5 Speed
*DHZ140: 12" 10" wheels, ASV leavers, Fastace 66rc shock, 1/4 turn throttle, polished intake manifold, a broken fake H-bomb exhaust, removed choke and a spot light. [SOLD]
4)grab some 20grit sandpaper and get ya index finger in there and sand hard ,puting in a protected vice is the best way.
4)this will take along time to smooth out the castings and to match either end of the inlets but its worth it ,so be patient
5)Now once you have polished it with the sandpaper it should be almost silky smooth
Cheers for the tips, they're pretty cool.
I gotta ask... 20 grit sand paper??? thats VERY coarse, i could imagine it making anything almost silky smooth.
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Dense terrain hill climbing, rut surfing Loncin 125. Advanced timing mod, 17t/37t, hi-flow air filter,>>> and a SC in the works... soon, my pretties!
yeah the port matching is a goer, definately a good thing, as for polishing the inlet to a silky smooth finish i've allways been under the impression that it's better to leave areas between the carby and combustian chamber with a slightly rough finish, bit of edge turbulance and that to keep atomised fuel suspended in the air stream... anyway guess i was wrong, anyone confirm that for me?
The walls of the inlet system and exhaust should be as uniform as possible, without any lips or protrusion, but with a rough and even finish. Any lip or deformation in the wall shape will cause a turbulent spot which causes a disruption to flow at greater port velocities. The roughened finish will not cause major disruption, but instead create a small and even surface turbulence at the port wall, which will basically keep the mix from separating and slowing at this point.
The best way i have heard it simply described is this: imagine the bonnet of a car whilst driving in the rain at 100kph. The droplets of water may only be traveling up the bonnet of your car at 1 kph or less. Why is this? They should be flying up the bonnet at close to 100 kph.
At the surface of a smooth object, the laminar air flow is slowed and has weird things going on. So imagine polished port walls as that shiny bonnet and the droplets of water as droplets of fuel separating from the air and slowly traveling up the port wall and upsetting the mixture strength, blend and speed.
I think motoman may have described this in this way, i can't remember where i read it, but it is a good way to help understand the principle. I finish all my inlet ports and manifolds with 80 grit rolls.
Now the exhaust can be polished, because there is no fuel separation to worry about and the exhaust gases are leaving the port under extreme pressure and at high velocity. Polishing here reduces the port surface area, therefore reducing heat pickup, plus it looks trick and impresses people!
the manifold ??
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