Port out the carby end of your intake manifold to make it the same size as the carby outlet. The manifold is a few mm smaller all the way around which in turn increases the amount of turbulence, as the air hits this lip of the manifold it bounces back towards the incoming air creating turbulence and disrupts airflow.
Use a rounded file until you get the right size and then sand it smooth, i started with 80 grit paper and went right up to 2000 grit for a smooth finish.
I was riding on tuesday at a place near where i live and there was 3 other standard orion's, a couple of times they tried to race me and my bike pulled away steadily from them along the straights, i also have a uni filter.
There was also a provert and a thumpstar that turned up later, they were hardly faster along the straights, just a little but then on the bumps they took off obviously because they have much better suspension.
hey mate so what your saying is: open up the part of the manifold that connects with the air filter? does it give alot of top end speed? what mods have you done to ur bike compared to the standard orions you raced? and were u roughly the same wieght
hey mate so what your saying is: open up the part of the manifold that connects with the air filter? does it give alot of top end speed? what mods have you done to ur bike compared to the standard orions you raced? and were u roughly the same wieght
Take the carby and manifold off your motor, then take the carby off the manifold and remember which way it goes back on as the two flanges on the manifold are different.
Then take the plastic spacer that has the seal on it (the one inbetween the carb and manifold and line the holes up with the holes on the carby end of the manifold and get a pencil and draw a circle around the inside of that. This is where you wanna file the manifold out to (this line). Then sand smooth once you have filed out to this point.
does it give alot of top end speed? what mods have you done to ur bike compared to the standard orions you raced? and were u roughly the same wieght
Just better acceleration. The only other mod i have done is a uni filter. I would've been heavier, im 20 years old and 83kg 6'2". The guys that were there would've been 15-16 yo and like 60-65kg i would say.
Quote:
Originally Posted by 125fanger
ok so the plastic spacer that is between the manifold and the engine is a smaller hole than the manifold, so i sand it back until it is the same size?
No, the plastic spacer is the same size as the carby outlet, you are filing the manifold out to be the same size as the spacer and the carby.
Quote:
Originally Posted by RabidDog12345
have you taken the choke out aswell?
Nope, i don't see how this would improve performance on a slide carburettor such as the 25mm mikuni, i can see how it works on the butterfly choke carbys though.
righto, which end am i going to file out when just looking at the bike... is it the end that enters the engine or the carby end? if it is the carby end, is that end smaller than the engine end? what am i filing it out to?
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