A few questions about how the engine works.

I'm starting to learn very slowly how the engine on a scooter works now, but there are still quite a few things I need to learn about so here goes.

1. What exactly is the needle for in a carb? How do I know it needs adjusting?

2. What is a gear-up kit and how does it work?

3. What are the reed block and petals and how do they work?

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On a different note what size rollers do I get to go with a 70cc kit, 21mm carb, stage6 replica exhaust, polini speed control kit and green clutch spings?

I know rollers are guess work at best but I need a weight to start off experimenting with so I dont waste too much money lol

 

try 5.5 or if not 7.2

and i believe the reed block seperates the oil from the petrol somehow im not to sure doe x

 

try around 3-4 gram m8

 

lol

when the piston creates the vacuum on the down stroke the petals open to allow the fuel/air mix to fill the crankcase

the needle determines how much fuel is mixed with the air, on 1/4-3/4 throttle. basically a variable jet operated by the throttle and then theres the slide etc.

gear up kit is uprated gears, so higher ratio which allows a higher top speed
the gears or split into two sets, primary gears and secondary gears with an input and output shaft

 

Yeah what alex said i knew it was something along them lines

 

thanks guys.

Also like to know what diference it makes on the piston when it has 2 rings rather than 1?

 

in simple terms with 1 piston ring you go faster cause there is less friction

with 2 rings you go a little slower but its more reliable and lasts longer

thats why race kits have 1 ring and like everyday kits have 2 rings

 

ah ok

turns out I can just about afford the stage6 70cc race kit. Would you advise against it and go for a 2 ring job instead?

cheers!

 

if your using it for everyday use which i asume you are its better to go with a 2 ring jobby like Polini Sport 70cc, my mate had a malossi mhr rep didnt last 6 months, infact didnt last 3 months lol, In my opinion i would advise going with 2 rings.

 

main reason is timings, can go harsher and more precise on port timings with a single ring

they wear out quicker and obviously theres only one ring end that could catch

 

Mhr rep is twing ring

 

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It looks like stage6 run through there pistons like no tommorow ! Think twice about stage6 go for a malossi or polini and yes 2 rings

 

Reed block works by opening on the downstroke and letting the fuel/air mixture into the combustion chamber, and slamming shut while the fuel is burning, to keep all that lovely compression inside the cylinder instead of leaking back out through the carb like an incontinent old lady.

Without being at all patronising, can I say well done for asking questions which show you want to learn about your bike, instead of making you look retarded.

 

haha well if I learn then I can sort things out for myself and not have to fill the boards up with posts that i'm sure most of you are tired of answering anyway.

I find it all quite interesting to be honest...if not a tad annoying at times lol

 

Cool!

This is what a reed block looks like

 

http://science.howstuffworks.com/two-stroke1.htm

pretty good site

 

Yeah i have seen them but going from pics i couldnt figure out wtf they done lol. I assume there a holes of some kind under the petals and when the vacuum is created the petals are closed over them? Why do they make carbon fibre ones then? Do they open and close faster than standard ones?

 

hit the nail on the head there, the vaccum from the piston moving up in the cylinder opens the reeds and draws the mix from the carb into the crankcase, as the piston gets to the top, the vaccum stops and the reeds snap shut, as the piston comes down, the mix is then forced up the transfer ports into the cylinder.

 

is there not a guide lying around somewhere with how reedblocks work etc.. along with like carbs, pistons, piston rings yatta yatta yatta...

i'll find it and edit it into this post


and where abouts in cumbria you from dude?