Expansion chamber

[Street Ryderz]

It does look nice, do you think that header is too long? Just seems a little big for these small motors

They do that on purpose so the pipe stages early and then acts as rev limiter that volume of chamber is widely used on 50-70cc scooters for decades now with a very wide power band suited to street use!

 

[Frankenstein]

How does that limit the revs exactly? By revs do you mean rpm or you mean it simply prevents the motor from reving up too quickly while not under load?

 

[Carlos motors]

It is expansion chamber for popular moped here in balkan states it's called Tomos and this exhaust is like one of tuning parts for it so i thought it could be good for me.

 

[Street Ryderz]

How does that limit the revs exactly? By revs do you mean rpm or you mean it simply prevents the motor from reving up too quickly while not under load?

It will limit the top rpm after the power band falls off because the wave timing will no longer support more r's!

 

[Street Ryderz]

It is expansion chamber for popular moped here in balkan states it's called Tomos and this exhaust is like one of tuning parts for it so i thought it could be good for me.

I thought so! should work well you just may have to do some fitting to mount it!

 

[Street Ryderz]

How does that limit the revs exactly? By revs do you mean rpm or you mean it simply prevents the motor from reving up too quickly while not under load?

looking at this dyno graph the top solid line is hp and the bottom dotted line is tourqe you can see that when the rpm peaks it falls off quickly after that because the pipe can no longer support the engines needs to keep making power!

 

[Frankenstein]

What's the norm for these motors again regarding rpm?

 

[Frankenstein]

What's the norm for these motors again regarding rpm? The pipe in that set up looks significantly different and would appear they are using sport engines and parts for that dyno...

 

[Street Ryderz]

The dyno graph was just to show how after the peak the rpm falls off quickly!That cylinder used in the graph can be fitted to our bicycle engine bottom end as a race build whats impressive is that it's producing over 8 ft pounds of torque !That pipe used has slightly more volume and shifts the power band up 1500-2000 rpm higher than the norm for street use!

 

[butre]

What's the norm for these motors again regarding rpm?

some of them will do 7 grand but you really don't want to go past 6 with stock bearings