Restriction in an arrow exhaust

[WestOzRS125]

There's only one type of Arrow pipe, but it does have a choice of silencers and there is a slight difference depending upon which year bike it needs to fit. It has no restrictor built in. There is a washer with a smaller internal diameter that is supplied and can be fitted in front of the silencer to quieten the bike down, at a loss of power.

I'm seeing a lot of mis-information here people. If you don't know, don't guess and try to pass it off as fact. Croftie, buy yourself a Haynes manual, pull your bike apart, rebuild the top and bottom end, then you'll know it's 100%. Until you know your seals and rings, combustion chamber cc's and simple things like the powervalve and solenoid are spot on, you'll be looking for answers here - to no effect.

Get your hands dirty - it's fun

[croftie]

Okay i must be doing something wrong i found the right size for mine screwed it in and onto the end of the psi clock, and when i crank it open with full throttle the psi needle does move?

[chrism15]

screwed in fairly tight?

if it doesnt move at all id suspect faulty gauge which i would send back as if you had 0 psi your bike wouldnt run at all never mind lack power!

find right thread connector for spark plug hole and wrap a rubber ring O ring over it to help with a seal

screw into the spark plug hole

screw other end into the gauge

turn ignition on

throttle wide open

press starter button till gauge peaks

you can also push the bike in 3rd gear to get a reading if battery is flat or starter motor isnt present (ie bump start)

[croftie]

i'll do a video tomorrow and show you, i mean there cant be a certain way to set it up? If its screwed in properly all tight with no gaps? Dont really want to send it back because it took forever to come

[chrism15]

shouldnt be very hard to set up, purely screw up and test away

a video should show us how its working but if its all done correctly and its still blows 0 psi id put money on the gauge being faulty as you engine wud not run with 0 psi

you should also have the engine at normal operating temp to get a accurate reading but it wudnt be a difference of 120psi

[croftie]

is was sat for like 30 mins after from riding home from work and still had 2 bars, does the choke need to be on or anything like that?

[chrism15]

choke off so it allows plenty of air into the system,also same reason for wide open throttle

[croftie]

103 seems a little bit of a stretch to me but all engines are different and conditions are different ect

if yours is the full power version you should be hitting around 90mph without much trouble

have you done a compression test? worth investing in one (about £15-£20) just screw it in spark plug hole and pump starter till the gauge peaks (with a full throttle to allow air into cylinder)

depending on how much compression is lost dictates what you replace, around 10psi could just mean a set of reeds or piston rings, when you start getting on for 20psi id look into crankseals, then 30psi - 50psi then look into a piston and or barrel

personally id just go with a set of new piston rings just to give it a little more of a kick, although you would need to run it in then!


you may find this interesting, the derestriction of teh suzuki rg 125 as alot of bikes are restricted very similary.. you may need to join the forum but its free AND there is a Rs125 section so check out this and it shows how the exhaust is restricted and i beleive the Rs 125 exhaust is the same restriction

you need to join to see the pictures (the pictures say it all) but doesnt cost a penny sooo or copy n past the links but i just joined as its all layed out then

http://www.125ccsportsbikes.com/foru...howtopic=87305

right sorry i havent replied i tested my psi and it was 115. Just re done my powervalve and just seen that my exhaust doesnt have any springs on it holding it onto the engine/manifold. Lots of oil is all inside around the bike, is that because of the gap? Will this add to the fact my bike is only doing 88 and running 22 bhp and its full power model arrow exhaust been dyno jetted

[Craig H.]

right sorry i havent replied i tested my psi and it was 115. Just re done my powervalve and just seen that my exhaust doesnt have any springs on it holding it onto the engine/manifold. Lots of oil is all inside around the bike, is that because of the gap? Will this add to the fact my bike is only doing 88 and running 22 bhp and its full power model arrow exhaust been dyno jetted

Absolutly. The exhaust is a very important part of making HP. Get things cleaned up and have the exhaust mounted properly, and I bet you will see an improvement.

Craig

[chrism15]

if the exhaust isnt tight on the manifold its gonna run like a bag of shit and gonna cost you power!

a two stroke engine works from back pressure from the exhaust, this is why 4stroke pipes dont work with two stroke engines because it doesnt have the same kind of back pressure

it will send your mixture and jetting off ect which is why you will have some oil ect round the exhaust manifold