bruzer

I have 2 4-stroke saito 45's and do not have exhausts for both. I went out and found fitings that fit the threading but the inner diameter is much smaller. I feel like this would be a problem but don't know for sure. I did not buy stock ones because this is a custom installation and the stock pipes are undesierable.

Thank you

FHHuber

How much ID change?

Smaller ID of the pipe means thicker walls.. so the pipe will be stronger. It also means more backpreassure in the exhaust system... that can rob a bit of power. You can reduce this a LITTLE by beveling the iside of the pipe. (VERY CAREFULLY... and clean out the metal filings completely.) But would it be worth the effort? (probably not)

You probably won't notice the difference the smaller ID makes unless its fairly significant.

swooper

bruzer, the stock header pipe on my Saito .45 measures 5.2 mm ID. Hope this helps.

bruzer

I have one other question. The crankcase vent port....does this just need to be open to air or does it need to be hooked to the fuel tank. I assume it needs to be hooked into the fuel tank as there would be no other method of lubeing the engine.

Thanks

As for the other question... I appreciate your help guys. I have a stock pipe....but only one of them. I am doing a twin setup so I need 2 and a custome pipe is pretty necessary. I may have a soulution from one of my friends so thank you for your info. If anyone else has any thoughts pllease post for me. Thank you

swooper

Just leave the crankcase vent open or run a piece of fuel tubing out of the cowl if desired.
Its purpose is to ventilate the case as the piston oscillates and to drain excess oil that blows by the piston ring. The blow-by is what lubes the lower end. That also creates the need for an after-run oil to minimize corrosion.

bruzer

OK. thank you all very much.