Cafe Racer Forum banner
1 - 2 of 2 Posts

· Registered
16 Posts
Discussion Starter · #1 ·
I'm in need of a couple of answers

1/ What is the Ignition timing in Degrees before TDC ?.
I was told anywhere between 20 -30 degs. ???? seems like a wide spread

2/ Using Maga cam can anyone give me the Header pipe length + Mega length and diameter. ( I was given it before but the brain cells are dying )

Thanks guys

· Premium Member
7,411 Posts
Timing on a stock engine with the advancer in place is 5 degrees BTDC and 35 degree BTDC fully advanced. Running 10/40 timing would add a bit of zip and wouldn't cause any problems.
I run a straight 45-47 degrees on the race bike.

The 2-1 pipes I make are 1 1/8" OD primaries about 24-25" long, collector about 6" (street bike), megaphone from 1 1/4" to 2.75-2.85" in 24".

Dyno testing myself and others have done on the 175 twins don't show a lot to be gained or lost on an exhaust system anywhere close to correct. A couple of inches here or there makes no difference that I can find. Differences of 3"+ start to change the characteristics of the power band some but don't effect max hp much. Smaller OD on the primaries down to 1" OD is fine...maybe better even. Longer tail pipe/collector and megaphone will aid torque.

Some pics of the 2-1 systems I'm working on here:

1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.