Jump to content
Sign in to follow this  

Rotax jetting

Recommended Posts

I have a modified 505 Rotax installed in an ATK frame, used for both street and dirt riding. The engine is a race unit from dirttrack, with a fully ported head (45 mm), big valves, a 675 cam and an 11:1 piston. The exhaust is free flowing to an FMF Q4 muffler.

The 44 mm Mikuni round-slide jets ok from idle to half-throttle, then bogs (too rich) badly until three-quarter throttle, then pulls hard on the main. It will run on top with a larger main, but it makes it too rich for mid-range running.

Current jetting:

220 main

40 pilot

XO needle jet

7DH5 needle (top clip)

I`ve tried leaner and richer mains, and leaner and richer needle jets and jets, although I only have a few needles and needle jets to play with.

What needle would work better at half-throttle in the XO jet....,

Thanks for any help on this.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...