Are jetting changes needed after head mod?

[Grayhorse]

I just got my modded head back from RB, before I sent it I thought my jetting was right on(RB carb). Will jetting changes be needed with the new head?

[IdahoCharley]

It should still be close.

A tighter squish (resulting in a better combustion) should allow you to lean it out a little from your previous jetting for a given temperature and alitude. Bottom Line - your engine should be a little richer (jetting wise) than it was prior to sending it to RBD.

[RBD]

Very well said IdahoCharley, spot on.

Ron

[IdahoCharley]

Very well said IdahoCharley, spot on.

Ron

Thanks Ron.

[river]

It should still be close.

A tighter squish (resulting in a better combustion) should allow you to lean it out a little from your previous jetting for a given temperature and alitude. Bottom Line - your engine should be a little richer (jetting wise) than it was prior to sending it to RBD.

Sorry for the rookie question. What is squish? And I presume you are saying one needs to install larger jets? What size (or is this obvious to experienced people?)?

Thanks very much.

[SS109]

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It should still be close.

A tighter squish (resulting in a better combustion) should allow you to lean it out a little from your previous jetting for a given temperature and alitude. Bottom Line - your engine should be a little richer (jetting wise) than it was prior to sending it to RBD.

Sorry for the rookie question. What is squish? And I presume you are saying one needs to install larger jets? What size (or is this obvious to experienced people?)?

Thanks very much.[/quote]
No, you would actually go to a smaller jet to get a leaner mixture.

As for squish, I hope this helps.

[river]

Thanks for the great pic.

I'm confused then; IdahoCharlie says it needs to run richer, but that the extra squish let's you lean it out. Does this mean if you put rb head/carb on a stock bike it will be too rich, and the squish let's you lean it, but leaving it still richer than stock?

Thx.

Thought I already posted this.......

[fuzzy]

No, what IC was it will run richer with the tighter squish....therefore requiring you to lean it out. If you had stock jetting you were most likely in need of a re-jet anyway. Read up on here on how to jet your stuff. Once you know how, it's an indespensable tool.