head rake

A friend asked me about raking his KZ1000... I suspect the bike is a 77 or 78 frame. I imagine it requires removing the front end and triple tree and cutting the frame neck. The bike already has the swingarm lengthened and came into my shop with only struts. I have modified the rear brake torsion arm mount (moved it back) so that the rear disk brake caliper could be located correctly (out of the way of the shocks) and installed some rear shocks. The fella inquired about raking the front end. Since I have never done this, it makes me nervous as doing it right would seem to be critical to handling and safety. Has anyone done this and in general, what steps are needed to make a precision cut and reweld. I am also not sure how to characterize the amount of rake. There is a certain amount of rake now. How is it measured and how much would be appropriate for a street bike still capable of decent handling and safety?

Here's a site that gives a basic definition of rake and trail, and has a calculator at the bottom of the page for figuring out the associated numbers:

www.rbracing-rsr.com/rakeandtrail.html

Depending on how wild your friend wants to get, it might be a better/cheaper option to have a set of raked triple trees milled - same result - rake is rake wherever you add it, but preserves the integrity of the frame and the option to go back to square one if ever desired...

Thanks for the link. If you do this milling to the trees, they would then be fixed at a different rake angle and you would have to buy a replacement tree to get back to the original spec? Who or what type shop would do tree milling?

wiredgeorge wrote:

Thanks for the link. If you do this milling to the trees, they would then be fixed at a different rake angle and you would have to buy a replacement tree to get back to the original spec? Who or what type shop would do tree milling?

The raked trees would be one-up originals machined new from billets; don't think that original (cast) Kaw trees would accept additional machining or have the meat available for same - so keep the originals for the switchback.

Since CNC is such a nice option, I'd think it isn't so much which shop does the machining as who does the designing - take the rake and trail numbers for a stock setup and extrapolate the results for what's desired vs. what's reasonable for additional rake and trail.

I'd think an outfit like this could handle it easily:

www.custompm.com

Had mine racked years ago by a couple of guys from the track. Not sure how much they took out of main top tube. It was either 3/8" or 3/4". All they did was cut some out, heat up down tubes and other(?) top tubes, stuck a long bar in head tube and pulled back, gave it a halfways good weld, gussetted the top, and head tubes. Ran it for 3 years after that with absolutely no issues at all. I would think as long as you can weld hafways decent and pull back good and straight you should be alright.

Raked triple clamps will reduce trail. The idea behind raking (talking drag bike here, not chopper), is to increase trail for high speed stability.

we had several long discussions on this topic a while back,is there anything in the archives? :whistle:

heres one post
another

Take a look here.
Frame rake