I Have been using various CRF related forums for the past few months gathering information about converting the forks on a CRF150F. Having just finished the conversion, I thought I would share what I found, and have completed. A small payback. Before reading any further, I would like to clarify that I am not some over-skilled machinist who always keep saying "that it's easy" while having access to tools not available to us mere humans ; I am however, not a hack wrencher.
Almost every fork conversion posting references an entity called REGER ENGINEERING. As far as I can tell they, and their products no longer exist. If you want/need to do the conversion,then you will have to be creative.
Last summer my son hit a tree, and bent his fork.
As you can see from the pic above, major repair is needed. You can also see, the replacement MX quality CRF-R fork is far more substantial than the play-bike fork that is equipped on the CRF-F.
Lets get started:
Once the old forks and triple clamp are removed, the CRF-R triple clamp cannot be directly installed.
As you can see, the lower threads for the stem are below the top of the steering head of the CRF-F. The stem must be pressed out, drill exactly 8mm of material from the bottom bracket stem hole, then press the stem back into the bottom brace. I do not own a press. Find a local machine shop, and they can easily do this step. $50-$100 depending upon the shop.
Below is what the re-inserted stem will look like:
Once installed, the bottom brace and stem will look like this:
Notice the "wings near the steering head that are steering stops for the CRF-R. The steering stops on the CRF-F are part of the bottom bracket, and they strike a small "stub" welded to the front of the frame. New steering stops must be added, or the triple clamps will strike the fuel tank. I drilled two holes into the bottom bracket, and installed some large rubber stoppers from the hardware store. I used some large flat washers to provide a hard cantact surface for contacting the CRF-F "stub". Time will tell if this is sufficient. Here is what the stoppers look like:
This photo shows the installed triple clamp with the stopper and the "stub".
AT THIS POINT I FULLY SUGGEST BUYING A CRF-R OR CR85 FRONT WHEEL!!!
Purchase a brake carrier adaper for the dual piston brake caliper, and you are DONE!! For example, search "CRF150R Dual Piston Brake Carrier" on the Applied Racing web site, and you will be done. YAY!!!
I say that based upon what I went through when I adapted the CRF-F wheel to fit. First of all, the axle on the CRF-F is 15mm, and the axle on the CRF-R is 12mm. I first attempted to find replacement bearings that were 11mm width, 35mm OD, and 12mm ID. NO SUCH LUCK. I even sent an e-mail to Timkin without a good result. Next step was to make a spacer that would fit between the OD of the axle, and ID of the wheel bearing. Thank you e-bay. Upon searching 12mm ID and 15mm OD tubing, a place in England, Great Britan ??, was located with stainless steel tubing to fit those dimensions. $15 for tube and $25 for shipping, the tube in the pic below arrived:
This pic shows how the CRF-R axle and CRF-F bearing fits with the tube:
Cut the tube to the width of the CRF-F wheel hub, and you will get something that looks like this:
Use the CRF-R spacers and a washer to fit the wheel to the forks. The large black "disc" no longer fit because the aftermarket rotor did not support the 4 holes. My shorty bent the rotor as well! I bought an extra dirt seal for the other side from the local honda shop, and used it as a dirt seal on the other side of the hub. Fit perfect.
So far the wheel conversion is easy. Once the wheel was installed, the real problem became apparent. The bolts for the brake rotor and the brake caliper mount conflict. Major bummer can be seen below:
In the pic above where I showed the tube, you can also see the brake caliper carrier I purchased from Applied Racing. When the new carrier is attempted to be installed, the rotor bolts will contact the carrier. At this point, I will leave it up to your creativity with either your checkbook, dremel, or machinist buddy to address the issue. I believe I made some decent non-engineering based adjustments to the fit/alignment to address this issue, yet would not want to be responsible for mother nature or murphy's law in the case they fail during use. I made similar mods to my track bike to fit off-brand calipers, and they withstand fist-fulls of brake at the end of a straightaway from 100Mph+. There, that is my disclaimer. Hint - button head bolts will gain you 1mm of clearance. The final install looks like:
Well, how's that for my 1st post on the forum?
Good luck, and watch out for those trees!!