Front end lenght

[PR WIS]

I'm building a Bobber. The donor bike is a 73 750 SOHC. It came with an extended front end. I'm thinking on using a 2006 CBR 600 front end on the build. I know how long the CBR 600 front end is, but what is the length of a stock SOHC. I want to be sure that when done the front tire has clearance and will not hit the exhaust when I hit a bump in the road. I have read that the rake on a stock SOHC is 27% and 28% on others. Trail is around 3 and 3/4 inches stock. How about the length?

[TOOLS1]

Length is not really what you need to be concerned about. It is the offset on the triple trees. The newer sportbikes do not have as much offset (usually none at all) as the older bikes. This means that as the fork compresses the tire comes closer to the bike/engine then with the stock front end at the same distance of compression. Shiny got into this with his "Water Buffalo" build, you can do a search for it, it is a really good read.
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[PR WIS]

Yes, I realize the offset affects the out come all so.Just need a staring point with length because that's one thing I can not measure with my none stock front end. PR

[shinyribs]

F2 and F3 CBR trees are the same. They have less offset than the SOHC trees,but more than most modern sport bikes today.

I have F3 600 forks and F3 1000 forks here. The 1000's are about 1'' longer than the 600's. I'll get some measurements and come back.

[Re-run]

I was going to measure the fork this morning but ran out of time before going to work. I will get it tonight after I get home, about 6:30ish.

I may be wrong but the front geometry is set by the neck tube. Any bike I have seen, the fork legs are 90 degrees to the top and bottoms of the tree. therefore, the neck sets everything. So, unless the neck was cut off and then rewelded with a different rake, you should be fine.

I do know the stock fork has 5.6 inches of travel. The stock wheel is also bigger than the cbr wheel, in diameter. And that is what might cause a wheel to hit, width won't matter. I know my cb tire is significantly taller than my fz tire.

Either way, I doubt there would be an issue of the cbr front letting the tire hit exhaust or anything else.

I will still get the stock length though.

[PR WIS]

The 1000's are an inch longer? That's a good thing to know. Thanks. I'm still not done reading the "water Buffalo thread. Work keeps getting in the way. I have time on my side. This is just a project, have 3 other bikes to ride for now. Thanks for the help. I look forward to learning more. PR

[Re-run]

Sorry i didn't get bake yesterday.

Anyways, I measured the very top of my fork leg, I did not do the cap, nor did I go all the way to the bottom axle cap. Only the fork leg itself, which is all that matters for this anyways.

Overall length is 29.75 inches.

So, unless the cbr fork is appreciably shorter, it shouldn't have any clearance issues. Especially with the smaller front tire diameter.

[PR WIS]

Thanks Re-Run! That helps. On the CBR 600 front end if I measure the same as you did its about 27 and 1/4 inches. Or 2.5 inches shorter. I believe the standard way to measure a front end length (except springers) is from the bottom of the top tree to the center of the axle. But I can work with with what you gave me thanks again. I also found out that travel on the CBR front ends is 4.7 inches, 1000 RR or 600 RR the same. Now I need to work on the offset and the amount of travel on the stock SOHC front end. PR