How To Fit.A 'Retro' CB750 Fender To A CB1100...

Bazbro_imp

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FITTING A 'RETRO' CB750 MUDGUARD TO A CB1100...

In this case, it is a 2018 CB1100EX.

I have used a genuine Honda CB750 1972 patten front mudguard (fender, m/guard).

After removing the front wheel ( http://cb1100forum.com/forum/showthread.php?tid=15104&pid=257750#pid257750 ), remove the front m/guard. 4x 12mm bolts.

Position the m/guard roughly between the forks, to see what you have and what you need to alter.  I needed to bend the large brackets to make them fit between the (wider apart) forks. I did this using a vice (vise).  CAREFULLY bend or straighten as necessary until you're happy. You may need to.keep coming back to do this.

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I found it easier at this stage to temporarily remove the front, upper stay (two 8mm bolts/nuts)

Cut off the redundant cable guide.

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Rustproof/paint this when you paint the central brackets, later.

The lower, rear, stays need to be modified to fit round the brake calipers /discs.
Measures 15cm along the stays, from the centre of the securing bolt hole on the end of the stay, and mark that position with tape. 

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I am NOT a metalworker and I'm  not entirely happy with what I've done here... it's OK but could be better.  A metalworker would certainly offer a better method.  Anyway, read and weep, metalworkers of the world!

CAREFULLY and slowly bend out the arms of the rear, lower stay, equally on each side - do this on the one rear, lower stay ONLY; the other stay remains intact.  Try not to bend solely at the screw securing point - it is weak there and could snap outwards or upwards. 

Bend outwards,  equally on each side, until the tape marks are 25cm apart - this will enable the stays to clear the brake calipers.

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Then, put the stay in a vice and, using a tube to bend it round, slowly and gently straighten the stay so that the tips are "about" 25cm apart (I stopped when they were 26cm - half a centimeter "spring" each side, I felt was acceptable).
They now clear the brake calipers on each side.

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Loosely bolt the stays onto the Special Brackets on the bottom of the forks - Note: these Special Brackets have to be made specially (they are supplied if you buy the Whitehouse front mudguard... at £430 ($560), whereas this genuine Honda mudguard is just £190 ($210) plus the bracket cost!).   I will supply dimensions below.  Any engineering shop could manufacture these if you are not able to do so yourself.  This is with many, many thanks to, and courtesy of, Ninemeister, on this Forum. 

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Line up the entire m/guard squarely in the forks, and temporarily clamp in position.  Refit the wheel, temporarily if necessary, to get the final position of the m/guard "just right".  Mark where securing holes need to be drilled.  It may be that only two bolts can be used, one on each side.  This is the case with my m/guard because the existing mounting bracket is so small.  This should not create a problem, provided the bolts are fitted securely.  Fabricating a completely new bracket is possible, of course, but I don't consider it necessary.

I used G-cramps to hold the m/guard in position while measuring.  I needed to straighten and then bend again, the central bracket, using my vice.

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Positioning of the new bolt holes is CRITICAL, and can affect the appearance of the entire m/guard, so be careful.

I am also concerned that removal of some of the bracing of the forks via the m/guard bracket (just two bolts instead of four securing the m/guard) 'may' affect handling.  Again, experience will tell me if an additional arch of bracing, under the m/guard, between the forks, will be necessary.

Finally, cut off the excess of the central brackets (if you consider necessary), dress down the sharp edges, undercoat,  paint, and fit back on the 'bike. 

Step back and admire!

I'll post a picture when it's all painted and fitted.
 
I agree with Houtman. I dread to think of the result shoul I embark on such a task.
 
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