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AJ.Valente

AJ.Valente
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The front safety bars on the early bikes are scarce items, particularly the left-side as that's where all the "drops" occur.

When I purchaced my current bike the left side looked like this:

Repairing Engine Safey Bar on '85 K100RT Bar1







As an unassuming buyer I didn't notice the bar was a bit wobbly, but later removed bars on both sides of the bike until they could be properly fitted.

After getting the lower farings off it was discovered the upper mounting stud on the left side of the engine had been sheered off (left/right):


Repairing Engine Safey Bar on '85 K100RT Bar3





Judging from corrosion on the right-hand stud it appears the stud on the left had been so weakened when the bike fell over it just snapped.



Most unusually, the support arm was later cut off and the remaining bar jerry-rigged in place. I say unusual, because in most cases the bars are simply discarded and roundles installed over the holes in the faring:

Repairing Engine Safey Bar on '85 K100RT Bar2





Just my lucky day as replacement bars are quite pricy, and I'm inclinded to fabricate another support bar and weld it in place of the old!



Last edited by AJ.Valente on Wed Mar 12, 2014 11:57 am; edited 10 times in total

    

AJ.Valente

AJ.Valente
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Repairing Engine Safey Bar on '85 K100RT EngineGuardAssyDwg

OK, so copying the image from the OEM manual (top) and taking a few measurements one arrives at a rough sketch of the part (bottom) to be fabricated.

Will be using common black pipe, which here in the USA comes only in 3/4" and 1/2" diameters. The 1/2" dia.  is preferable to 3/4" in this case because, while a bit smaller in diameter than the safety bar, it is easier to work with and will save weight.  

Thanks to Motorworks.UK have acquired the bracket that attaches to the sump. Also acquired two (2) OEM rubber studs to mount safety bar to the bracket. The latter are pricy when new (~$40), but found a pair on E-bay (lucky, lucky) for about $25. Local hardware stores will supply the remaining needed hardware.

Fabrication steps:

a.) Bend the pipe to 35 degrees.

b) Cut long end of the pipe on a diagonal to match the existing gap on safety bar. Will have to construct a temporary jig of wood to maintain the proper orientation. When complete, weld the pipe to the safety bar.

c) Cut the other end of the pipe to necessary length. Orient the 3" mounting flange (see drawing) so it is positioned roughly above the bracket mounting hole and weld the flange in place.

d) Drill bolt hole in mounting flange to match existing hole in bracket.

Note: The above drawing was later modified to include real dimensions used in fabrication.

end.



Last edited by AJ.Valente on Wed Mar 12, 2014 11:59 am; edited 3 times in total

    

AJ.Valente

AJ.Valente
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Repairing Engine Safey Bar on '85 K100RT EngineMountBolt







Work is stalled temporarily, I'll explain.

In the photo above (left-red arrow) a black iron bar is bent to 35deg. The next step is to partially assemble the engine guard to the bike, then remove that assembly along with the lower bracket to be placed in a jig. Once the jig is assembled the process of cutting and welding the support bar can begin. Obviously that didn't happen--the hold-up being the upper mounting stud.

In a previous post we found the upper safety bar mounting stud broken off in the mounting bolt. Attempts at heating the bolt and removing the broken stud with an easy-out did not work.

If the mounting bolt and safety bar stud were of the same diameter this would be an easy fix, but thats not the case. As it happens the bolt is an engine to frame mounting bolt, while the safety bar stud is one diameter smaller.

Thjis being the case I ordered (E-bay) a set of engine mounting bolts (right) containing the one bolt (red arrow) I need to replace. Once the replacement bolt arrives we'll mate it to a replacement stud and work can continue.



Last edited by AJ.Valente on Wed Mar 12, 2014 11:59 am; edited 1 time in total

    

George R

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Hi - when you are replacing the special bolts on both offside and nearside, gently jack up the engine at the front and with the new bolt, centre it in the hole then adjust the height of the block so when the bolt is threaded in, it will thread up most of the way without a wrench.

When these bolts are removed the engine unit will drop - maybe only a few millimetres but it will make the replacement difficult if not checked. I found out about this when I had to repair a mounting thread in a block because the owner had screwed in the new bolt off centre and at an angle and because it was tight, used a socket and bar but because the engine had dropped and he had not noticed; the bolt did not screw home.and the protection bar Z mount was still slack. So it was an engine lift job and a repair thread (helicoil type) to fix it properly..

Hope this is of assistance.

    

AJ.Valente

AJ.Valente
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@George R wrote:Hi - when you are replacing the special bolts on both offside and nearside, gently jack up the engine at the front and with the new bolt, centre it in the hole then adjust the height of the block so when the bolt is threaded in, it will thread up most of the way without a wrench.

Will do. Thanks for the advise.

    

AJ.Valente

AJ.Valente
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Repairing Engine Safey Bar on '85 K100RT Step1






OK, so now fabrication step one (left):

The engine bar was fitted to the bracket mounted on the oil pan. Then the bar and bracket were removed as one assembly in order to get the proper orientation.

Step two (right):

The brace was cut to the diminsions of the drawing and then held in place to mark the area to be welded to the bar. The brace was then clamped in the vise and a wedge cut from the side where it meets the bar.



Last edited by AJ.Valente on Wed Mar 12, 2014 12:00 pm; edited 2 times in total

    

AJ.Valente

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Repairing Engine Safey Bar on '85 K100RT Step2


Step Three(left):

Cut out the flange, drilled a hole and mounted it to the bracket.

Step Four(right):

Tac welded the brace to the bar and the flange. Then, fit checked the assembly to the bike before proceeding to weld the assembly.



Last edited by AJ.Valente on Wed Mar 12, 2014 12:00 pm; edited 1 time in total

    

AJ.Valente

AJ.Valente
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Repairing Engine Safey Bar on '85 K100RT Step3



Step five:

With the assembly welded it was fit checked again to the bike. Turns out the mounting flange hole was a bit off, so the hole was expanded to permit all the bolts to line up. Note, the flange is a bit wider (right) than the stock piece and that gave us extra edge margin for just this eventuality.



Last edited by AJ.Valente on Wed Mar 12, 2014 12:00 pm; edited 2 times in total

    

AJ.Valente

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Repairing Engine Safey Bar on '85 K100RT Step4






Conclusions:

The fit is very close, but not perfect. It turns out the mounting flange was not perfectly level to the bracket, however the rubber mounting studs have a little give to them so it still works out OK.

All is left to do now is emery cloth the welds to pretty them up. Once it's all re-painted it will be hard to distinguish from original. cheers

-end-



Last edited by AJ.Valente on Wed Mar 12, 2014 12:01 pm; edited 1 time in total

    

CommanderKewl

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Nice work aj.
Thanks for the lowdown
Mike

    

88

88
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@CommanderKewl wrote:Nice work aj.
Thanks for the lowdown
Mike

+1


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Repairing Engine Safey Bar on '85 K100RT Ir-log11 88....May contain nuts!Repairing Engine Safey Bar on '85 K100RT Ir-log11

"The world is a book and those who do not travel read only one page." - St. Augustine from 1600 years ago & still true!

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