Engine Guards

[TomB]

The three-point guards, though I think they look better, were only available on the '78. It was found that the three-point DIDN'T protect. When they fold back, they broke the covers and many times, cases. The two point protectors bend back fairly easily and lay over the covers and take the asphalt grinding, and tend to protect much better than the three-point guards.

That middle bar on the three-point guards is the main culprit. It hits the front of the covers before the rest of the bar can when it folds from a layover, and all that pressure pushes from front to back on your cover, breaking it, and many times the case where the bolts go in for the cover and get ripped out sideways... instead of pushing in towards the engine in the case of the two point guards.

I like your reasoning here, I always didn't like the two point because they folded round and hit your case smashing it, a friend had a set of two point on his XS and needed them a few years ago, they folded onto his engine and smashed it kinda confirming what I'd assumed, however I see your point about them folding and sitting against the case and being sacrificial but only see that working in a gentle off. I also see your point about the three point front mount smashing the case too, though as TC says, a well designed/made three point wouldn't do that.

My original XS1100 came with engine guards fitted by the PO, they are two point but the top tubes link together in front of the crank case so they can't fold round, this seems to be the best of both worlds, and unfortunately I had the oppurtunity to test them out a lot of years ago, they worked perfectly, wish I could say the same for myself. I have since made my own engine protectors in Sched 40 316 3/4" NB stainless pipe.

[TopCatGr58]

Hey Tom,

I like that design, you get the added strength of the solid bar all across the front top of the engine and congruent with the curved portion that wraps around to the bottom. A few questions, how did you BEND that pipe, did you use a torch and heat it up, did you use a hydraulic pipe bender?? I also see in the first picture that it's in 2 pieces, does it go together with a slip joint or did you weld it solid? If so, I would imagine that you have to lift or pull the engine to install the guard FIRST???

You say it's Sch., 40 pipe, but what is the wall thickness you used?

Part of the problem with the commercial ones is the mounting brackets that are attached to the pipe sections....they seem too long and or too thin which allows them to bend/flex under the impact pressure!

I don't know the strengths of the different sized and thicknesses of the types of pipe that can be obtained for this type of project. And I'm no engineer, so I would like to see some ideas from other folks with more "schoolin' " than I as to design variations, frame mounting points to use, etc.!

T.C.

[skids]

Good looking case guards.

[TomB]

I can't take credit for the design, my first XS11 came with a set of chromed engine protectors, I copied their design for my other XS11's.

The bends were 90 degree bends done by a mate in our works pipe fitting shop on the hydraulic bender, we couldn't do 180 degrees so did 4 bends and I cut and joined them using 316 stainless wire in my MIG, the pipe is 316 stainless offcuts, I think the set on the monoshock bike is Schedule 40 (heavy pipe) and the set I made for my 5K7 Sport were Schedule 10 (still pretty heavy pipe) Schedule 5 , 10 or 40 are gauge thicknesses for pipe, to give you an idea of thickness I use 1"NB Sched 5 pipe for exhaust headers like the ones on the red frame bike posted earlier, Sched 40 is about 1/8" thick.

The diameter I used was 3/4" NB, (nominal bore) pipe, its similar in diameter to all the case guards' pipe I've seen, and its common pipe so any pipe fitting shop or fabricators will have the benders to fit it.

Here is some info on Schedule 40 stainless pipe Clicky

The join at the top in front of the crank case is a slot together join, a short piece of Sched 40 1/2" pipe is slotted inside the 3/4" pipe and welded to one side so it can slot into the other side on assembly, this join sits just below the CCT
These are the guards I made for my 5K7


I welded it all together with internal plugs and full depth welds

[DGXSER]

Points of failure

IMO, the engine guards are designed to protect in a drop scenario, not a lay down at any speed.

If it helps at all, here is where mine bent when I had my "incident" a few years ago. While it all happened in a flash, I am certain my speed was less than 20 mph at the time of impact. As near as I can recall, the left side engine guard caught the raised black top edge after the bike dropped off and when it bent back and hit the bike, it flipped me into the guard rail, where I exited stage right, and the bike then slid its way down the guard rail.







It would appear the tubes themselves do not fail, its the bracket right at the tube connection that bends. The plate is just not thick enough to resist the torque of the force that distance out. What might help is a gusset between the bracket and the tube. I am not sure the three point system will hold up that much better, as the brackets are likely to still give.

But the full width tube that ties the two sides together as Tom has it is definitely a stronger piece. Much more likely to withstand a moving lay down.

[TomB]

Anybody got a picture of what the 3 point type looks like and how they bolt on?

Here ya go Click


.

[fredintoon]

This is a listing from Ebay of the three point guard.

http://www.ebay.com/itm/1979-79-YAMA...699ca4&vxp=mtr

Hi Rodger,
sez it's sold for $19.99 but what intrigues me is that it was just the right-hand one being offered for sale.
Did the leftie get damaged in an upset?
Or perhaps the rightie was removed to install a sidecar mount?
And did the buyer only need the rightie?
Or what?

[latexeses]

Hi Fred,
It was just a listing that I saw that showed the 3 point. Mine aren't even on the bike right now. The guards on my bike were "used" by the PO. Trying to find some chrome work that won't cost as much as a room addition on a house.
Around here....... Headlight bucket, ears and fork cover/badge = $350.00. Afraid to ask about fenders.
Think I'll look in Mexico.