Front upper motor mounts question

[Cobia]

This is for my XJ but it's the same for the XS, almost.
Is there any reason why two bolts and thick fender washers cannot be used instead of the long bolt and the tube which holds the bushings in place in the front upper engine mounts?
Actually, I misplaced the 'longer than factory' long bolt which also secures my 3-point case guards at those points. I know I can buy a SS all-thread rod and cut it to fit, but I kind of like the cleaner look of the two individual bolts.
It's kind of busy looking in that area with the extra factory frame reinforcement pipe, and then my case guards, to add another horizontal line...
I don't see where that long bolt would any more rigidity to the frame when it has a flimsy tube on the inside of the bushings.
Any and all informed opinions welcome.

[TopCatGr58]

Hey Cobia,

Well, I'm not sure how "INFORMED" my opinion will be, but I'm going to give it a shot!

After reviewing the microfiche, and some photos I have of my bike and a few others, I've come to this conclusion! We know how "flimsy" the frames are on these, and combining those two points with that adjoining spacer/bar "may" provide a little more rigidity against side twisting/flexing of the frame...it makes another cross bar in the "A" design of the frame coming down from the NECK when looking straight on at the engine from the front. There's a beefier cross bar on the frame down below that, but the tube may help provide more frame stiffness. And if you use separate bolts/nuts/washers for each joint, then you don't have that solidity there. Whether it really does provide much rigidity to the frame, I don't know, but that's my uneducated guess??

T.C.

[greatnw]

I'm adding the engine guards to mine and that seems like an extremely good idea to me TC.

[BA80]

I'm not sure it would help the rigidity of the frame but I can see how it would most definitly stabilize the down force on those 2 little loops of cast aluminum the mounts fit into. Single bolts in each one may cause a twisting of the mounts and possibly crack or break the case.

Just thinking that there was a reason for it when it was built. JAT. There may be no problem at all but that's what comes to mind for me.

I have some extra bolts and spacers if you need. They should be the same for an XJ as for an XS.

[Cobia]

Thanks TC and Greg,
Hadn't thought about the possible frailty of the cast aluminum loops on the case, although they look pretty beefy to me.
Yet, the XJ has an additional frame crossbar about 6" - 8" above the lower one we have in all XSs, not to mention the much larger/beefier gusset joining the backbone of the frame, the stem/neck, and the engine cradle.
And that additional frame crossbar is what leads me to believe that the "tube" may not contribute that much rigidity to the XJ frame, it basically just keeps the bushings from migrating out of their mounts to the center. Yet, it does make for an additonal semi-rigid crossmember in that area.
Having ridden both of these quite often and under many different conditions the XJ frame definitely feels more rigid.
And, thanks for the offer regarding the bolts, Greg. I'll do some measuring and let you know.

[DGXSER]

Hey Cobia,

I also would think that the tie together is more about controlling motor movement than rigidity in the frame. If it were my bike, I'd want that longer bolt. I know I still have a couple the foot peg bolt here, and probably that one as well if you need it, I had the engine guards so it would be long enough. Yours for shipping if you do.

[BA80]

No problem. However, you said you were installing some engine guards? If they are the type that use that long mount bolt as a mount the stock bolt won't be long enough. Some SS allthread IS what you will need.

I don't think there is anything else that will work.

[bikerphil]

The single long bolt setup may lessen engine vibration some directed to the frame. Adding 2 large washers to the inner side of the engine castings might increase vibrations, defeating the purpose of an isolated rubber mount. Try it and let us know.

[Cobia]

Phil,
It'll be interesting to test both scenarios and I think I will. In the meantime I'll go stock.

Don,
I sent you a PM, re: your offer for the bolt.

Thanks.

[Cobia]

BTW Phil,
The washers I used were big enough to provide stability to the area and appropriate to the bolt size, but only large enough to keep the engine mount metal sleeves in place. There is no contact between the washers and the engine case so I don't think there will be any vibration transfer.

[Spookysxs11]

does anyone know if the rubber in these mounts is still avaliable or another place to get it or something creative that works

[BA80]

I have a few good used ones laying around if you need some.

[Spookysxs11]

Thanks I will keep it in mind.... I think they are getting close to having to be replaced.