Front engine mounts

[GSX1400Convert]

I'm confused, My 750 slabbie motor has a pair of rubber front engine mounts, and I'm sure the 1400 does too.

When mounted solid at the bottom, and at the rear, the idea of front rubber mounts doesn't make sense.

Unless the factory had headstocks falling off, left right and centre, and put the rubber mounts there to increase the degree of flexible area. 

Any thoughts?


Also, during my little overseas bike trip, the front end drifted and slid out 3 times, two with buggered tyres and once with new tyres.
Is this a regular thing with the 1400's when under the pump?

I decreased the fork dampning a tad, thinking it may be a little harsh, but it happened again after that.
Rear tyre has no chicken strips, yet the front still has a 10-15mm of chicken strips equally on both sides.

[KiwiCol]

As for sliding out when under the pump, it's not happened with me, but I may not push as hard as some.  Irish in Oz pushes his (or did) so he may be able to answer that for you. Mr Nitrous would also have an answer I'd bet.

Also might pay to mention what tyres you were running & their profile. What the road surface was & tyre pressures you ran.
Stripes on the front, dunno, unless the geometry has been altered by raising the forks or a different front end maybe?

@Irish in Oz   @Tony Nitrous

[froudy]

The Mk1 and Mk2 Bandits have the front rubber engine mounts too. I could never really see the point either. As you said..the rest of the lump is locked in solid

[grog]

Never thought about, sure seems strange. Someone will have an answer.

[Irish in Oz]

Apparently it's to do with natural engine frequency, which could get worse I suppose if say you where cruising (without fenders  ) at 5 thousand rpm then the amplitude got worse and maybe a speed wobble could occur.
Not required on race bike as they are always changing their rev range.

[KiwiCol]

5,000rpm is pretty quick cruising .  .  .  around 160/170k   

[Irish in Oz]

I was thinking of the Slabbie.

[Andre]

This explanation makes sense to me:

I think the answer is that the back 2 bolts are the main structural components of the engine mounts, very similar to Honda's practice on many of their early small bore bikes. the engines hung from the rear housing and the cylinder just hung out in the breeze.
The front and top mounts on the slightly larger Rebel engine serve more as "steadies" to keep that bigger engine from deflecting side to side while the rear mounts basically hold the transmission rigid to the frame and swingarm mount.
If Honda wanted to rubber mount the entire engine, they would have to mount the swingarm directly to the engine casings and rubber mount the entire engine, swingarm, rear wheel combination just as was done on the Norton Commando. (the sprockets have to be rigidly aligned and a fixed distance from each other to make the chain drive work and survive for a normal lifespan.)

https://www.hondarebelforum.com/f28/why-is-the-front-motor-mount-rubber-mounted-62785.html

[Dan B]

Rigid mounts help dissipate vibrations through the frame, but cause metal fatigue.
Rubber mounts help absorbs some of the vibration that would be transferred to the frame, reducing the stress on the frame. They have there own set of problems though but I can't remember off the top of my head.
Maybe the 14's frame/engine is weak at the front?

If you search 'stressed member frames' or 'different types of motorcycles frames' on Google i'm sure you could get a better answer

[Irish in Oz]

https://www.tandfonline.com/doi/abs/10.1080/03052150512331314542?journalCode=geno20

[grog]

Take me a while to get round all that Irish, i will. I can rember hardlys, rubber mounted shook motor to bits, solid mounts shook rider to bits. Guess they never read your post.

[Irish in Oz]

Guess they never read your post.

Only the wise one's do Grog.