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tweaking top engine mount for AL frame flex

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We often read about how older steel frame YZ250's are preferred for woods/enduro use versus

the stiffer late model '05+ aluminium frame YZ250.  Comments like : better front end 'feel', less vibration, etc.

 

Based on the YZ250F motocross engine and frame, the latest generation WR250F is described has having thinner / flexier 

top engine mounts than the MX version of the bike, purpose designed to better suit the off-road type usage of the WR.

 

My question is, on my strictly off-road trail ridden Honda CRF250X (again a chassis initially based on a stiff MX race bike)

would altering the top engine mount (trimming away portions, drilling holes, less torque on bolts, removing it altogether)

gain in any way some noticeable improvements in: handling, feel, traction etc. ?

No jumping or high speed maneuvers, mostly 1st-2nd gear technical rocky trail and traction challenging situations.

 

I'm open to experiments but, I'd also like to avoid having to weld up a cracked frame by going too far.

 

Thank you all ahead of time for your experiences and opinions.

Edited by mlatour

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Some bikes you feel the difference when changing engine mounts but not all bikes get as much differance. 

+ for a average Joe i dont think you feel the difference like pro racers do.

But with that said,  the only way to know for sure is to test it, its not so expensive if needed to replace so i think i will test it too just to see if it helps me also ☺

Edited by skorpan777

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In 2005 whilst working with the Yamaha national road race team we removed the front engine mounts to introduce more chassis flex. It was a very noticable and instant improvement.

Pull the bolt out and ride. You will soon know if it is better or not. Your greatest enemy here is long term fatigue. A short ride should be fine. If you like the effect but are worried about long term issues, there are methods of anchoring the motor that still allow a small amount of flex.

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Terry, by removing the mount, what changed in the handling characteristics on that particular application ?

 

It's effect must no doubt greatly depend on frame layout,

say a CRF's 'semi-double cradle' versus a 'single backbone' like a YZ125 / YZ250 aluminium frame.

Thinking the YZ style frame would flex way more with less support at the engine mount.

Edited by mlatour

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Agreed.....but chassis flex contributes not only to traction but also impact transferrence. Just as tyres are an intergral part of suspension, so is the frame. Everyone knows what a dog the 97 CR250 was.

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I have had holy %$#@ with finding suspension compliance with my 01 CR250 in the woods. Revalving to date has been an expensive flop. I have often wondered about doing something to the engine head stay, frame mounts, etc but afraid to ruin something.

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YHGeorge

You seem to have no luck with your forks. Next time you have them apart, clean the inside oh the alloy tubes thoroughly. Then inspect the inside to see if you have worn through the anodising. The usual spot is around the triple clamp region. A wear patch here is common and will really mess with your fork action.

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