GP800 - Custom Screen Modification

Here it is, the DIY screen modification for the GP800. It stems from a suggestion from JT at Thompsons that the standard screen blade for a 125/250 Gilera Nexus might be usable as a second screen on bikes where the standard screen does not protect enough. However the Nexus screen blade is too flat for the GP800. It could work if it was carefully curved (with the aid of a hairdryer) but there did seem to be another solution. The standard screen from an MP3 looked good for the GP800 - but it also needed a degree of modification.

In order to line up properly and provide sensible mounting, the lower section complete with bolt holes needs to be removed as well as the top of the side mounting holes. Here it is with a neat(ish) curve applied where the top hole has been cut out.

JTs suggestion that rear exhaust mounts from an original Mini might make good mounts/spacers seemed like a good place to start however these are a bit big and unsightly but I guessed that Vauxhall Cavalier fuel pump mounts might do the trick (like the Mini metalastic "bobbins" but smaller).

Before I tried the Cavalier fuel pump mounts, I bought packets of every washer and grommet under the sun together with some GT Moto "Aluminium Screen Screws" (at £10 ouch). These were the really clever idea - unfortunately, they just pulled through the hole I cut in the screen under light hand pressure - they would never have survived the wind blast at motorway speeds.
After drilling my GP800’s screen and using a combination of coachbolts and grommets to create a kind of rose joint arrangement I bolted it all up and went for a spin.

Not an entirely successful operation to be honest.

Firstly, at slow speeds it squeaked and creaked - I presume I had put some stresses in one screen or the other when bolting them together. As I got up to 50, wind pressure stopped the squealing and I headed for the M1.

Now things started looking up - with the screen fully upright, the increase in frontal area stops all windlast and buffeting was definitely reduced - but......... IT'S VERY VERY VERY NOISY - IT SOUNDS LIKE YOU'RE IN A WIND TUNNEL - YOU DON'T FEEL IT BUT YOU CAN CERTAINLY HEAR IT.

I came back down the M1 with the screen at it's lowest setting - still plenty of protection from the wind but just as noisy.

Next step was to increase the separation between the two screens. I also took the opportunity to do a better job of sanding and finishing the cut edges.

The separation was achieved by using nuts as spacers and this allowed the coachbolt to be tightened on to the MP3 screen first. This allowed the screen to rest on the GP800 screen so that I could tighten it down in rotation to avoid putting any stresses in that might cause creaking.

Grommets were fitted where the bolts pass through the screens with penny washers each side to spread the load. A quick "round the block" roadtest revealed no creaking and the only problem was that despite increased spacing, the two screens just touch at he top where the GP800 screen has it's maximum curve causing a "tapping" noise and also scratching both screens. I cured that temporarily with a bit of old hose.

After about 50 miles each way on a motorway at sustained high speeds - the new solution was definitely quieter than before - although still noisier than the standard screen. It was quite gusty on the M4 and no problem at all - in fact I was probably going a bit quicker than usual so it must have been keeping the wind blast down.

However (you knew there was going to be a "however" didn't you) by the time I left the motorway and was pootling towards Northwick Park, I noticed that the squeak/creak had returned. I'm guessing that the force of the sustained high speeds had put stress into the rigid mounts. There was also slight cracking. Surprisingly, the cracks are in the MP3 screen which is mounted using original holes rather than the GP800 screen which has been drilled.

I now know why Reseach & Development is such an expensive buisness. I stopped at good old Moshi's Auto spares and bought the Vauxhall Cavalier Fuel Pump mounts (four of them at £2 each ) to give me a "flexi mount - I should have done that in the first place.

The problem of the MP3 screen touching the GP800s screen at the centre top was cured by a piece of visor rubber (like a short sticky backed car wiper blade).

I fitted the second biggest penny washers I have together with the rubber washers from a garden hose connection. The biggest washers I had were an affront to aesthetics (and lets face it the nyloc nuts I have now are hardly pretty) but we'll have to see how that effects the cracking. I've marked the extent of the cracks with a black felt pen to see if I've arrested their spread.

Finally, I cut and reshaped the sides - this may further reduce the turbulence and is certainly neater. All I need to do now is spend some time with brasso where the multiple cutting, sanding and simply removing and refitting has left me with a few scratches.

And here 'tis