250 Raptor A-arm width

[nzraptor]

We are building a Raptor 250 for mx. Can anyone advise me what width to use up front +3 or +4. The plus 3 appears to be the norm but the opportuniy to go a little wider is quite inviting however I am afraid of making the machine more over square and ruining the geometry. Also neutral or +1, +2 forward. Any help would really be appreciated.

[Adams granddad]

We’re riding MX and I'm not an expert, so don't quote me, but I've been told that you get improved steering characteristics when the centre of the wheel is closest to the centre of the steering ball joints also when it’s moved slightly forward. I’m also told that the rear track should always be wider than the front.

With that information we are just finishing off building Adam’s 2010 race bike and we have the following set-up: -

+4 +0.5 long travel A-arms, camber and caster adjustable, with 20x6-10 tires on 4:1 wheels, width is 47.69" at 7" below frame.
+1" swing arm.
+6" axel with 18x8x8 tires on 5:3 wheels, width is 48.2".

The A-arms are the first 250 production set made by Houser and are simply the best A-arms we have ever fitted, they come complete with all seals and roller bearings.

I'm hoping it will handle like a dream, can’t wait to get it on the track!

[nzraptor]

Thanks for the info, +4 appears to be a new approach to the 250, we have been looking at the LSR +3+1 and the JDP +4+1/2. Were not aware that Houser had them available also. Can you help me with your measurements? I am 39" across the front @7"stock (approx) with a 3:2 off set, add 8" to that and take away 2" for the 4:1 off set and I get 45". Is it the camber giving you the 47.69? Do you have any more pics of your bike?

[Adams granddad]

The figures came from John Houser, but I've checked myself by putting a square against the tire and marking the floor and it does measure just over 47 1/2". Yes it is the camber that increases it, we have ours set at the max 4 deg at the moment.

No more pics just yet, there's a few more bits to finish off before we unveil it fully. Keep an eye on Adam's website, I keep adding a few shots of it on his news and quads pages, in fact I've given more away on this forum than anywhere else!