With alot of body rake, it could be causing the spindle to sit more vertical than it should, thus loosing its desire to want to center itself. Add loose steering, and it could be a hand full. Adding more caster to compensate will help the problem but may not fix it. 
 
Mike
		 
		
		
		
		
		
		
			
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				Mike Redpath 
Musclerodz & Customz
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