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2010 400ex




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  • Similar Tagged Content

    • By afa913
      Am i better off to just replace the bearings or buy the whole carrier?
    • By afa913
      Anyone know a place i can find a used stock pipe for a 400ex?  I would love to find a take off
    • By Jordan Alexander
      The title is for attention. I’m prepping my cylinder head off of an unknown year 400ex to install on my quad. And I’m examining it and there’s literally a Jewish start( Star of David) protruding from the metal on the camshaft side of the head. It’s not imprinted or etched/ engraved. It’s coming out of the metal. DOES ANYONE HAVE INFORMATION ON WHY ITS THERE??? I’ve attached a picture 

    • By 400ex
      So after my 400ex pep up (High comp piston, stage 2 hot cam, and some others), There was a malfunction with the rocker arm jam-nut; guess it wasn't torqued to spec. The rocker arm nut caused the lash to become too out of clearance and I bent a valve on a test rip high in the rpm range. There was no damage to the piston but only that valve, a couple dents in the head, and a completely destroyed valve guide. So I decided to take it upon myself (after watching kenoconnors race porting instructions and reading up on this subject) to port my cylinder head significantly. I had the head decked, cylinder honed and smoothed/polished the dome/exhaust port (intake wasn't polished but dimpled slightly to ensure fuel atomization). So after porting, decking the head, I had all valves and guides replaced/reamed, 5 angle valve job, and recut seats, then I installed xr400 gaskets (for higher compression), carb jets; 42 pilot, 175 or 6 main not sure, dynojet needle, k and n filter with no lid, enlarging of header ports and big gun eco slip on exhaust for a 450r, trx 250r coil (adds 1000+ rpm to limiter), 11:1 85mm piston, stg 2 hc with springs and retainers replaced, and polished rocker arms. I then replaced both sprockets one down in front and stock in rear, o ring chain, and 18in tires. There is a larger list of mods but these were the only ones affecting acceleration/performance. On the dyno, this quad put down 42rwhp and was estimated at 46 to the flywheel. Once again this was 42 to the wheel on the stock bore/carb size/header. All this was done at 16 yrs old. You may not be able to see it in the picture but peak whp was 42 on a mustang dyno.


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