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View Full Version : grinding welds on 400ex stock pipe


brad_300ex
11-20-2002, 07:45 PM
i am new to quads and i was wondering what u ment when u grinded the welds off the head pipe. i am getting 400ex soon and i would like to know what u guys are talking about.
thanks
lilpoppy
11-20-2002, 07:49 PM
All you have to do is pull off your headers and look into the end that bolts onto your engine. At the very end of the pipes you will see that there is a weld all the way around the very end of the inside. All you have to do is use a dremel tool or something like it and gring it up. It will give you more air flow for your exhaust.
brad_300ex
11-20-2002, 07:57 PM
hey, thanks for your advice. i will have to do that when i get a 400ex
F-16Guy
11-20-2002, 08:02 PM
yeah, poppy's right. The welds are there to secure the machined fittings (that mate to the cylinder head) to the head pipes. Grinding them down flush with the head pipe inner diameter will give you smoother (and more) flow. It should have no effect on strength.
Stevo
11-21-2002, 02:21 AM
If you grind out the welds do you have to rejet, and also is the sound any better or worse, louder or quieter. I have a pro-circuit t-4 slip on right now with stock jetting. How do u think it would sound with the welds grinded out and that slip on?
tprender
11-21-2002, 07:35 AM
I don't think that it would make anydifferece in the sound. Maybe the jetting might change by 1 size up. If you have a slip on and you did not rejet, you need to to get the most out of the exhaust. Try going to a 155 main and a 42 pilot and see what happens.
KAWSAM62
11-21-2002, 08:08 AM
THE IDEL WILL CHANGE A LITTLE FOR THE BETTER AND THE ENGINE WILL BREATH BETTER JUST A TAD LOUDER A MORE THROATY SOUND AT LEAST WITY A FMF SLIP ON MAYBE I LITTLE BACK FIRING BUT NOT BAD BUT WILL IT REV BETTER YOU BET PROBLE NEED TO REJET A 40 PILOT MAYBE UP 2 SIZES ON THE MAIN WATCH PLUG COLOR ONE OF THE FEW FREE MODS THAT ACTUALY WORKS WELL HOPE THIS HELPS:devil
timewass
11-26-2002, 10:04 AM
I have a pro-circuit t-4 slip on right now with stock jetting.

I don't know your elevation, but I'm at between 1300 - 1900 feet ASL and I had to go to a 160 main. Stock jetting seems very lean to me.
bklyn400ex
11-26-2002, 01:39 PM
i ride in PA, i have a WB R4 slip on, ground welds, modified airbox, K+N filter, i didnt rejet, do u think i should, it seems to be running fine, will it run better, faster if i rejet. If so what size do u think i should go to??

thanx
KAWSAM62
11-26-2002, 01:46 PM
proble a 40 pilot and 2 sizes up on the main but the plug color will tell the story check it :cool: