400ex: grinding headpipe welds

[AAAirbooorn]

Yeah , do I need to rejet now that I've done this?

If so, what do you recommend?

Engine is stock except for the Sparks key.

[cals400ex]

you should fine with stock jetting. your elevation levels or the temp you ride in should affect jetting more than those welds in the header.

[Billdog350]

I had the Sparks key, billet end cap, Uni filter and 155 main jet in my 2000 400ex. When I took the header off and ground out the welds it made a HUGE difference!!! Very noticable! Way more grunt and it revved throughout the powerband much better. I can't believe Honda didn't clean that up from the factory! I just used a Die grinder (dremel should work too) and ground down the welds. They are quite hard and will take a few grinding bits and a good amount of time to grind but the work is well worth it!

[sickmojave]

I had very little to no gains from this mod :p

[cals400ex]

Originally posted by sickmojave
I had very little to no gains from this mod :p

i am with you on that one.

[AAAirbooorn]

Gains would be nice but I'll let you know and I was grinding on those welds forever too.

[ewalker302]

Heres some pics when I did mine.


http://www.exriders.com/vbb/showthread.php?s=&threadid=90615&highlight=bored+welds

:bandit:

[400exdad]

Originally posted by AAAirbooorn
Gains would be nice but I'll let you know and I was grinding on those welds forever too.

If it took you that long, you need a bigger tool! :D :D

I noticed a difference... a smoother and more free rev. Everything else was stock at the time.