OH, also, when you get it installed, I am very eager to hear about the effects of that lightened flywheel. Complete report please ?

 

Yes I read all that from Marcelino's original post...but until someone's done some flow bench work to back that up or some other definitive test like porting their intake port/bigger valves vs stock, how do we know the restriction is not the air box where it all begins? (which is part of the intake tract of course)

You guys are all snowed in, but when the weather breaks, someone with a non-CV carb and maybe an after market air filter (so it's already had its breathing improved) needs to remove the air box boot and go for a ride to see if there's a difference


I'm still replaying my ride the other day in my mind..trying to think if it really was any faster...Right away the bike felt more lively..frenetic.. even as I accelerated into and around traffic doing less than 45mph without pinning it.

Twice I went thru the gears and both times I was either late on the 1-2 shift or for some reason my usual clutch pull wasn't working

Kind of like when you get on a faster bike and whoa it's way ahead of what you're used to..already at the top of a gear waiting for you to DO something? (shift!)

I'll admit I don't have much ride time with this new carb, but I know when and how to shift this bike and it was there before I was.

 

Ya sure, but I think I'm going to ride it the way it is off and on for a week to get used to the air box mod and be able to appreciate the lighter flywheel once it's done. I'd love to put it on tomorrow but I think I need more seat time as-is so one mod doesn't blur into the other.

 

Actually I the air box volume etc is sufficient, it's the spaces between the seat etc that perhaps aren't allowing air into the air box fast enough?

 

Makes sense to me, one could then perhaps run the lid on then just drill holes on the sides to allow more air? Although I'm not sure what the lid would be protecting at that point...maybe forcing air through the sides vs the top for more velocity?

 

In my case I know I'm slightly rich and removing the lid only made it louder without much gain that I could tell. That is why I responded in the first place as it makes since that the seat may not allow all that much more air to enter and a few holes in places with minimal obstruction might be the way to go. Like I said I've played with this mod on a lot of bikes and something worth mentioning is whole size as there are inserts that provide some protection from water in that size and 1 1 inch hole is better than 2 half inch holes, I bet Richard already knew this but I found out thru trial and error.

 

Went out to get more familiarized with the air box mod. The bike ran well but seemed a little hot (not sure) - though looking at the spark plug later it wasn't lean looking

Just to see what happened I came back and raised the 9EBY1-50 needle to the 4th groove from the top-one richer from the middle, and the bike did not hesitate or show any signs of the mid-range now being too rich at all

Next, I swapped in my largest mj - a 135 in place of the 132.5 and it still just pulls..maybe winding a little higher rpm than before

(I'm at 100' or so ASL)

That's the largest main jet I have, though larger ones will be here in a month I hope

Glad to not be running around too lean.

I need to find someone to race who's close to my bike's speed so I can gauge the value of mods.


I used 1" holes the right side of air box; I used one size smaller on the left side-so I am still good to go unless some of the holes are in a curved part of the air box wall. Not a big concern, I can run without all the little filters in place

 

I'm starting to wonder if this bike hasn't had the cam mod done already. There's just tremendous amounts of seemingly unstoppable torque everywhere. Which is a bit of a surprise after jumping to a 36mm from the 34mm. I've had the valve cover off 2x but never thought to look at the cam gear placement-I'll be sure and do that next time I have the tank off.

My straight thru exhaust may be letting me run richer than most of you. It's very similiar to the one DRC sells; a bit shorter in overall length the norm and having a megaphone style mid-pipe.

This unit was throaty but not annoying on my slightly modded XR200, but on the Kaw it's just loud-more so since the air box mod. I didn't find the exhaust note annoying before I did it. I'll have to keep it a gear up as I cruise around just to keep it quieter for me.

I did notice a couple times when testing the larger main jet that if I rolled the throttle open more and more I could feel what seemed to be the main jet kicking in. Or so it seemed.

I noticed that on the XR as well when I started richening up the factory lean main jet.

It was pronounced enough you couldn't miss it if you tried. Maybe that's main jet nirvana or something?

 

I raised my 9EBY01-50 needle one more notch to full rich this morning, and the bike seems to love it I can feel a surge or is it bigger surge during the transition into the mid range than before the change.

I could have instead gone to the P8 needle jet...but that wouldn't have been as precise a one increment change unless there's a way to calculate that the new needle position should be X when going from 4th notch down/P6 to where with the P8.

Somehow the engine seemed to maybe be running cooler, though I wasn't out long.. and it was really enjoying the small amount of additional fuel.

I guess not having any air jet in it at all is giving me a bit leaner mix throughout the rev range, but that should be a good thing as long as you can jet for it. If I added either the .7 or .9 air jet I have here I'd have to kind of start over with the jetting


How much the required richer jetting and power increase is due to the holes in the air box is uncertain, but so far it's all good!


While I had the seat off today I was eyeballing the available air inlet spaces adjacent to the air box and imagining the seat kind of sealing off the top.. there isn't a lot of atmospheric to air box inlet area left when it's all assembled !

 

So after ventilating the air box:

I've gone up two sizes on the main jet and 2 notches richer on the needle


Main jet before was 130, tried 132.5 and now 135 (biggest I have for now)


Needle clip was in the middle, now it's full rich