When servicing my cbr600f yesterday I came across this, dunno why its been done can anyone shed any light??

its duck tape by the way




Dave

 

A previous owner before you probably bought a DYNOJET jetting kit for the carbs, and 'drilled' holes in the airbox (as prescribed in the Dynojet instructions) to 'open up' the intake a little bit.

THEN, they changed their mind and taped over the holes.

When you hear about a "drilled" airbox, that's what it means. Minus the duct tape, of course.

You can leave it like it is, no problem. If you like, take the duct tape off, and the extra intake noise will make you think you're going faster. ZOOM, ZOOM!

 

Okay no worries will leave it as it is then, assume there is no performance gains to be had by removing it?

is there any way to check if its still got the dynojet kit in? TBH it doesnt feel fast enough tho..........

 

yea next time you clean the carbs see what number is stamped into the main jet, with a drilled airbox it would be 118 or higher. Also the needle jetstaper very rapidly on Dynojet needles, and are about the width of a toothpick for about an inch and a half.Does the bike currently have a K&N Filter installed?

More than likely, the previous owner removed the filter and jet kit and sold separately.

 

That's what gives you that cool "freight train" sound![&:]

 

cheers guys!!

tds94probe- I recon your right mate, someone took them out. If theythen didnt balance the carbs propperly, could that be why I still have a couple of small flat spots in the rev range??? (about 3-3.5k in low gears and about 8-8.5k in higher gears)

Dave

 

nope, thats just the Hurricane for ya. LOL.

Your low range problem can be adjusted a little bit by ensuring that the float height is set to around 8mm (I know the manual says 9 but I like it a little richer). and your 8000-8500 flat spot can be fixed by reinstalling a dynojet kit, or you could try putting another spacer or 2 under your fuel needle in the slide, which will richen that out a bit.

If you want a cheap dynojet kit to try, I have one for sale. Its not a complete kit, but it does give you everything youd need to go faster. Only thing missing is the rest of the main jets. What youd get is dynojet fuel needles installed in drilled carb slides (this will save you from having to drill your own in case you dont like it) and a set of DJ120 Main Jets (you will need to remove the tape if you install this.)

I didnt really have a problem with the kit really, I just wanted to be sure a 120 was right for my area/elevation/humidity ect. So I went with a Factory Pro Kit instead.