Over on the RS Riders forum, there was a discussion about cutting holes in the stock air box to open it up and provide more air. Obviously, if you do this drastically then you'll need to re-jet.

I was wondering, if I want to lean out my bike a little, could I drill a few small holes, check the plugs from time to time, and drill a few more if I want to adjust it leaner?

What are the chances that I'll get it right without having to re-jet?

I would like to lean it out for three reasons:

1. Better gas milage.
2. Should help with the sticky valve syndrome, of which I have had a few minor symptoms.
3. Odo supports lean running for Roadies.

I would like to lean it out this way because I'm cheap, and the bike is low on the family totem pole for our scarce resources. You know how it goes.

Old Shep

Are you all stock?

Don't feel bad Shep , we're all cheap! (well, at least me and my posse)

Shep, I did the Poor Man's BAK a while back. I am fighting with running too rich. I would say it added a mile or two, but I swear the bike also feels much "crisper". My dealer rejetted with a Cobra kit when my pipes were put on. I am certain he did not do it right, as I am down to 37 MPG even after the mod. I just got my MaxMix PMS screw, and I am waiting on one more part before I take things apart to put in the MaxMix. I will need to check my needle and clip as well.

As far as holes, I drilled 1/2 holes in the back and bottom where they are not seen at all. I also put 4 1" holes in the front edge. From everything I have read you can not get too lean, so I would not worry about the number of holes. BTW - the plastic will be everywhere after you drill, so don't do it at the kitchen table

There is a good technical article on this site for reference. Also, per someones recommendation here (good, good folks and advice here fer sure!) I bought some 1" plastic filtered covers for the holes in the front edge. Check out Rocky Mountain ATV.

Have fun.

Musky, no, not all stock. It's an '05, I had Cobra staggered loboys installed at the shop from new, and the dealer said he put in a 165 main jet (after incorrectly first installing a 195 and I was running way rich and getting 32 mpg tops brand new). No other jet or PMS alterations. I assume the AIS was bypassed, I think it has to be with the Cobras.

With about 27,000 miles on the clock, I get about 40 mpg on average (has varied between 49 and 32), and my plugs look OK, but slightly on the rich side. I only get sticky valve symptoms in cold weather. Otherwise it runs very well.

White Star, Can't get too lean? Encouraging. Let us know how the Mixmax goes. Where is that tech article?

Big Bear, yep. Wouldn't mind a few of those tax breaks. And hell, I'd play baseball for one year for a measly ONE million! I'm about 4% as good as A-Rod! (But they didn't ask me.)

All - thanks for the replies.

Old Shep

Musky, no, not all stock. It's an '05, I had Cobra staggered loboys installed at the shop from new, and the dealer said he put in a 165 main jet (after incorrectly first installing a 195 and I was running way rich and getting 32 mpg tops brand new). No other jet or PMS alterations. I assume the AIS was bypassed, I think it has to be with the Cobras.


If you have the pipes and have had jetting done then hell yeah, start drilling. With pipes and a stock air box you didn't need to jet. Dealers are jet happy and they always do it too rich. I'm guessing it is a 165 Mikuni jet? Don't know if the AIS has to come off for the cobras but if it can stay on then I don't think it has to be bypassed. Wouldn't hurt to do it if it isn't. Or take it off all together. Your mileage isn't that bad. A little tweaking will probably help. My average is 44 mpg. If I'm bad assing around in the city gunning from light to light it goes in the dumper. You will probably need to tweak the PMS for best results also. The dealer should have done that when he swapped jets so the brass cover should be drilled already.<br><br>Post edited by: Musky, at: 2007/01/23 08:39

Shep,

Did he just replace the main or did he also replace needle?

Doc

Doc, Musky,

Dealer did not touch the PMS or the needle. Said he didn't like to mess with the stock Yamaha setup. He only did the main jet because it was written on the Cobra instructions so it wouldn't be his fault if it messed up.

I could be wrong about the main jet. He upped the size. So if stock is 165, then he installed a 175. He just should have left it alone. The sheet he gave me was for Dyna jets, not Mikuni. They come with the Cobra kit. I can't trust the dealer, come to think of it. I'll have to take the carb off and look at it myself.

Last night I cut two 1&quot; holes in the back side of the airbox. I don't want to cut holes in the front due to wind-driven rain. I travel long distances in the summer, and sometimes I have to ride all day in the rain to make distance. This year, I'm either going to the Grand Canyon or Glacier N.P. from St Louis. Can't wait!

I'd say your dealer doesn't know what he's doing.

The stock main is an Mikuni 165. If he put in a Dyna 175 then that's the equivalent jet .... it's not a 'larger' jet. Mikuni and Dyna jets are numbered differently (see the Tech Tips section).

I want to again stress that you should not just change jets ..... you need a different needle also.

Don't worry about &quot;wind-driven rain&quot;. The whole front of my aibox is open and I've never had any problem. But then I haven't been riding in a hurricane.

Doc

Shep I have learned that when it come to a dealer I will never trust what the do. I have had some very bad experances with my dealer and jetting. From now on I do it myself then I know it's done right.