XR650L Airbox Modification Question

[Failtron]

Hello All,

           I've Got a Mikuni pumper on the way and the instructions say to cut a 45mm hole to allow more air flow but do not specify where.  The air is obviously being drawn in through the top so I'm wondering if cutting a hole in the side could actually hurt the air flow somehow?  Should I cut it in the removable side panel and install some kind of mesh to prevent dirt and debris from entering or cut in on the opposite side?  Any suggestions from someone who has successfully completed this modification would be greatly appreciated.

 

Thanks

[XR650L_Dave]

Does the carb actually flow more than the stock CV carb? The stock carb is pretty big.

I'd put the hole in the most water-protected location and put some mesh or louvers over it.

[Failtron]

I'm not sure but I'm assuming that it does based on the directions to cut a hole to provide more air as well as de-snorkelling.  I think the stock is actually .5mm larger if im not mistaken.  It seems like my only options are to cut into the removable side cover or into the airbox itself but it doesn't look like anywhere will comfortably fit the 45mm hole they recommend on the actual airbox.  There is a spot directly in front of the intake on top of the airbox but there is a bunch of wiring positioned there. Have you heard of anybody opening up the side panel and installing vent filters?

 

On another note,  are you THE dave?

[cjlemon]

1 hour ago, Failtron said:

Hello All,

           I've Got a Mikuni pumper on the way and the instructions say to cut a 45mm hole to allow more air flow but do not specify where.  The air is obviously being drawn in through the top so I'm wondering if cutting a hole in the side could actually hurt the air flow somehow?  Should I cut it in the removable side panel and install some kind of mesh to prevent dirt and debris from entering or cut in on the opposite side?  Any suggestions from someone who has successfully completed this modification would be greatly appreciated.

 

Thanks

Cut a hole behind the exhaust side panel instead.  The hole does not have to be a 45mm hole, but could rather be a series of smaller holes equaling the same area.

[cooldudesmd]

Where did you order your carb? Did you get the adapters as well? I cut 6 1" holes in the top (only) of my airbox and installed slightly oiled Uni vent filter things.

[Failtron]

I ordered it from Mikunioz in Australia.  It comes with an adapter for the air box side.  I think the exhaust side is definitely the way to go for cutting the holes after looking closely.  If I did the math right it takes 3 1" holes to equal approximately the same area as a 45mm hole. I don't see how its possible to make 6 1" holes on the top.  It seems like that would be the optimal place, did you put them under where the cluster of wiring is? If it is within the realm of possibility it would be awesome if you could take a picture of what you've done and show me.  The uni vent filters look great I've got some on the way.  

[cooldudesmd]

Oh okay i am on the other side of the water looking for someone with the carb and adapters! I will have to send pics when i get home from work. Don't know how to explain where i put them exactly but I didn't bother under those wires as i plan on the battery relocation going there eventually. You may or may not like how I did mine, but give me a few hours and I'll hook you up with some pics. [emoji1303]

 

[heart_of_darkness]

If you cut holes holes above the air filter, you defeat the nice splash baffle that was engineered in.  If water isn't an issue, you could extend the existing opening rearward.

 I imagine the factory air box opening already has a larger cross sectional area than the carb bore.

[Failtron]

I think there is more to it than the size of the intake vs carb bore. Opening it up is recommended by mikuni so I assume it is necessary for optimal performance

 

[cooldudesmd]

 

As promised.

 

You'll have to use your imagination for some of the pics to get exactly where they are, but it should be pretty obvious.

 

I put silicone on each one to make sure it was sealed. And did it without completely removing the airbox. I did loosen it though.

[Failtron]

That looks great. I'm going to get to work on it now thanks a lot!

 

[JoeRC51]

There isn't enough room under the seat between the frame rails for airflow as it is , put your vents outside of the frame rails like above or on the sides preferably so water doesn't drip onto the filter during washing or rain. You can also trim the lip on the stock airbox opening down , but leave a little to act as a dam. If you look on the bottom of the stock seat , towards the front of the bike from the stock opening , there is a rib that runs from side to side , cut that rib off flush with the bottom of the seat.

[cooldudesmd]

There isn't enough room under the seat between the frame rails for airflow as it is , put your vents outside of the frame rails like above or on the sides preferably so water doesn't drip onto the filter during washing or rain. You can also trim the lip on the stock airbox opening down , but leave a little to act as a dam. If you look on the bottom of the stock seat , towards the front of the bike from the stock opening , there is a rib that runs from side to side , cut that rib off flush with the bottom of the seat.

I plan on doing the seat rib trim later with the battery relocation. My pods were placed mostly with future battery location and water intrusion resistance in mind. However, I don't disagree with any of your statements. OP- my way isn't the "best" way in terms of pure performance. You may want to consider what Joe said above.

[JoeRC51]

Just now, cooldudesmd said:

 

I plan on doing the seat rib trim later with the battery relocation. My pods were placed mostly with future battery location and water intrusion resistance in mind. However, I don't disagree with any of your statements. OP- my way isn't the "best" way in terms of pure performance. You may want to consider what Joe said above.

 

If you put the battery under the seat , you'll need more airflow from somewhere else.

[cooldudesmd]

And when NicheCycle gets their parts together I'll need more air flow for the pumper [emoji1303]

[JoeRC51]

Just now, cooldudesmd said:

And when NicheCycle gets their parts together I'll need more air flow for the pumper

What are they out of stock on ?

[cooldudesmd]

Carb to engine head I believe. Its been a month or 2 since the order was cancelled and about a month since I called and was told I'd be emailed when they had the missing adapter.

[JoeRC51]

Just now, cooldudesmd said:

Carb to engine head I believe. Its been a month or 2 since the order was cancelled and about a month since I called and was told I'd be emailed when they had the missing adapter.

Try searching it on E-bay and Amazon , I know I've seen them elsewhere recently.

[Failtron]

That is a great idea, thanks!

[Failtron]

I should elaborate lol.  The vent placement above looks great it seems like combining that with removal of the seat rib will probably provide enough air for the pumper.  I'll find out in 3-5 business days ? My only concern is gluing them in there.  Are you able to remove and clean the foam filters from the inside and replace them?