Modified Carbs and Airbox Mods.

[koko64]

Thanks Nate. Some years ago, I had a similar email conversation with him getting the same response.  I gave up and bought FCRs instead. PM sent.

[koko64]

After more testing with modified carbs and airbox as shown, I have had to adjust jetting by leaning the needles two notches (#5 down to #3 on  DJ730's). In a warmer climate like in our Northern states I would also run 35 pilot jets instead of the 37.5's fitted (as oem 40 pilots were too rich).  Maybe the airbox mods effect wave tuning in a way that reduces the lower end fuel requirement via improved efficiency or maybe there is better fuel atomization from the carb mods assisting this, or both. No matter, the set up is more efficient. I am running 165 Mikuni main jets, stock slide springs, Dynojet 730 needles, Factory Pro needle jets and 37.5 pilot jets. The bike performs well enough with this carb/airbox combination to not miss my FCRs. The "not too bad" performance and the excellent choke allowed me to sell the FCRs for much needed cash. However, avoiding carb icing by wrapping the intake manifolds and running an oil cooler cover in cold weather has been essential.

[koko64]

After plug chops and  playing with the idle mixtures and needle positions, it appears fuel efficiency may have improved (even with Mikuni 165 main jets). With 37.5 pilot jets I have to run the idle mixture screws at 2 1/2 - 3 turns out rather than 3 - 4 turns out with 40's. With the 37.5 pilot jets the idle got blubbery with 3 1/2 - 4 turns out and fouled plugs. I may try 35's again. This is opposite to the normal relationship between pilot jet size and IMS settings so there must be greater efficiency. Needles got dropped two notches from 5 to 3 as I found previously. Fuel range is now about 200 miles out of the early 18 litre tank with highway use.

[Howie]

Dyno time 

[koko64]

Not with my money
With db killers and no FCRs I reckon its down to 80 odd hp from 86. It's fun, but slow.

[koko64]

20170906_100411 by Tony Kokonis, on Flickr

A finished item, cleaned up with polished bellmouths. Running this one on the old Monster 900.

20170906_100450 by Tony Kokonis, on Flickr

20170906_100419 by Tony Kokonis, on Flickr

[pepeducat]

I did that.

Disassembly, cleaning and reassembly with a Dynojet kit.













And I'm going to put them on the engine, hoping to gain some responsiveness







Finally to breathe I'll put it to him

[koko64]

Very cool. Modified oem manifolds or Malossi?

[pepeducat]

Modified oem manifolds 

[koko64]

Cool

[greenmonster]

What is easiest to do:
Big filter  https://www.flickr.com/photos/150482584@N03/35538853483/
or small  https://www.flickr.com/photos/150482584@N03/shares/a4j6Dw  ?

Which do you think works the best?
No need f support under filter, in mid section (filter being sucked in etc)?

[koko64]

I didnt use a support for the smaller one,  it was very rigid. I think maybe a Pani sized filter might be a good size for next time. I would then epoxy in the cross brace up under it for support. It depends how much fiddling you want to do.

I did not do back to back tests between the filters above. I think a slightly smaller filter than the DU0900 like a Pani filter will fit the lid easier.

[koko64]

I'm looking foward to seeing how Pepe's split singles go.

[greenmonster]

Txh, Tony.
Could you give me the link where you modded the inlet rubbers?

[ducpainter]

Pepe`...did you lengthen those manifolds?