Main jet upgrade

[Gouraami]

Hi Guys

I have decided that I am going to start experimenting with bigger main jets. I want to order 3 sets of these:

http://www.aliexpress.com/item/Mikuni-motorcycle-carburetor-main-jet-Bandit-FZR-BS26-EN125-main-injector-nozzle-12-main-jet-9/32243535818.html?spm=2114.01010208.3.2.o3S75R&ws_ab_test=searchweb201556_10,searchweb201602_1_10037_10017_507_10032_401,searchweb201603_9&btsid=c3cf3597-d7e6-427a-bb13-d4bb681a9213

Anyone bought these before?

The reason I want to start experimenting is because I am sitting with the common flat spot around 6000rpm. I have the needles set all the way up, adjusted the floats to 13.6mm and have the the pilots set at 2 turns.Next step, bigger main jet and try to get the needles back to the middle mark. There was diffinetly a performance increase when lowering the float heights, according to the FactoryPro website, decreasing the float height is the same as going up a jet size.

My question - I currently have #100 mains in, what should I order (I can order 3 sets)? Start at #105 #108 and #110? Or should I go with bigger jumps, #110, #115 and #120? I have never replaced main jets before, so I don't know how large a change a #105 to a #108 or #110 would be. Can I relate it to a percentage? Would a #120 deliver 20% more fuel than a #100?

Thanks

[Squishy]

Never tried jets from China..
I just went to my local dealer, and bought some '2nd hand' (who cares) original mikuni jets. They were $10 for 4.

For the rest, my BST33SS 59HP edition runs absolutely awesome with #110 jets combined with a free flowing exhaust.
The difference was night and day on my bike. With needles +1 rich as well I can lift the front in 1st gear by snapping the throttle and leaning back a bit. No clutch.
Top speed went from indicated 185km/h to 215km/h.
I'm using stock airfilter.

With baffle in the exhaust, it loses some of the gained power but it's still just as fast as stock but you can lower the needles back to stock/middle setting without getting the flat spot 4-6k rpm. That's how I run it now.
I've drilled a hole in my baffle to allow freeflow of the exhaust while keeping the volume down.
As said with +1 rich on the needle it's even stronger, but I'm running stock needle setting for fuel economy and for trips to the mountain, where it becomes too rich.

[Gouraami]

Thanks for info Squishy, I also have the 59hp version, looking forward to better throttle response.

Are you at sea level?

[Squishy]

Thanks for info Squishy, I also have the 59hp version, looking forward to better throttle response.

Are you at sea level?

Yes, but I've ridden it at up to 2500m in this configuration (stock needles, #110 jet).
Obviously it will lose power at this altitude, but no other problems.
#110 jet and +1 on the needle, will probably be too rich on anything above sea level. Even here it starts surging a bit (awesome throttle response though).

Just for comparison I rode to 2500m with stock jet (100) and +1 on the needle and I had problems on 1/4 throttle (riding away).
I had to use stock needle position the next time, and deal with the obvious flat spot at mid range.
Now with #110 and stock needle, i had no problems at 2500m yet no problems with mid range. Apparently the main jet gives only a little bit more fuel at 1/4 and more at 1/2->midrange.

[Gouraami]

My Jets arrived!

Ended up ordering 108, 110 and 112.  Everything arrived as ordered 

The 6000rpm flat spot is gone, but it still won't run on the middle clip on the needles, I had to adjust them one richer.

It feels a bit flat at full throttle though... I am going to try the 108's and see if I am simply imagining it or not 

[Squishy]

Just note that my #110 is used with BST33 carbs (not BST32) and open exhaust.
Even with the aftermarket exhaust, when I put the baffle in, most of the extra top-end power is gone... I now use a custom baffle that allows more air.

[Gouraami]

I also have BST33's on with the open exhaust

But - something I have thought of now - I am using the BST32 plastic slides in the BST33's as I have a set that are in better condition than the 33's slides.

I should probably swap out and see if there is a difference or not