Went riding today with my new 686 motor today and it lived up to all expectations. Could stay in front of those 450s all day for a change and even beat my buddies raptor for a change. Didnt get a chance to do a plug check today but am a bit concerned i may be a bit lean on the mains. Sixsixt brought this to my attention and i was wundering what other people would be using . Current specs
1/ 11/1 ross piston 102mm
2/ port n polish
3/stage 2 hotcam + springs
4/ full yoshi
5/ kn no lid outerwares
6/ 165/170 mains custom needles 25 pilots
I am at sea level riding at about 70 degrees and bike performed really good. No flat spots and super responsive. What do you think ???????

 

mikuni or dynojet?

I am going to try 170/175 with the dynojet kit here shortly, based off info from a dynojet technician

 

all that motor work and you think you are lean and you still rode it all day.I would pull that plug as soon as possible before you pay for another motor job.

 

I ran the same setup except I used the stage I cam & it absolutely ripped with 165-170 mains.
The only problem is that on the dyno it ran a little lean on the top end.

You'll need to richen up the top end a little. If you increase the mains to 170-175, you may notice that the midrange runs a little rich regardless of clip positions. If it does, then you may need to try unconventional sizes/settings. Welcome to jetting hell, experimentus maximus!!
Good luck.

 

Run 180/185 mikuni mains, imo. I run 190/195 dyno jet mains and needles for my setup at sea level.

 

i have close to the same setup and i run 155 160 in mine but im at about 8200'. the other place i ride i run 160 165 which is at 6000'

 

I run 172.5 and, 175 Mikuni Mains and, the needles on the 3rd Clip from bottom w/ 2 and, 3/4 out on the air screws.. Mine seems perfect in all areas on the rev range. I also run the lid off w/ a K&N proflow setup. I'm running 100-110 octane gas if that matters.

 

CaptBags, please tell me where I can get a Mikuni main jet size of 172.5, I need one to perfect my jetting for dyno runs.
Thanks

 

Thanks for the replies guys. Ive ordered some bigger mukuni jets (175 180 185) and i will keep raising the main jet size until it starts effecting WOT performance then i will go down one size and i should be pretty close to the mark. Then i will play with the needle settings.(been down this path before as i look after my mates 2 raptors as well) Our pump gas over here is premium 98 (98 octane)

 

Hey Chimmer- Sorry i missed the ?. I got mine from my builder.