Triumphrat

grzegorz

ok let it start ....wanted to start new thread about it as need some help and opinion from people with more knowledge about tunning than me

My bike Triumph Bonneville America
- 904 Wiseco kit
- 813 TPUSA cams
- ignitor remapped by Pieman (best money ever spent)
- gutted airbox(no snorkels ,restrictor plate removed)
- "breath" air intake
- Keihin CR-S carbs
- Epco exhaust

Bike going strong no problem there but recently been on dyno and not really happy with result was too rich in a first place ....

after reading a lot on this forum about tunning and how helpful Air/Fuel ratio gauges are ,decided to buy one ..Innovate MTX-L and welded bung into crossover pipe.

Today was my first day riding with gauge on the bike and here we got results; 118 main jet ,needle 3rd clip position

Idle............ 13..........1100 rev
1/4..............11.8.......3200 rev
1/2..............12..........5000 rev

had no chance to open throttle to WOT not enough road and with half throttle was doing 90 mph (shown on speedo)and going up to ton

because i done those markings using masking tape in throttle and housing first time ever noticed that I'm normally using trottle opening from 1/4 to 1/2

Any advice?

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beemerrich

You need to get the main jet squared out before you start playing with the needle position. Take the bike out where you can pull full throttle for a good 20 seconds & see where you are at on the main jet. The partial throttle conditions are good and rich right now, so no worries about hurting anything. With a 118 main, my guess is you are quite lean on the main jet...

BTW, make sure you order some needle shims if you end up getting bigger mains - or get the appropriate size SS washers from the hardware store (they work) since you're going to need to fine tune the needle at some point.

Regards,

--Rich

B02S4

^ What he said...

grzegorz

-ok 120 main(AB jet) read somewhere that it should be the same as Keihin
-needle 2nd clip from top

Idle around 14
from 0 to half throttle about 13,6
WOT down to about 12 (but this is not confirmed as run was to short)

weather wasn't great..very strong wind and wet surface

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mikeinva

You need to know what the a/f is at redline before you will know what main jet you need.
you dont have to use 5th gear to do this 3rd or 4th will give you a good idea.dont even worry with the needle untill you get a/f wot at redline.Changes to the main jet will change what the needle does.

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Why do I feel young on my bike

grzegorz

ok where should I be with WOT ?

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beemerrich

What Mike said. My bike likes high 12s at full throttle for max. power. I'm cheating currently with about 13.5 a/f on a full throttle pull to keep my 3/4 throttle from going pig rich.

The needle selection for the CR carbs is limited and in order to get the correct initial diameter for my setup, I had to go one size bigger in initial diameter (i.e. leaner on the keihin chart) than typically supplied with these carbs. In doing so, the needle length (L1) is shorter/taper happens quicker, thus making 1/2 to 3/4 throttle go quite rich. What is needed for my setup is a leaner needle with a longer L1...unfortunately, there in no such animal short of having one made one-off...

Your current setup sounds promising. But do dial in that main before going further.

Regards,

--Rich

mikeinva

they seam to run there best at 12.5 to 13.0 wot at red line.If you are running stright gas closer to the 13.0 if you are running 10%eth closer to the 12.5

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Why do I feel young on my bike

grzegorz

gas..........the grade is different here than USA or Canada we got 95 in usa its 91

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beemerrich

A 13:0 to 1 A/F ratio is probably optimal based on what you're saying. What mike was trying to say is that if your gas has ethanol in it, run it a bit richer than that...like mid to high 12s...

Good luck,

--Rich