Tuning from rear pipe

[Lovetoride007]

 I am tuning my CV 44 carb, What AFR difference is there from front cyl to rear cyl, when tuning with an AFR meter and you are in the rear cyl, should I assume when the rear is dialed in the front is close ?   
Thanks for any advise

[Jeffd]

I think pipe plays a roll ie 2:1 2:2 length of headers etc.  I just had a afr on my supertrapp 2:1 done and rear/front was near identical on WOT rear was just slightly leaner from 1800-2500 wot and at cruise under light load rear was leaner 14.8 vs 14.1 for the front.  I am sure there are many other varibles tho.

[fuzznut5197]

I would like someone to clear up this vague understanding I have of cyl-to-cyl afr equality. On a carbureted bike, it was "common knowledge" that the front cyl always ran leaner than the rear cylinder. The tuner would always stick the sniffer up the front pipe, knowing that the rear is slightly richer and not have to worry about it. Now with EFI, this general trend seems to be reversed?

[Lovetoride007]

Jeff
Is your bike EFI or Carb?

[Jeffd]

cv40

[rigidthumper]

Getting a perfectly flat AFR in 1 cyl is no guarantee that the other cyl is even close. Since carb bikes share the fuel supply, you should check both cyls and shoot for the best overall compromise.
HTH
Robin

[Jeffd]

hope this works.

[attachment removed after 60 days by system]

[Lovetoride007]

Jeff
That's what I was looking for . I was not sure but had assumed the rear is a little leaner , so I will tune my rear cyl to the leaner side of 14 to 1
Thanks

[FLTRI]

Typically the rear cylinder will run leaner unless the exhaust system was carefully designed create more even AFRs as the case with the Supertrapp 2into1 system.
There are more variables that can and do play a part in front vs rear cylinder AFR.
Bob

[Lovetoride007]

Supertrapp 2-1 is what is on this bike,

[Jeffd]

Typically the rear cylinder will run leaner unless the exhaust system was carefully designed create more even AFRs as the case with the Supertrapp 2into1 system.
There are more variables that can and do play a part in front vs rear cylinder AFR.
Bob

Bob, do you have much experience with tuning carbed supertrapps?  Do you think if I went down to 10 discs with the open end cap I would richen up enough to make a diff?  It runs very good, does not surge or spit back thru the carb and I am getting excellent mpg and it warms up quickly without much choke (enricher) but was thinking maybe I should be smidgon richer.

[Jeffd]

bump hoping fltri sees it.