Jetted Carbs.

[Jonesey]

I've inherited a set of vtr carbs that the previous owner said were dynojetted.
I have stripped them, and it turns out to be correct, however the mains are BOTH
190 jets! Reading previous posts where the average jets seem to be 180(ish),
these seem on the large side.
What kind of gains can be expected from such large jets, and is it unusual for both jets to be the same number?

[tony.mon]

Dynojet use a different sizing system to everyone else, so their 190 does not equates to Honda's, Mikuni's or Factory Pro's sizes.

So 190 in Dynojet sizing might not be too big. Try a plug chop after a 30-second full throttle run and see what it tells you. Also, if you're running race exhausts and a K&N they also affect sizing- the FP recommendation is that you go up 2 sizes for these mod's.

Usually there are different sizes front and rear, but it's down to the dyno operator as to what they find is most effective. Rear cylinder runs hotter, but as it's water-cooled and all, you'd expect if there was that much difference you'd also have differing plug heat ranges, wouldn't you??

[Pete.L]

jonesy Said

What kind of gains can be expected from such large jets,

Unless you have unbaffled full race exhuast they are too big. You'll actually have less power because the bike won't be able to burn the excess fuel going into the pots
Std pipes will run a 170 main and a good race pipe will take a 180. Most aftermarket pipes claim they can be fitted with out rejetting so nearly all of them will run best on the 170s as well.
It's just a rough guide for you Jonesey but the only true way to tell is to get it on a dyno meter and see what a tuner can get out of it. 5- 10 bhp is pretty normal.
Pete.l