Originally Posted by bvette85
I have a 05 Honda shadow spirit 750, and put Vance and Hines straight shots exhaust on(with the baffels in), then took it to the local Honda dealership to have the carbs rejetted (with a dynojet kit, stage 1) and a k&n filter.
My question is that since I got it back it seems that it has a lot less power when going up hills, and also the exhaust is poping alot and it seems like it gets worse as time goes on. Is this normal loss of torque from the pipes? Also my gas milage went from 65mpg down to 45mpg. Did they not jet it right, or is this normal???
It sounds like you are running way too rich on the main jets and too lean in the idle circuit.
That is why you are noticing such a drastic fuel mileage drop.
You are going to notice a little bit of a drop (probably 3-5mpg), that's
simply the price for power. However, 20mpg is way too excessive.
That is most likely because the main jet in that rear cylinder is way too big.
It's been my experience that when Dynojet says to use a given size
jet, they are usually right on the money. They only problem I've found is
that their recommendation for needle position has always been 1 notch off.
If Dynojet says it should be in position 3, I run them in position 4, from the top (more rich).
I looked at the Dynojet instructions for your bike and according to them,
you should be running a 102 in front and a 104 in the rear.
My suggestion would be to put the 102 in front and the 104 in the rear.
Run the needle in the 4th notch from the top.
Be sure that the mechanic drills out the slide lift holes in the vacuum pistons.
That hole HAS to be enlarged or else the calibration of the needles and
main jets will be off. There should have been a drill bit included in
the kit to drill that slide lift hole.
I have never had to change the pilot jets, when rejetting for a stage 1 kit.
At idle, there is very little change in the fuel demands and/or the air flow.
There is plenty of adjustment in the existing pilot jets to compensate for
the change. Dynojet recommends starting with the screws 3 turns out.
I'd start with that and if it needs more, give it 1/4 turn out at a time until
the popping stops. You should not have to go more that 3 1/2 turns.