Went up to a #140 main jet

[Crab_Cake]

I had a #137.5 on there before with a #45 pilot jet and needles 1 notch up from the bottom. Today I put a #140 on there along with new manifold gaskets.

Holy crap.

The bike was pretty strong off idle before but got anemic with throttle. The thing now just screams. It is much much faster and I am very happy.

Lesson for the day is to keep trying.

 

[gentlemanjim]

Bravo!

 

[inxs]

Lesson for the day is to keep trying.

- works sometimes with she who [thinks she] shall be obeyed too

 

[bradshaw106]

did you have to lower your needle after installing the larger main jet??
what are you running?? pod's, straight pipes??

 

[Crab_Cake]

did you have to lower your needle after installing the larger main jet??
what are you running?? pod's, straight pipes??

I have mikes XS pod air filters and pea shooter exhaust. The needle is at the second notch from the bottom.

 

[bradshaw106]

im thinking my bike can handle some more fuel...

 

[marvintheminnow]

what carbs are you using?

 

[Crab_Cake]

BS34

I have a 1980 special.

 

[marvintheminnow]

are you running pod filters or chopped exhaust?

 

[Crab_Cake]

are you running pod filters or chopped exhaust?

Pod filters and peashooter exhaust.

I am actually thinking of going to the last notch on the needles and seeing if that is any better. I will report back.

 

[marvintheminnow]

before you went up on the jet and down on the needle was your bike dogging out in the midrange throttle area?

 

[Crab_Cake]

before you went up on the jet and down on the needle was your bike dogging out in the midrange throttle area?

oh yes. It was good right off of idle but lost a lot of power from 1/4 - open. I don't really have anything to compare it to but it feels good now.

I kind of want to keep going up until I know it is too rich and then back down.

 

[marvintheminnow]

how do you know its not too rich already? are you checking you plugs? im in the same situation and my plugs look black but it feels like im not getting enough gas. i went down and it got worse. i think the black plugs may be from it not running correct with the throttle open and not a sign of it running lean like i 1st thought.

 

[Tz250racer]

Black smoked plugs are definately sign of an overrich mixture.You trowing to much fuel in the motor and the black color on the plugs is a sign of bad combustion and unburned fuel.

 

[Crab_Cake]

Just an update.

Today I went to the richest needle setting possible and synced the carbs. There is just the slightest wiff of smoke out the pipes. Barely visible.

I definitely gained a few horsepower today though. The bike is running really nicely. So it might be a touch rich right now but I would rather be too rich than too lean.

 

[nj1639]

xsjohn would say to watch out that you don't wash your rings. Now being somewhat of a novice to some terms, I wonder if that means to much unburnt fuel in the cylinders and ending up in the crank?

 

[XSLeo]

Wash the rings is when to much fuel is in the combustion chamber and washes the oil off the rings and cylinder walls. The lack of oil wears the rings and cylinders out.

 

[Crab_Cake]

Wash the rings is when to much fuel is in the combustion chamber and washes the oil off the rings and cylinder walls. The lack of oil wears the rings and cylinders out.

Thanks for the advice. Like I said though I would rather be too rich than too lean.

Anyways the bike has tons of power and is buttery smooth. I have a high output coil, new plug wires & caps, and NGK iridiums coming in from Mikes. That should help a lot with the fuel burn.

 

[650Skull]

The other guys have said it............ i have spoken to many an XS owner who has had to rebuild the top end due to washing of the bores because of a to big a main jet, and lifting your needles to the top as well .........it does not take long and if you did a trip to your grandfathers and back with your carb set up you will have done the damage.......yes we miss the one tracked mind .......broken record xsjohn ...............but he would keep hounding and hounding for your own sake to try and save you the problem where you are headed. If you set these up properly you would still get the performance you are after and that takes into account the altitude you live at and the right temperature/environment when setting them

 

[Crab_Cake]

Well from what I have read you are supposed to keep increasing richness until the bike stumbles. Then back off two jet sizes.

My bike hasn't stumbled yet and is running better than ever. How do I know if it is too rich?