just replaced the top end, now..........

[YellowDragon]

.. it seems I've lost some of the bottom end. I just upgraded from an oem piston to a weisco. I remember there being a little more low end snap.

Is this normal to loose some bottom end but gain noticable mid to high with a piston/ring swap?

Can I just do some rejetting to solve this problem and try to get a little more low end snap? Maybe some better reeds?

Thanks in advance

[digipoi]

Did you set the power valve adjustment spring/screw properly when you put it all back together?

[YellowDragon]

when I put the screw back in, the manual told me 1/2 turn. I did so and then manually moved the valve. It didn't seem to have much "spring back". I may have turned it just a tad more. Would that be a cause of my problem? If so, can you explain to me how that works so I know next time?

Thanks

[Dave2122]

The tighter the spring the slower the valves open and the "more" low end you will feel.

Could also be you have now changed the squish band with the piston at top dead center. This is a very important aspect of 2 stroke tuning. You need to make sure the squish area is the same as the stock piston and head combination. Call Wiesco and see if they can give you the figures on thier piston vs the stock set up.

[YellowDragon]

By squish area, I take it you mean the gap between the top of the piston and cylinder head when the motor is at top dead center, right?

Cool, thanks for the ideas. Time to check some things out!

[Dave2122]

That is correct. Check and see if they make them to the stock spec.

Also note the change in my above post it is important!

[YellowDragon]

Thanks Dave. As for the valve, I think I tightened it just a tad more but still feels sluggish. I'll just adjust it a few times and ride it after each adjustment. Hopefully I can dial it in.

[Dave2122]

Dont forget you also need to bed the piston and rings to the cylinder to create a good seal. This process will take some time especially if you used a Wiesco "forged" piston.
Forged pistons will take a fair amount longer than a cast piston to bed into the cylinder. So you may end up after roughly 10 hours of moderate riding start to see an improvement in the low end performance. Remember also NO wide open throttle for the first hour of use on the new top end.