Should I jet for a .020 overbore?
- Thread starter maverick
- Start date
It wouldn't hurt at all. A stock bore (66mm) is 195 cc's. Boring .020" over stock gives you a 66.50mm bore, which is calculated into 198 cc's. Going up a size in main jet would definitely be beneficial. However, its not all done there. You will need to perform plug chops to confirm the jetting is spot on (or close to spot on). It never hurts to run rich, but you do lose a little power and foul plugs.
Regardless you should already have a larger than stock main jet having an aftermarket pipe on it.
Someone correct me if i am wrong but i don't think a first overbore would require a jet change,BUT anytime anything is changed concerning intake and exhaust plug chops should be done to confirm things are running propper.
And a leakdown test after the rebuild.
Just taking the snorkel off and puttting new reeds in put me up to a 270 main with everything else stock,and increased power on the arse dyno.
Someone correct me if i am wrong but i don't think a first overbore would require a jet change,BUT anytime anything is changed concerning intake and exhaust plug chops should be done to confirm things are running propper.
And a leakdown test after the rebuild.
Just taking the snorkel off and puttting new reeds in put me up to a 270 main with everything else stock,and increased power on the arse dyno.
There is no need to rejet for the rebore.
With a DG pipe you should be running at least a #250 - #260 main jet owing to its better breathing properties.
Jetting must be confirmed by a plug chop.
As stated by YamaZuki, a leak down test should be done after a rebuild.
With a DG pipe you should be running at least a #250 - #260 main jet owing to its better breathing properties.
Jetting must be confirmed by a plug chop.
As stated by YamaZuki, a leak down test should be done after a rebuild.
Thanks for the reply's,
Since I still have the stock muffler mounted to an aftermarket DG pipe, does that still require jetting or is it usually when there's an aftermarket pipe + muffler?
I was previously running a 240 jet before removing the head. Plug was colored grayish/black which may mean kind of rich?
Mabe the 240 jet would be a safe starting point after overbore?
Thanks
Since I still have the stock muffler mounted to an aftermarket DG pipe, does that still require jetting or is it usually when there's an aftermarket pipe + muffler?
I was previously running a 240 jet before removing the head. Plug was colored grayish/black which may mean kind of rich?
Mabe the 240 jet would be a safe starting point after overbore?
Thanks
anytime you change the head pipe you should chop to confirm jetting. a silencer doesn't make a difference imo.
Air box Lid does factor into the Jetting as well , With the lid off , Your Going to need one If not Two sizes bigger on the Main jet