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DisillusionedPrepper · 01-09-2017, 06:36 PM

Hi, and welcome to the forum.
I hope you can read this all the way from Oz. The fonts might get blurry...

First off, the power increase is minimal on any BBK install. You are basically raising torque more than HP. What makes these cylinder kits worth the effort is on hill climbing ability, and take off from a dead stop. You usually have to pair these kits with lighter rollers?sliders in the 5.5-7 gram range, and a stiffer control spring along with heavier fly springs in the clutch.
Those mods allow the engine to rev higher before beginning to roll, and allow the engine to kind of down shift into a better ratio on hills.

Now for the interference problem.
Those big valve heads can be one of two different heads. It can can mean a 69mm valve stem (vs most OEM 64mm stems) or a larger diameter valve crown.
You have to know which version you have.

Most likely they sent you a 69mm stem head.
All is good tho because you can correct the problem by buying a set of 69mm head rocker arms.
If you have the larger diameter crowns you can correct that by shimming the cylinder base with 1-2 additional base gaskets. There is enough slack in the timing chain to allow for this.

Another thing that MUST be considered is carb. jetting.
You will have to increase the main jet from the normal 97(ish) to around 100(ish).

I know this will all lead to more questions so please feel free to ask.
There are some very experienced scoot owners here, and I'm sure they/we will have you smiling in no time.

01-09-2017, 06:36 PM	#2
DisillusionedPrepper Join Date: Dec 2016 Posts: 109	Hi, and welcome to the forum. I hope you can read this all the way from Oz. The fonts might get blurry... First off, the power increase is minimal on any BBK install. You are basically raising torque more than HP. What makes these cylinder kits worth the effort is on hill climbing ability, and take off from a dead stop. You usually have to pair these kits with lighter rollers?sliders in the 5.5-7 gram range, and a stiffer control spring along with heavier fly springs in the clutch. Those mods allow the engine to rev higher before beginning to roll, and allow the engine to kind of down shift into a better ratio on hills. Now for the interference problem. Those big valve heads can be one of two different heads. It can can mean a 69mm valve stem (vs most OEM 64mm stems) or a larger diameter valve crown. You have to know which version you have. Most likely they sent you a 69mm stem head. All is good tho because you can correct the problem by buying a set of 69mm head rocker arms. If you have the larger diameter crowns you can correct that by shimming the cylinder base with 1-2 additional base gaskets. There is enough slack in the timing chain to allow for this. Another thing that MUST be considered is carb. jetting. You will have to increase the main jet from the normal 97(ish) to around 100(ish). I know this will all lead to more questions so please feel free to ask. There are some very experienced scoot owners here, and I'm sure they/we will have you smiling in no time.
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