A9 cam with a BVH or not????

[larryhobman]

Looking for a little advise to see if an A9 cam is going to lower my compression or not when using a big valve head.

My next build is a 52mm kit with a BVH, very open performance exhaust, A9 cam?. going to try a flat slide carb for better throttle response.

I have 2 flat slide to try a 30mm and a 28mm.  Let me know what you think I shoiuld try first?

I currently run a 50mm set up, A9 cam, standard valve 50mm head and a 24mm cvk carb from a 150cc scoot.

[Petro]

I found a 24mm carb is to large for any size BBK on 49cc scooters... What jet are You running on it on Your current bike?
An A9 will not lower Your compression, more the opposite I would say. On my bike I am happy that I can use the starter even when cold, couldn't that on my previous ones with the same kit...

I think You can forget anything above 24mm carb on a 85cc, it will run of course but WOT will not work at all in my experience. I might be wrong and honestly I really hope so...

Edit: Saw You running a 1.03mm jet. 

[larryhobman]

My current set up with the 24mm carb works great. I am doing another build for me as my son wants the 50mm on his scoot. He has a 47mm and a 18mm carb final drive 15:1 and I blow it away with my 50mm I pass him like it is still stock. I do have an 11:1 final drive in my current BBK which will be on the 52mm build unless I drop to 9:1 I do have those gears too.

[Petro]

I tried on a 24mm but couldn't get it running properly, at 4/5 throttle already I had to much mixture flowing, if I went down on my jet the low 2/3 suffered, well not really suffered but was only a little more responsive than an 18mm... Not to mention the consumption which is very important to me went up about 30%...
Due to those 30% and that I had to be cautious not to overthrottle I gave up quite early. I need to mention that playing around with carbs isn't high on my list of killing time though...

About a A9 cam, be careful when installing, my Airsal 50mm kit was hitting the valves and only 3 bottom gaskets could fix that, and that was with the stock head with 16/18mm valves...

I recommend a big valve head before a 2Xmm carb any day, If one can have both it's a win/win.

[larryhobman]

I have it all to try, I am just trying to see others experience so I do not fail right away. I have 49/17 gears, A9 cam, the 52mm kit with a new BVH, 28mm flat slide and a 30mm flat slide both brand new.