Loosing power after 5 mile run at WOT

[islander]

So I got a 2009 Keeway Venus for free from a friend of mine. He forgot to mix oil with the gas and the motor seized.

I installed a Hoca 70cc BBK, 21mm PWK carb, performance intake, CF Reeds, Hoca variator, Hoca clutch with 1500 springs, new 792-16-30 belt, ebay performance CDI, ebay performance exhaust, ebay performance coil, and tachometer.

I started off with a #98 jet and 4g rollers, it bogged like crazy and back fired, this blew out the CF reeds. Replaced the reeds with FG reeds and tried to get a plug chop, managed to rev to 10k and blew the needle bearing on the piston pin. Hoca kit was wasted.

BBK #2 was a ebay 70cc kit , down jetted carb to #94 and while trying to tune the bike, the needle bearing gave out again. BBK #2 was wasted.

BBK#3 is a ebay kit, installed a wiseco needle bearing this time and down jetted carb again to # 86. Variator sliders are 3 ea 7 grams and 3 ea 4 grams. This is where it stands now. At 8k max rpm I can pull to 35 mph, revs drop to 7k and hold there as it climbs to 40/42 mph max. After a few miles of WOT driving, revs slowly start to drop to 6k and speed drops to 25mph it then feels as if it's going to die.

Any suggestions as to where I should go from here would be great. I have no base line so I don't know what type of performance I should be getting or how fast this thing should be. I have ordered another Hoca cylinder and high compression head and plan to up jet to #90. Any thoughts/suggestions would be greatly appreciated. I want to be able to hit 50mph and cruise at 45mph.

Thanks for any help.

[moofus02]

Could be lean and getting hot. With that many small end bearings trashed i would look real close at the small end of the rod

Sent from my SPH-L720 using proboards

[2strokd]

Sounds like moofus is on the right path. Its getting hot for some reason.

[islander]

Thanks for the input. I rejetted today to a #90 and got nowhere fast. It bogged so much that I could barely take off. Pulled the plug and found that it was fouled with a bunch of gunk. Cleaned the plug and rejetted to #80, I'm now able to hit 52 MPH (speedometer reading) at 7k. With a strong head wind I can maintain 40 MPH at 7k at WOT. I'm sure that I could probably get a little more by tuning my variator but for now, I am just happy to be riding this scooter. It's a blast.

As far as the needle bearings, those were my fault. I was so in a hurry to ride that I just took it for granted that they were the correct size for my con rod. It turns out that the first two BBKs had supplied needle bearings that were 2mm undersized. I didn't catch that until BBK #3 which was why I ordered the wiseco after reading a post from Brent. I really got to stop drinking while tinkering. Now I'm just waiting on an iridium plug for a better burn and hopefully a little more power and better gas mileage.

Thanks again guys.