Might be a dirty or worn float valve, allowing too much gas into the carb float bowl than then flows past the needle into the carb venturi --- some of which would perhaps end up not in the engine but on the black. But if that was the case i'd expect your scoot to be running pretty badly ... and you say it is doing well.
the carb is fairly new. I wouldn't expect worn anything. I did take the cover off to change the main jet when I got it a month ago, but I didn't notice anything then but I also wasn't really checking. There's a lot of salt and sand on the roads, enough to slip on, so maybe something is clogged?
It does seem like there is a slight accel lag sometimes. When it lags it boggs sort of or feels like it is vibrating harder, but powers through it in a second or less and overall performance is good.
If it idles ok and is ok at 1/2 throttle and above, could the slow pilot jet be at play as well as the accel pump?
Post by spudsmckinsey on Feb 13, 2015 22:32:57 GMT -5
I also recently installed the 100cc (50mm, actually 83cc) BBK
Did you do other engine mods? Big Valve Head, A9 cam, exhaust ?)
I didn't do ANY other mods. I got better launch and hill climbing, but ZERO top end increase.
I tried to scan through your posts for the info but gave up after about 5 minutes.
My BBK came with a jet and I installed it but it wasn't marked so I have no idea what size it is. Some say it is a # (standard supplied with 02Starriders kits)
IIRC, I didn't get any hesitation like you did. But I did go to a # main jet. My biggest problem was that the air box proved to be inadequate to supply air for the bigger piston. I also think the "100cc" BBK may desperately need the big valve head. Not sure yet. Just a theory I'm woikin on.
Those 8 gram weights are the culprit I'm betting on. Try going down to 6 gram (I prefer sliders).
Ok. When I got it, it had 10gram rollers. The 8 gram rollers I installed came with the BBK from 02Starrider.
I'll order some 6 gram weights and try that. I thought heavier weights would tend to push the variator closed earlier, forcing the belt to have a larger radius up front making the scooter change to top end gearing earlier? Won't lighter weights cause it to stay in "lower gear" longer?
Truth be told, my engine doesn't sound right to me. It seems to be limited. At higher RPM's it sounds choppy and rough like it's just not developing clean power. It may be that this motor is just not healthy. It may have too much power robbing vibration caused by main bearing wear and it's being aggravated by the 83cc piston. Just speculating. I'm also gonna try a different CDI and coil.
I really need a tach. I don't think it's getting above about 6000 rpm.
The other thing I need to do really badly is start the motor with the cover off and watch the belts as I rev it.
I never noticed a performance drop while using the BBK from scorpion products (the ebay seller you mentioned). I am running a brand new install now though, getting great performance, leaving cars behind at stop lights and they stay behind cuz of good speeds.
What mods did you do other than the bigger piston? Cam? Big Bore Head?