Hey all, wow the 4 stroking post here have almost confused me now as both seam to have valid points.
However I thought I would give some feedback on what has taken place on my daily commuter, (I'm not doing the conversation on distance, speed etc for this one)
Quick recap: I'm doing 2 x 31km one way trips a day that take roughly 50 - 60 min drive time with the engine running all the time, clutch pulled in downhills, 3/4 to WOT on straights and WOT on hills (I have many, clime from home to work is 500m above sea level)
It's a basic Chinagirl engine with a CNC performance head, standard NT carb and a 52 tooth sprocket for these hills. She does 50km/h easy on a straight, 40km/h on a decent hill (25°-30°incline) about 35km/h on a steap hill (35°incline) and 22km/h on a 40°plus hill
The bicycle has done 1900km in 2 months
I've clean the head and cylinder 3 times in this time, have had a crazy amount of carbon build up. I've tried BP6HS plug but carbon build up happened really fast, currently using BP8HS, and have had no issues for over 1000km with it.
I've tried Soooo many different oil to fuel mixes and currently using the Castrol racing 2 stroke oil at 45:1 but have been experiencing issues since the swop from the normal Castrol 2 stroke oil. Still getting huge carbon oil build up and more so now. I've tried going leaner but getting a lot of vibration, so today I reverted back to 35:1 with a smother ride.
My biggest issue at present is the loss of power on these long hills (rough 10 - 15km/h less and virtually losing all power on the bigger 40° hills!?
On a straight I still hit 50km/h she does seem a bit slower on throttle reaponce though. The same when revving her with the clutch in, she revs up to full a bit behind the throttle, she takes a few seconds to reach full rpm after I've WOT her.
II checked the ports and had a huge build up of carbon on the exhaust port (1/3 clogged)
The exhaust pipes were just as bad. Cleaned them as best as I could but still having the power loss.
Cylinder and the head are smooth, no scuffing visible, rings look ok but seem a bit loose in comparison to the first time I opened her up to clean them.
I also tried setting the carb pin on notch up for leaner fuel mix but seemed to make no difference, when I moved it one notch down from its original spot I had a real boggy drive and she could hardly reach 30km/h on a straight.
I'm also struggling with the idle, currently have the screw all the way in to maintain the idle.
MMost of these problems started when changing the oil, although having 200km on the new oil I could almost say it's just coincidence.
The engine does feel like it has weight to it or that it's stiffer than it was once started. (the cam shaft turns easily when I've had the engine opened, so I don't think it's a bearing issue)
What could be the cause of this power loss?
Exhaust?
Rings?
Carb?