russell jupp
06-25-2012, 06:10 PM
Hi all,
just coming to the end of a complete restoration of a 2001 GPR50. Superb little bike, but i have an issue with carb settings, and was hoping for some advice?
The motor is a standard 50cc, with a 17.5mm PHVA carb. Starts on the button, and runs perfectly.
However, below 8000 rpm, it doesnt have enough power to pull away on a slope without slipping the clutch. Between 8000 and 10,000 rpm it goes like a rocket, and will easily rev beyond the red line in 6th gear on the flat or downhill. The slightest slope, revs drop below 8000, and its down a couple of gears to keep it going. If I have to stop and then restart on a steep hill, there's not enough power to pull 2nd gear.
Now, it has a full ARROW exhaust system, and a K&N style air filter. It also has a 13t front and 50t rear sprocket. I changed the main jet from the standard 86 to 110, but to be honest there appears to be very little difference in performance between the two. (if anything, it runs slightly better with the smaller jet)
The other remaining jets, needle and slide are standard.
I'm reluctant to let my son ride it yet, as its quite tricky, and a bit tiresome to ride, as its all or nothing...
My questions are this:
1. Is this how its supposed to be?
2. Is this a gearing issue, as I do have the standard 52t rear sprocket, but I'm hoping i dont have to use it as i guess the top speed will reduce from a very impressive 60mph to a painfully slow 40ish mph?
3. Should I still be using the standard spark plug which i think is an NGK BR8ES?
Any advice is appreciated,
thanks,
Russ
:confused:
just coming to the end of a complete restoration of a 2001 GPR50. Superb little bike, but i have an issue with carb settings, and was hoping for some advice?
The motor is a standard 50cc, with a 17.5mm PHVA carb. Starts on the button, and runs perfectly.
However, below 8000 rpm, it doesnt have enough power to pull away on a slope without slipping the clutch. Between 8000 and 10,000 rpm it goes like a rocket, and will easily rev beyond the red line in 6th gear on the flat or downhill. The slightest slope, revs drop below 8000, and its down a couple of gears to keep it going. If I have to stop and then restart on a steep hill, there's not enough power to pull 2nd gear.
Now, it has a full ARROW exhaust system, and a K&N style air filter. It also has a 13t front and 50t rear sprocket. I changed the main jet from the standard 86 to 110, but to be honest there appears to be very little difference in performance between the two. (if anything, it runs slightly better with the smaller jet)
The other remaining jets, needle and slide are standard.
I'm reluctant to let my son ride it yet, as its quite tricky, and a bit tiresome to ride, as its all or nothing...
My questions are this:
1. Is this how its supposed to be?
2. Is this a gearing issue, as I do have the standard 52t rear sprocket, but I'm hoping i dont have to use it as i guess the top speed will reduce from a very impressive 60mph to a painfully slow 40ish mph?
3. Should I still be using the standard spark plug which i think is an NGK BR8ES?
Any advice is appreciated,
thanks,
Russ
:confused: