Bike loses powers up and down hill

C

Carson2000

New Member
Hello. A problem I have with my motorized bike is when I go up or down a hill the bike loses power. What I usually do when going down a hill is I disengage the clutch coast down. What happens now since I got the high performance carburetor the engine will die slowly when going down a hill. I give it a little throttle to keep it going until I reach the bottem of the hill and the idle is normal. It's harder to tell if I lose power going up a hill since I'm giving it more throttle but I believe power is decreasing. I never had this problem with the stock NT carb but otherwise the carb does give more speed on flat ground. What is the fix for this if there is one?
 
Check your float level and the angle of the carb.
Level the carb and set the float level to stock specs.
This is a start.

Steve
 
You posted this > "What happens now since I got the high performance carburetor the engine will die slowly when going down a hill."

Have you tried increasing the idle speed. I don't know what carburetor you have but most will have an idle speed adjustment.

As far as a "high performance" carb. Your original NT would have given you all the performance you'd need if it was properly tuned. Did you ever try experimenting with jet sizes?

Tom
 
The idle speed is good the jet size is good. The NT is nothing like the this new carb and I notice a difference. I experimented by lifting the bike up from the back end while it was idling as a simulation of going down a hill and the idle started to drop.
 
Is your tank full of gas? If it's only half full, sometimes the gas can all rush to the front of the tank when you are going down a hill causing the engine to sputter and lose power or even die. This is particularly true if the bicycle has a top tube that is level with the ground or has very little down angle to it. I've had this happen on my mountain bike. One solution is to put something underneath the front of the tank to make it angle back a bit.
 
2door said:
You posted this > "What happens now since I got the high performance carburetor the engine will die slowly when going down a hill."

Have you tried increasing the idle speed. I don't know what carburetor you have but most will have an idle speed adjustment.

As far as a "high performance" carb. Your original NT would have given you all the performance you'd need if it was properly tuned. Did you ever try experimenting with jet sizes?

Tom
Click to expand...

you are speaking about jet sizes. Do i need to drill out my main jet needle to increase this? If so what bits do you recommend ? If i buy the jets individually, do they come in packages ? I done some searching but the only size i found was a #69 and ive read that #68 is a good start. Im trying to prevent having to repurchase parts.
 
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jMrL said:
you are speaking about jet sizes. Do i need to drill out my main jet needle to increase this? If so what bits do you recommend ? If i buy the jets individually, do they come in packages ? I done some searching but the only size i found was a #69 and ive read that #68 is a good start. Im trying to prevent having to repurchase parts.
Click to expand...
You'll read from some builders, like me, who do not go by published 'jet size'. They have proven to be nebulous at best. What one vendor calls a #68 another might call a #70.

We don't go by 'jet size' but solder and drill the jets to an orifice size that works best for us. It would be very uncommon to have a stock carburetor that comes 'too lean'. Most are way over rich (jet size too big) and need a smaller orifice.

That said, you'll need to have an engine that is properly and completely broken in before starting to worry about best performance. 200 to 300 miles is recommended to say your engine is ready for performance enhancements.

Tom
 
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