Engine Trouble motor knocking/no torque

[namefail]

motors 3 tanks in and has gotten progressively worse. works well on straight aways and slight inclines. is 4 stroking i think but im not sure how to exactly determine that. but i live up a pretty big hill and ive had other bikes that climb it so i know its not that bad. but this guy just loses all power and knocks pretty bad. has a cent clutch on it. might be losing power that way. i dunno any help would be swell

 

[Fabian]

If it's a fresh engine, start by ditching the standard CDI and replace it with a Jaguar CDI. The knocking sound could be a number of things but i doubt the centrifugal clutch is the problem.
When new the manual clutch will need time to bed itself in. I would look at tightening up the flower nut on the manual clutch by 2 index points, to get a little more clamping force on the pressure plate.

How hard have you revved the engine?
Have you gone downhill at speed without pulling in the clutch lever?
Is the air filter securely tightened?
Do you have any air leaks?
Are you running a cylinder head gasket?
Does the engine use 6mm or 8mm studs?
Is the cylinder head centrally located on the cylinder?
Have you disassembled and reassembled any engine parts?
What octane fuel are you using?
Are you adding any oil to the fuel?
Is the carburettor using standard jetting?
What type of spark plug is installed in the engine?

 

[Deleted member 12676]

Jet it leaner

 

[namefail]

i was thinking it might be a blown head gasket but i havent noticed any air/oil leaks. how do you jet it leaner? ill look it up

i might have revved the engine to high at first trying to climb hills. i use ngk bh6, 91 octane/oil with stabilizer.

 

[Deleted member 12676]

For leaner running at mid throttle you just lower the needle in the carb. For leaner full throttle running you can replace the main jet or solder it shut and use a micro drill bit to make a new and smaller hole. Click onto my signature link to read more.

 

[Fabian]

What is your final drive ratio?
What is your wheel diameter?
What is the fastest speed you've seen when going downhill?

 

[V 35]

My first build ... Bike ran ok, was very dissapointed in total lack of torque, thought concept of being able to pedal downright silly, as
bike was very hard to pedal . Re-adjusted drive chain [ little too tight ] big difference in pedaling . My flower nut was one click too tight,
that said, the bike now pedaled OK [ not great ] and the engine now revved up easier. Torque gradually improved as clutch broke in, after a cable adjustment, bike was now a satisfying ride. Lift rear wheel with sparkplug removed [ easy turning = no compression ] and check drive
for ease of movement. If bike is stiff, you'll have no torque.

 

[namefail]

thanks jaguar. i moved the clip down to the the leanest setting and it pulls alot better. handles the med ranged hills without issue. the big hill it pulls well enough but at open throttle it still knocks and decelerates but ill work on that. might order a new main jet. thanks again man and the site you put together is pretty intense. good stuff!

 

[namefail]

its 46 tooth sprocket 26inch tire 2.125.

with the leaner setting its weaker pulling from a dead stop but has more torque on incline which is ideal. it just basically died and over heated before i changed the setting

 

[Fabian]

What is the fastest speed you have seen going downhill using the new engine?