loss of power By gnf (Read 703 times)

[gnf]

Hi new here, i just installed bbk on my keeway 2 stroke everything seems good spark plug is light brown, starts good, good compression, take off and acceleration is great top end is good to, the problem i am having is when i hit some bigger hills the rpms drop way down and the speed to, it also does the occasionally when i let off the throttle and hit it again, i tried a heavier torque spring and it helped a little but not much, is it possible that the clutch is the culprit and the sheave is not closing when it should or should i be checking for something else? Thanks

[Alleyoop]

If rpms drop a lot climbing hills your weights in the Variator are to Heavy, You need to put in lighter weights so the rpms will not drop only your mph should drop. You may loose a little top end but you can find a good medium.
The reason the Torque spring helped is because it take more rpms to open the clutch pulley.
Alleyoop

[gnf]

right now i am running 4 gram weights, i was thinking maybe the clutch was not closing the way it was slowing down and losing rpms going up hill, i do have some lighter weights that i can try and see how it works out.

[Alleyoop]

No your running the 4 gram weights which is light enough. Does the motor BOG going up hill or when you let off and hit the throttle again? What does it do when you let off and hit the throttle again? It could be your fuel mixture on the carb, does it hesistate does the motor make any kind of sound etc..
Alleyoop

[gnf]

if it is a small hill it just goes right over them bigger hills it just seems to loose power rpms and speed drop it doesn't really sound like it is bogging but more of the engine just slowing down as it climbs the hill and some times when i let of the throttle it seems to have to build rpms back up again, it doesn't hesitate at all when this happens and other than that the take off is good and driving on level ground is fine.

[Alleyoop]

Ok, you mentioned some very important information and that is this "I LET OFF THE THROTTLE AND IT SEEMS TO BUILD RPMS BACK UP".

That means it is running LEAN, needs more gas, now is this a 2 stroke or 4 stroke, because the 2 strokes have a different type of carb(usually the throttle cable is going into the top center of the carb). Is that the type of carb you have?
Alleyoop

[gnf]

yes it is a 2 stroke with the cable going in the top

[Alleyoop]

Ok here is what your Carb probably looks like and I labled what everything is:
And also how to adjust it:
Alleyoop



If your carb has a SCREW near the AIR FILTER side of the Carb it has a AIR RATIO MIXTURE Adjustment screw.

Turning the Air Ratio Mixture Clockwise RICHENS it Turning it Counter Clockwise LEANS it.

The Idle Speed screw is in the Center of the Carb. Turning that Clockwise RAISES the Idle and Turning it Counter Clockwise LOWERS the Idle.

[RED]IF YOUR CARB HAS A SCREW ON THE INTAKE SIDE GO SEE 4TS CARB TUNING.[/RED]


[blue]ADJUSTING YOUR AIR RATIO MIXTURE:[/blue]


[red]YOU WANT THE HIGHEST RPMS OUT OF THE AIR RATIO MIXTURE SCREW:[/red]

Start your scoot and Get The Engine Nice and Hot about 5 minutes so that the Enricher IF it has one is no longer Allowing Extra Fuel to come in. Then do the following to fine tune the Air Ratio Mixture:

NOTE: The Air Ratio Mixture is very [red]SENSITIVE[/red] and it does not take much to be off so only make small adjustments.


[red]AIR RATIO SCREW:[/red]

FIRST TRY RICHENNG THE AIR MIXTURE FROM ITS CURRENT SETTING:


[blue]RICHEN THE AIR RATIO MIXTURE:[/blue]

1. Turn the Air Mixture Screw CLOCKWISE 1/8 of a turn and wait 10-15 seconds to let the engine catch up with the new setting.

a. If the RPMS go up REPEAT #1 UNTIL the RPMS GO DOWN OR NO CHANGE(then go to b).

b. TURN the Air Ratio Mixture Screw COUNTER CLOCKWISE 1/16 and that should be your highest Air Ratio Mixture setting—GO TO #3.


[green]******[/green]If on the FIRST 1/8 TURN from the STARTING Position IN #1 ABOVE the RPMS GO DOWN OR NO CHANGE , turn the Air Ratio Mixture Screw Back the 1/8 turn to the Starting position and wait 10-15 seconds until the engine catches up -- GO TO #2 [green]******[/green]


[blue]LEAN THE AIR RATIO MIXTURE:[/blue]

2. Turn the Air Mixture Screw COUNTER CLOCKWISE 1/8 of a turn and wait 10-15 seconds to let the engine catch up with the new setting.

a. If the RPMS go up REPEAT #2 UNTIL the RPMS GO DOWN OR NO CHANGE(then go to b).

b. TURN the Air Ratio Mixture Screw CLOCKWISE 1/16 and that should be your highest Air Ratio Mixture setting—GO TO #3.


[red]IF YOU GOT TO THIS POINT AND NOT INSTRUCTED TO GO TO #3 THAT MEANS THERE WAS NO CHANGE IN RPMS FROM DOING #1 or #2 ABOVE, IT IS TIME TO CLEAN THE CARB:

YOU NEED TO CLEAN YOUR PILOT JET AND PASSAGE AND AIR PASSAGES AND THEN START FROM #1 AGAIN.[/red]


[blue]IDLE SPEED SCREW:[/blue]

The Idle Speed Screw on a Carb that are on most 2Ts is in the CENTER OF THE CARB LEFT of the AIR RATIO SCREW.

To Lower the IDLE you turn it COUNTER CLOCKWISE to Raise the IDLE you turn it CLOCKWISE.

3. If after adjusting your Air Ratio Mixture your idle is to fast Turn the IDLE SPEED SCREW COUNTER CLOCKWISE until the Rear Wheel JUST Barely wants to Turn ---GO TO #4.


[red]TEST YOUR ADJUSTMENTS:[/red]

4. Now give the Throttle a QUICK twist and the RPMS should climb up quickly without hesitation or bogging and come down to where you set your Idle at.


[blue]Problems with the IDLE:[/blue]

1. Give the throttle a quick twist:

A. If the rpms drop below idle speed, then recovers (or stalls), it is [red]RICH[/red] —Turn the Air Mixture Screw Counter Clockwise 1/8 turns at a time and go to #1.

B. If the rpms do not drop quickly to the idle speed but hang and drop slowly it is[red]LEAN[/red] —Turn the Air Mixture Screw Clockwise 1/8 turns at a time and go to #1.

[gnf]

my air fuel mixture screw is a sealed one anyway to get to the screw?

[Alleyoop]

Here you go:
Alleyoop

[gnf]

cool thanks! will try this weekend

[Alleyoop]

Goog luck, now remember the plug is only about 1/8 thick so What I would do is drill 1/16 hole and not go over 1/8 deep then get a small screw and screw it in and turn and pull. That way you will not hit the screw behind it.
Alleyoop

[gnf]

thanks for all the help worked out great