Engine has way less power after reed kit installation?

jeeprider

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#1
I put a reed valve kit on my 80cc 2 stroke from bikeberry and I bought the windowed piston off of ebay. I measured the stock piston before buying the windowed one and measured it when it came in the mail, and it is the right one. My problem is, is it will idle fine, but when I go to accelerate, it basically shuts off under full throttle. If I go easy on the throttle, it will stay running but has very little power. Such little power thatr I have to pedal it sometimes to help it get the RPM's higher. Once the RPM's get up there, it runs fine and has good power. Any ideas? I did put a bigger jet in it after the reed kit install. I'm stumped. Any help will be appreciated.
 


briheen k

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#2
What carburetor are you using?
Do you still have stock carb installed?
Have you checked your throttle cable adjustments.?
 

Frankenstein

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#3
Did you re-jet? When you go to a reed you usually need to make the carb richer, one good start is the needle clip, if you move the clip to the bottom it should richen up and help a bit with the lower end torque, which is where you seem to have problems
 


jeeprider

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#5
Did you re-jet? When you go to a reed you usually need to make the carb richer, one good start is the needle clip, if you move the clip to the bottom it should richen up and help a bit with the lower end torque, which is where you seem to have problems
I did try and adjust it, and it just made it worse. I don't know whether to go leaner or richer. I put the stock intake back on it and it runs perfect. I'll have to install the reed kit again and get a video.
 



Stoneman

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#8
The only thing I thought that maybe the reed is creating less crankcase compression
I’m not sure what one he’s talking about though

Not enough cylinder compression? I’m not sure if that would matter with adding a reed
 

Frankenstein

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#9
The only thing I thought that maybe the reed is creating less crankcase compression
I’m not sure what one he’s talking about though

Not enough cylinder compression? I’m not sure if that would matter with adding a reed
Well, if he had a windowed piston and switched the intake only then it shouldn't be running at all.. I think the cheap reeds lack something, I've noticed the petals don't alway stay closed or lay flat when you look at them, especially after using it they just stay slightly open. For all he knows he has an air leak on the valve or a cracked Reed.
 

Stoneman

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#10
Haha, was thinking the same just after I finished typing as I noticed that on one of the ones I have

It could explain why it’s working at high revs as it might have enough pressure to close it off or it not be such an issue at high revs

I was thinking of putting mine on glass with sand paper and flattening them
Even the screws seem to warp it a little when they screw in
 

Frankenstein

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#11
Haha, was thinking the same just after I finished typing as I noticed that on one of the ones I have

It could explain why it’s working at high revs as it might have enough pressure to close it off or it not be such an issue at high revs

I was thinking of putting mine on glass with sand paper and flattening them
Even the screws seem to warp it a little when they screw in
I could correct the problem and it would work, but then they would warp in the open position again. He said it couldn't full throttle but could move slowly if he was gentle with it.
 


jeeprider

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#13
If the reeds leak even just a tiny bit, would it cause that much of an issue? I can suck some air through the reeds, but didn't think it was enough to cause a big dramatic issue.
 

FurryOnTheInside

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#14
I'm sure you can check.. I think the air filter would be very oily if the reed valve is indeed allowing significantly more of the a/f to get reversed and blown back out than the piston port intake and a notched piston skirt or lowered intake commonly does anyway. The piston skirt isn't a perfect seal either.

There are supposed to be two types of reed, apparently. Some of the valves come with carbon fibre reeds and some come with a fibreglass pair. If you have any issues you can't solve with the type you have you could try to track down the other type, which will have a different set of issues to solve and/or avoid. :rolleyes:

You probably need to make a bit more room at the ceiling of the intake port to allow the upper reed to open fully. Not sure that's the problem but it seems to be necessary from what I have seen, which is just a cylinder and rse style Reed valve that I haven't got around to putting together yet.
Why they made the valve point straight in when the intake port is angled downward is a mystery to me. :rolleyes:
 
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Frankenstein

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#15
I'm sure you can check.. I think the air filter would be very oily if the reed valve is indeed allowing significantly more of the a/f to get reversed and blown back out than the piston port intake and a notched piston skirt or lowered intake commonly does anyway. The piston skirt isn't a perfect seal either.

There are supposed to be two types of reed, apparently. Some of the valves come with carbon fibre reeds and some come with a fibreglass pair. If you have any issues you can't solve with the type you have you could try to track down the other type, which will have a different set of issues to solve and/or avoid. :rolleyes:

You probably need to make a bit more room at the ceiling of the intake port to allow the upper reed to open fully. Not sure that's the problem but it seems to be necessary from what I have seen, which is just a cylinder and rse style Reed valve that I haven't got around to putting together yet.
Why they made the valve point straight in when the intake port is angled downward is a mystery to me. :rolleyes:
Oh yes, I ground some out just because it didn't look right by eye, I wanted to give it room, I guess if you can't slide the valve up while against the port then it may not have room to open and is starving the motor.

I also took the time to use the copper spray from permatex to make a nicely sealed unit on all the gasket surfaces. Another curiosity, what did the plug look like? Maybe the angle of the carb changed too much and you have a different issue all together.
 


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