help air intake problem

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hr2510

New Member
Dec 23, 2008
13
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florida
have a 80cc powerking kit installed and engine does not want to start. have checked and double checked everything, but here is the problem, am not getting any air draw through air intake or getting very little at all. did have engine running, but soon cut off. am running 16 - 1 mix for breakin period. have checked spark plug and it has no oil buildup and have gone through everything twice. engine does have good compression on down stroke, but again very little or no draw on air/gas instake. any ideas? am thinking it is the piston rings, but would like some more input before a complete teardown.
has anyone had this same problem with new kit/engines. thanks for any ieas or input.scratg
 
misteright1_99

misteright1_99

New Member
Mar 21, 2008
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Treasure Coast, Florida
I would check to make sure the clutch is not slipping under compression. If it is that might be why you have no air draw. Check your cable to make sure it is adjusted properly, if it is, there is an adjustment under the cover on the right side, take the cover off, remove the setscrew, and turn the "star" nut in 1 or 2 positions.....
 
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drhofferber

New Member
Jun 22, 2008
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did you checkn your ground wire...had that problem...just take the ground wire from the engine and mount it on the frame...just to see if that is the problem..black to black color to color and cap the white...good luck...have fun...dennis
 
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hr2510

New Member
Dec 23, 2008
13
0
0
florida
ground is to the frame and all wires are matched up by color, did try and take kill switch wires yellow/red to white off.. no luck.. going to pull right side cluck cover off and take a look. perhaps that might be it.. again many thnx...
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
You say good compression, no draw...how are you checking it?
Remove the carb and check for "draw" at the intake. Then remove the intake and check for it right off the jug.
Another place to look would be the shaft seals and base gasket.

BTW- 16:1 is very overly rich with oil. Go to 24:1 and you may find better results no matter what else you find.

Do you have confirmed spark?
 
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hr2510

New Member
Dec 23, 2008
13
0
0
florida
pulled the cluch cover off and tightend the star nut and still no go. will reset the cluch back and start looking at other things that i may have missed. again many thnx..
 
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hr2510

New Member
Dec 23, 2008
13
0
0
florida
yes.. pulled the spark plug as well as the air/carb intake. have great compression on head/spark plug, but little or no air draw on intake. placed carb back on to see/hear/ feel any draw. you can not hear the air being pulled through the carb. again am beginning to think it is the piston rings, or seals. have spark so that is ok for now. will check them next. may have a vac leak that ill try and run down as well.. again may thnx guys...
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
If you have compression, it's not the rings.
Did you check the cylinder with the intake and carb removed?

99% of the time, it's the intake gasket or the carb to intake.
 
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slipdrive44

New Member
Dec 3, 2008
34
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0
Tucson
I have been working on intake modifications and forced induction type things all week over my school break, what i have learned is that these engine breathe INCREDIBLY little air, you can (and I have) run the engine at wide open throttle, put your finger over the filter and barely feel air moving.
They only move 18cubic feet per minute. That mean that over the course of the five seconds or so you are trying to feel or detect airflow only about a water bottle volume of air has moved...slightly...

Check your FUEL FLOW. At the shop this has been a big one that people don't seem to think of. Make sure your needle is adjusted, that your bowl is filling, and your throttle is opening. OH! and make sure your fuel petcock is OPEN, soo much wasted time thinking the engine has a problem when the fuel is shut off!
 
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slipdrive44

New Member
Dec 3, 2008
34
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0
Tucson
slipdrive44 said:
They only move 18cubic feet per minute.
Click to expand...
This being at wide open throttle. FULL THROTTLE it sucks less than half of a dust buster.

do the math on a 50cc engine at 6000 rpm. it is about 10.6 CFM
80cc is about 17 CFM

The Black & Decker Pv1205B 12v Cordless Dustbuster is a Handheld vacuum with 25 watts power. Has 38.85 CFM air flow
 
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hr2510

New Member
Dec 23, 2008
13
0
0
florida
have spark plug off and carb/intake off .. put the cluch on and rolled bike / motor over, moving the piston up and down . placed fined over spark plug hole on top of cynder.. engine would stop moving / rolling.. had plenty of pull.. placed finger / hand over air intake with carb off .. no air pull. when motor was running you could hear it pulling air and fuel through the carb. will go over everything again and start looking at something diffrent that i may have missed. will replace intake gasket tomorrow and pull head cover off as well and check it too. again many thnx bike guy joe.
 
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slipdrive44

New Member
Dec 3, 2008
34
0
0
Tucson
Check the magneto rod seal. Behind the magnet there should be a plug sealing the rod against the crankcase.

Listen to your motor, it HAS to be pulling air from somewhere.
 
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