WeedWacker Friction drive help?

ajay007

New Member
Sep 21, 2014
8
0
0
Newyork
Hey there guys,
i recently got interested in friction driven bikes from youtube, watching bunch of cool videos. Eventually leaning and reading more on forums such as this one. So i decided to buy a weedwacker from ebay for cheap. I finally won a bid on a ryobi 26cc 28120. Got it mounted and everything setup. first time i tested it it was really good, about 1 min, i stopped it for a final design. make things stronger and stuff.

then when i tried the finalized bike again, it wouldn't run at all, just could hear it turning on when starting to pedal but then, dies immediately after pressing the throttle. i have no clue what can be the problem.


things i tried so far,
1. adjusting the carb
2. tightening the peg on the spindle, make sure no movement or free spinning.
3. pedaling for more then a block before throttling

if anyone has any idea what i can do to fix it please chime in, as i am stuck
k thanks again guys zpt
 

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Ludwig II

Well-Known Member
Jul 17, 2012
5,070
638
113
UK
The first thing I'd check is whether the pipe is actually in the petrol in the tank. Experience has shown this to be beneficial.
 

wheelbender6

Well-Known Member
Sep 4, 2008
3,964
96
48
TX
Thats a very tidy install. Engine stall could be an air leak. If your fuel lines don't feel soft and flexible, replace them.
 

Flattie42

New Member
Feb 16, 2014
15
0
0
Delaware
If you can get the bike running with the rear tire lifted off the ground by spinning it by hand, try seeing if the engine revs up while freewheeling...

You might need to richen the high and lowspeed needles on the carb since it now has to pull the weight of you and the bike...

There's a chance the carb could need a cleaning or a rebuild...
 

ajay007

New Member
Sep 21, 2014
8
0
0
Newyork
If you can get the bike running with the rear tire lifted off the ground by spinning it by hand, try seeing if the engine revs up while freewheeling...

You might need to richen the high and lowspeed needles on the carb since it now has to pull the weight of you and the bike...

There's a chance the carb could need a cleaning or a rebuild...
um i tried messing with high and the low screws. didnt seem to help. I'll try again, should i tighten it all the way then keep loosing by 1/4 every time till it runs?
 

Flattie42

New Member
Feb 16, 2014
15
0
0
Delaware
I would start at 1-1/2 turns out from bottom on both screws, I've seen a lot of engines that have this as the factory setting, and yes try turning it out in 1/4 turn increments until you can get the engine running and tune from there...

Another way to test if the engine is working properly and if there's a problem with the carb is to put a teaspoon of gas down the sparkplug hole and try starting the engine. If it dies out after a few second then the problem is surely carb related.
 

ajay007

New Member
Sep 21, 2014
8
0
0
Newyork
ok ill try that now ill keep updating... also i have to put the gas in the spark hole plug to test it?? IS that safe?
 

ajay007

New Member
Sep 21, 2014
8
0
0
Newyork
If you can get the bike running with the rear tire lifted off the ground by spinning it by hand, try seeing if the engine revs up while freewheeling...

You might need to richen the high and lowspeed needles on the carb since it now has to pull the weight of you and the bike...

There's a chance the carb could need a cleaning or a rebuild...
i just tried to run it with the wheel off it didnt work at all
 

Flattie42

New Member
Feb 16, 2014
15
0
0
Delaware
The sparkplug could be dead or dying, have you checked for spark? Remove the plug from the head and put the wire back on the top of the plug and touch the threads to the cooling fins... Have someone turn the enigne over and look at the electrode tip for a strong blue spark.
 

Ludwig II

Well-Known Member
Jul 17, 2012
5,070
638
113
UK
The plug cap may be separating from the lead also. Are the contacts of the coil cleanly and firmly attached to the motor?

Whatever the cause, a dull, weedy, purple spark is not your friend.

One quick question. Nothing's been washed with water, has it? I once had a plug with purple lightning down the outside of it, instead of the blue stuff being inside the engine.
 

ajay007

New Member
Sep 21, 2014
8
0
0
Newyork
The sparkplug could be dead or dying, have you checked for spark? Remove the plug from the head and put the wire back on the top of the plug and touch the threads to the cooling fins... Have someone turn the enigne over and look at the electrode tip for a strong blue spark.
ok will try that now, if that isnt the problem most likely its the carb then right.... i read gasoline containing ethanol can be harmful to 2 stroke engines even with oil?
 

Flattie42

New Member
Feb 16, 2014
15
0
0
Delaware
If you have spark and compression and do the test with gas down the sparkplug hole, it should rev up for a few seconds then die quickly... This is because the fuel is now inside the crank case & is being mixed and ignited as the engine turns over until it all burns up... If this happens then you know that your coil is firing, the sparkplug is making spark, & the piston,, rings, crank, & bearings are still functioning inside the engine.... The problem is surely carb related... If it doesn't make a reaction while doing the test, then it could be one or a few other things wrong with the engine internals, excessive carbon buildup on the exhaust port, or improper sparkplug gapping...

ok will try that now, if that isnt the problem most likely its the carb then right.... i read gasoline containing ethanol can be harmful to 2 stroke engines even with oil?
That's right ethanol is the usually the main culprit behind problems with carbs like yours... If you've seen what the rubber diaphragms look like inside the carb you'll notice that they're extremely thin. The worst thing to do is to empty the carb and let it sit and dry for storage.... The ethanol will warp & harden the diaphragms and the carb will be rendered useless until rebuilt... Best bet is to use high octane pump gas like 91 or 93 with a bit of fuel stabilizer if you're just running the engine stock unmodded.
 

ajay007

New Member
Sep 21, 2014
8
0
0
Newyork
If you have spark and compression and do the test with gas down the sparkplug hole, it should rev up for a few seconds then die quickly... This is because the fuel is now inside the crank case & is being mixed and ignited as the engine turns over until it all burns up... If this happens then you know that your coil is firing, the sparkplug is making spark, & the piston,, rings, crank, & bearings are still functioning inside the engine.... The problem is surely carb related... If it doesn't make a reaction while doing the test, then it could be one or a few other things wrong with the engine internals, excessive carbon buildup on the exhaust port, or improper sparkplug gapping...



That's right ethanol is the usually the main culprit behind problems with carbs like yours... If you've seen what the rubber diaphragms look like inside the carb you'll notice that they're extremely thin. The worst thing to do is to empty the carb and let it sit and dry for storage.... The ethanol will warp & harden the diaphragms and the carb will be rendered useless until rebuilt... Best bet is to use high octane pump gas like 91 or 93 with a bit of fuel stabilizer if you're just running the engine stock unmodded.

Also to come think of it it was running extremely hot the first time i had it running... so i guess i need a new carb. Also do u know any performance carbs? for the ryobis or are the all universal carbs?
 

Citi-sporter

Member
Jun 16, 2014
169
20
18
North Bend, Or,
Two major obvious problems I can see. You disabled your forced air cooling when you removed the engine fan shroud and the friction drive 'drum' is way too large for such a small engine. This is only half the displacement, if not even less, than most bicycle engines made. It should be running a friction drive of maximum about 7/8"'s of an inch or smaller in diameter.

Lugging an over-worked and undercooled engine will surely cause it to not last long.

Try to buy non-ethanol gasoline, check Pure fuel.org for your local stations carrying nonethanol gasoline. Also most modern weedie 2 cycles need about a 40:1 fuel/oil mix.
 

ajay007

New Member
Sep 21, 2014
8
0
0
Newyork
Two major obvious problems I can see. You disabled your forced air cooling when you removed the engine fan shroud and the friction drive 'drum' is way too large for such a small engine. This is only half the displacement, if not even less, than most bicycle engines made. It should be running a friction drive of maximum about 7/8"'s of an inch or smaller in diameter.

Lugging an over-worked and undercooled engine will surely cause it to not last long.

Try to buy non-ethanol gasoline, check Pure fuel.org for your local stations carrying nonethanol gasoline. Also most modern weedie 2 cycles need about a 40:1 fuel/oil mix.
i dont know what a fan shroud looks like? also the diameter is too big for the peg? ill change it right away to a 7/8 of an inch one. can u just explain what the fan shroud is? thanks alot- AJ
 

curtisfox

Well-Known Member
Dec 29, 2008
5,073
1,460
113
minesota
Fan shroud is the flywheel cover the directs the air around the head and cylinder to keep it KOOOOL...........Curt
 

a_dam

New Member
Feb 21, 2009
351
0
0
Momence, IL
Shrouds are overrated. If the bike is not moving, then I wouldn't have the motor revving high for a long time. But as long as the bike is moving there will be plenty of airflow. I've used "unshrouded" 25cc motors for thousands of miles with no overheating problems. I even grind the flywheel fins down considerably for more clearance around tire.