49cc 4 stroke problems. its about time!!

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linnix13

linnix13

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Oct 7, 2009
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Ok so i have defeated the odds and reached close to 2000kms on my hoot, and so far its holding up, but i just got back from a 4am ride with my buddy, and boy am i glad i got home.
its -15(with wind chill its -29) we were out for a good 5 hours and at around 3am i noticed something awry with my bike. we were about 15kms away from home in the middle of nowhere(rail trail its deserted late at night) and my bike started chugging, only in the low rpms and it wasnt to bad, i told my buddy we need to get home.

the further we rode the worse it became, i began to loose power and it has a horrible engine seizure like sound from 5kph to about 15kph. and it bogs and backfires and stalled a few times, it would chug and spit and pop and then gain a sudden few strokes of abnormally strong power but then subside. the first time it stalled i was about 7kms away from home and it took a good 6 pulls to start it with the throttle cranked. it stalled again and once again, then one last time when i pulled into the drive.

now im glad to have made it home. i was freezing to death so i put it in the garage and will have a look at it tomorrow, maybe its a bad plug or bad gas? could be something simple but i suspect it has to do with the valves. any input from you guys would be greatly appreciated.

:-||

~thanks in advance, Linnix13
 
W

wdbtchr

Member
Jan 31, 2008
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carb iced up? If it runs OK after thawing and drying out, that's probably all it was. Try a little iso propyl alchohol in the tank. (red bottle of Heet, not yellow) That should clear out any moisture in the tank and lines. Used to happen all the time on gasoline powered equipment in the cold.
 
linnix13

linnix13

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Oct 7, 2009
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wdbtchr said:
carb iced up? If it runs OK after thawing and drying out, that's probably all it was. Try a little iso propyl alchohol in the tank. (red bottle of Heet, not yellow) That should clear out any moisture in the tank and lines. Used to happen all the time on gasoline powered equipment in the cold.
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ok so the ice and cold may have played a part in it. the stalling, but thats it. the engine still starts and runs fine, mid to high rpms are perfect and power is good, but the low rpms on a hill or from a stand still are this violent rumbling. like the engine is unbalanced and about to blow itself apart. but if i just ride it out after the rpms get back up its fine. so what could cause this?
 
Dan

Dan

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May 25, 2008
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Moosylvania
Bummer, I and a bunch of folks were cheering you on. Hope it is some thing simple and an easy fix. 2000kms km = 1242.742 mi. (Had to look it up) Your Hoot GB still doing good?
 
GearNut

GearNut

Active Member
Aug 19, 2009
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Check the crankshaft runout. I have had a few mini bikes act exactly as you are describing when the crank bearings went bad. I hope this is not your situation though.
 
M

marts1

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Sep 18, 2009
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Vehicles use warm air to keep carbs from frost build up in cold weather. Without this they don't run very long just as wd has said.
 
karma1968

karma1968

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Oct 6, 2009
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hamilton
would be funny if all you had to do was clean the plug :) i get the same thing when i have to much slop or play in my drive chain.

i already removed the push rods and rockers to have a closer look. there's no way those parts should fail. remove the rocker cover have a look.
 
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linnix13

linnix13

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Oct 7, 2009
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Dan said:
Bummer, I and a bunch of folks were cheering you on. Hope it is some thing simple and an easy fix. 2000kms km = 1242.742 mi. (Had to look it up) Your Hoot GB still doing good?
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the first thing i thought it was was the hoot. but i took the cover off and its all fine. it still runs. just poorly. i put another 10kms on it today and once i get going it smooths itself out and runs great, i will just keep riding it till it dies. im getting my car on the road in a week anyways so whats to lose? and its not the bearing.
 
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Motor Boys

Motor Boys

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Nov 6, 2009
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Cambridge
-15 iced up carb, I suspect as well. As I recall it is also kept in a cold garage, correct? Let it thaw out the engines are great and will last forever, and the gear box is holding up well, so why kill it? Throw a space heater near it for a few hours and and try to get some ici like, another member told you, I'd hate to have you kill it for the sake that you are getting a car. By the way haven't spoken to you since Christmas, I hope your holidays were great!
 
linnix13

linnix13

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Oct 7, 2009
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Motor Boys said:
-15 iced up carb, I suspect as well. As I recall it is also kept in a cold garage, correct? Let it thaw out the engines are great and will last forever, and the gear box is holding up well, so why kill it? Throw a space heater near it for a few hours and and try to get some ici like, another member told you, I'd hate to have you kill it for the sake that you are getting a car. By the way haven't spoken to you since Christmas, I hope your holidays were great!
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yes i had an amazing holiday! i got a 1972 kawasaki ke100 that needs work. and im rebuilding it so that takes up some time. i will try to de ice the carb and see if that helps. i have a few space heaters so il give it a go. thanks
 
civlized

civlized

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Apr 28, 2009
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Hey linnix, I just wanted to give a different theory. I have had 1 HS engine that started acting like you described. I kept riding it and it locked up on me a few miles from home. After getting home and resting some, I took the engine apart and found that the bolts on the piston rod cap were way loose. The locked up feeling was actually the piston rod jammed into the block by the crank shaft. 1 bolt was barely hanging in and the other was in the bottom of the engine. I put everything back together and used a little loctite. The engine still runs today. This happened about 3 years ago. It doesn't normally get very cold here, so I'm not used to carbs freezing and how that affects an engine.
 
linnix13

linnix13

Member
Oct 7, 2009
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civlized said:
Hey linnix, I just wanted to give a different theory. I have had 1 HS engine that started acting like you described. I kept riding it and it locked up on me a few miles from home. After getting home and resting some, I took the engine apart and found that the bolts on the piston rod cap were way loose. The locked up feeling was actually the piston rod jammed into the block by the crank shaft. 1 bolt was barely hanging in and the other was in the bottom of the engine. I put everything back together and used a little loctite. The engine still runs today. This happened about 3 years ago. It doesn't normally get very cold here, so I'm not used to carbs freezing and how that affects an engine.
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really? wow that means i have to tear my engine apart!!
 
F

freewheeling frank

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Mar 10, 2009
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ridgway colorado
ya could be mechanical but me thinks its just the cold if it was mechanical it would get worse at high revs not better= high revs means more heat, i also have quite a few miles on my hoot not near 2k but alot and no probs except breaking the woodruff key which was junk built one outa good old american iron keep er gteased no problem, later frank
 
civlized

civlized

New Member
Apr 28, 2009
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Alabama
I just wanted to give you something to look for if it doesn't get better after you thaw it for a while. I am not saying take the motor apart. I kept riding mine till it wouldn't run anymore. I kind of figure you might do the same.
 
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