Engine Trouble Low power after remounting engine to new bicycle

micromaster22

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Jul 14, 2017
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Quick story
Old bike frame broke while riding. The frame had snapped right above the rear mount due to a small crack that got worse after a month of engine vibration. (Vibration isn't bad, I used the frame with knowledge of the crack) During my ride the back wheel seized and I slid to a stop. The engine had rotated to the left around the rear mount. It was still attached to the rear and it rotated and touched my left knee. So I just swapped over to a huffy cranbrook
STATS
80cc motor running Lucas Semi 20:1 ratio was running beautiful
#65 jet ( I have 60-80)
After a few rides after buying this engine i heard a rattling, the small clutch gear bevel screw had unscrewed and was sitting in the clutch case cover. I screwed it back in very tight and it had unscrewed again and boogered up the threads. I ordered a new bevel gear, screw and woodruff key as well as a gear puller.
MY PROBLEM
Engine mounted very well, looks phenomenal. Not a fan of coaster brakes so I am adding hand brakes form my old frame. The first start on the new frame produced a tremendous amount of smoke ( my initial thought was fuel in the engine still) With alot of smoke it was barely any power. I moved the clip to a leaner setting and i got a little more power. Im thinking of changing the jet again, maybe its still to rich? IDK. Im lost. I was getting tremendous speed and power before my old frame cracked and the engine shifted over. I thought it was my throttle assembly because it's old and I boogered it up getting it off the old bike so I ordered a new one.
QUESTIONS
Did I booger up the crank shaft when everything shifted so hard?
Why after remounting the engine did I start running so rich?
Could this power loss be caused by the bevel gear and or woodruff key?

Any help would be greatly appreciated. My daily driver went from 38mph to a wopping 10mph.
I can provide pictures and video upon request.

THANKS!!!!
 


crassius

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I posted here a while back about a guy with a big arm and really big hammer that seized a motor shortly after putting on bevel gear. Seems when he used impact driver to tighten the bolt he must have smacked it so hard that the crank pinched the rod big-end bearing (can't be sure what happened but the big-end was stuck when it failed, so this is my guess).

Take out your spark plug and check that motor turns easily.
 

micromaster22

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I posted here a while back about a guy with a big arm and really big hammer that seized a motor shortly after putting on bevel gear. Seems when he used impact driver to tighten the bolt he must have smacked it so hard that the crank pinched the rod big-end bearing (can't be sure what happened but the big-end was stuck when it failed, so this is my guess).

Take out your spark plug and check that motor turns easily.
I have yet to mess with my bevel gear. In the past the screw had came out so I tightened it back on there, it fell off again and after that I rode around without the bolt for the bevel gear. No issues until my frame cracked and the engine shifted. I ordered a new gear, bolt, washer and woodruff key but I have not installed it yet.
 

crassius

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In that case, I'd look closely at the crank seal behind that gear to see if it is losing compression there. I'd also check wiring for bad spots and check that nothing is blocking muffler after the move.
 

micromaster22

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Af
In that case, I'd look closely at the crank seal behind that gear to see if it is losing compression there. I'd also check wiring for bad spots and check that nothing is blocking muffler after the move.
After removing the bevel gear with the gear puller, how do I check for loss of compression? Also, for the muffler do I just remove the muffler and check for blockage? I font understand this power loss its very frustrating.
 

crassius

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for the seal, look for oil residue around the seal, for muffler just try running motor with muffler loosened for a 1/8 inch gap

a compression test would help too

occurs to me that some case bolts may have gotten knocked a bit loose too - clean motor and check for oil along seams of case
 

micromaster22

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Af

After removing the bevel gear with the gear puller, how do I check for loss of compression? Also, for the muffler do I just remove the muffler and check for blockage? I font understand this power loss its very frustrating.
for the seal, look for oil residue around the seal, for muffler just try running motor with muffler loosened for a 1/8 inch gap

a compression test would help too

occurs to me that some case bolts may have gotten knocked a bit loose too - clean motor and check for oil along seams of case
Ok. I am going to mess with the jetting, bevel gear, check for oil and mess with muffler tonight/tomorrow
 

micromaster22

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Ok. I am going to mess with the jetting, bevel gear, check for oil and mess with muffler tonight/tomorrow
After noticing the woodruff key was gone I replaced it and gained more power an performance, still no where near what I did have but it better than yesterday. Am I getting closer?
 

micromaster22

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sounds like it - just take it one thing at a time
What should I check for next? There is no oil around the case, there is gross grease in the clutch case but idk if that's normal for grease to change color. How do I get the bevel gear on all the way?

EDIT
Bevel gear is on all the way, still no performance change. Idles fine however. ALSO, when I'm rotating the bevel gear, clutch gear and 10 tooth sprocket slowly, you can here a wet sounding air noise coming out the carb. Is that normal?
 
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