new engine..bogged out. new need help :)

B

bronson9

New Member
Hi everyone,

So this is my first build. It is an 80cc boygofast 2stroke. I assembled the bike and within minutes of having it gas'ed up I was zipping around the neighborhood no problem.
I ran a half a tank or more out on the first set of rides. Going a mile or so then back and stopping for a few minutes then start up and run another mile and repeat. All the while starting and running very smoothly. I did this for an hour or two and then stopped to make dinner. After dinner (an hour later) I could not for the life of me get the engine started. FINALLY after 30 minutes or more of pedalling and skidding to a stop the engine finally started. From that point on the engine was sounding bogged down, like the choke was on or something (it wasn't). I decided to take a longer ride because maybe it was a little flooded or something or maybe the engine needed breaking in so I drove it about 5 miles or more away from my house- keeping ok speeds, never full throttle, just easing on and off - trying to get the engine to clear up......after the 30 min ride or 5 miles the engine completely bogged down and shut off and hasn't started since.

When I got home and looked at it the plug had obviously been fouled. It was black and oily all around. The oil ratio I had been running was 32:1 (as the manual instructed for break-ins). There was gas and oil residue around the carb,plug, and muffler. I have cleaned the carb, and muffler off, replaced the spark plug ( which last night I connected and taped to the engine head to test for spark ---it IS sparking---) and drained/changed the gas and added in a lighter 24:1 (6oz oil-1gal).

but still no start :( I'm not sure how to adjust the needle on the carb if that is my problem, nor do I know how to check for a compression problem?

I did not know much at all about small engines or bikes before I did this build and joined this forum-- but I think I have checked out on the Fuel, and Fire .. ?

suggestions..comments.... Thanks alot!!
 
also it could be my imagination ..accompanied by lack of proper terminology... When I drop the clutch..it seems the engine turns over too freely...not enough..catch? to get it to turn over properly..etc.

again this might be normal..just adding info
 
bronson9 said:
also it could be my imagination ..accompanied by lack of proper terminology... When I drop the clutch..it seems the engine turns over too freely...not enough..catch? to get it to turn over properly..etc.

again this might be normal..just adding info
Click to expand...

When you pedal it & pop the clutch, are you sure the engine's actually spinning? Are you sure the clutch isn't slipping?
 
Thanks frank I'll go check and tighten those two things...

Venice - I'm positive the engine is actually spinning. After pedaling up to a brisk speed and popping the clutch I can hear the engine pudder and try to turn over just before the bike slows down to a very slow speed and stops. The reason I suspect the clutch to be slipping ( I dont know how to tell for sure if it is or not) is that the engine sounds to only be getting a good turn once the bike has slowed down to a slow speed.....? I'm not sure. Just learning and trying to piece it together myself. thanks for the help
 
Good news! The motor started!! I think the new plug and 24:1 gas had alot to do with it but tightening down on the muffler and carb connections I think did the trick. It is still somewhat boggy but not nearly like it was when it went out on me but I think this is due to the engine still being new and the fact that it hasn't been run for a week or so.

Thanks for the help!!

but is 24:1 a safe ratio ? and, it still takes many tries to get the bike started...due to I suppose a slipping clutch? maybe i'm wrong.. idk

thanks again
 
check your head bolts, you might be losing compression. look around the head gasket and see if there's any black gunk coming out of it. DO NOT over torque them, DO NOT crank them down when the engine's hot, and DO NOT remove a spark plug on a hot engine (the threads might come out with it.)

24:1 is richer than 32:1, and that's what most people recommend for break-in, so it's safe. if it was running good at 32:1, i'd go back to that.

if your plug is still black and oily, you can try moving the clip on the needle up a notch.

black oily plugs will foul out and cause your engine to bog, hard to start, or not run at all.

also, clean out the sponge in your air filter. when your bike runs rich, the sponge fills up with oil and can't breathe.

a simple way to check if your clutch is slipping is like this:

with the lever pulled in, walk with your bike. it should roll free, with no drag except for the chain moving. if it drags or skids, then adjust the cable till it rolls free.

try the same thing without pulling the lever and the bike should skid. it shouldn't even roll and go "whump whump" at all with no weight on it (remember, you're walking alongside it.)

if the back wheel's rolling at all (besides a foot or so of play back and forth) without the lever pulled and you pushing the bike, you're clutch cable needs to be a little looser.

if it is skidding, pull the lever slowly and see where it starts to roll free. if just a tiny little squeeze makes it release, it might be too tight.
 
Ok so yesterday morning I got the bike running on a new plug and new 24:1 gas...(from 32:1)... and by tightening down the carb fitting and the muffler... (no black gunk around the head either).

I ran it for a while and it seemed to be running great...I took it back in the house after riding, let it cooled, messed with some little cosmetic things and then went back out.. No start again..

I checked the plug and it was black and oily again.. NOT as black and oily as it had been with the 32:1 gas mix... Do i change to a 16:1? or is that a dangerous mixture..

I was going to get a new plug and mix some new gas just not sure if I have a gas problem or not.. This new engine has now had almost 2 tanks run through it.

also..i'm kinda a noob. how do you adjust the carb needle?
 
Take us step by step the process you use to mix the oil. 16:1 should be MORE oil than 32:1, therefore less dangerous. It'l gunk up the motor but you can always clean it.
 
running at 24:1 fuel with new NGK BP6HS plug and adjusted the carb needle to one notch above stock (one notch down from the most top notch) I got a nice 30 minutes or more run time..the engine stalled out once but I managed to get it going again.. I got home, waited an hour for things to cool, then tried to start the engine again but cant seem to get it running.. I made sure things were cool and took out the plug... a small bit of oil and a dark tan color.. better then the other 2 plugs Ive used >< . The engine wont start..is it still too rich ? Do i move the carb needle up another notch
 
I'm breaking in a bgf motor myself with less than 5 2.5l tanks on it.I my self was at 32:1 then went to 25:1, and now I'm at 16:1. My engine doesn't have any problems starting. I was running into a bog down problem to but I think I have it fixed, goodluck..flg.
 
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