Engine Trouble 80cc ht won't start

[crassius]

here's what I've seen:

1) carbs jetted so large that a new engine won't run unless the needle is dropped all the way to the last position to lean out the mixture

2) spark plugs fouled such that they will spark outside the engine, but they won't jump the gap when under compression in the engine

3) CDI units that spark well, but have a timing problem so the engine never starts

4) single speed bikes that are hard to pedal fast enough to get the engine to start the first time

5) new engines that won't start the first time without putting the choke on

all the above assume that you're seeing a spark outside the engine and that the engine is turning over when you pedal it

 

[Big Red]

here's what I've seen:

1) carbs jetted so large that a new engine won't run unless the needle is dropped all the way to the last position to lean out the mixture

2) spark plugs fouled such that they will spark outside the engine, but they won't jump the gap when under compression in the engine

3) CDI units that spark well, but have a timing problem so the engine never starts

4) single speed bikes that are hard to pedal fast enough to get the engine to start the first time

5) new engines that won't start the first time without putting the choke on

all the above assume that you're seeing a spark outside the engine and that the engine is turning over when you pedal it

All good points crassius, but lets wait to see if the coil solves his problem before we confuse him with an overload of information. Sometimes too much info can be just as bad as no info. A little at a time so he can absorbe it. After all, I think he's a newbie. (Sorry about that if yer not a newbie bro.)
Big Red.

 

[crassius]

One could only hope that he would go thru the list one item at a time rather than all at once : )

Last week we had a POS engine that we fought for many hours - finally, a THIRD CDI with good spark got it running - much like the inquisition, no one expects two bad CDIs with good spark in a row right out of the box : (

 

[Big Red]

One could only hope that he would go thru the list one item at a time rather than all at once : )

Last week we had a POS engine that we fought for many hours - finally, a THIRD CDI with good spark got it running - much like the inquisition, no one expects two bad CDIs with good spark in a row right out of the box : (

Yeah, One could only hope.
I've done the same thing with coils. TWO IN A ROW, ya gotta be kidding me!!! He just got CDI confused with COIL, otherwise I think he would have it running by now.
Big Red.

 

[rider30ab]

Status: motor still won't start BUT;
We bought 2 used bikes with motors. One of which we new would run. The other was new and never been started. Both motors were mounted on bikes.
We quickly got the first motor running and is then became obvious that our original motor ( the one that started this thread) was completely lacking compression. So now to tear the motor down and figure out where the compression went. Or maybe the clutch is acting up. We (son and myself) noticed the clutch behaving differently on the original bike as compared to the new motor that starts fine and runs well.

We will keep the thread posted as we progress. Next step is to contact the company we bought the motor from and find out if they have had any problems with other motors. We are out of warranty time but just looking for info.

 

[Big Red]

I did everything I could to make sure if you knew the engine was turning over.(posts 2&4) If it does turn out to be a slipping clutch I'm sorry for all your trouble. The very first few posts were about your clutch slipping while the engine was under compression and that you should make sure your clutch was tight enough. I've never heard of a new engine having no compression at all. Make sure all the head bolts are tight and try it again.
Anyway, keep us posted and good luck.
Big Red.

 

[rider30ab]

We know the engine is turning over. With the plug pulled we can poke a dowell rod into the hole and feel the piston move. We can also see the piston move through the intake port. Until getting the new motors (new to us) we didn't understand just how much back pressure we shuould feel when trying to start the engine. Now we do.
Thanks for all of your help. Will keep you posted as to our findings.

 

[Big Red]

You can tell any slipping by looking at the clutch. Remove the cover and push the bike or turn the engine over some other way. The entire clutch should turn and also spin the small bevel gear. if it's slipping you'll only see the center part of the clutch turning and the outer clutch gear and bevel gear will pretty much NOT be turning. The entire clutch has to turn to engage the engine. The engine will turn over MUCH easier with the plug out so doing it this way is not the best way to check for a slipping clutch. The extra pressure of compression is A LOT and will put A LOT more pressure on the clutch, so checking with the plug removed is NOT the way to check for a slipping clutch. Put the plug in and make sure the ENTIRE clutch and small bevel gear is turning when trying to start the engine.
Red.

 

[rider30ab]

Missing Spring

Perhaps we have found the problem. We are missing a spring that applies pressure to the clutch. When you take off the clutch cover and the next disk, under that disk is a spring. We don't have that spring. Can you, or anyone name that spring and tell me where to get one? BikeBerry has a spring called "main clutch spring" but it in the picture from their catalog appears to be much stronger than the one I'm wanting. Anyone know if this is indeed the correct spring? http://www.bikeberry.com/engine-kit-parts/clutch/main-clutch-spring.html

We took another motor's clutch apart and seen the spring we are missing.
I'm trying to figure out how to attach a picture of the missing spring. When I figure that out perhaps all of this will make more sense. Thanks for your help and patience.

 

[crassius]

http://www.bicycle-engines.com/Coil-Spring-Part-3.html

there's your spring, but if you have the one you took a picture of, it should be easy for you to look around the house & fins something that will work