Engine Trouble Engine wont start? TROUBLESHOOTING GUIDE


Local time
6:26 PM
Jan 22, 2008
Essex, England, UK
If your Happy Time engine isnt starting then work your way through this guide to identify and fix the problem. Still no hope? then just ask...
With many thanks to BoltsMissing who compiled this great troubleshooting guide. Thanks to Lordoflightaz too for a few tips :)

Firstly start off by checking that the fuel petcock is on and you have fuel. Check the wires to the CDI. Make sure that they are connected. The cheap connectors come loose

1. Remove spark plug, check gap.
2. Check for spark with lead on plug and earth spark plug on cylinder head fin.

Lift the rear wheel, and give it one good hard pedal down as if you are
kick-starting a bike. If plug sparks at the tip, re-install the spark plug. (just bear in mind that I have had plugs that fire under no compression(Not in engine)but had no spark under compression(In engine)This can be a pain if you Don't know this.You could pull your hair out with this problem,new plugs are cheap!)

2a. If no spark, check Plug cap. I had to replace mine with a NGK Right Angle spark plug cap, (don't know the part No. though)
2b. Repalce lead anyway with Copper wire lead.
Check for spark again with new lead and plug cap
That's the electrical done from start of lead to end of plug tip.

If Spark, then go to Fuel.
If No Spark, go to Magneto and CDI.
But don't just replace the Magneto and CDI unless you do all the obove to.
That way you have a clean sweep out of sight out of kind type of thing of the electrics.


Remove Carby, AFTER Spark is all clear as explained above.
Remove fuel bowl, see if it was full or any fuel was in there.
If not, check fuel line and needle/seat where the fuel line plugs in.
There may be some grit.
If it had fuel in fuel bowl, re-fit carby.

Fuel is OK up to fuel bowl end.

Clutch adjustment, just go through the motions at the cable end. There should be no slack.
Can't say much about whats behind the clutch cover, never had one with problems ,yet.

By this time you probably flooded it trying to start and doing the other testings.

Then as last resort as I mentioned earlier,
Tow start,
and this will "flush out" the remaining cob-webs, and it ought to go.
Tow around the block or whatever until all reasonable doubt is undoubted if it still don't start. Be very careful though as this could be dangerous!

Failing a tow start, then start the inspection process again the next day, so take a break, it's only a Happy Time (HT) engine.
This time check for Head/Lower cylinder/Exhaust and Carby Gasket leaks etc.
Point is, dwelve deeper into the problem.
Tow again if all looks OK.

Remember if an engine has compression, fuel (air and petrol) and a spark then it must fire, it doesnt have a choice! ;)
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Sounds like the engines are junk.... Or...

Back in the early 60's I helped my sister's husband get his BSA ready for a ride. We cleaned and polished that big single (I think it was 500 CCs) all morning. I was 14 or 15 at the time and this was going to be my first motorcycle ride so I was wound up tight when it came time to start the bike....

Any of you who have been around British motor vehicles can see what came next, an afternoon of trouble shooting that ended with my brother in law being towed by his friend' truck. Never did get a ride that day, which was a big disapointment, but I learned that if I couldn't fix it I wouldn't own it.

As for these little $150 engines, I was looking at electric bikes last week, but I would have to wait awhile before I could drop a grand and a half on a bike...

Heck, last month I was in a bike shop where I saw a $4,000 bicycle! I can remember when a new Chevy cost less than that.
I would like to add that i have had plugs that fire under no compression(Not in engine)but had no spark under compression(In engine)This can be a pain if you Don't know this.You could pull your hair out with this problem,new plugs are cheap!
I had a problem with my HT not starting. There were 2 problems. The first was the clutch was slipping and unable to turn the engine over. I adjusted the clutch until it could turn the engine over. The other was the kill switch dying. Remove kill switch from the equation and engine ran fine.
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wont start

got my motor in an it ran for 10 seconds. Then wouldnt start no matter what I did. Had spark at the tip of plug. Got a new cdi an it started right up an been running good. Did a resistance check on both cdi an they were different. Like I said, I had spark but it wouldnt start.It was frustating.

Towed mine upto about 30 and couldn't get more than a slight tingle
from the plug ( yes I did use the redneck plug tester and held on to it )
I'm not sure how to find the information to test the mag or coil , can
anyone help?
hard starting

Ride Anything, before you do anything else I suggest that you disconnect the wiring from the killswitch altogether.
Connect the blue wire from CDI to blue from engine.( or green to green if thats what color it is)
Connect the black from CDI to black from engine.
Cap off the wire wire.
Make sure that at no point anywhere that bare wire is touching any part of the frame.
See if it starts now.
If it does,then you can shut down the engine using the choke.

Wow , I love a fourm with quick responces :D

I tryed all the usual tricks with the wiring with no better results
I was hoping somebody would tell me i forgot to remove a secret
shipping spacer or something. As I ended up with 2 of these things
I tried switching coils too.
What should the plug gap be anyway ?
thanks all.
yep its either the killswitch stealing your charge or if thats not it, then your going to need a new magneto, cos that redneck test should have sent you off your bike!
No kill switch so I'll have to check the mag. Does any thing like a shop manual or
specifications even exist for these things ?
I do have another engine I could throw in and try but where is the fun in that.