Help!! - No spark on 48cc motor (brand new)

[Watcher05]

Thanks for the great replies!

That's right fetor56, I haven't received the CDI yet but I was very persistent and being a long weekend and all I just kept adjusting things, although the spark was very intermittent. I did take strip the spark plug cap back re-adjusted the gap on plug to .30 (is this right??) and it eventually started firing after a lot of pedaling around the back yard.

I've also adjusted needle up and down & have left it back on second notch (the way it came). Cleaned carby and placed inline petrol filter on.

As far as putting and o-ring in and trimming intake/exhaust gaskets.....no, I haven't. Didn't realise this was necessary!! As far as the exhaust manifold goes it blew itself out, so I need to replace it! Please explain about trimming gaskets (will do a search).

Also, I'm running it at 16.1 fuel mix - is this too rich? Have read that 20:1 would be fine for breakin period?

thanks so much for the replies.

NB: to moderators. I know that we’re encouraged to search the forums to get info first. Believe me, I’ve searched and searched and have picked up some great info but I suppose that there are so many variables when a bike won’t start, that it won’t just be in the one spot. So apologies if this info is being repeated.

 

[fetor56]

I use SP gap .025" or .63mm.
Here is the thread about o-ringing your carby....it's important:
http://www.motoredbikes.com/showthread.php?t=4976

With ZBOX engines the actual engines intake/exhaust ports are oval while the carby intake manifold is round and so is the exhaust manifold.
Both gaskets are round but they seal against an oval surface so u need to get a Stanley knife and gently trim them out....you'll see what i mean.
Block both ports with rag if your going to do this so u won't get any gasket material inside the engine.
I also got a dremel and made the carby intake manifold and exhaust manifold oval shaped but that's not absolutely necessary....the main thing is to trim those oversized gaskets cos they restrict fuel vapor flow to the engine and exhaust gasses flow from the engine.

 

[Scottm]

I admire you

I'd stick with manufacturer's suggested fuel ratio for your engine and NO synthetics until the rings have seated. Don't worry after a while all the kinks will be worked out and you will be infinitely wiser about your motor and your bike. It's a pain now it seems, but it's part of the whole experience. Bike and rider bonding. MBc is the best tool in the tool box.
And when people ask you can honestly say "Yeah! I built it".
I admire your stick to it attitude. Don't over complicate things.
You and Fetor will have to get togther soon and go ridin and tinker with each other's bikes.
Keep up the good work.

 

[fetor56]

I'd stick with manufacturer's suggested fuel ratio for your engine and NO synthetics until the rings have seated. Don't worry after a while all the kinks will be worked out and you will be infinitely wiser about your motor and your bike. It's a pain now it seems, but it's part of the whole experience. Bike and rider bonding. MBc is the best tool in the tool box.
And when people ask you can honestly say "Yeah! I built it".
I admire your stick to it attitude. Don't over complicate things.
You and Fetor will have to get togther soon and go ridin and tinker with each other's bikes.
Keep up the good work.

Not sure about "soon" Scott...Watcher is in Northern New South Wales(dunno exactly where) while i'm in Adelaide,South Australia.I'm guessing that's a distance of approx 1300Mls so i'll need more than a cut-lunch to drop over his place.
Who knows,perhaps one day we'll meet...perhaps one day i'll meet some of my Northern Hemisphere friends.

 

[Scottm]

Oops, I missed a few sparks in my cyclinder. I saw Australia and forgot about the NSW. That would like me riding from here to MBc central in Washington, except you'd have to cross the water.
Sorry to go OT and I appreciate the geography lesson. Perhaps and equator rally in the pacific. We could rent a cruise line and ride around the deck as if it were a board track.

 

[Dockspa1]

Definately seal your exhaust pipe. 2 strokes require a little back pressure in order to run properly. I agree that you need to back your SP gap down to a max of .025.
They really are skimpy on the copper when it comes to the pick up coil so if you can get your spark plug to a finer gap it should help. Mine runs good at about .022.
Just some thoughts.

 

[Watcher05]

Okay, I suppose I should give a bit of an update since my last post.

Yes, I did get my motor going......eventually. I'm not sure if I mentioned but when I previously had it going, I did blow the exhaust gasket. Fixed it and the next day do you think that I could get the motor going? No! :???:

Believing that it was an intermittent electrical issue (which I think the original problem was) kept trying to get the little beast started. I was all out of ideas until I thought I'd take the exhaust right off. Low and behold, I'd forgot to cut the hole out of the freakin gasket!!!!! I hope I didn't blow any other gaskets in the process but she seems to be purring along now. Not sure why on earth I didn't but just obviously forgot. Doh! That's not to mention to get it started originally did take a fair bit of effort and I think it was a dodgy spark cap. Stripped it back and had some sort of success.

I'm feeling a little bit sheepish and wasn't going to tell you guys but thought it maybe worth something for others starting out: check and recheck!

 

[fetor56]

You got it, "check and recheck!" ...and while your standing around sipping your coffee and smoking cigs recheck again.
Anyways your upwardly mobile.....GOOD.

 

[Watcher05]

Hey Fetor, sent you a message.

ta

 

[Scottm]

Confession is good for the soul. See here that you are not alone http://www.motoredbikes.com/showthread.php?t=6004
Glad it's runnin now.