Hard starting

K

kaneto

Member
I have a fully broken-in 66cc slant head kit. It used to run ok until recently. Now I have to peddle more than usual (not an awful lot but still definately faster) to get it started. It began when I put a resistor sparkplug (BPR6HS) to try to reduce the interfernce with my speedo. I had to peddle like a maniac to start it but once it warmed up I killed it and started it again without problems. I tried it again the next morning to the same result. Then I put the old plug back in and now it starts but it's still harder than it used to be before all that. Any sugestions?
 
sometimes, using resistor plug, or resistor wire, or resistor plug cap will weaken or completely kill the ignition

these things have very weak spark at cranking speed - any resistance can weaken or kill it

did you use diff wire or cap?

I'd also try a new plug just to see.
 
I didn't change anyting else on the ignition. I also tried NGK BP6HS (i didn't gaped it, because I don't have a gauge at the moment but it looked the same as stock plug ) with the same result as the chinese plug- a bit hard to start but after that it works ok. It also starts without any problems if the engine is warm.
 
these get leaner as they run in - maybe a bit of choke at cold start or check plug reading to see if carb needs to be set a bit richer
 
crassius said:
these get leaner as they run in - maybe a bit of choke at cold start or check plug reading to see if carb needs to be set a bit richer
Click to expand...
It doesn't run at all with the choke on since I first put it togheter (I tried that too when the problem began). I also tried using the primer button but it only took more time to start. I will play with the needle position when I have time but i doubt that's the reason. It always used to run too rich at idle so I think it's unlikeley that it suddenly leaned out so much.
 
try choking until it pops a few times, then start it with no choke (with practice you'll be able to push choke off while riding with heel of your shoe)
 
Try a NGK-B6HS plug gapped at .025"

Also, when you use the choke to start it, only raise the choke lever 2/3 of the way up. ;)
 
crassius said:
try choking until it pops a few times, then start it with no choke (with practice you'll be able to push choke off while riding with heel of your shoe)
Click to expand...
Most times it starts on the second try anyway (without choke). As I said it never started with the choke on (even if it's only 1/3) except in cool mornings (I never tried it in actual cold cuz I got it in the end of april and we had a pretty hot spring and summer) and even then it starts easier with no choke at all. I will try it anyway this weekend as well as properly gaped sparkplug.
If it proves to be electrical problem is it deffinately the CDI or it can be the magneto? And do you know of a good method to diagnose that?
 
if it starts OK warm, I'd not think it was electrical - more likely a tiny bit off (toward the lean side) at your idle setting when cold, which may be more trouble to fix than it is worth (just live with it) or try setting idle screw higher/lower to see (assuming you leave it at idle rather than twisting throttle when trying to start)

note that folks with single speed rear wheels will always have a hard time getting motor well up to speed when pedaling
 
It turned out to be an air leak. I had trimmed the intake gasket to match the port but it looks like the part between the opening and one of the studs was too narrow and ended up tearing, thus allowing a little bit of air to be sucked in thru the thread when the engine is cold.
Tomorrow I will make new gasket (it's getting late) and test to see if that is the only problem.
I'm wondering if I should try the BPR6HS again. It was the hardest to start with but the engine had a bit more torque in mid RPM than with the BP6HS or stock plug
 
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