Occasional Starting Problems

[superdan54]

Hi everyone!

I'm having some starting issues with my 2005 zx50. I'd say a good 40% of the time it starts up fine, but oftentimes it just doesn't for whatever reason (usually the problem happens after longer rides, but not always). One thing that does seem to happen pretty consistently is that after unsucessfully attempting to start 3 or 4 times, I'll hear a shot of compressed air coming out the exhaust. After this the scooter starts. Also, I'm usually able to kick start it when I have problems starting it electrically.

I thought it might be due to having a lean mixture, however I pulled the spark and it's brown, and I have a slightly rich setting on my air/fuel screw. I'm wondering now if the starting problem is electrical in nature. The reason I'm asking is that all of my problems seem to arise from a vacuum that is created when I turn the key on to engage the electrical components (starter, CDI). The same vacuum is also released when I disengage the electricity. The red kill-switch doesn't do anything, but when I turn the key off after killing the engine, I hear the same shot of compressed air out the exhaust I mentioned above.

Could the CDI be bad or something like that?

[Shaka]

Welcome Super Dan!  Whoo Hoo, another ZX50!  We need more of these around!  The Agility's are taking over!   As for your starting problem, it could be many things!  The CDI is one of them.  These scoots have notoriously bad CDI's, although I've never had trouble with mine.  Supposedly if the CDI has been de-restricted they are more prone to failure.  Has yours been de-restricted?  I had similar issues with mine and I suspected the CDI, but it actually turned out to be the voltage regulator.  It could also be the stator.  I'm not sure what the compressed air your hearing is.  Possibly un-burnt fuel/air that was pressurized but is now escaping?  If you don't have one, you need to download the service manual.  There is a link under the General Discussion board, under Links to Service Manuals.  The manual will tell you how to test the electrical components.  Your starting may also be caused by low compression.  Have you done a compression test?

[wordslinger]

                                  




                                          A50s RULE!!

[zombie]

It could be carbon clogging the exhaust/exhaust outlet on the cylinder head. As it heats up during a ride it will expand, and make it harder to start when hot. Pull the exhaust pipe off, and look inside the pipe, and cyl. to see if it is building up carbon. There is no practical way to clear the exhaust pipe except to replace it. This is all based on you having the factory pipe. Inexpensive 2t oil will leave alot of carbon behind. If you have 1/8th" or more in the pipe end you can bet the rest is worse. Also Put in a NEW spark plug. That ALWAYS helps. Let us know what you find, and we are all happy to help you!  Welcome to the forum!

[wordslinger]

...oh yeah, and welcome to the forum superdan!!!


peace

[superdan54]

Wow looks like I came to the right place  .

A little side info that may help as well. I bought this beauty last year and it only had 70 miles on it! Problem was it had been garaged for 3 years and I had to replace the petcock, carb & battery to get it running. I also derestricted the CDI and replaced the boss drive. Later on last year I put an aftermarket variator on it. It runs great & up to 50 mph and now my only problem is this frequent starting problem.

I have downloaded the manual before, I actually compiled it all into one PDF if you would like it instead of having one for each chapter. Since the problem is that the "starter motor rotates but engine doesn't start", there's only 4 suggestions given: 1. faulty starter pinion 2. starter motor rotates reversely 3. faulty starter clutch 4. weak battery. Of course it could probably be something else but I thought I'd at least work through these first . Off the bat I think I can eliminate battery and the starter motor rotating reversely. So that leaves me w/ the starter pinion & clutch. What's the difference b/w the two? Aren't they the same thing? Or are they referring to the auto-bystarter as a clutch?

[superdan54]

thanks again for the help & the greeting! I think I'll try the simple things first like replacing the spark plug. I'm not incredibly handy or knowledgable, so things like compression tests and replacing the exhaust are a little intimidating . Having a scooter though has been a GREAT introduction to all of it though.

edit: One thing I might add, the starting problem happens both when it's been sitting for hours, and just after a ride, so I'm not sure that it would be due to the carbon expanding, however it is a novel idea I would have never thought of  .

[wordslinger]

...the starter pinion is inside the cvt cover...

..it's a mechanical, spring returned device that extends onto the flywheel's teeth when the starter motor turns...


..if you can kickstart your scoot, then there's always the possibility that the pinion is not extending....

..however, if the engine turns over, then the pinion is extending...

..removing the flywheel is required to gain access to the pinion...

[Shaka]

When it won't start with the starter, will it start with the kick start?  Definitely try a new plug if you haven't already.  Next easy thing to check/test is the voltage regulator/rectifier.  The "good" values are in the service manual.  It is under the front fairing.  Next time it won't start I'd pull the spark plug and check to see if it is sparking also.

[sidthesloth]

Yesss, another ZX50, keep em coming, Sorry I can't help with your problem, but welcome to the forum, plenty of people here only too happy to help. I did have starting problems with mine but I think that was low compression.

[zombie]

" One thing I might add, the starting problem happens both when it's been sitting for hours, and just after a ride, so I'm not sure that it would be due to the carbon expanding, " The expansion is a worst case scenario. My focus is on the expelling gases you here. There are loads of possibilities so one step at a time, and it will be running fine.

[wordslinger]

The same vacuum is also released when I disengage the electricity. The red kill-switch doesn't do anything, but when I turn the key off after killing the engine, I hear the same shot of compressed air out the exhaust I mentioned above.


..i think that's the key to figuring this problem out...


...not that i know what th' f*ck causes it, but it's gotta be a clue....

[zombie]

It could be carbon clogging the exhaust/exhaust outlet on the cylinder head.

[superdan54]

Well it's been somewhat cold & rainy rainy & and I've been crazy busy so I didn't have time until today to tinker with it. However, I may have solved the starting issue. The spark plug gap was at least twice as wide as the 0.6mm specified in the manual. That coupled with a possible weak spark could have caused the problems. After changing the spark plug out it fired up right away! However, I didn't have time to take it on a long ride or anything, but hopefully I'll be able to do that and see if that fixes everything. Thanks again for all the help!

[zombie]

90% of the time that will get you right. (new plug) I wonder what the other symptoms were?