So..... I was stupid and pinched the throttle cable putting the tank on. When I started the bike and it redlined. (scared the **** out of me and obviously p****d off the neighbors)  It was at night and I thought I was pushing the kill switch, but I was actually pushing the flange on the light switch.  I heard a screech, bike died.  When I tried to start it, it was obvious I had no compression (removing the head confirmed I melted a ring into the piston).  Parts on the way.  But, before I tore it apart I noticed a distinct ticking sound coming from what sounded like the headlight area when kicking to confirm the compression with a gage.  Sounds somewhat like when a spark arches.  The bike is new to me (hence trying to find the kill switch in the wrong place) and I had just put the headlight and computer back on the bike (that was in a box with tons of other parts).  Reading through all the posts here, I'm hoping I didn't fry the CDI, but it really sounded like the clicking was at the headlight or the little computer gage. 

Any ideas?  As soon as the piston set comes in I can do some more testing, but really anxious to get the bike running (first Trials bike!)  and may need to locate additional parts.

Thanks in advance.

There is a rectifier or regulator behind the head stock under the tank for the fan... these are known to fry at times ... ticking could have been this unit cooking. If you find it  and it’s bulging at the sides it’s bust!

26 minutes ago, thall1 said:

There is a rectifier or regulator behind the head stock under the tank for the fan... these are known to fry at times ... ticking could have been this unit cooking. If you find it  and it’s bulging at the sides it’s bust!

Thanks for quick reply. Found that, and not that I profess to have any electrical expertise, but it's not bulging and I stuck an ohm meter on it and it appears to be amongst the living. Interesting that the ticking was only when kicking the bike over and I never heard it before when starting the bike prior to my meltdown.....

Well you can use an ohmmeter, so you should be able to check the wiring for the headlight and other components for short circuiting. disconnect the light and see if you can still hear clicking. Make sure there is no live loose connector(s) touching an earth point. Sort the throttle and hope that the cylinder is not badly scored. ?

1 hour ago, section swept said:

Well you can use an ohmmeter, so you should be able to check the wiring for the headlight and other components for short circuiting. disconnect the light and see if you can still hear clicking. Make sure there is no live loose connector(s) touching an earth point. Sort the throttle and hope that the cylinder is not badly scored. ?

Thanks, a little scotch brite and the cylinder looks great. I can still see hone marks.  I've owned a number of two strokes before and never seen one so clean on the inside.  Either the owner previous (previous to the guy I bought it from who said he hardly rode it) had recently redone the top end, or this is an extremely low milage bike for it's age.  The existing piston was marked "A" on top.  Does that indicate a replaced piston?

Just got a call my parts came in today.  I'll be putting it back together this week end and see if I can isolate the ticking.

Thanks all!

Ron

The A refers to the size of the piston. They are grouped into size bands and matched to a bore. you need to make sure you put an A back in or you will almost certainly end up with a loose or tight piston

Since you asked for ideas , any chance the fan is stuck "on" and you're hearing that?  It's unusual for a low-power electrical component to make noise. I could believe that an electro-mechanical device (say, a relay or a fan) could make a "clicking" noise. There's likely a thermostat in the radiator, but that's an electro-mechanical transducer; I don't know if it could be energized to produce a sound, but it may be possible if things are really bolloxed.

So, I feel silly.  I got the bike back together and kicked it over slowly with the plug out to identify the clicking sound.  Turns out the horn button was stuck on.  Not enough electricity to make it sound like a horn, but enough to eminate the clicking sound.

I do have another question.  Putting the airbox back on I can't seem to slide it all the way on the carb, and I can't recall what it looked like prior to removing it.  does this look right? it's like it's not long enough to slide all the way on.  Any tips? 

Huh? Your trials bike has a horn? Well that's a new one for me.

As for the shortened air box boot; yes, it can be an issue, but the solution is relatively simple to realize.

Loosen all the band clamps and position the carburetor out of the way. Then use a heat source (like a heat gun or a hair drier) to heat the air box boot until it becomes  soft and pliable. Heat evenly. Then push the carb fully into the boot and secure with the clamp. Then push the carb into the reed cage and secure with a clamp; the boot will stretch. Finally let the assembly cool and your boot should now retain its elongated state.

You definitely want to maximize the reed/carb/boot engagement to minimize the chance of dirt getting in via those connections. 

Edited February 24, 20206 yr by d2w

Hi ron, looking at your photo.. shouldn't your band clamp be on the rubber flange closer to the carb?... on left side of the pull tab.

10 hours ago, d2w said:

Huh? Your trials bike has a horn? Well that's a new one for me.

As for the shortened air box boot; yes, it can be an issue, but the solution is relatively simple to realize.

Loosen all the band clamps and position the carburetor out of the way. Then use a heat source (like a heat gun or a hair drier) to heat the air box boot until it becomes  soft and pliable. Heat evenly. Then push the carb fully into the boot and secure with the clamp. Then push the carb into the reed cage and secure with a clamp; the boot will stretch. Finally let the assembly cool and your boot should now retain its elongated state.

You definitely want to maximize the reed/carb/boot engagement to minimize the change of dirt getting in via those connections. 

Yep, a horn. The bike came with a bunch of OEM street legal stuff in a box and just for ****s and giggles, I'm putting it on. Ordered a plate for it too.  Not sure I'll actually get it though.  I've got a little condo in the Mountains with a 2 mile street ride to the trails and I'm more lazy than smart............

Hey, thanks.  Your suggestion worked like a charm!