Electric start issue

[FastDoc]

This one puzzles me, and I'm good at this sort of thing. I earn an excellent living making diagnosises.

Try jumping the bike's battery to your car. No need to start the car. See whwat she does when you are positive the started is at 100% RPM and there iss plenty of energy for the spark.

Compression is possible, but these CB's don't seem to have that as a usual problem (unless a valve is too tight and not closing). Plus, I'd think it would effect the kick starter also/more.

I still say this is electrical.

Trust me. Try the jumper cables and report back.

BTW, nice diagnostic tool with the spare CDI. :idea:

[phil]

i have 2 ideas but not great ones i have seen some models that disengage the starter when the clutch is pulled=pull the clutch and starter turns but the engine is not or not as much but then the kick start wont work with the clutch either (work with me people im grasping at straws here) the better idea is really fasdocs the hooking of booster cables for checking a weak battery is correct i think it will crank when you boost it heres why: i have seen the engine turn and turn for what is reasonable to be a lot more than it should and not start you really need it to zip it. i have found this on the bikes and diesels, i have theroies on why and if intrested ill explain.

[islandboy312]

I'll try the jumper/car battery test after the compression test. I do have a brand new, fully charged battery in the bike, and the starter sounds as energetic as it ever did.

On a few occasions, I think, maybe, I've heard a high-pressure fart from the top end during start-up. I've heard the noise before on a 2-stroke single when the head gasket was weak.

I recently did a thorough valve adjustment.

A 12mm compression gauge hose is difficult to find out here in the sticks, but I found one I can borrow. Tomorrow, I'll know, and report back.

Thanks - Dan

[Weldangrind]

Originally Posted by phil

i have found this on the bikes and diesels, i have theroies on why and if intrested ill explain.

I'd like to hear your theory Phil. Let 'er rip.

[phil]

ok diesel first, they fire from the heat of compression without the speed the the first charge is heated enough to fire but by the second compression stroke the temps have cooled and so on that why you have smoke and a few hits but never cranking and ive seen one do this for 30 mins just grinding, but there again i have yet to figure why a powerstroke with bad glow plugs wont hit in hell with the blowers on :roll:
the bikes (and given time i can prove/disprove this one i just havent time i have the tools ) with the precision that we have in the electronics :? i think the pick up coil, and the windings in the stator dont produce a clean enough signal between sines for the cdi to get a clear idea of whats going on both these are the simple version because i type poorly but just if anybody wants to know im looking for the "mechanical think tank" job just building and trying stupid stuff like this and ill work long for little just cant find a sponsor for those really tuff problems like antiseize being used for cpu heatsink paste, can magnets be self motavated, how many beans does it take move a weight a mile if only obama would look at me :P

[Weldangrind]

You're an interesting guy, Phil.

I'm with you on the CDI comment. It works great in theory, but dynamics and heat throw curve balls.

Ok, antiseize heat dissipation properties aside, what do you mean by self-motivated magnets? Are you suggesting a sort of auto pole-switching that would power a motor? I think they call that perpetual motion. With apologies to Homer Simpson: in this house, we obey the laws of physics! Seriously, what do you mean by the magnet reference?

BTW, your typing isn't that bad, you just might want to insert a period now and then. :wink:

End hijack.

[phil]

the diesel and the heat im not even sure that is a theory im almost sure thats just a statement, because like my son said at 4 yrs old where theres smoke theres fire. he's eight now and i have got him a little deeper now the saying is if your going to be stupid you have to be tuff, and think with your dipstick but second came from tv and he thinks its funny :evil: I never used the p word because i know that would never be possible but i will say sometimes your going to have to prove it to before i agree that im wrong or just stupid. but i will say this if such a machine could be built, and the motion was started in order for it to work the biggest problem would be regulating speed. IF (big if) friction was over come, and that is the problem, then it would gain speed,,,,a lot,,exponentialy. and my GUESS is the problem would be control much like the first problem had by rudolf diesel
sorry second end of hijack i forget to avoid rambleing

[FastDoc]

I had another idea. :idea:

Did the starter ever work? Maybe it's wired backwards? Spinning, but the wrong way? You'd never be able to tell, and there would still be spark...

[islandboy312]

Okay - I just did the compression test on the 2 Roketas. The Good Bike, the one that starts with the electric starter, cranks @80PSI. It's Evil Twin (mine), that won't start with electric starter, cranked @130PSI. NOT what I expected to see. The Good Bike (500 miles on it) hasn't had a valve adjustment. Maybe that's why it cranks low, but it starts and runs, so that's another issue.

Same compression gauge, same test procedure, tests done within 5 minutes of each other. Test repeated 3 times on both bikes.

Based on the sound, the starters on both bikes were spinning the engines over at the same RPM, or very close.

Most Asian bikes have the starter gear engaged all the time. A one-way clutch (roller ramp) allows the starter to spin the engine, then free-wheel when the engine is running and spinning the gear the opposite direction. If the starter were running in reverse, it wouldn't spin the engine.

Good point, Doc - Yes, the electric starter on the Evil Twin worked fine for the first 1k miles or more. I haven't removed it or fiddled with it.

Reluctantly, (possible fried bike electronics) I tried the jumper cables off my car battery. The starter spun the engine at about the same speed, but still no start.

Next test is to use a timing light and see if the timing at idle is the same on both bikes. Just maybe the pickup rotor on the Evil Twin is keyed to the crank with a partially sheared key.

I'm not giving up!

BTW, I noticed on the Metric Parts HQ that both of the 200cc engines they list parts for are OHV engines - no OHC's.

[FastDoc]

I'm rarely stumped, but you've got me here. Maybe it's time for a 'lightweight conversion', pitch the starter and declare victory? :P

I'll keep thinking about this one.

I can't quite make sense out of the compression readings either, but at least you know there's no big engine problem.

[Cal25]

Can you defeat the kill circiut at the CDI? That would rule out most of the wiring and switches as a cause.

[Weldangrind]

I'm not familiar with your specific motor; is it OHC? If so, the vast difference in compression numbers make me think that the timing chain jumped.

[phil]

how about jumping to the starter turn everything on like your going to kick it take the jumper cables attatch to the frame then with the starter lead disconnected hook to the starter

[warrior91]

too much valve adjustment or out of time is my diag.
My buddy has a polaris 500 sportsman that would wheel over with the starter just fine...but not start. when he pulled the rope once it would start right up.
Now a 500 cc bike is not what you want to pull start time after time so he took it to a mech. buddy and he adjusted the valves and adjusted the timing...now with the same batt. the old polaris fires up on the electric start.
I think you might find a diff between your 2 bikes with the timing light.

[phil]

now you have to try adjusting the valves, i need a theory for that one, or make something up i always found it easier to start a hard starting machine by electric or drifting. anybody ever seen a worn out rx7 :wink: