starting issue, electrical or fuel delivery... By rockville9 (Read 1,662 times)

[rockville9]

last night I unscrewed this piece (the electric choke) and started up the scoot.  the little needle extended as the engine warmed up, but i'm really not satisfied with the results of my efforts.

I feel like i've gone through major repairs, and still have the cold-start problem.

the only way i could get the engine started yesterday was to crank the starter like, 10 times, while holding the throttle "full-open".  

this is pretty much the same problem i had before i did any work, and it feels like i went through the whole process and didn't fix anything, other than re-threading the exhaust manifold to 8mm for a stronger, tighter fit.

i've replaced...the starter, carb, CDI, ignition coil, starter button, tuned the carb air/fuel mix, checked for solid "ground" connections, and even used a grinder to make sure that metal touched metal (and not paint or grime).

what's up with the cold starts?  I live in Chicago, so this is going to continue to be an issue for me, and only get worse as the morning temps start to go down...

[alleyoop]

SO with the ENRICHER out and your thumb over the hole it still had a hard time starting I gather from your post.

Ok, now when you say it cranks and cranks IN THOSE CRANKS does it fire but not start or nothing just cranks?
If nothing then take the plug out and see if it is wet or dry.
If dry then we will know when cold it is not getting fuel sucked in. If wet then for some reason the plug is not firing or a very weak spark.
Alleyoop

[rockville9]

I feel like we may be getting close...

Yes, I put my thumb over the hole. Had hard time starting. What did we do by taking the "enricher" out (just wondering...)? My finger had some gas on it...

When I cranked & cranked, yes, there were tiny, little "putt-putts", acting like it just didn't want to fire or something...

When I ran the "spark" test, from one of my last posts, when I kept saying "no spark", I may have been mistaken. I had my wife help me here a bit, but she held the loose spark plug next to my ear (risky business, I think, but at least we know I can trust her...). Now, during this time, I heard a tiny, tiny, TINY "click", even though we couldn't see anything.

I guess the times before, since I just had the plug sort of dangling, I couldn't hear the clicks.

Anyway, I will definitely try again tonight, and quickly pull the plug and let you know. But based on the "tiny click, spark" from above, what could cause the "weak spark"? We have a new coil & CDI?

You're doing a terrific job helping out here. You're getting close to being added to the will...

[alleyoop]

The way to check for spark is pull it out of the motor OR if you have a spare plug stick it in the BOOT CAP and HOLD the spark plug on the VALVE COVER or MOTOR(NOT THE FRAME) and crank it. You should see the spark plug firing nice BLUE SPARKS.

What you where doing holding your thumb over the hole is acting like the ENRICHER FEEDING EXTRA FUEL to the motor that is why you had some fuel on your thumb.
How to check for SPARK and COMPRESSION while you have the PLUG OUT.
Also when was the last time you adjusted the VALVES, since it is a 50cc adjust them both to .003 inchs.
Alleyoop

[rockville9]

Well, I think the problem is solved. I NEVER, not in a million years, would have thought that the valve clearance would have made a difference upon starting. But, I broke the whole thing down again tonight, found out that the cam was also one tooth off from TDC. So I re-adjusted the timing chain, got the feeler gauge and adjusted the valves to both .004.

It started right up on the very 1st push of the ignition. I didn't get a chance to cold start again after it cooled, down, but I'll do that tomorrow. I adjusted the idle again once the engine warmed up, and I'll re-do the fuel mix tomorrow also.

So a hearty thanks. I'm pretty sure i got the engine just about tuned and my starting issues are behind me. Time to RIDE!!!

[alleyoop]

FANTASTIC!! Glad your a happy camper.
Ride safe
Alleyoop

[rockville9]

awful news. got the scoot started & went for a test ride. after about 10 min, it conked out. it would only idle. easing back on the throttle killed the engine. i let it sit for about an hour to cool down, but had a real hard time getting it back running. i had to push it over to a parking lot where it is right now.

it felt like it was ever so slightly bogging down as i throttled up, almost like it wasn't "giving all it had". however, i was still able to achieve the same top speeds as i had in the past, but i felt like i didn't accelerate as quickly. I was on my way home when it died...

i had the engine going while i was working on it in the alley at my house, i had it running at full throttle, just fine. i did the "vroom" test. strong all the way through. i thought everything was fine. the only things i did between the last time i had the engine running at full throttle was adjust the valves, ease back on the idle & replace the plastic body work...

after walking home to get my tools, i gave a quick effort to adjust the fuel mix, but to no avail.

WTF happened?

i hope this made sense. i had a hard time collecting my thoughts and getting as much info out as possible...also, when i replaced the seat, the seat-lock mechanism won't un-latch the seat. i'm probably the biggest fuck up to ever try to work on a scoot...

[alleyoop]

Since this happened AFTER you adjusted the valves, I question if you adjusted them correctly and when the PISTON was at TOP DEAD CENTER.
So right now Take the plug out and stick your finger in the hole and hold it nice and snug HOLD THE THROTTLE wide open and crank it over. If it has good compression it should LIFT the finger off the hole If not then you may have a bad valve or broken rings.
Alleyoop

[rockville9]

Well i went over to the parking lot last night, confident the scoot would start up, and IT DID (on the 1st try, i might add...). I was able to ride home, but stayed way off the throttle. it felt like it was bogging down through mid to lower RPM, but i don't have a tachometer, so i don't know what RPM we're talking about...

got home and did the "vroom" test. it was really lagging on the initial pull of the throttle, but once it past that and had the carb on full open, it fired pretty well (no back-firing either, that used to be a bad problem). on my failed test ride, i was riding full throttle for about 1/4 mile, slowed to make a turn, and while turning, it died.

when i adjusted the valves to .004 the other day (before the test ride), i also popped the camshaft back 1 tooth, as it looked like the two small holes weren't quite lined up with the cylinder head. is it possible that the cam was in the correct position before the valve adjustment? i'll probably have to post a couple of pictures for you to see where my marks and setting are...

i'm thinking there still could be a fuel/air mix issue.

also, i've got the same gas in the tank as when spring first hit, so the fuel in the tank is like, 10wks old.

[alleyoop]

Yes take a couple of pictures, 1. Rotate the motor so that the CAM SPROCKET two little holes are LINED UP with the TOP of the head LIKE IN PIC #1, THEN take a picture of the CASE POINTER and the FLYWHEEL so I can see if the timing is right or you are off on the CHAIN by 1 or 2 teeth.
Alleyoop

PIC #1:

[rockville9]

These are pictures from before I set the valve clearance.  This is also the timing setting before I replaced the cylinder head, since this one has the emissions notch, and the new head I ordered was non-emissions.


Anyway, this setting looked 1 tooth off to me, so I rotated it 1 click clockwise, when looking at it down the camshaft.

I've gotten it started everytime for the past week.  It's never died like it did, but I have gone very easy on the throttle.  I get no back-fires, it doesn't die when I stop, and the only issue i have right now is it seems very sluggish in the mid-rpms.

basically, it seems to work better than before in some areas, and worse in others.  weird.

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[alleyoop]

Well the cam timing on the first pic looks right on BUT when it is like that WHERE does the case pointer point to on the FLYWHEEL is the QUESTION. Just having the came aligned does not mean that you are NOT off on the timing if you took off the chain. So align it like in picture #1 and then take a picture of the Case Pointer and Flywheel timing marks.
Alleyoop

[rockville9]

I forgot to take a pic of the flywheel. Taking all the plastic off is such a pain in butt.

I rode the scoot a bit further today than I had since I put it back together. I'm sure there is something minor holding back the accel. I'll have to find the time to get it apart and take pics of where we're at on this.

Today, it ran nice. Pretty crummy accel, but otherwise fine.

Quiet too. Which is a big change from before. I'll have some pics of the engine in about a week.

Thanks for your help.

[alleyoop]

Hey if your happy with it ride on.

[rockville9]

So i was pretty much going to try to get through the winter, but as i was riding yesterday, i saw some oil spots on the foot deck. I didn't think too much of it, i just thought i was water or something splashing up through the plastic piece in the center just under the seat (i haven't replaced that yet...) but when i stopped, i looked down in there, and saw a lot of moisture around the carb. even more alarming was the moisture on the concrete after i left the scoot over night.



what could this be? do i need to tighten some fuel lines? could this be causing the lack of accel?

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