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Post by hkelman on Aug 2, 2009 20:29:57 GMT -5
I have a 150cc with 1100 kilometers purchased new last November. It has begun to die after getting warmed up - about 2 miles of road speed riding. engine has knock sound before dying. After about 5 minutes it will start and run ok until hot again. Replaced the spark plug, adjusted valves, adjusted mixture screw. Mix screw did not have much effect at all. Spark plug appearance indicates it to be running too lean and overheating. This issue happened one time shortly after buying the scooter but not again until recently. Began again the week after I did an oil change (don't know if any relation there.) Any ideas? Anyone run into this problem?
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Post by flfrmn540 on Aug 2, 2009 22:18:27 GMT -5
I had the same problem. I was lost. Had no idea what was causing this problem. I asked a scooter mechanic. He told me to replace my stock intake manifold. He advised that the stock intakes can develop cracks over just a short time causing the scooter to conk out.
I replaced with a new aluminum intake and haven't had a problem since.. Hope this helps..
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Post by hkelman on Aug 3, 2009 17:10:51 GMT -5
I'll suggest this to my mechanic but he already used ether to check for intake leaks with no effect. The engine should have increased rpms when the ether hit the leak area.
Still open for suggestions.
Thanks.
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Post by performancescoot on Aug 3, 2009 20:58:50 GMT -5
It's the coil. I've had a few bikes this happened to.
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Post by ootscoot on Aug 4, 2009 9:28:52 GMT -5
you may want to check the pick-up coil in the magneto/stator. this little pick-up sometimes goes out when hot - can be replaced without removing the magneto, just two screws, when looking at the magneto, it's at the 10 o'clock position.
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Post by snakebit on Aug 4, 2009 13:08:25 GMT -5
Spark plug showing lean condition, knocking sound, sounds like possible
pre- ignition. Did this start after refilling gas tank? Possible low grade fuel.
Possible advanced ignition timing, defective pick-up and or cdi box. Check
timing advance with strobe light.
Snakebit
Jerry
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Post by snakebit on Aug 4, 2009 15:03:24 GMT -5
Forgot something, you just changed oil. Are you sure you put the right
amount back in? What grade did you use? Is it possible you messed up
and put gear oil in engine.
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Post by hkelman on Aug 4, 2009 15:50:33 GMT -5
Thanks to flfrmn540, ootscoto and snakebit for the hints. Already tried: Replaced jets (1.03) with larger ones (1.10 and then 1.12); Replaced cdi with regular new one then high performance; Replaced stator and pickup; Adjusted valves; removed head and inspected valves and cylinder; Checked intake and engne for air leaks; Checked all fuel lines and tank for restrictions; checked wiring. Next the mechanic is replacing the whole carb in case the body passages are clogged. Still runs too lean and overheats then dies. We are stumped! Wildfore Motors no help at all! Still trying! Oil 5W50 per manufacturer - proper amount used.
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Post by snakebit on Aug 4, 2009 21:20:54 GMT -5
Checking for air leaks with ether or other combustibles works pretty well
at low RPM , not so good at higher RPM. Checking a bike sitting in a shop
is one thing, but one working under a load, road vibration, frame flex and
other variables is a different story. Don’t totally dismiss the possibility of
air leaks based solely on the ether test.
How about the oil pump? Does anybody know how to hook up an oil pressure
gage to one of things scoots and what the readings should be.
How about the belt drive? Could it have a problem that might be putting extra
load on engine.
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Post by slowscootin07 on Aug 5, 2009 16:07:29 GMT -5
If you're running way too lean, you'll cook you piston. Lean engines run a lot hotter and the knock knock you hear before it dies may be a severely overheating motor that is one step from seizing up on you. a few miles until it does it is not good and it sounds more like an oil passage or air cooling blockage to over heat it that fast. First thing I would do is to re re recheck all vacuum/manifold areas and get a bigger jet in there for sure. another thing to mention/ask that is it a knock knock knock sound or just a single knock.
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Post by hkelman on Aug 5, 2009 20:53:49 GMT -5
Another day and more tries. Tried a whole new carb in case the tiny passages were blocked within the body. Checked all the electrical ground and hot wires with an idea it could be a weak spark. Next resort is to take the engine apart and visually inspect the rings and pistons beyond what can be seen with just the head off. My mechanic has consulted with other excellent mechanics in this area and they have no idea at this point. We will try any and all of your suggestions so keep them coming and thank you.
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Post by gary2gs on Aug 5, 2009 21:51:08 GMT -5
When the carb. was replaced, did that include a new fuel enrichment valve? If not, could it be staying open when the engine is hot?
Gary S.
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Post by hkelman on Aug 6, 2009 16:59:56 GMT -5
Thanks gary2GS. I do not know if the valve was tried but I will ask. Another development, both head lamp bulbs have blown sometime during this ordeal. Cound electrical issues be causing the whole trouble? (Or just cheap bulbs that cannot take the on/off and low voltage whe engine dies?)
"Experts" still stumped. I am thinking of telling them to try replacing the whole head assembly. The knock, knock, knock seems to be from the head.
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Post by gary2gs on Aug 6, 2009 17:44:48 GMT -5
I sure an electrical problem could cause everything, but I won't have any idea where to begin. Especially trying to troubleshoot over a forum.
I would replace the bulbs with well made ones and hope they're not related to the other problem.
Gary S.
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Post by jimh on Aug 6, 2009 19:40:07 GMT -5
Could a bad oil pump cause these problems?
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Post by brahdahood on Aug 8, 2009 1:21:08 GMT -5
if your running Lean most likely your engine is overheating. I have the same problem and I re-jetted to a higher main 130 but to high so I went with 115 and its running better but I wanna try a 125-128. I'm thinking that solved my problem, i've been riding all day but it was in the 70's today. I will know for sure when it gets really hot and Humid.
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Post by brahdahood on Aug 11, 2009 1:19:21 GMT -5
Found my problem, it was the vacuum hose connected to my intake manifold. The hose did not have a ring clip on it so when it got hot the hose expanded and created a vacuum leak which could not pump any fuel to my carb. Once I secured the hose and put on a ring clip my issue was resolved. The simplest thing is always the difficult...
ALOHA!
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Post by gary2gs on Aug 11, 2009 1:52:57 GMT -5
Good Deal. A lesson for all of us to replace those rubber hoses and clamps with better quality parts.
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Post by rocketdog on Aug 11, 2009 3:30:13 GMT -5
How about the vacuum fuel valve. I replaced mine with a manual one soon after I purchased my scooter, but I understand the stock ones don't last long. As I understand it they can go bad and starve you for fuel at speed. So it could be working ok at idle and making your scooter run lean in the upper rpm range. Also I didn't see where you replaced the the stock fuel filter. You might try that first. Go pick up one for a lawn mower engine.
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Post by hkelman on Aug 24, 2009 19:26:24 GMT -5
Thank you all for the suggestions. Have checked all but the Auto Enrichment Valve. I am going to try it next. I got tired of paying the mechanic and so have the scooter in my garage and working on it a little at a time. Found out hte carb was not really replaced but just cleaned and visually checked. I have a new carb to try but I am leaning away from the carb to electrical problem.
Latest developments - we discovered that the problem is taking less time to appear. We made sure the motor started properly then left the key on, engine off, for a short time, then when we tried to start it it was running bad. After I got the bike home, I examined all the wiring thinking it may be a wiring problem. I tried the test again after correcting some questionable connections. Same results. I checked the wiring for hot temperature and noted that the Auto Enrighment Valve (why dont the just call it the choke?) was very hot. This is where I had to stop because my spouse wanted me for dinner. All comments and suggestions are being investigated. Thank you all.
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Post by gary2gs on Aug 24, 2009 20:27:29 GMT -5
You say all suggestions; well get rid of the spouse and eat out. It's cheaper. KIDDING!! Actually a divorce will empty a bank account in a heartbeat. Trust me, I know 2 well.
It's called an enrichment valve because it allows in more fuel when cold. It does not choke off the air as an older car would do.
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Post by gary2gs on Aug 24, 2009 21:44:07 GMT -5
I was thinking about this. While the scooter is cold and running well, try heating up individual parts like the CDI, coil, connectors etc. with a heat gun or hair dryer. See if you can duplicate the problem. Then see if cooling a part with freon spray or some type of cold air heals the problem.
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Post by hkelman on Aug 25, 2009 12:17:03 GMT -5
To gary2gs:
Sounds like the auto enricher acts like the cold start injector in a car fuel injection system. Makes sense. What happens when it stays open and continues to allow too much fuel? Can it stick too far closed and cut off the fuel too much?
Great suggestions! At least the second ones about using a hair dyyer and cold air to test components. The air from canned air used to blow computer parts clean should get cold enough. About the wife - if she were not present I would have a real motorcycle by now, but miss alot of other good things in life. Though tempting at times I think I'll ignore that suggestion.
QUESTION: Should the Auto Enricher get hot to touch? This seems to me to indicate an electrical problem in the valve controler. I have not had the chance to follow up on my thoughts yet.
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Post by gary2gs on Aug 25, 2009 12:56:41 GMT -5
One step at a time.
1. If the fuel enrich. valve stays open you will run rich.
2. When hot, it seals a port in the carb. I don't think it can close to far unless it it jams itself and sticks in the carb. port. If that happen the scoot would be hard to start and hard to keep running until the engine warmed up. Much like a choke stuck open.
3. It may get hot to the touch. Not really sure. I think there's a wax like fluid in there that expands when hot forcing a needle type valve into the carb. port, so it must get some what hot.
4. If you use the heat test, don't forget to test the voltage reg. which is really a high wattage diode and can break down electrically with excessive heat.
5. Remember, this is not a fool proof test. A hair dryer may or may not get hot enough.
Keep us posted,
Gary S.
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Post by hkelman on Aug 25, 2009 19:19:56 GMT -5
Cannot do the heat test any more. The problem is now happening within a short time of starting the engine. Interresting today I unpluged the auto enrich valve and had trouble from first start. Pluged the wires back together and started fine - ran about 2 minutes. Tried to cool with compressed air but no results. Tried compressed air to cool voltage reg and no results. Only need to have key on, engine off, about 1 minute to cause problem when starting now. I'll know immediately if I locate the problem now. Will check auto enrich valve with meter and 12 volt first, then replace carb next. Wife does not want me to try and upgrade her 50cc at all. She fears I'll do something to get it running bad.
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Post by gary2gs on Aug 25, 2009 21:56:05 GMT -5
Well, I can understand where your wife is coming from. Just take out the exhaust and variator restrictions and call it a day. Leave everything else alone.
If the engine is cold (sat overnight) and just turning the ignition on for a minute or so (engine not running) causes the problem, it sure sounds like an electrical component problem. Which ones get voltage? Guess it depends on how yours' is wired. CDI, coil, regulator, pick-up coil, is there a temperature shut down switch, the fuel enrich. valve probably will heat up. Don't forget the connectors that may have some corrosion and build up a resistance with heat. I guess you could check all of these by touch. Maybe cool a hot one with cold air. See if anything changes.
What you said about the fuel enrich valve is screwy. I guess it could be stuck, not seating correctly or some other malfunction. Seems like a good idea to pull it out and test it with 12Vdc. and go from there.
I've reread this thread again. Two questions. Whatever happened with the light bulbs? Do you still have the original carb. jets?
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Post by harrywr2 on Aug 26, 2009 8:43:19 GMT -5
CDI's tend to suffer heat related failure before they finally fail. Strap a bag of ice to the CDI...problem goes away you found your problem
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Post by gary2gs on Aug 26, 2009 10:41:16 GMT -5
CDI's tend to suffer heat related failure before they finally fail. Strap a bag of ice to the CDI...problem goes away you found your problem I like it! I guess any CDI would have voltage applied when the ignition is on even if the engine is not running. Gary S. |
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Post by harrywr2 on Aug 26, 2009 11:06:17 GMT -5
CDI's tend to suffer heat related failure before they finally fail. Strap a bag of ice to the CDI...problem goes away you found your problem I like it! I guess any CDI would have voltage applied when the ignition is on even if the engine is not running. Gary S. There is electonics in the CDI... micro fractures in the circuitry tend to get worse with every heat/cool cycle. In the early days of computers(maybe they still do it) quality manufacturers 'burned in' computers before shipping them to weed out most of the micro fractures. Still had tons of 'heat related' failures. I seriously doubt Chinese CDI makers put the CDI in an oven at 250 degrees and run them for 24 hours prior to shipping them. |
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Post by gary2gs on Aug 26, 2009 11:48:45 GMT -5
I'm hate going of on a tangent, but I will this once.
Sounds like you've done some environmental thermal shock testing?
Gary S.
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