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Post by Moat on Nov 23, 2013 7:29:45 GMT -6
... but I did notice his scoot was to far retarded to start off His timing was almost on the "F" when it should be on the "T". "F" stands for Fire, "T" stands for Top Dead Center. His idle ignition timing should have been on the "F", and not the "T" (which would have been waay too retarded). Bob |
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Post by Moat on Nov 23, 2013 7:24:05 GMT -6
The reality is a motor can make more power if it fires just a hair after top dead center. Umm, the reality is a motor will run like poo if it fires "just a hair after top dead center" - if you could even get it started, that is. Virtually all spark-fired engines ignite the mixture well before TDC - typically 8 to 20 degrees BTDC @ idle, and 25 to 45 degrees BTDC at speed. Actually, the majority of the fuel is already burned before the piston even reaches TDC. The reason for spark advance is that it takes time for the mixture to burn. In general, the more spark advance (degrees BTDC), the higher the peak combustion pressures produced - and therefore more torque. The limit to how far spark can be advanced is determined by detonation (not pre-ignition, which is something different) - in which case power drops off dramatically (followed shortly by molten/broken engine parts). Bob |
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Cam shaft
by: Moat - Nov 10, 2013 10:19:53 GMT -6
Post by Moat on Nov 10, 2013 10:19:53 GMT -6
but it's impossible for the engine to run if you have the cam/crank parameters set at the orientation you described. I think you may have misunderstood his post, Bashan - he basically had it timed right, but was just looking at it wrong - one turn of the crank away from lining things up correctly. |
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Cam shaft
by: Moat - Nov 10, 2013 10:11:18 GMT -6
Post by Moat on Nov 10, 2013 10:11:18 GMT -6
... but after doing it correctly this morning it is like a new bike. Goes like a dream up hills and feels so much better. Sweet!  Just a simple mistake - easy to overlook, easy to fix. |
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Cam shaft
by: Moat - Nov 10, 2013 2:59:55 GMT -6
Post by Moat on Nov 10, 2013 2:59:55 GMT -6
Burning question is why is my cam 180 degrees out but still working. The camshaft turns at half of the crankshaft speed - IOW, it takes two revolutions of the crankshaft to rotate the camshaft once. So if you had just rotated your flywheel one more turn around to the T mark (360 degrees), you'd have found the cam had rotated 180 degrees, and the "big hole" at the proper 9 o'clock instead of 3 o'clock. That's normal - you just so happened to be looking at TDC (Top Dead Center) of the exhaust stroke instead of TDC of the compression stroke, by mistake. Now... your cam timing might be spot-on, but if you set your valve clearances there (big hole at 3 o'clock instead of 9 o'clock) - then they are set wrong (very loose) and likely the reason for the "tinny" clatter you mention. Valve clearance must be set at TDC of the compression stroke only! |
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Post by Moat on May 26, 2013 5:30:39 GMT -6
Hammer and drift, from backside. Then grind a little off of the old race's OD and use it (or a socket that's ever so slightly smaller than the original race's OD) to tap/drive/seat the new race home - little by little, round and round, keeping the new race aligned in the bore as you go (critical!). You will hear/feel the sound of the "hits" change from a duller "tunk" to a sharper, solid "ring/ting" when the race is fully seated in the bore.
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Post by Moat on May 22, 2013 22:03:01 GMT -6
My mech also talked about the CDI... How do I know if it's AC?  ? ..... ...Edward from BMS Motors Part Dept said that Valve Clearance should be (00.6 - 00.8 IN-EX). From the Scooter Doc Library, here's a post about identifying CDI's - scooterdoc.proboards.com/index.cgi?board=electrical&action=display&thread=4996And like these guys already mentioned, those valve clearance specs you gave us should actually read 0.06 - 0.08 mm ( millimeter) - which would be about .0025" - .003" ( thousandths of an inch). Yes, .004" - .005" would be fine/safer for now... if maybe a little noisier. |
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Post by Moat on May 22, 2013 6:50:53 GMT -6
Hmm, I dunno... but an engine that noticeably COUGHS, then dies abruptly, would make me suspect ignition. Myself - I'd first replace the spark plug with a good NGK and inspect all of the coil/plug cap/plug wire/CDI wiring/engine-to-frame ground wire for any bad/loose connections. But heat may be exposing an intermittent failure in the CDI, HT coil, trigger coil or stator windings (if the CDI is AC).
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Post by Moat on May 6, 2013 16:11:48 GMT -6
DO NOT BE RUNNING THAT MOTOR or turning it over, until you find it +1000 to what Alleyoop said ^^ - don't even turn that thing over until you find the screw AND the nut!! |
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Post by Moat on May 5, 2013 16:07:12 GMT -6
The methanol released from spraying windshield washer fluid evaporates away in just minutes (seconds?) - what's left is relatively quickly broken down (fed apon) by microrganisms in the soil - so no harm done. My guess would be that the environmental harm just from puttin' down the road is far more significant (or turning on home lights, or turning up/down the thermostat, or buying plastic-packaged food/drink, watching TV, doing laundry, mowing the lawn, ...or running the very computer that you're here surfing on, or... etc., etc...). Methanol in washer fluid is a non-issue, IOW.
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Post by Moat on May 1, 2013 17:39:18 GMT -6
... and if the case is open to the bottom of the crank, isn't it possible it could scavenge some oil to the piston and out the exhaust side? There is an oil seal between the gearcase and crankcase. If the seal is bad, then yes - it can leak gearcase oil into the crankcase, causing an excessive amount of smoke/unburned oil out the exhaust. Normally, the level of gear oil will remain constant, as there's not many places for it to go (unlike crankcase oil in a 4-stroke) - but if a crank seal is leaking, you may see the oil level drop over time, with no other visible leaks. Has this one's oil level been dropping lately? Given the scoot's age, a bad seal is definitely a possibility. Also, the oil injection system in QT-50's have been known to allow oil to dribble into the motor when parked - not sure if it's a worn pump or bad check valve (if it even has one?) that causes that. Some folks just disconnect the pump and run pre-mix, with no problems. |
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Post by Moat on Apr 22, 2013 17:49:38 GMT -6
Yeah that was what was loose, I just replaced it. Some spark plug caps require that the threaded tip is installed - some caps require that it be removed. Which does your cap fit? |
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Post by Moat on Apr 22, 2013 17:42:58 GMT -6
I went to test the new spark plug again and just holding the spark plug wire and nothing else I get a little jolt through the wire and brake lever? The spark leaking I mentioned in an earlier post could very well be the cause of your wet-running problems. Getting a jolt like you said is an indicator that the wire's insulation is not up to snuff, and could stand being replaced. Leaks/shorts like that will only be much worse when wet. Depending on the way the wire is mounted into the coil (some are molded to the coil in one piece - others are plugged and screwed into the coil - even others have an additional threaded cap to hold the wire in place) - you might be able to replace the wire alone, or otherwise just replace the coil/wire/cap as a unit. A worthwhile test might be to spray the coil/wire/cap with water, while the scoot is running in the dark (at night) - sometimes a spark leaking/shorting will be visible and/or audible. |
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Post by Moat on Apr 22, 2013 13:48:01 GMT -6
I noticed when it was running, underneath had a air flow around the exhaust pipe coming from the motor.... that area I couldnt pin point it. Most likely that was just normal airflow from the cooling fan you felt there. |
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Post by Moat on Apr 22, 2013 6:59:18 GMT -6
Don't believe what they say that the Fuel Ratio Mixture is only for IDLE, that is Flat out wrong. I never said * only* for idle - read again. But that's besides the point. The bike was seemingly running along just fine. Then it was left out in the rain, where it immediately afterwards ran poorly and bogged at WOT, with a very black plug (too rich) as a result. Did the raindrops magically reach up inside the carburetor and adjust the idle mixture screw to be too rich? Of course not - so why are you (and others) advising necorum to rectify his problem by fiddling with the idle mixture screw? That setting is not the root cause of his (rain related) problem - it's flawed troubleshooting logic, and misleading advice - serving to confuse more than help. But yes, Alleyoop - the idle mix adjustment steps you gave in the above post are right on the money, and should get necorum's idle mixture back on track. But - just as you laid them out - those adjustment steps are for idle mixture setting... not for addressing mixture problems further up the range of throttle opening. That's where slide taper, needle jet, needle taper and clip position/shims, main jet, slide spring, etc... come into play. See my point? Adjusting the idle mixture on a 7 year old scoot that suddenly runs bad at WOT after sitting out in the rain, makes little sense.  |
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Just a simple mistake - easy to overlook, easy to fix.
? .....