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Engine woes
Jul 20^th, 2014 at 11:31am

OK, several of you were at the field on Friday 2 weeks ago when my 50cc started giving trouble. It starts fine, runs great to 1/2 throttle then quits, quickly. Only thing I had done was replace the carb diaphram.

I cleaned the carb, paying special attention to the little itsy screen - same problem.
I replaced the fuel lines - same result
I REPLACED the carb. Exactly the same results.
I cleaned the inline filter and checked the tank filter - same results

Today I 1) replaced the ignition battery pack, even tho it tested Ok - same result
2) replaced the plug - same result
3) swapped out the entire ignition - same result

What am i missing ?????? Angry

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« Last Edit: Jul 20^th, 2014 at 11:33am by Fingers »

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dano Aerobatic Pilot The Avon Splish Splash!! Offline Forum User LastOn: Feb 25^th, 2020 Join: Jul 7^th, 2011 Posts: 429 Reputation: 0 Kingston, NS Gender: Awards: 2 Mood:	Re: Engine woes Reply #1 - Jul 20^th, 2014 at 2:25pm With cowl off check movement of throttle plate. .................. check movement of throttle arm (sometimes they slip). Check timing (28deg. BTDC) Check spacer block for cracks etc. Hope this helps
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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,095 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #2 - Jul 20^th, 2014 at 6:27pm throttle plate move to full extent...on both carbs. no cracks either reed block wouldn't timing ( no sign it's moved) affect starting as well?" engine quits hot...
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whitey Club Member Night Vapour Long Duration Champion - Moncton 2013 Fun Fly Offline I Like My Vapour LastOn: Today Join: Mar 10^th, 2011 Posts: 420 Reputation: 1 Bedford, Nova Scotia Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #3 - Jul 20^th, 2014 at 8:26pm Hey Sandy. How thick is the wall of your fuel tubing. I've seen a situation like this when the tubing is too small for the engine and when you try to give it gas, it can't get it because of the restriction. just a thought....Mike
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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,095 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #4 - Jul 20^th, 2014 at 9:43pm Same tubing I've been using for years - not same tubing but same roll. And standing behind engine while running it I can see the line - no "sucking" or air
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Yak Man

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Re: Engine woes
Reply #5 - Jul 21^st, 2014 at 5:40am

It's time to go a little deeper. Check and see if there's a stuck ring or even a broken one. That would answer a lot of questions. Do a compression test on the engine. A normal two stroke cyl should have around 90 to 100 psi. below 70 is getting low. Yours may be different. Check the liner and piston.
Also make sure all the bearing are in good shape.

Unless you missed something in the fuel delivery system or ignition system your running out of stuff to check

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« Last Edit: Jul 21^st, 2014 at 5:42am by Yak Man »

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waverider Aerobatic Pilot The Great White Flounder Offline Frozen Solid LastOn: Aug 7^th, 2020 Join: Nov 8^th, 2010 Posts: 499 Reputation: 0 Edmonton Gender: Zodiac sign: Awards: 1 Mood:	Re: Engine woes Reply #6 - Jul 21^st, 2014 at 3:58pm Fuel is bad? Had this on a. Brand new honda engine New fuel new oil Good luck
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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,095 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #7 - Jul 21^st, 2014 at 6:42pm waverider wrote on Jul 21^st, 2014 at 3:58pm: Fuel is bad? Had this on a. Brand new honda engine New fuel new oil Good luck is new fuel, new oil, thanks Brian
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stryker Trainer Box Offline Forum User LastOn: Jan 6^th, 2019 Join: Aug 5^th, 2011 Posts: 27 Reputation: 0 New Glasgow Gender: Zodiac sign: Mood:	Re: Engine woes Reply #8 - Jul 24^th, 2014 at 8:25pm Sandy, Are you running a regulator for the ignition pack? I had one that would do the exact same thing, ended up the regulator didnt do a good job with a 2 cell battery.
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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,095 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #9 - Jul 24^th, 2014 at 9:16pm yup, have a regulator and am going to change that next - haven't had a chance to this week, maybe tomorrow afternoon, thanks Paul
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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,095 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #10 - Jul 25^th, 2014 at 4:22pm not the regulator...........................
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Re: Engine woes
Reply #11 - Jul 25^th, 2014 at 4:50pm

some questions
1. when the engine dies does it sound like a lean out? or does it just stop firing? eg runs up to 1/2 throttle and then nothing just windmills???

2. i had a thermal issue causing the bad piece of electronics to stop working and the engine just quit firing. Is there any other electronics that because of VIBRATION or THERMAL that you haven't replaced???

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Brian H
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waverider Aerobatic Pilot The Great White Flounder Offline Frozen Solid LastOn: Aug 7^th, 2020 Join: Nov 8^th, 2010 Posts: 499 Reputation: 0 Edmonton Gender: Zodiac sign: Awards: 1 Mood:	Re: Engine woes Reply #12 - Jul 25^th, 2014 at 4:53pm if it was engine internals then the engine would struggle up to half power. How does it respond to a throttle slam?
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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,095 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #13 - Jul 25^th, 2014 at 5:49pm throttle slam to 1/2 is great.......anything above that dies, fast, no hesitation, doesn't matter if slam or creep..... hold just below the "quit" point, engine does seem to surge
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dano Aerobatic Pilot The Avon Splish Splash!! Offline Forum User LastOn: Feb 25^th, 2020 Join: Jul 7^th, 2011 Posts: 429 Reputation: 0 Kingston, NS Gender: Awards: 2 Mood:	Re: Engine woes Reply #14 - Jul 25^th, 2014 at 9:52pm new engine...
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waverider Aerobatic Pilot The Great White Flounder Offline Frozen Solid LastOn: Aug 7^th, 2020 Join: Nov 8^th, 2010 Posts: 499 Reputation: 0 Edmonton Gender: Zodiac sign: Awards: 1 Mood:	Re: Engine woes Reply #15 - Jul 26^th, 2014 at 12:54am Is the throttle servo closing when you command past 1/2 throttle Sod's law of servos??? OR Crankshaft sensor mag pickup has it developed a funny? OR has the optical developed a cataract? Ie a funny If it was the piston and or ring(s) you would be down on power below half throttle
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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,095 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #16 - Jul 27^th, 2014 at 12:14pm Thanks Barry, but not the Hall sensor...then by past the voltage regulator AND the optic kill switch..... still no joy
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waverider Aerobatic Pilot The Great White Flounder Offline Frozen Solid LastOn: Aug 7^th, 2020 Join: Nov 8^th, 2010 Posts: 499 Reputation: 0 Edmonton Gender: Zodiac sign: Awards: 1 Mood:	Re: Engine woes Reply #17 - Jul 29^th, 2014 at 3:02am Gaskets leaking? With time and normal vibration, the screws that seal the crankcase from air leaks loosen just a little and air gets into the engine through leaks in the crankcase gaskets.
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Fingers

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Re: Engine woes
Reply #18 - Jul 29^th, 2014 at 9:11am

waverider wrote on Jul 29^th, 2014 at 3:02am:

Gaskets leaking?

With time and normal vibration, the screws that seal the crankcase from air leaks loosen just a little and air gets into the engine through leaks in the crankcase gaskets.

to ensure there is no leakage I put small run of silicone around the gaskets, both on the original and the new carb.

To clarify, at 1/2 throttle, one step before engine quits, it does "slightly" hunt or surge - next step, stop...

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whitey Club Member Night Vapour Long Duration Champion - Moncton 2013 Fun Fly Offline I Like My Vapour LastOn: Today Join: Mar 10^th, 2011 Posts: 420 Reputation: 1 Bedford, Nova Scotia Gender: Zodiac sign: Awards: 3 Mood:	Re: Engine woes Reply #19 - Jul 29^th, 2014 at 9:19am Hi Sandy. What engine is it exactly?
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