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Post by mopojo on Jan 22, 2014 18:01:01 GMT -5
Been hearing some banging lately while uphill @ or around WOT and stripped the ped down to inspect. There was this scale built up and I noticed a small dent in the piston face. Seems the sparkplug was making contact with the piston at times (maybe at high temp and under load?). I filed the sparkplug at black arrow and cleaned all the scaling from valves (what a B****!). Everything is back to normal, more or less. What causes this scale to build-up or is it just normal? This head has 10,000 +/- and it is the first time I actually noticed the scaling. No; about 500 miles ago I went from 50 to 63 cc and saw a slight powdering: Nothing like the caking shown in the pic. Any advice from the pros to keep cookie dough out of the combution chamber? Thanks, Mopojo   |
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Post by jjoshua20213 on Jan 22, 2014 18:29:44 GMT -5
What kind of gas are you using?
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Post by buford1488 on Jan 22, 2014 19:06:07 GMT -5
as you all know i do work on these heads everyday... this one has got to be the worst build up of carbon i ever seen....wow..thanks for sharing.........
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Post by alleyoop on Jan 22, 2014 19:11:57 GMT -5
I would be surprised if the valves are actually sealing. WOW! you need a rebuild .
Alleyoop
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Post by mopojo on Jan 22, 2014 19:24:47 GMT -5
Shell 92 octane from dedicated hose.
All is shiny and new alleyoop; had to gently *with force* scrape away the scale with my trusty Leatherman in between dousing with Seafoam. No leakage.
What can I do to retard the growth in the future? What am I doing wrong (if anything)?
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Post by jjoshua20213 on Jan 22, 2014 19:40:20 GMT -5
Seems as if your running too rich, but then again, idk
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Post by alleyoop on Jan 22, 2014 19:40:43 GMT -5
I would try 87 octane, the higher the octane the slower it burns. High Octane is for high compression motors to slow the burn. So for our small scooter motors you want it to burn faster to get a little more power.
Alleyoop
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Post by jjoshua20213 on Jan 22, 2014 19:59:23 GMT -5
Is it possible the rings didn't seat well and are causing blow by?
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Post by mopojo on Jan 22, 2014 21:19:44 GMT -5
I meant to say  octane. I'll try a lower grade. I just checked the sparkplug again and the gap had been closed considerably when the piston bounced off it. Regapped and filed to round the edges pretty good. I'll check performance tomorrow and try to readjust with proper spark (lately I have run into idle issues.... hmmmmmm).. Would a gap that is too small not burn properly and cause rich running? As for the rings; I think they seated as I have no problems with compression, torque or HP: No smoke, no stalling and no loss of oil (my vent tube runs back and down). |
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Post by jjoshua20213 on Jan 22, 2014 21:42:15 GMT -5
Essentially yes. A gap too small will produce a weak spark and not burn all the gas. But for the cud shown on your bike it would have to have been like that for awhile. I have a bike that hit the spark plug one time in its whole life. Why I still don't know but it never happen again. i put a second gasket on it to pull it further from the piston. The bike had shitty fuel economy around that time and ran rough. I wonder if it has something to do with the 64mm and 69mm valve difference. I didn't check the parts when I bought and put them on I use in everything, never had a problem. I actually notice a performance loss in my scooter when I use regular, when it was 39mm and when I upgraded to 50mm, but then again every setup is different |
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Post by mopojo on Jan 22, 2014 23:27:19 GMT -5
Thanks for all input. I always scoot away from here a winner. I really have no-one else to discuss this with (the wife thinks I am obsessed: LOLOLOLOLOL!) so I'll be back; after an early morning run in the cold....  |
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Post by mopojo on Jan 22, 2014 23:37:01 GMT -5
... But for the cud shown on your bike it would have to have been like that for awhile. Last sparkplug purchase was about a month ago: Probably 300-400 miles on it. Damn that worries me. I'll for SURE check plugs from now on. They say hind-sight is 20/20. Guess that makes me a jack-arse.  Edit: I see what you're sayin' (I think). Not a couple hundred, but a few thousand miles? |
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Post by jjoshua20213 on Jan 23, 2014 1:37:17 GMT -5
... But for the crud shown on your bike it would have to have been like that for awhile. Last sparkplug purchase was about a month ago: Probably 300-400 miles on it. Damn that worries me. I'll for SURE check plugs from now on. They say hind-sight is 20/20. Guess that makes me a jack-arse. Edit: I see what you're sayin' (I think). Not a couple hundred, but a few thousand miles? Ya, but at the same time i'm not a pro, it could happen in a couple hundred. Or it could even be a different cause. But in my experience it sounds like gas isn't fully being burned. |
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Post by alleyoop on Jan 23, 2014 15:31:21 GMT -5
There go 87 octane  Alleyoop |
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Post by mopojo on Jan 23, 2014 18:57:11 GMT -5
Well, the plug re-gap got my cold idle back (  ) and the filing of ground electrode made me feel more at ease and may lessen that PANG-ing sound uphill +/- WOT: Wont know till I go cross town tomorrow. The bike never ran this well. It use to struggle to get to 8,000 RPM when I installed 63cc. About 1,000 miles into the install it wants to creep up around 9,000 RPM as a cruising speed. I gotta keep an eye on the tach to and try to keep it between 7,500 and 8,000. @ 8,000 RPM throttle is at around half. I don't want to blow it. Also do not know if the tach is correct.  Next tank we'll try 87 octane. Guess it will take a while to see if it inhibits crack-growth on my valve stems....lol Since I am "Obsessed", maybe I will notice a change in the running or responsiveness. |
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..BAD TO THE BONE..
octane. I'll try a lower grade.