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Post by crf45or1991 on Apr 18, 2012 9:03:25 GMT -5
well recently iv had the crave to upgrsade my scooter and i wish i have thought otherwise. i put on a high flow exhaust,air intake,cdi,coil. The bike was running great top speed increased and it accelerated better; until yesterday when i was cruising down the street and the engine blew up!! The engine just shut down,smoke came out of the exhaust and oil was coming out of the header. So now the engine is seized! The only thing i could think of is it was deffinatly running to lean and overheated. Luckily a complete top end is just under $100 hopefully thats all that got damaged. When i put it all back together all the stock parts are going back on. these things are meant to be with what they where built with. just my 2 cents
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Post by spandi on Apr 18, 2012 9:19:50 GMT -5
Hope everything goes ok with the rebuild and your back on the road soon, but I'd wished you had told me this before I strapped on the two JET ENGINES to my scoot!
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Post by chromestarhustler on Apr 18, 2012 9:47:25 GMT -5
upgrades + not tuning it afterwards = death
the upgrades are fine, if you know what your doing.
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Post by Pony66 on Apr 18, 2012 9:53:00 GMT -5
You said it "defiantly running too lean and overheated" Fuel cools the valves and piston on contact. When running lean this cooling does not happen and boom. Running lean during break in with too tight ring gap would be quick death. One can put parts on an engine and another is meticulous with the build, setting perfect ring gaps and torquing to spec in the proper pattern. Watch some videos on building engines. Not scooter videos, notice where they file all the 90o angles. Watch how you place the ring in the cylinder, using piston, to set the gap and then deburr the edges. Wipe all parts down with lacquer thinner using paper towels, never rags. Use tons of Lucas Assembly Lube, put some in the ring grooves just before you slide the cylinder on. Be perfect in every detail and check torque specs twice. Maybe this will help. www.chinesescooterreference.com/pdf/50_150cc_gy6_shop_manual.pdf |
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Post by leroysunl on Apr 18, 2012 13:13:50 GMT -5
Here is the way I figure it: Our Chinese scoots are mass produced with certain metals/tolerances/quality control. They are made cheaply to a low price point. They are not made in a Ferrari or Porsche or Honda factory to the highest quality specs. To hot them up requires not just bolt ons but cooling, tuning, engineering to a higher level than most of us have, IF you want reliability. Changing externals doesn't improve on metals/casting in crankcase, barrel, shaft, piston etc. You can make a silk purse out of sow's ear? LF
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Post by crf45or1991 on Apr 18, 2012 14:18:52 GMT -5
Im sure if i did what i was supposed to do = jetting it, it would have been fine... but since the shop i went to doesnt like working on chinese scooters they just told be to unscrew the fuel/air ratio screw the make it run more rich... you win some you lose some.
Im wondering if im better off buying a whole engine or just replacing the top end, because i dont think id want to do any mods to make the parts fit...
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Post by skuttadawg on Apr 18, 2012 14:36:01 GMT -5
Get Taiwan engine parts and a real carburetor
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Post by skuttadawg on Apr 18, 2012 17:19:43 GMT -5
A 2T is more fun to tune and ride
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Post by orphansoul on Apr 18, 2012 19:35:08 GMT -5
You were probably running 4-6 jet sizes too small if you didn't re-jet.
Other than that, you would have been fine.
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Post by rivaling on Apr 18, 2012 19:36:04 GMT -5
I have a secret 63 and when I bought it used with replacement rings installed on it, it had not been re-jetted (still original sealed carb) I could tell it was too lean by the way it heated up, smelled hot, etc. I think I put 30 miles on it before I bought a replacement carb and 88 jet. Noticeably running cooler now. I try to limit running it at WOT still.
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Post by Blueboy5000 on Apr 19, 2012 6:04:02 GMT -5
Well if you put performance parts (or any parts really) and do not properly adjust and tune your machine, then the machine failed because of you, not because of upgrades.
If you suspect you were lean, you should not have been cruising. You should have properly adjusted and tuned your carb BEFORE you went riding.
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Post by Pony66 on Apr 19, 2012 7:48:59 GMT -5
Here is the way I figure it: Our Chinese scoots are mass produced with certain metals/tolerances/quality control. They are made cheaply to a low price point. They are not made in a Ferrari or Porsche or Honda factory to the highest quality specs. To hot them up requires not just bolt ons but cooling, tuning, engineering to a higher level than most of us have, IF you want reliability. Changing externals doesn't improve on metals/casting in crankcase, barrel, shaft, piston etc. You can make a silk purse out of sow's ear? LF Check out the Dayang factory. It is quite high tech. Its easy to assume everything from China is the same but they are quite different. My iPhone is mass produced in China and it works fine. |
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Post by crf45or1991 on Apr 22, 2012 20:43:01 GMT -5
Well I opened her up and it looks like the head is toast, the piston has a hole melted through the top, but the cylinder looks like it can make it. Since it seized it doesn't look like the small pieces of metal made it to the bottom end(hopefully). So I just ordered a head and piston with gasket set! Pretty cheap only came
Out to be around $60. Hopefully the assembly is a breeze and she fires up!
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Post by MEAN_MOTOFINO on Apr 23, 2012 1:20:50 GMT -5
I would not recommend lucas on new rings. I have always used a light coat of ATF and they seat almost immediately.
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Post by qwertydude on Apr 24, 2012 10:45:43 GMT -5
If you melted a hole in the cylinder, you got metal particles and even worse aluminum oxide in your engine. Aluminum oxide results from the burning of the aluminum. It's what sandpaper is made of. When that and metal particles gets in your engine it's darn near impossible to get out. Flush your engine really well, I'd personally would just replace the whole engine.
The parts you're going to buy will probably run almost as much as a new engine anyways. Or just replace the parts and hope a few thousand miles down the line that the engine holds up.
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Post by crf45or1991 on May 6, 2012 20:13:46 GMT -5
Well I put her together and it turns over and runs well, I havnt driven it yet. Only time will tell how long she'll last. hopefully for a long time! I don't mind the rebuilds though, as long as I have the time to do it I think it's fun : )
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