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Post by drewfinn on Oct 5, 2013 22:42:51 GMT -5
2009 Motofino 150 qt2 157qmj....Out riding today after valve check,sudden and immediate loss of compression...I have the valve head off,and it looks like the valves have been contacting the piston...further scrutiny reveals that I can see light around the valves...is this normal? I am at a loss...please faithful forum followers...HELP!
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Post by Rebel on Oct 6, 2013 0:37:39 GMT -5
Seeing light around the valves when the head is off is not good. You would have no compression. You say the valves were hitting the piston. Does the piton have damage? Isitcracked or does it have a hole?
You need at least a new head I think, with new valves as well.
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Post by drewfinn on Oct 6, 2013 9:23:52 GMT -5
Thats what I was thinking...about twenty-five bucks on e-bay. I don't see any serious piston damage,just some shiny spots. Well,here I go again. If it hadnt become a mission of genuine affection for my "Slippery Slope Scoot" I'd scrap it and start over when taxes come back! Thank so much!
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Post by Rebel on Oct 6, 2013 15:28:15 GMT -5
It is not a bad job. You did make sure the timing chain didn't slip out of place?
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Post by drewfinn on Oct 6, 2013 18:49:31 GMT -5
Yeah,zip tied it in place,the idea of having to break open my crankcase didnt sit too well with me. Head with valves ordered up and ships tomorrow,hopefully Ill have it by Wednesday.Would a modified exhaust without proper jet upgrading have contributed to the valve burn out? I was running a stock exhaust with some holes punched in..."knock a couple holes in there,it'll be throaty as all hell" for a half a year before I went unifilter,120 main and raised the needle.
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Post by Rebel on Oct 7, 2013 1:04:42 GMT -5
Yup certainly could have contributed to the valve problems. You need to put a bigger jet in it.
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Post by drewfinn on Oct 9, 2013 17:55:53 GMT -5
okay,new valve head installed and viola...no compression...any good tutorial links on how to seat new valves? Im seein light around the new exhaust valve,possibly blow by caused by this?
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Post by Rebel on Oct 9, 2013 23:40:19 GMT -5
You didn't mention a new head(i hope you got a new one) just the valve. Hand lapping the valves is not difficult. Did you adjust the valve lash?
here is a youtube vid with a guy lapping the valves on a car motor, it is all the same as any other motor.
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Post by drewfinn on Oct 10, 2013 15:29:51 GMT -5
Yep,got the new head with springs and valves installed,but it doesn't appear that the time was taken to seat them in properly...my Dad tried to teach me the process thirty some years ago and I had no interest or aptitude,now I at least have interest and need!Guess its off to Harbor Freight.
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Post by drewfinn on Oct 12, 2013 15:15:29 GMT -5
Okay,literal hours of grindin away at both intake and exhaust valves...no light visible,nice fit,valves lashed .004 intake,.005 exhaust...getting the timing chain properly reset a bit tricky,but accomplished.I dont have a compression gauge but I can tell its nowhere near where it should be.Should I grab the tools and take apart the cylinder head next? The darn thing wouldnt budge when I tried...rubber mallet? Crowbar?
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Post by drewfinn on Oct 12, 2013 17:19:44 GMT -5
Hmmm...got cylinder head off...twisted freakin wreckage...cracked cylinder...wrist pin torn out of piston...total apocalypse inside...that would explain a lot...just not how....guess it's new engine time...insert heavy weary sigh and sniffle.
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Post by Rebel on Oct 12, 2013 22:26:20 GMT -5
I don't know if you need an entire motor. You could put a new crank in it an a big bore kit for less than buying a motor. New motors would cost enough to consider just getting a new scooter.
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Post by drewfinn on Oct 13, 2013 12:37:59 GMT -5
Still not sure of the possible damage inside the crankcase...the piston is literally shredded like aluminum foil,wrist pin torn right out,bits of shiny shrapnel are visible,and,I honestly don't know if I possess the ability to re-build it. I do knw that a new 150cc gy6 is around 300 bucks...either way it looks like the season is over for me til tax time,or,sudden economic windfall! If I were to buy new,what are some chinamendations...Im 6 foot and 180lbs,living in hilly terrain in upstate NY
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Post by drewfinn on Oct 14, 2013 16:36:17 GMT -5
So I worked out the costs and Im going for the 59mm bore so that Idont have to have the case bored...will my new valve head fit right to it? New tools needed:impact wrench,flywheel rotor puller,and what else? New crankshaft will be ordered from scrappy in a couple days.I'm totally new to all this so any and all advice is appreciated. Thanks!
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Post by Rebel on Oct 15, 2013 23:14:41 GMT -5
The head should fit.
Yup new crank , you need motor seals, you will have leaks of you do not replace them. Be sure to lube them with some grease. A full gasket set should have all the gaskets you need. A torque wrench would be nice so you can make the bolt and nuts tight to factory specs.
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