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Post by dragono on Jan 4, 2014 21:56:23 GMT -5
So first Thank you dawgs. You all have helped me more than you know if I could send little thank you notes I would. Anywho got this scooter a few days ago and typical story "it doesnt run". So I got the thing to run and it does pretty good for a scooter with 6000 miles on it. In any case if I run it for a few minutes then turn it off most times it will electric start just fine. However after letting it sit it won't start, it'll just kick over till next year and I have to start a ton of starter fluid into the carb to get it to stumble bumble then finally start. So I replaced the carb thinking it was just gummed up and old. But it still does the exact same thing. I compression tested it and i'm only reading 60psi. (I do sometime question the compression tester i have) So in the morning I will drain all the gas , re-adjust the valves, and clean out the old gas from the carb and see if that is the issue. I don't know how long its been sitting. I'm open to all suggestions because im new to the 150cc world of scooters.
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Post by carasdad on Jan 4, 2014 22:15:32 GMT -5
With that mileage...does sound like it needs a valve adjustment..A tight valve would cause compression loss..I would try that first even before fiddling with the carb. I have a plan of action I always use.. ONE THING at a time then test run it. Reason is because..I know if it gets worse the last thing and only thing I did..was what made it worse. If i do 4-5 adjustments at once and it runs bad...it's anybodies guess what caused it..and it takes time to figure out what went wrong..  When you think about it..a compression loss always equals a vacuum loss on a normally aspirated engine. Therefore it can't suck fuel in for a good start...and ya end up using starting fluid to get 'er to 'pop' Set your valve lash first..then come back and tell us how good she is running..  |
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Post by dragono on Jan 4, 2014 22:26:26 GMT -5
I adjusted my valves last night to .003 for both intake and exhaust. However that was at night so the job may have been done poorly to say the least. I will re adjust them in the morning using .004 intake and .005 exhaust as I'm seeing that most folks seem to use that setup.
Will Report the the "morn".
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Post by carasdad on Jan 4, 2014 22:45:25 GMT -5
I adjusted my valves last night to .003 for both intake and exhaust. However that was at night so the job may have been done poorly to say the least. I will re adjust them in the morning using .004 intake and .005 exhaust as I'm seeing that most folks seem to use that setup. Will Report the the "morn". Great..so if that does not raise compression..we know the opposite of compression in an engine is vacuum..therefore it is not getting fuel/air flow. So rings may be be worn. An intake leak would cause poor fuel/air suction but will not affect your compression...only the vacuum. Piston/rings and a leaky valve will cause both compression and vacuum issues. Since you had to adjust in the dark and plan to recheck them tomorrow..please do keep us informed about what ya find.. Glenn |
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Post by dragono on Jan 5, 2014 11:29:09 GMT -5
Ok so the Exhaust valve was tight when I went to re adjust them. However this did not fix the issue as it still wont crank up unless I guess it starter fluid. If I spray some right down the intake and it sputtured right up could I rule out low compression? In any case im going to change out the gas. Couldn't hurt. Will report back again soon.
Follow up:
Flushed out the tank put fresh gas into the tank and cleaned the carb and the fuel lines with no luck. I still must spray starter fluid into the carb to get it to start.
Also how do these 150cc get extra gas at first. I know on the 50cc carbs there is a little pipet that sticks up and squirts extra gas into the carb if you pull all the way on the throttle. I noticed that the original one I have does have one and the new carb I purchased doesn't have one.
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Post by urbanmadness on Jan 5, 2014 13:19:10 GMT -5
Ok, don't worry about the carb for the moment. If the valve lash is correct, and you still have 60psi compression, (it should be over 100 psi) then it's time to do a top end rebuild. You either have a bad valve, or the rings are toast. In any event, it can be rebuilt for under a 100 bucks including the head, if you stay stock and do it yourself. These are great engines to do your first rebuild on, because they are simple and if you follow directions, very hard to mess up... Watch a few youtube vids on how to do it. Its an afternoon project, even if you have to pull the motor out of the bike to do it. Two afternoons if it you have never rebuilt one before.
Also, most 150cc carbs don't have the accelerator pump. Some do, most don't. Don't worry about it. The jetting in an aftermarket carb is usually in the ball park, but you can always put your stock one back on.
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Post by dragono on Jan 5, 2014 13:37:33 GMT -5
Ok how would I test to see if valves are bad? I know a trick to see if rings are bad and I have done a top end rebuild before but on a 50cc but I'm guessing its pretty much the same. I'm going to retest the compression now that the valves have been re-done. I will report back.
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Post by millsc on Jan 5, 2014 15:15:46 GMT -5
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Post by carasdad on Jan 5, 2014 15:30:28 GMT -5
Ok how would I test to see if valves are bad? I know a trick to see if rings are bad and I have done a top end rebuild before but on a 50cc but I'm guessing its pretty much the same. I'm going to retest the compression now that the valves have been re-done. I will report back. less than 100psi is low...surprised it even 'pops' Checking valves for a leak is similar to a compression check..but lots more involved!! You can buy a new head cheaper than the time..parts and labor you'd spend checking the valves. You can take the valves apart by removing them and look for pits or burns around the valve heads and valve seats. But me..I just replace a head..they are cheap. millsc..THAT is a super cheap price for the kit..wow..includes the entire top end. I've paid that much for a head with valves alone! |
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Post by dragono on Jan 5, 2014 18:05:42 GMT -5
I decided to pour gas into where the valves are seated at and I see that it leaks through the intake valve. However for 80 bucks a whole rebuild kit is worth it. I will check with my local scooter place tomorrow to see how much they charge for their parts. (I hate waiting for stuff to come in the mail)  |
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Post by millsc on Jan 5, 2014 18:39:37 GMT -5
You get the parts in three days from the seller I posted the link for.
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Post by carasdad on Jan 5, 2014 18:59:32 GMT -5
I decided to pour gas into where the valves are seated at and I see that it leaks through the intake valve. However for 80 bucks a whole rebuild kit is worth it. I will check with my local scooter place tomorrow to see how much they charge for their parts. (I hate waiting for stuff to come in the mail) If you can watch gasoline flow through the valve while seated..yup..that puppy leaks! Hope they don't charge a lot for parts like they do around my place. They charge just over $400.00 for an 80 BBK install on a GY6 50 engine.. EEK! I charge less than 1/2 that..hmm..  |
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Post by dragono on Jan 9, 2014 18:31:26 GMT -5
Update: Ordered the kit and did a top end rebuild and it ran great for about an or two hour. (not running constantly) Now it'll start up just fine by itself but now it seems to be dieing out when I give it gas. If I let off of it before it dies it idles fine. I put a new carb on it and I cannot figure out for the life of me why its doing this now. These 150's have more air lines going everywhere so that may be the case.
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Post by sym200 on Jan 10, 2014 12:12:39 GMT -5
Did you try adjusting the fuel/air mixture?
Sent from my XT907 using proboards
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Post by alleyoop on Jan 10, 2014 17:15:48 GMT -5
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..BAD TO THE BONE..