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Post by sharp9 on Aug 17, 2012 12:34:07 GMT -5
I bought this scooter from a friend for my son. It ran good for a couple weeks and stopped running. Was always a lil hard to start( had to hold throttle open a little while cranking to start) This is what I've done so far to help i Changed spark plug New fuel filter( inline) Adjusted the valves to .002 intake and .002 exhaust new carburetor(stock)
Here is where I am now. It will start and idle good but at WOT white smoke comes out of exhaust at around 6000rpm and looses power. I checked main jets on both carbs and on new it is 75 with a adjustable needle( put c clip at top). Old carb had 78 main jet with a fixed needle. Any help with this situation would be great.
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on Aug 17, 2012 13:16:45 GMT -5
if your clip is at the top of the needle it is in the leantest point you raise a needle to make it rich and you lower it to make it lean also if you had a 78 before and its the exact same carb you are proably lean there too heck your proably realy lean a lot of these scoots come too lean from the factory to meet smog and ahve to be upjeted to live a long life
i would put the other main jet in put the needle clip in the center slot and do 2 plug chops one at wot and one at 1/2 throttle(make sure to use a new plug for each one as you are looking for a 2mm smoke ring not that old plug color bull that doesnt work any more becuase of all the additives in the fuel) the wot will tell you your main jet jetting and your 1/2 will tell you about your needle
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Post by sharp9 on Aug 17, 2012 15:17:13 GMT -5
Thanks for the reply but doesn't the white smoke out of exhaust mean I'm already running too rich? Plug is black now. I'm game to try anything so I'll try it. Had the carb off a lot now so shouldn't be a problem. Would the valve adjustment be off? (.002 on both)
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Post by Rebel on Aug 17, 2012 16:38:08 GMT -5
Running rich on a four stroke will be black smoke. White smoke will be oil burning. You may have a burnt valve if it had run too lean for too long. O.002 is a minimal clearance, you can go a little bigger if you think they are not closing enough.
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Post by sharp9 on Aug 17, 2012 17:43:53 GMT -5
Only been in current condition for about a day. Only drove it in current condition for maybe 1-1 1/2 mile. When I seen smoke we shut it down and brought it home. I'll do another valve adjustment and maybe try to use old carb jets and needle to put it back to original specs. If that doesn't work I'll try working with combination of the two. BTW there is no smoke at idle - 3/4 throttle. Thanks for all info
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Post by Mystic on Aug 17, 2012 19:47:17 GMT -5
Have you checked to make sure the bystarter is good? i would set the valve lash at .005 personally
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Post by sharp9 on Aug 17, 2012 20:29:33 GMT -5
I'm assuming it is good with it being on a new carb. How would you check it? I'm new to scooters and these type engines so trying to learn all I can to do most of work myself. Also how do you know ( with all different opinions on valve lash settings on the Internet ) what would be the right valve setting for your scooter?
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Post by Rebel on Aug 17, 2012 20:39:02 GMT -5
First you should download one of the manuals I have links to, notice the blue letters in the bottom of my sig line? that is a link to where I have links to service and owners manuals.
A bad bystarter will show when you rev the motor but I think it would be below the 6000 rpms. Still not a bad idea to check it out. Take it off and and apply power to it, it should open up after a few minutes.
Most people use 0.003 - 0.005 to adjust the valves, but I have seen 0.002 used by some, As long as they do not make noise the bigger gaps are fine.
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on Aug 19, 2012 16:41:03 GMT -5
white smoke is steam from water in the fuel blue smoke is oil but some times will look white
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Post by Rebel on Aug 19, 2012 18:50:24 GMT -5
Well, white isn't fuel anyway, steam would probably be soon after starting it, not after you have been running for a while.
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Post by sharp9 on Aug 20, 2012 15:18:41 GMT -5
Ok so just up jetted carb from 75 to a 78 same idle jet at 30( 30 was in both carbs). Took fixed needle and put it in new carb and also adjusted valves to .004 on both. Does better from 1/4-3/4 and idles good but still under a load has white/white-blue smoke coming from exhaust and looses power. Takeoff is slow also.
Took off nipple line from valve cover and has smoke coming out of there(at idle). When I took off top of carb to change out needle it wasn't the color of gas almost looked like it had a black oil tint. 5500-6000 is tops on rpms when it cuts out
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Post by Rebel on Aug 20, 2012 17:37:19 GMT -5
I bet you have worn rings. That smoke coming out of the valve cover is blow-by getting past the rings and into the crankcase then out that vent.
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Post by sharp9 on Aug 20, 2012 20:01:45 GMT -5
What would make rings wear so quickly? I know my son rode it pretty hard for the couple weeks we have had it ( long flat country roads), but never thought it could have happened to a 1-2 yr old scooter. What are my options from here and how extensive will the work be? Thanks for all the input! I've learned a lot through these forums.
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on Aug 20, 2012 22:08:53 GMT -5
poor break in could be a cause the po could have ran it with the crap oil that it was shiped with or just being riden hard normaly they come jetted lean to pass smog so just plain running lean can wear things out faster
at the very least it will be a rering maybe a piston will be needed maybe the head needs to be rebuilt you realy cant tell till you have it apart
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Post by Rebel on Aug 21, 2012 0:51:13 GMT -5
I looked back and didn't see how many miles it has. If it has just a couple hundred or so it could be the rings are still just breaking in to and have not worn in to seat well yet.
if they are worn out though I'd pick up a big bore kit and put in it, a reasonable size one is not too much money and the job is not that bad. It is the tuning the carb it back up that might be a little time consuming. A big bore kit with a new head goes from around $50.00 to $70.00 on ebay for kits with gaskets, get one that does not require the case being bore out, really don't get one that needs the case bored, you'll need to pull it all apart and it makes it a much bigger job because you have to clean the filings out to prevent damage later.
If you get one of the kits without a head you'll want to lap the valves, not hard to do, you can get a hand lapping kit at your local auto parts place, it is just using some abrasive past to clean the valve and the valve seat.
Does it have the stock CDI?
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