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  #1  
Old 08-03-2015, 08:41 AM
cowboyona426's Avatar
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Default Suzuki DS80 not running right- please help

     

On Saturday I picked up a 1993 DS80 for my oldest daughter. When I went and looked at the bike it ran OK, but not perfect and had been sitting with old gas in the tank for over a year so I drained the tank and disassembled the carb. The carb was left to soak overnight in a bucket of carb cleaner and reassembled the next day. Once I put the carb back in I have had no success getting the bike to run correctly for more than maybe 1 minute tops. When it does act normal it runs great, but 99% of the time at WOT it stumbles and burbles like it's loading up but it will not clean out, and if you let off the throttle it just dies. I have tried running it with and without the air filter, the pipe is not blocked, fuel is flowing well from the tank, float is not sticking, float is shutting off the fuel... I'm at a loss. I have not checked the reeds yet because it requires pulling the cylinder but that is my next step. I would just like to know what the jetting was stock so I can be 100% everything is set how it should be and use that as a base line.
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Old 08-03-2015, 03:45 PM
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Main jet should be an 87.5 and pilot 25. That was my first bike but it was an 86. I never once had to touch the jetting on it. I would venture to say it has something to do with the float needle or float height. Did you blow everything out with compressed air? shake the float and make sure theirs no fuel in it.
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Old 08-03-2015, 04:55 PM
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I had one as a kid too, all I ever had to do was add fuel and oil and clean the air filter. I loved that bike, which is why I was happy to find a decent one for my kiddos.
I would agree with you that it must be float or float needle related; I'm going to check float height tonight. All jets are clear, all carb passages were blown out with compressed air... I'm baffled. The float floats and no sound of liquid inside when you shake it. I'm guessing float height may be off but that's just a guess. Checking the reeds requires removing the cylinder but I already ordered new reeds and all new gaskets so I can go down that road if need be.
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Old 08-04-2015, 08:08 AM
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Last night I pulled the carb to verify the jetting, everything is stock. I set the air screw to 1.5 turns, then checked the float height. It was higher than it should have been so I adjusted that, the bike fired up and ran great. It stumbled a little when you cracked the throttle but a little tuning with the air screw was making progress until it started bogging out again. I rolled it back inside and checked spark again, definitely has good spark. I pulled the top end, piston and cylinder look great and reeds look like new. My last ditch thought is that there is some old gas crud inside the fuel tap that is working it's way out and into the carb so that's where I'm going to go next.
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Old 08-11-2015, 08:21 AM
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Last night I put new reeds in (not really needed but I was in there so why not), replaced all the top end related gaskets, cleaned/checked the carb again, new air filter, new plug properly gapped... and this little bike still won't run. My last ditch thought is that the oil pump is over-oiling for some reason... I've tried everything else I can think of. Any input?
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Old 08-11-2015, 10:05 AM
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Crank seal leaking?
Low compression?
Weak spark?

Paw Paw
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Old 08-11-2015, 10:20 AM
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Quote:
Originally Posted by PawPaw View Post
Crank seal leaking?
Wouldn't a leaking crank seal cause an air leak and cause it to idle too high?

Quote:
Originally Posted by PawPaw View Post
Low compression?
One tool I do not have that I need is a compression tester... compression feels good and seems adequate based on my finely tuned testing tool (me). Piston, rings and cylinder are all in great shape... I did not check ring end gap however. The one time the bike ran long enough to ride it ran very well and had good power for an 80cc bike.

Quote:
Originally Posted by PawPaw View Post
Weak spark?
Spark is nice and blue and consistent. I do need to ohm test the coil just to rule it out but I'm having a hard time finding a good service manual or the specs for the coil. I think I'm going to order the service manual offered by Cyclepedia.com since I can't find an electronic copy of the factory manual (really trying to get the bike running by the weekend for my kiddo).
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Old 08-11-2015, 12:35 PM
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A leaking crank seal can draw trans fluid into the combustion and still not cause an air leak or idle issue. A leak test will only test the other side of the seal used during compression. However a vacuum test will tell of the crank seal is leaking.
Make sure the muffler is not clogged or wet.

Paw Paw
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Old 08-11-2015, 01:20 PM
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Exhaust is not clogged, the spark arrestor has been removed unfortunately. I did not see any residual fuel or oil in the crank well but I will definitely consider doing a leak down and vacuum test.
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Old 08-11-2015, 03:27 PM
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The removal of the spark arrester in those little bike have a bad effect on the running of the engine. It will throw the jetting off.

Paw Paw
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Old 08-11-2015, 03:35 PM
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I'm trying to locate a replacement spark arrestor for it. It's horribly loud without it and it irks me that someone removed it... they are simple to clean if they get plugged and there is nothing to be gained by removing it other than ringing ears.
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Old 08-11-2015, 06:49 PM
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You're gonna laugh and it's probably remote but, make sure dirt daubers haven't plugged up any vents.
A buddy had that happen on a vent and I had them plug up a weed whacker exhaust.
Hey, strange but true
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  #13  
Old 08-11-2015, 07:25 PM
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The fuel cap vent may be clogged.
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Old 08-11-2015, 08:21 PM
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Both of the above are very good suggestions if the bike set for a while.

Paw Paw
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Old 08-12-2015, 08:05 AM
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Good suggestions on the vents, not sure there's much to be gained there though. I don't believe this bike has a crank case vent, and if it does I haven't seen it yet. Carb vents are not plugged. Fuel cap vent hose was replaced with one of those little anodized one way vents.

Update, without using the choke and with just a dab of throttle I was able to get the bike to start last night. It idled perfectly, though a bit smokey, and would rev up with a blip of the throttle. I let it idle for a few minutes and blipped the throttle several times with no issues, adjusted idle speed and everything seemed great. Curiosity got the best of me and I tried full throttle, which made the bike stumble and die again. It would not clean out after holding the throttle open for a few minutes at near full throttle, if I let off the throttle it would just die.
I adjusted the oil pump per the manual, let it sit for about an hour and repeated the above sequence of events with the same results. Even after the oil pump adjustment it was pretty smokey at idle, I'm wondering if the oil pump has failed... I'm out of any other ideas.
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Old 08-12-2015, 08:57 AM
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I find oil pumps to be very unreliable especially after a long time...
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Old 08-12-2015, 08:59 AM
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Quote:
Originally Posted by stevo450 View Post
I find oil pumps to be very unreliable especially after a long time...
They work all the time on snowmobiles, I don't see why a bike should be any different but it does seem that they are problematic on bikes. Hoping I can keep the oil pump on this one though, not having to mix gas for the little bikes is helpful.
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Old 08-12-2015, 11:04 AM
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Man, YouTube is just perfect for this situation.
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Old 08-12-2015, 11:09 AM
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Quote:
Originally Posted by Tharrell View Post
Man, YouTube is just perfect for this situation.
Got a link?
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  #20  
Old 08-12-2015, 04:17 PM
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No I was suggesting you post so the guys here can actually see and hear how it's running.
I just thought it would provide something words maybe cannot.

Btw-I think 78SuzyQ on TT has the answer, I was gonna suggest running a wire through the Jets and passageways.
Followed by carb cleaner spray. It's always worked for me.
I use Berrymans and an ultrasonic cleaner but the wire works every time.

Last edited by Tharrell; 08-12-2015 at 04:24 PM.
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