Runner
Scoot Member
Posts: 23
Location: Greece
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Post by Runner on Apr 6, 2015 11:45:43 GMT -5
Hey guys, Im having some trouble starting my Gilera runner 50. When its still hot itll need a little throttle to start, but to start it cold is a nightmare! I'll be on the electric starter for a while before i can hear that its about to start ( and it'll start with the help of the throttle only). Then when it eventually starts the engine is clogged with excess fuel so it smokes like a m%f*ka for a minute or so before it burns it all out.
I've adjusted the mix screw to 1 and a half outwards as was recommended by a mechanic i went to. Idle screw adjusted too. Fuel supply is ok, air box is clean and no holes, cracks etc, sparkplug is new. Manifold is new. All pipes to and from carb are fine (no vacuum loss).
I was given a hint that it could be the autochoke in cases like this. So i took it apart, cleaned it, checked it was hooked up to power properly. But how can i check that the autochoke functions correctly so i can rule it out? And if not the autochoke then what?
Any ideas???
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Post by thatcrazyguy on Apr 6, 2015 13:06:07 GMT -5
In cold situations, kick start a few times to warm up the gears. Then use electric start. I had the same problem, I got a new fuel petcock(fuel pump) and it fixed the situation lol
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Runner
Scoot Member
Posts: 23
Location: Greece
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Post by Runner on Apr 6, 2015 15:26:46 GMT -5
It's defo not the petcock for me, or anything before the carb fuel wise for that matter, the carb gets fueled properly.
I'm trying to achieve a one-touch start but something's going on from the carb onwards i reckon...
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Post by Sitticuss on Apr 6, 2015 16:01:44 GMT -5
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Post by niz76 on Apr 6, 2015 16:05:53 GMT -5
Sounds like you have a new sparkplug and everything seems to be in good working order... in this case it might be time to do a compression check. Sounds like it might be taking a good soaking of fuel and oil to get the compression up high enough to start... just a hunch. Anything under 90 psi and the scoot usually won't start at all. 100-120 is OK but not optimal... 140 to 160 psi would be perfect for one-touch starting...
EDIT: I've found a simple way to increase compression is to remove the head gasket and use copper spray only- provided there is enough "squish clearance" between the piston top and the bottom of the cylinder head. Brent has gloriously covered the topic with a how to vid:
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Runner
Scoot Member
Posts: 23
Location: Greece
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Post by Runner on Apr 6, 2015 17:15:20 GMT -5
The idea of opening the engine itself is new to me, so any tips would be appreciated.
If I open it up and close it does that mean everything will remain as it was? Do i change gaskets when i close it again? is there any special treatment for this part of the bike? I'm afraid I'm gonna bolt it back up and have f&%*ed something up.
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Post by Sitticuss on Apr 6, 2015 17:26:24 GMT -5
The idea of opening the engine itself is new to me, so any tips would be appreciated. If I open it up and close it does that mean everything will remain as it was? Do i change gaskets when i close it again? is there any special treatment for this part of the bike? I'm afraid I'm gonna bolt it back up and have f&%*ed something up. I'd go with testing the choke first. It's easier than tearing into the engine. I don't think its a compression problem but I don't know how many miles are on your scooter etc.
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Runner
Scoot Member
Posts: 23
Location: Greece
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Post by Runner on Apr 13, 2015 6:36:22 GMT -5
It's not the choke. I feel the choke housing heat up after a little, so there's power, it always idles properly on time and doesn't cut out.
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Post by 90GTVert on Apr 13, 2015 7:40:57 GMT -5
If the petcock or float malfunction or are set improperly it can cause flooding on start up, especially when the bike sits for long. It may be soaking the plug almost immediately if this is the case and generally will start easier when you hold the throttle wide open.
Before tearing the engine apart, even though a head gasket swap isn't a big job, I'd suggest trying to get a compression reading and to find out just how quickly it's flooding. Try checking the plug after just cranking it a few times and see if the plug is covered in fuel. Might as well check the spark while it's out. If it runs well it's prob fine, but it takes maybe 30 seconds to see how it's sparking. Check the plug gap as well.
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Runner
Scoot Member
Posts: 23
Location: Greece
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Post by Runner on Apr 13, 2015 10:51:25 GMT -5
There's nothing to set on the petcock, there's no tap. It's a simple one with a vacuum line and brings fuel to the carb no problem. It's one of these... I've tested the float with the bowl off and the fuel line still on the carb. Fuel flows down into the bowl. I pushed the float up and the needle stops the flow as it should. Also I've noticed the sparkplug being soaked as you say.
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t2no
Scoot Member
Posts: 55
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Post by t2no on Apr 17, 2015 11:00:42 GMT -5
Hey man, i have the same problem. On cold engine i cannot start. I have to putit on the left side for 10-15seconds and then it starts like a charm. The same like yours it smokes like hell for a while and the stops and everything fine. I have changed everything in this scooter, 3 carbs, all that u listed above i have done as well and i still have this problem. Please guys help us solve this mistery?
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Post by 90GTVert on Apr 17, 2015 12:26:38 GMT -5
A slightly high float height can allow seemingly normal operation, but with an overly rich condition at idle or very low throttle. Since the plug is soaked, no need to worry about too little fuel. Now you need to find out why too much or why it's not igniting it. If it's flooding a temp help may be to hold the throttle wide open to start it till the issue is sorted out. Having to tilt the scoot to get it to run really sounds like a float height issue to me. www.youtube.com/watch?v=xBCzVg4kUN0
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t2no
Scoot Member
Posts: 55
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Post by t2no on Apr 19, 2015 4:53:18 GMT -5
It is for sure not the float, because I have dellorto phva carb with plastic float all the way. You cannot adjust that. What else could it be?
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Runner
Scoot Member
Posts: 23
Location: Greece
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Post by Runner on Apr 19, 2015 11:24:20 GMT -5
I have a Weber carb and the float is all plastic too! So no adjusting that.
I've tested it with the bowl off needle works fine and the float itself sits as it should with the top surface parallel to the bowl (as stated in the video above that 90GTVert posted). Also does not stick on anything when moving from the empty position upwards.
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t2no
Scoot Member
Posts: 55
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Post by t2no on Apr 20, 2015 13:42:26 GMT -5
My mechanic told me that I am starting my scooter wrong way. I open full chocker, and give around half throttle. How it should be done? no throttle at all? Is because of that it floods the engine with gas and smokes after?
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