Going insane !

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nastygramus

nastygramus

New Member
Feb 25, 2011
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NE illinois
Ok here it is in a nutshell I have a GT5 pull start w/ centrifugal clutch cns car v3 (just so we are on the same page carb came with the blue air filter) I believe with around 150 -200 miles on it .40:1 This motor starts and runs GREAT idle smooth revs nice get on and ride and is runs for about 3 minutes starts to bog and dies ? things I've tried new gas,plug,carb,intake gasket and before changing had the carb off for a good inspection and cleaning ( was spotless inside no visible crap) it gets a new gas cap today and a new intake gasket
Driving me nuts
 
crassius

crassius

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Sep 30, 2012
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Does it start again or stay dead till it cools off?

May be leaking head gasket or case halves when engine expands. Check for leaks/seepage in those areas.

Could also be something inside the muffler, but not too likely.
 
Blakenstein

Blakenstein

Member
Sep 15, 2009
561
2
16
Alta. Canada.
It could be a gas/ air ratio . it could be running a bit too lean,.
Try it again and this time when it starts to bog , stop and pick up the rear of the bike by the frame, with the rear tire of the ground and give it a rev. if it starts to run good again . then your gas /air is too lean. and /or your muffler is dirty - lots of oil, .
Also, the lead wire from your magneto to your plug might be faulty.
I learned that having spark and a running motor means nothing to a faulty line.
What happens is that the motor will start and run for a while, but the vibrations will cause the faulty lead to stall engine . I replaced the lead with an automotive one and no more problem.
Also do you have a vac hole coming from your cylinder to your carb??? if so, remove the plug and give the motor a fast pull with the carb removed to see if there is any pumping air action comming out of there. then make sure when you install the carb, that those holes ( in the carb and the cylinder are lined up properly. a lot of times the slightest movement when installing the carb can cause the gasket to block part of the hole.
 
nastygramus

nastygramus

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Feb 25, 2011
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NE illinois
Thanks for the input guys ! crassius no when it dies it wont restart not sure if its when it cools or me tinkering with it? JonnyR just got the new cap today! Blankenstein Ive tryed changing mix ratios as well as gas and carbs the plug wire is my next adjustment and not sure about the vac hole your talking about ?
Thanks again guys with your help We will figure it out
 
Blakenstein

Blakenstein

Member
Sep 15, 2009
561
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Alta. Canada.
I just looked up your motor I dont't think you have a vac hole. You carb and system is different from mine. My carb is like what some chain saws have. I t will run upside down. Inside my carb there is a little diaphram ( membrane ) . Besides the bore in my cylinder for the carb throat intake, there is a tiny little hole in the cylinder that comes from the bottom end inside the engine and lines up with another tiny little hole in my carb. The motor pumps gass air from the bottom end, through the hole and turns the carb membrane into a pump that pumps and forces the gass from the carb reservoir into the motor.
Any way, enough af all that. I'm just telling you what I was asking about.
This might sound crazy, but maybe you could try go for a ride without the exhaust pie on. Try run it with an open manifold, around the block a few times, - if nothing improves, at least you know what it is not.
 
fatdaddy

fatdaddy

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May 4, 2011
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It runs till it overheats, wait till it cools off and it starts again. First, you didn't say if it was a BRAND NEW engine. If it is, I'll tell you what I found out, (I won't say from who.) On the new engines coming out they have the "new style" high compression head. If you run a thin head gasket on it IT WILL OVERHEAT. Yeah, I didn't believe it either. I put on the thick head gasket,( like the guy said,) and it ran like a champ, no more overheating problem. I know it sounds like a bunch of crap, but it worked, Really.
fatdaddy.
My first guess was the tank/cap vent, but that seems to be covered. And running a bike with no pipe at all may not be the best idea. Cold air can warp all kinds of stuff in a hot top end. If ya think the exhaust may be clogged then just yank the end cap/baffle out. it will free it up enough to check it that way.
 
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crassius

crassius

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Sep 30, 2012
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Just had a thought. If you pull the head to check for leaky gasket or marks where the piston might be hitting the head, check also for a number on the piston next to the little direction arrow. We had some (red bat I think) engines with #4 and #3 pistons in them. Measured them and found them to be 40micrometers oversize & 30micrometers oversize, but in a standard sized barrel. These were binding in the bore as soon as they warmed up.

I wouldn't recommend honing the barrel unless you were desperate, but getting an unmarked standard size piston should fix it.
 
fatdaddy

fatdaddy

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OK Nasty, If it ain't a overheating problem then there's only one other thing it could be, The Carb. I just looked at a pic of the NEW AND IMPROVED V3 carb, and it does have a float bowl. That means it also has a float needle. Just like the old style carbs the needle and seat in the carb can get clogged. In this case probably not COMPLETELY clogged. If you let it sit long enough, little by little enough fuel will seep by, fill the bowl enough to let it start again, run for a minute, empty the bowl, then die. Let it sit for a while again, ect, ect.
If you ran the engine, even for a second, without a fuel filter then you might have some crap in the carb. If you always used a filter, then even from the factory it could have got some trash in it. So thats what I would do, Check the fuel inlet/ needle seat setup. This has happend to me a lot on the old style carbs. It's frustrating cause by the time you check the bowl for fuel, OF COURSE it has fuel in it, Cause it took a minute or two to check it and it filled up again. I'm just sayin it can fool ya into believing it's OK when it's not.
fatdaddy.
 
nastygramus

nastygramus

New Member
Feb 25, 2011
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NE illinois
Thanks I've used a fitler from day one and I've tried that with two different carbs the carb that came with this motor that has about 200 miles on it went thru it twice changed carbs ( new carb out the box) and did the same twice. Im stating to think it might be the magneto Ive tested it and the coil with good readings thinking it might be when it gets hot it might have issues . might be grabbing at straws but something has to fix this thing and with everybody's help I will if its the last thing I do
 
moonerdizzle

moonerdizzle

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Jun 28, 2009
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Cheese head capitol
crassius said:
Just had a thought. If you pull the head to check for leaky gasket or marks where the piston might be hitting the head, check also for a number on the piston next to the little direction arrow. We had some (red bat I think) engines with #4 and #3 pistons in them. Measured them and found them to be 40micrometers oversize & 30micrometers oversize, but in a standard sized barrel. These were binding in the bore as soon as they warmed up.

I wouldn't recommend honing the barrel unless you were desperate, but getting an unmarked standard size piston should fix it.
Click to expand...
you cant hone a chrome lined cylinder at all. and none of the pistons i have had a number on them, considering im sitting on a stock pile of them to coat up, both hi and low wrist pin styles, 49 and 66cc.
 
fatdaddy

fatdaddy

New Member
May 4, 2011
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San Jose, Ca.
nastygramus said:
Thanks I've used a fitler from day one and I've tried that with two different carbs the carb that came with this motor that has about 200 miles on it went thru it twice changed carbs ( new carb out the box) and did the same twice. Im stating to think it might be the magneto Ive tested it and the coil with good readings thinking it might be when it gets hot it might have issues . might be grabbing at straws but something has to fix this thing and with everybody's help I will if its the last thing I do
Click to expand...
Last time I told someone, IT'S THE COIL, turned out he forgot to put fuel in his tank. It went on for a few days before he realized it.
Most people say MAG when they mean COIL. The MAGneto is the weird shaped MAGnet that spins. The COIL is the thing thats COILed with copper wire and wires coming off of it. And sometimes the venders call it a magneto coil.
Anyway, can't hurt to try, Coils are only $12.49 W/free shipping.
http://www.ebay.com/itm/Magneto-Coi...800&pid=100016&prg=1006&rk=1&sd=330748077570&
fatdaddy.
 
biknut

biknut

Well-Known Member
Sep 28, 2010
6,631
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Dallas
If it's it not a faulty gas cap vent, then it's probably the magneto coil. I had 3 fail this summer on my new Flying Horse motor. They all went intermittent at first. Would work when cold, but fail sometime after warm up. After a few more days they quit working altogether. After disconnecting the kill switch I never had anymore coils fail. The kill switch burns them up.
 
crassius

crassius

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Sep 30, 2012
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moonerdizzle said:
you cant hone a chrome lined cylinder at all. and none of the pistons i have had a number on them, considering im sitting on a stock pile of them to coat up, both hi and low wrist pin styles, 49 and 66cc.
Click to expand...
hence my remark that I don't recommend honing, however, if you're desperate you can get a couple thou off it if you work carefully and those oversized pistons are only a couple thou too large
 
fatdaddy

fatdaddy

New Member
May 4, 2011
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San Jose, Ca.
biknut said:
If it's it not a faulty gas cap vent, then it's probably the magneto coil. I had 3 fail this summer on my new Flying Horse motor. They all went intermittent at first. Would work when cold, but fail sometime after warm up. After a few more days they quit working altogether. After disconnecting the kill switch I never had anymore coils fail. The kill switch burns them up.
Click to expand...
I used to fry coils before I found out about that stupid white wire. The white wire is actually a power wire connected directly to the coil. Using it for the kill switch creates a direct short to the coil, Viola, burnt coil.
Since I've been using the blue and black wires I've never burned a coil. Hooking the kill switch to those simply interupts the spark going to the plug, no direct short to the coil.
When I was a kid, ( a long, long time ago,) lawn mowers and rototillers would have a peice of spring steel connected to a head bolt or other part of the motor, and you would push it over against the spark plug. I still think this is the best way to stop an engine. SO, how about one side of the kill switch to the top of the plug, or attached to where the plug wire comes out of the CDI, and the other side to the engine or frame. You might get a little shock sometimes if yer not carefull, but you would never burn up a coil and you still have a kill switch. Not having a kill switch is not the recommended way to go. If yer throttle sticks at 35mph yer gonna REALLY WANT a kill switch.
fatdaddy.
 
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