Puch Dart Surging under throttle

Need some diagnostic help with my Puch Dart.

Got everything setup properly, finally and went for a ride down the road. Seemed to be doing alright until I went down a hill full throttle. Bike sort of bucked, lost all power, then came back, then bucked again, did that a few more times until the only way to run it was to use 1/8th throttle.

Was the engine soft seizing or was this something else? It's all stock so I'm not sure why it would be soft seizing unless I absolutely murdered the timing on this thing but I think I got it pretty close to within spec.

Thoughts? This is my first e50 motor.

Re: Puch Dart Surging under throttle

Overpriced Parts /

Bombing downhill can lead to a Seize, whether from fuel starvation and or high timing you, you could have a piece of something come loose making blockage somewhere in fuel system

I never run a new to me engine/bike until I pull the topend, clean and address anything in there, pull the carburetor and pitch the internal screen filter in banjo fitting and clean everything, Check, clean or change the petcock and filter for good fuel flow, make sure the exhaust is unblocked, inspect the transmission and clutch and service the magneto,

Of course brakes and wheel-bearings too.

Taking apart everything first on every bike I got, nine times out of 10 I found issues, many that were bad enough if not addressed would have led to catastrophic results.

Re: Puch Dart Surging under throttle

> Overpriced Parts Wrote:

> -------------------------------------------------------

> Bombing downhill can lead to a Seize, whether from fuel starvation and

> or high timing you, you could have a piece of something come loose

> making blockage somewhere in fuel system

>

> I never run a new to me engine/bike until I pull the topend, clean and

> address anything in there, pull the carburetor and pitch the internal

> screen filter in banjo fitting and clean everything, Check, clean or

> change the petcock and filter for good fuel flow, make sure the exhaust

> is unblocked, inspect the transmission and clutch and service the

> magneto,

>

> Of course brakes and wheel-bearings too.

>

> Taking apart everything first on every bike I got, nine times out of 10

> I found issues, many that were bad enough if not addressed would have

> led to catastrophic results.

That's the confusing part. I've completely gone through the entire bike as you said, even down to the wheel bearings, etc. This was my test run before I prepare to sell the moped.

It has been suggested that the carb may have been starved for fuel due to going WOT down a hill; or perhaps the angle of the carb had something to do with it. The Dart uses quite a long fuel line also which isn't ideal for fuel delivery.

Re: Puch Dart Surging under throttle

The old bing carbs have issues with their float needs getting bloated and sticking open or shut. You may not be getting a smooth enough fuel flow thru the float fuel inlet. Give the inlet a good polishing and make sure the rubber tip on the float needle is firm and smooth. No bloating or squishy feel.

Re: Puch Dart Surging under throttle

♣Slew Foot♣ /

Clogged jet.

Re: Puch Dart Surging under throttle

Ya seems like a clogged jet or poor fuel delivery. Check the flow out of the tank. The float could be sticking too. May need a carb rebuild.....New float and needle and such

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