Acceleration

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Schrockie

New Member
Jun 14, 2015
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Ruskin, Florida
I just installed a Flying Horse 66cc 2 stroke and having problems at full throttle. Accelerates like a champ then @ 24-25mph it fells like it hits a wall and starts kickn' and spittin'.

Spark plug threads are wet but ground & center electrodes dry dark brown. Both intake/outtake gasket been cut to fit. Carb needle set to highest/lowest. Fuel line is clear and free flowing.

I also have a Stinger 66cc I'm rebuilding, this bike did 30-35mph. I took the carb and exhaust from this and put it on the horse, same results. On a test run one day it pepped up and got to 35mph then quit running altogether. Exhaust nuts worked themselves off. Is this telling me I need to do some work on the exhaust side(because it started running better when it was loose)?
 
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crassius

Well-Known Member
Sep 30, 2012
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USA
it may be telling you that a lot of vibration is foaming the fuel - I'd first check motor mounts and look for frame cracks
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
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Littleton, Colorado
The rubber in your engine mounts is contributing to the problem. Get rid of it and mount the engine solid to the frame.
There are many pages of discussion here regarding engine mounting and rubber. It doesn't work. It doesn't eliminate or reduce vibrations but will cause a host of other problems. Mount the engine as it was designed to be mounted and that is to the frame with no resilient material between the engine and frame.

Tom
 
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crassius

Well-Known Member
Sep 30, 2012
4,032
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USA
if spacers are needed in a mount, a piece of PVC is good (I always use a piece of PVC in rear mounts just to protect frame)
 

Schrockie

New Member
Jun 14, 2015
25
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Ruskin, Florida
Well, I'll be darned, that seemed to clear up the problem. I had the exact same set up with the Stinger motor and never had that problem. Went ahead and put a new Spark Plug wire and boot on, old one was toast.

On the bottom mount, running both a center bolt and U-clamp, no rubber! Should my spark plug be that dry on break in? I'm running 20:1, plenty of smoke, but shouldn't it show some signs of being rich? Got it up to 33mph and was still climbing, took some real estate, then backed off. Took temp reading of 340F off the head right after shut down on a 2 mile round trip. Around how many miles should the break in process be done for?
 

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2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
I personally like to see 200 miles minimum on an engine before I consider it broken in. I'm one of those who don't 'baby' a new engine but I don't abuse them either. You should be able to run WOT, wide open throttle, for short durations but don't hold it there for long periods. Give the engine a chance to cool during long hard runs.

20:1 fuel oil mix is okay but you can safely drop that ratio to 32:1 and be fine.
Your plug looks surprisingly good for a new engine running your fuel/oil ratio. I wouldn't change anything for a while. Let the rings seat and you'll get even better performance as the engine accrues miles. 33 mph is actually impressive for a new engine. I think you got a good one.

Tom
 

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Thanks Tom, I'll post progress updates. I take it my head temp was normal?
340 is actually a little on the high side from what others have reported. I've checked my head temperature with a non-contact laser type thermometer and they usually run around 275 F. The accuracy of the thermometer is important however and those who rely on temps like the type that takes temp readings from a sensor attached under the spark plug or to a cylinder head nut.

Others might chime in with more information regarding temperatures.

Tom