Compression but no fuel

Hi all, have a problem I hope some of the experts here will be able to help diagnose.

Just bough a little Honda sky 50 as a non runner. Really good all round condition but previous owner had been told might need new piston.

am told the fault originally started when riding where power started to drop significantly then when stopped lots of throttle needed to keep her running. Closed throttle stalled never to start again.

I have spark. Piston and barrel look fine and I have 150 psi compression.

Plug however seems to be dry therefore suspect not drawing fuel.

Carb has previously been stripped with no problems found. Will prob do this again myself to be sure.

If I suck on the vacum line to the tank I get good fuel flow to the carb.

Have tried with air filter removed. Haves checked exhaust for blockage.

Now if I pull the fuel line from the carb while cranking over I do not get fuel flow.

Does this indicate a poor vacum being generated at the intake?

Also, I can't feel a significant suck at the carb inlet.

I removed the intake to inspect the reed valve. Nothing obviously wrong there. I tried cranking the engine again to observe what happens. Couldn't see any movement of the reeds but not sure if I should.

I'm a beginner and.learning as I go but I'm starting to suspect leaking crank seals not allowing a vacum to be generated at the intake/carb?

Any advice appreciated please. Replacing crank seals sounds like a big job. Not sure if it can be done without splitting the crank case? Either way I don't wanna try doing it until am pretty sure.

Thank you
Steve

 

had a similar problem before and was because of a large slit in the inlet manifold, was sucking in alot more air than it was supposed to completely messing up the mixture, was the last thing i would have expected aswell as the last thing i ruled out doesnt sound very likely in your situation but just shows you check everything before making an assumption on the problem as it could cost you a fair bit ruling out and changing things that could be irrelevant to the problem

 

Quick update .

After exhausting all other logical options for not getting fuel into the cylinder I decided to check the crank seals.

Made up a contraption with a bit of wood and two bolts to hold the variator and rotor whilst undoing the nuts. The variator nut was particularly stubborn but came off in the end.

Then purchase a generic fly wheel puller for £12 to remove the rotor and starter gear. Stubborn to get off but got there eventually.

Sure enough the seal on the rotor side had been mangled up so there was effectively no seal. Took quite a while to get it out of the casing as it was well wedged in there. Fortunately the bearing looks fine as far as I can see and am confident have got all the bits out.

The variator side seal was in one piece but was in poor condition and stuck to the crank i.e. rotated with crank.

Have new seals on the way. On the rotor side the torn up seal has scored the casing a little (probably added to myself trying to pull the remnants of seal out with long nose pliers) so I think I will use some liquid gasket to fit that seal to be on the safe side - not sure what type of selant to use yet - will see what the local motosave has on the shelf tonight.

As sson as I get her all back together I'll post an update.

 

Confirmed. 2 new crank seals and she started 3rd kick and now running sweet.

 

sweet