E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Hate posting simple stuff like this but I am fed up.

1975 Puch Maxi, 14mm Bing, believe it is the 1.5 or 2hp. Upjetted to 72, no air filter, Tecno boss pipe. Tops out at 35-40mph when running.

Ped was running fine, it stopped running due to debris in carb, then got rained on and had water in the tank and carb, so I cleaned/de-rusted the tank, replaced petcock, cleaned carb, and took the head and cylinder off to clean that, put it all back together, doesn't run. I have done this once before to replace the piston and it fired right up, so I don't think I overlooked anything. I have no idea what's happening here. Have spark, gas is flowing, and apparently it has compression - put a compression meter from harbor freight on it and it peaked at 90psi. Spark plug is new as of 2 months ago, Tecno boss pipe is about 8 months old. All gaskets are good.

When I engage the clutch and pedal, I hear a weird "squishy" sucking sound that I never noticed before. Maybe that's normal and I just never heard it. I have not put an air filter back on yet, but I have run this bike with and without. What else do I need to check?

Got this Maxi a year ago and it has run a handful of times, and when it runs, it runs awesome, so I at least know it is capable. (edited)

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

In order to cover all the bases, I also took off the stator cover and there was a little pool of water in there.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Check inside your spark plug boot for water. The stock one pn my Maxi used to hold some water in it when it'd get rained on, then the bike wouldnt start.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

90 psi is too low. Check base, head gaskets and piston and ring.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

If there was water in the stator, your points may be rusted and need cleaning

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Overpriced Parts /

Micheal H. Wrote:

-------------------------------------------------------

> 90 psi is too low. Check base, head gaskets and

> piston and ring.

90 is fine

The psi could be more then that especially if your Psi gauge has a hose

Some puch engines (1-1.5 hp with thick head gaskets) when new barely made 90 psi

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Thanks for this. Had no idea/couldnt find any definitive guide for compression. this makes me suspect the rings now because it seemed too easy to get the piston back in.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Gauge is at the end of a 1' hose.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

This will be the first thing I do when I get home, BUT, i am getting spark, so wouldnt that mean the points are ok? Still gonna do it but I originally wrote this off since there is spark.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Ok I assume this e50 has the same starter clutch deal as on my puch e50 magnum. Pull the spark plug and pedal with the starter cable engaged. See if ya hear the motor spinning. Otherwise that squish is the cam trying to engage but actuall not with success... That's my guess. There should be a way to tighten the cable as a first fix attempt. The compression is probably a red herring. This is rain related and if ya have spark you do have to look elsewhere.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Motor is definitely spinning. I actually did the thing youre saying to do. I didn't have the gas cut off though so I had a nice gas/air spray shooting out of the spark plug hole. Piston is definitely pumping. Nothing feels off as far as the clutch goes.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

And you are using a new spark plug or actually saw spark off the electrode?

So make sure the float is ok on the carb etc etc. sounds like you are almost there. When this shit happens always use a new spark plug.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

I did actually see the spark. Could the plug still be shot in some way even though it appears to be functional? I'll pick one up and test this...

Carb is spotless. the float floats, float needle is good, float height is good.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Princess Rapunzel /

I had a problem, replaced my low-compression E50 hi-torque top end with a used stock 50 kit, still not kicking over. I was super confused, I thought I had fuel, my plug was getting wet, seemingly good compression (didn't test it) and my spark plug, althought a little fouled, had seemingly good spark. Bought another BH6S at Orielly's, put it in and blam, fired right up. My E50 seems to be a bit picky with it's plugs, sometimes it'll work on one, other times not. Try a brand new BH6, it might fix your problem if you'v been using old plugs.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

See even the royalty agrees!!!

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Well I got it to run for about 2 seconds after putting in a new plug and cleaning the points, but only after pedaling like a madman, and had gas blowing back out of the air intake and later on, out of the end of the exhaust.

After trying to start it a bunch, I noticed gas also leaking out of where the exhaust meets the cylinder, so i decided i needed to seal that better. I originally re-used an old gasket there, but I had a new one on hand and wanted to really wrench it down. It's a boss pipe that has the fat header and needs to have those long brass nuts from treats that are super hard to work with, so I figured i could get it on there better if I just took the cylinder off and put the pipe on it, then put the cylinder/pipe back on as one piece. In the process, I snapped a piston ring and ripped the base gasket! Good times.

When I had the pipe off though, I poured a TON of gas out of it, so maybe, just maaaybe when I was trying to start it with a bad spark plug, the exhaust became blocked with gas that had nowhere else to go since it sure as hell wasnt getting burned.

Everything is in pieces now. Piston ring and base gasket is on its way to me from thee kingdom of treats. (edited)

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

My two stroke motorcross builder buddy has described in

The past a similar condition where the case just gets full of gas and unless fully

Drained just won't start. So yea I think that's what happened.

Turn off the petcock when ya finish putting back together and turn it on just before you are starting it.

It might be wise to have the carb off the intake as a trial and open the

Petcock with the carb upright and make sure the float is working perfectly and not dumping gas.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

I don't believe you when you say it doesn't have a leak. How did you test that?

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

if you had water in tank and then de rusted tank and prob used more water or some kind of solvent I bet there is still some fluid in there. there is space below the petcock to trap fluids you'd literally have to flip the frame upside down to completely drain and then let air dry for a few days. I like to cheat with a heat gun on low in the fill hole to help evaporate the residual water.

the starting stopping with backfire out intake and exhaust sounds like a water in gas symptom or maybe your timing is a hair off.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Thanks for this. I tipped it over on its side when draining and shook it around, and I also ran gas through it a few times but yeah.. .i see how there could still be a little water in there.

Re: E50: Rebuilt engine/carb. Have spark, gas, compression, no air leaks. Won't start. What else can go wrong?

Double Trouble Dan /

you are getting too much gas. jet/float/ water/ plug failed.

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