WTF!?!?! Puch cutting in and out!?!?!

While at WOT my Puch cuts in and out like a stall then kicks back in and takes a few seconds to recover, gets up to speed backs off and kicks back in. Not sure if it is too rich. Tried jets from 78 to 86. 78 jet was the best.

70cc TCCD kit, 15mm carb with a 217 atomizer. 82 jet, slide needle at second from the top. 18x40 gears and a muffler that has zen on the side. It was given to me so I am not sure about what it is. It has a big expansion chamber on it.

It ran fine with a 78 jet in it, but topping out around 40mph. Wasn't sure if the 78 jet was too lean. Also had the boss techno pipe on it. When I went to the bigger Zen I thought an upjet would get more MPH and make it run ok. but having problems. Is the 78 jet right or too lean. I have a 76 as well. Which way do I jet?

Any ideas?

Re: WTF!?!?! Puch cutting in and out!?!?!

Beard Road Bruiser (SoB) /

Condenser and points. Go for it.

Re: WTF!?!?! Puch cutting in and out!?!?!

Overpriced Parts /

See if it does it without a air filter

Re: WTF!?!?! Puch cutting in and out!?!?!

I am not using an air filter. Took it off a few weeks ago. It was running good without it, just changed the exhaust to the bigger expansion chamber. It didn't cut in and out with the 78 jet. Is it too rich? with 80 and over?

Re: WTF!?!?! Puch cutting in and out!?!?!

Overpriced Parts /

Put the old exhaust on it and see if it still does it

Re: WTF!?!?! Puch cutting in and out!?!?!

Check for air leaks. But I had that sort of prob with my tomos and it turned out to be a Cdi prob flywheel was all rusted to shit also

Re: WTF!?!?! Puch cutting in and out!?!?!

Also, check your carb float needle...

Re: WTF!?!?! Puch cutting in and out!?!?!

Float adjustment ? Dirty fuel filter or cock . Fuel flow is running out .

Re: WTF!?!?! Puch cutting in and out!?!?!

just did a complete rebuild of everything on my bike and mine was showing symptoms of bad points condenser, turned out the gas cap wasn't ventilating. run for a little create a vacuum and stop fuel flow, then the tank would slowly seep air and let gas flow to the carb when taking a break.

Re: WTF!?!?! Puch cutting in and out!?!?!

Clogged gas cap vent will do that too . Yup ,

Re: WTF!?!?! Puch cutting in and out!?!?!

OK

So what I didn't do in the beginning of this mess was take both engine covers off. Had I taken both covers off, I would have seen that the fuel line kinked where the cover was pinching the fuel filter against the bike. So with the line kinked, it was not getting the proper amount of fuel. Goes to show that even guys with experience need to take everything off to see the whole picture and not just go for what we think it might be. I went up and down the jet route from 76 to 86. Now I have to do it all again so I know which jet will work the best with the larger pipe. STUPID STUPID STUPID.

Any idea jet wise for the zen pipe?

Re: WTF!?!?! Puch cutting in and out!?!?!

So it wasn't the kink either. HOLY WTF!!!!!!

Started from the top 86 jet. Now down to an 80 jet. It actually ran up to speed. 40-45mph on speedo. Then it gets to 50 and the it starts to back off, kick sputter and the level off at 40 and takes it's time to get back up to 50, then, in and out again. Tomorrow, after letting the bike and my temper cool down time, I am taking the zen pipe off and going back to the techno boss. Entry level pipe, but at least she ran at 50mph on speedo and was consistent. Not worth the frustration trying to get the bigger pipe to work to get a little more speed.

If anyone has some theory that I missed please chime in and maybe kick start my thinking on this whole thing.

Re: WTF!?!?! Puch cutting in and out!?!?!

What plug are you using?Have you tried throwing a new spark plug in there and going for a spin?

Re: WTF!?!?! Puch cutting in and out!?!?!

I vote for point gap.

Re: WTF!?!?! Puch cutting in and out!?!?!

HGK 5 plug. Points haven't been messed with since I kitted it and have it running. Will try a new plug as well.

Re: WTF!?!?! Puch cutting in and out!?!?!

Hepatitis J [OFMC] /

wait did you try the condenser like dude said?

Re: WTF!?!?! Puch cutting in and out!?!?!

Yep - I'm in agreement with the very first response...and you're not gonna like it.

This is definitely an ignition issue. You'll know you have a condenser issue if you see a blue spark from your point gap while revving the engine. Start there.

Your points are likely fine, unless they are now carbonized from arcing. A condenser is...like, 5.99 at NAPA. It's easy and cheap. Do it. If shit is still weird, then you need to adjust/replace your points...and get the timing SPOT on. I was actually just reading my RD400 manual (the RD has a points ignition...I was amazed, actually) and they made a point about getting the timing PERFECT. There is no 'close enough'. Get a timing tool if you don't already have one and make the magic happen!

It's not hard - all the steps are laid out nicely in the wiki. You can do this in an hour, tops.

Re: WTF!?!?! Puch cutting in and out!?!?!

So my question is why doesn't it happen all of the time? I could be riding for a half mile before it starts. I can be on the throttle for a while then it just starts to happen.

I changed the plug and went back to the Techno boss. I took it out and had it hitting 55 on speedo for the fastest speed yet for almost a mile, then it started to sputter again. I backed off came to a light then got on it again and it was fine. If I hold it around 40 or so on the speedo, it is ok.

Timing was done by the shop I go to and it all worked fine until I put the Zen pipe on. Now it does this. I went back to original set up and it still happened.

Could the condenser have gone bad? Suddenly?

Just frustrated.

Re: WTF!?!?! Puch cutting in and out!?!?!

Salsa Salsa /

My cdi coil went bad and it did this.

before I went cdi, my condenser when bad and it did this.

Once my plug type was too hot and it did this.

I had a radiator gas cap that didn't vent and it did this.

Ji had a float that was not adjusted correctly and it did this.

Re: WTF!?!?! Puch cutting in and out!?!?!

I think it's your float also. I had the exact same problem and it felt like the engine was not able to rev all the way out. What it ended up being was that float level needed to be adjusted because it was flooding the carb. A good way to see if this is your problem is to cut your fuel(off on the petcock) while you are in the throttle and see if you are able to rev all the way out without the hesitation and the sputtering. Don't do it for too long though(u will seize!!), just see if you can rev all the way then turn fuel flow back on.

Re: WTF!?!?! Puch cutting in and out!?!?!

mines doing it too! fuuuuck!

Re: WTF!?!?! Puch cutting in and out!?!?!

Lukas McWhorter /

Run a B7HS plug gapped at OEM spec. I had the same problem till today when I fished a new plug out of my tool box and put it in.

OEM calls for B6HS, next one up is a NGK B7HS and it works really awesome.

Re: WTF!?!?! Puch cutting in and out!?!?!

[Radium City] kyle k $ /

b7hs would actually be one down for plug hotness, but I vote for fuel issues of either flooding or bad venting. I had same stuff happen recently

Re: WTF!?!?! Puch cutting in and out!?!?!

Overpriced Parts /

8 plug is good for a kit

Sounds like a fuel problem like that cloged little filter that hides in a banjo fitting on the carb

Re: WTF!?!?! Puch cutting in and out!?!?!

Mike is that the bike you rode with us? Didn't you say the tank was dirty then you cleaned it? You need to check your fuel flow I bet it's getting clogged. Pull out the petcock and look.

Re: WTF!?!?! Puch cutting in and out!?!?!

i ditched my fuel filter and clamped some 1/4 inch hose to my 'cock. now i'm 4 stroking. no more in/outs. all blast! kits like a lot of gas. try that dude.

Re: WTF!?!?! Puch cutting in and out!?!?!

Dan,

Yes this is the chopper I have been riding with you guys.

The fuel bowl has been full and with clean gas in it when I was changing the jets trying to get it right. The filter is dirty after the tank cleaning. But clean fuel is getting to the carb. There could be dirt in the pet-cock. What I don't get is why does it ride fine for about a half mile, then start doing it. Why not when it is getting up to speed?

Same question with ignition problems, why only at top speed? Why not at all speeds? I am thinking about getting new points and condenser. I have a new pet-cock on the other bike that hasn't been used yet. Will swap that one out and try that. Also going to swap out the coil from the other bike to see if it is the coil. All of this sensitivity is driving me nuts.

It all started after putting after swapping to the Zen pipe............. (edited)

Re: WTF!?!?! Puch cutting in and out!?!?!

Think about it what you just said. Use a little of the common sense what is different about when you first start the bike then ride it for a half mile? Hmmm when you first start it the bike is cold then you ride it fast and the bike gets hot! What does that indicate?

Re: WTF!?!?! Puch cutting in and out!?!?!

Well I heard from mike beez that this is usually caused by the clutches building up a resonance. as the springs extend all the way out from centrifugal force the k constant of the spring wants to pull it back into it's original shape (see theory of elasticity) as a result theres a competition between the arms spinning out and the springs pulling in which can create a resonance frequency that makes it SEMM like you have a bad groundd causing a bike to cut in and out.

Re: WTF!?!?! Puch cutting in and out!?!?!

It could indicate a couple of things. Again two stroke is still somewhat confusing to me in some ways. Could be a fuel problem or it could be a ignition problem. Luckily between the two bike I have, I can swap parts one at a time until I figure it out. With it being so sensitive. Time consuming yes, but there are so many different suggestions and theories to go with. After a Pet-cock swap I will try the coil after the coil swap I will get new points and condenser. Something has to be the correct thing.

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