Decompressor problem, help before i bash my Maxi

The engine just shut off while i was riding today for no reason at all, i pulled over to an adjacent parking lot and yanked the plug to see if i had spark and I did. no problem there. i checked to make sure the fuel was flowing, it was flowing fine. i checked the wiring to make sure the kill switch isn't being activated, no problem there. I always carry a minumum of three extra plugs with me as a precaution, all NGK quality, and they all had a good spark. I tried each plug to no avail, only one plug the NGK-B6HS R worked and when it did it took me for about 15 seconds then the engine bogged down BADLY and shut off. After that i spent three hours on the road _far_ from home trying to get the useless machine to start. The plugs were all working fine but when i screwed them in there was NO popping sound whatsoever to give me an indication that the engine was even trying to start. The first hour i tried to start it I noticed that the decompressor valve was leaking, even when closed. I didn't think this was a problem at first become my decompressor valve is always leaking at the bike always starts no matter what. The second hour I got multiple backfirings and surprisingly, a few misfires, then it just quit for good. The decompressor is adjusted perfectly as to manufacturers specifications and is in the same shape as when i was riding it at 40mph yesterday and i haven't touched anything since then so what the hell?

Re: Decompressor problem, help before i bash my Ma

clean the carburetor, this is the only thing i can see.

i'm pretty sure something went into the carb and blocked the jet


Re: Decompressor problem, help before i bash my Ma

how can my engine flood if a jet is blocked? the fuel is flowing quite freely...

Re: Decompressor problem, help before i bash my Ma

oh and another thing, my compression is practically non-existent, i dont' know how i got the thing going so well in the first place. my piston rings are worn to scrap

Re: Decompressor problem, help before i bash my Ma

this is on a Puch Maxi? I have never seen, or heard of a Puch with a decompression valve on it, what kind of top-end is on it? What all has been modified on it?

You said compression was low to begin with, maybe the rings finally gave out. Try pouring a little straight oil(4 storke) into the cylinder and then try to fire it, if it runs for a minute then stops it is likely time for new rings.

Re: Decompressor problem, help before i bash my Ma

i have a decompression valve on my puch too

Re: Decompressor problem, help before i bash my Ma

is there anyway you can get a picture? I have owned over 10 Puchs and never seen a decompression valve on one, I had never heard of one on a Puch until this thread.

The Puchs I've had have what some people call a decompression lever, the lever you pull to start the bike, but the name is misleading, it does not cause decompression at all, it manually engages the clutch to turn the motor over. It either pulles on a lever on the clutch side cover(1 speed) or runs down into the clutch side cover(2 speed)

Bikes I have seen with a decompression valve are Sachs, Kreidlers, Motobecanes, and several others, but the decompression valve normally sits in the head(except in a Kreidler I have, its in the cylinder itself) and when engaged opens up to lower compression in the cylinder to make it easier to pedal and get the motor turning. I have never seen or heard of a Puch like that, but provide a picture if you can, I'm always up to learn something new.

Re: Decompressor problem, help before i bash my Ma

Leon Swarmer /

If you have a leaking decompression valve, it isn't working right, even if it is adjusted to specs. Add low compression and it's a wonder it would do 10 mph>...

No decomp valve on my Maxid


Re: Decompressor problem, help before i bash my Ma

my maxi has a decompression valve on the head.

it's really a decomp. valve.

the cable you use to engage the clutch continues and goes under the engine to the head and decompress the compression.

It does both at once, like a sachs. (i have a sachs)

i'll try to take a picture when i can.

also, it's a 1974 BOMBARDIER puch maxi-S, probably the BOMBARDIER maxes the difference


Re: Decompressor problem, help before i bash my Ma

yeah, mine is a BOMBARDIER type as well, quite frankly i could do without this stupid decompressor valve. all it has served me so far is with backfiring. so you guys think i need new rings or a whole new piston? i was planning on upgrading to 70cc anyway and maybe a fresh start would help me out.

hey gb

is there any way to get my Maxi running with a totally _different_ head so that i no longer have to worry about the decompressor?

Re: Decompressor problem, help before i bash my Ma

Yeah put a head on that doesn't use a decompressor valve. It is that simple. Your bike does't need one to run. But if it has one you better hope it is sealing right.

Re: Decompressor problem, help before i bash my Ma

i simply disconnected mine.

works well

you could try to disconnect yours and using a spring to keep it closed


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