Soft Seize: what it is, causes, prevention, myth?

today i was cruising around my 77 maxi with a polini on it. i have only been able to open it up for a few days now. today i was cruising around 42mph on the flats when i heard a loud screeching noise and the bike quickly stopped. checked the plug, normal chocolate color. cooled it down and it started again. my assumption is that a soft seize is caused by a lean mixture. but the plug looked fine. i haven't pulled the cylinder off yet, that's tomorrow project. does this sound like a soft seize. if it is what is still usable in there. and finally how do i prevent it from happening again. someone recently said it was a myth, true or not.

Re: Soft Seize: what it is, causes, prevention, my

im interested in this too

Re: Soft Seize: what it is, causes, prevention, my

Leon Swarmer /

Troll said it was a myth. It 's very real.

usuallly by poor lubrication/lean mix. What else did you do when you intalled the polilni?

Others will give more detail I'm sure.

Re: Soft Seize: what it is, causes, prevention, my

rebuilt everything. stuffed crank, 3 shoe clutch, biturbo, polini with reeds, port job. i filled up today and put in about a 40:1 ratio of non synthetic

Re: Soft Seize: what it is, causes, prevention, my

Yes, soft seize is caused by insufficient lubrication and/or by expansion of the piston to the point that it cannot move freely in the cylinder. Either of these conditions could conceivably cause a soft or hard seize by themselves, but they typically happen together, such as traveling at high velocity with the throttle not sufficiently opened to allow a decent amount of mix into the combustion chamber. The mix actually cools the piston when it enters the chamber, as well as carrying the lubricating oil. So not enough mix = too hot and not enough oil = piston sticks.

Re: Soft Seize: what it is, causes, prevention, my

I personally like this description.

And yeah, don't listen to anything Targaped (aka Olympian) says. He's just trying to stir shit up.

Re: Soft Seize: what it is, causes, prevention, my

i didn't get that sound though. i got a really loud whining vibrato. i also thought it may have been a busted reed. but i guess i can't tell until i pull it apart

If you don't fill your oil reservoir you will get

a hard seize - soft seizes are myths /


Expanded piston rings maybe - not the piston

Expanded cylinder wall maybe .. /

So .. the answer is to make sure you have oil in your reservoir. Simple.

Linda - I'm just speaking plain facts

I'm not the one who slings shit /

or accuses people of shit disturbing.

Re: Linda - I'm just speaking plain facts

He doesn't have oil injection because its on a Puch. If you don't know what you're talking about then don't post.

The difference between a hard seize and a soft seize it that the soft seize will come unstuck when you start it up again. A hard seize will not.

Weeder - if poster here had to know everything

There would be no posts posted /

So get off the weed and start thinking straight.

A hard seize can be freed

Mr. Frustrated by silliness /

Weeder - if you substantiated your definitions with confirmation from reliable sources you might be seen as being reliable.

Re: Soft Seize: what it is, causes, prevention, my

Matt Scout The Scouting Dcon /

Pull the engine apart. Seizing is a very real occurance and the proof exists in your piston and cylinder. Take them apart and examine them. Take pictures and post them in the repair forum for help. Good luck, seizes do suck. I still have to examine my own after 20 miles of hard riding...sigh.

Re: A hard seize can be freed

You're telling people to fill up their oil in their reservoir on a moped that doesn't have an oil reservoir. You don't see a problem with that?

Yes a hard seize can be freed but it takes more work than simply starting up your engine again.

You don't know anything about me, so don't judge me.

Re: Soft Seize: what it is, causes, prevention, my

Ok. I have had this happen to me. riding along and all of a sudden bog down follwed by the rear wheel locking up and the engine just LOCKED. Not stalled..LOCKED.

So I pushed it to the side of the road. Checked it all out and it seemed fine. Let it sit for about 20 mins, added some more oil to the mix than usual and it ran perfect after that. It was a hot day, like 88+ outside. And I was on a slight incline. Not sure if this has anything to do with it since it's air cooled. Anyhow, I took the head off and all when I got home, Some VERY slight damage to the piston. Since then all has been fixed / replaced anyhow. All I know is that it ran fine after the "Soft-Seize" up until I replaced it all anyhow.

(BTW I have a 1978 Honda Hobbit Engine on my 81 bike, just for info.)

Re: Soft Seize: what it is, causes, prevention, my

targaped, if you had ever even taken apart an engine you might have a shred of credibility. Why don't you go get your son in law to change your piston rings again while you have some special "father-daughter time"?

Re: Soft Seize: what it is, causes, prevention, my


Re: Soft Seize: what it is, causes, prevention, my

Chris Powers /

If I remember correctly it is correct that a hard seize is indeed when the piston is fused to the cylinder wall, and in need of tear down, re-bore, and the like, where as a soft seize is less dramatic it is basicly the beginnings of the same process... if the situation is not fix... it will lead to a hard seize. Also, a soft seize can cause scaring in of the piston and or cylinder wall... and should be inspected (take the head off and lookie).

I had not really thought of it but is makes sense that if you are hauling ass and let up on the throttle you are no longer supplying the rapidly moving piston and chamber the much needed love juice to keep it lubricated.... good point.

Re: Soft Seize: what it is, causes, prevention, my

brutal james. just brutal.

soft seizes do exist, james has proven that to me on two of my peds.

Re: Soft Seize: what it is, causes, prevention, my

it definetly sounds like a soft seize. assuming that nothing is scored, and the rings are alright. i can still ride it. i should upjet, and use a richer mix. correct?

and by the way, i was hauling ass and let off the throttle a hair and it happened.

Piston groves

if you carve some shallow groves into your piston approx. .5mm apart it will help to keep you cylinder better lubricated and also provides a better sealing surface. this will help to prevent your engine from seizing.

Re: Soft Seize: what it is, causes, prevention, my

yes, bigger main jet and maybe a little more oil. I use 32:1 Mobil 1 in my 65 malossi, which is what Malossi recommends.

Re: Piston groves

what? you have to be shitting me right?!

Re: Piston groves

100% serious the groves should be .2-.3mm deep

Re: Piston groves

yeah don't carve your piston

Re: Piston groves

it's true, sorry to inform you

here you go

i can get you info if you want. it's real


Re: Piston groves

so then if the piston is scored from the seizure, and if i were to buff out any knicks, would that help

Re: here you go

oh i see! grooves in the other direction

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