soft seize?

[Wheelman-111]

Greetings:

When the piston descends, some gas blows out, so less goes up the transfer ports.

[motormike]

Okay,....does that answer my question ?...if it does, I need to ask a different question......

[Bear45-70]

....I understand how a crank seal will lean the mix....How does a crank seal reduce compression ?......

2 stroke 101. You first pressurize the fuel and air mixture in the crankcase and force feed it into the cylinder. Less pressure in the crankcase, less pressure in the cylinder.

[Mystic]

booyah you just got skool'd motormike hahahhahah

[motormike]

I sure did....and the Bear's answer accomplished in two lines what i haven't been able to grasp in 40 years..... ....thanx fred......

[bakaracer]

Greetings:

If your compression dropped 30PSI, it's more than a soft seize. Time to dismantle and inspect, then find the reason.

i took everything apart after the compression test. rings, piston, and jug all look good. any suggestions on why the compression might have dropped so much?

Post pics of the piston and jug. If the bike died like you said what happened and there was a seize,there are going to be lines on both the piston and cylinder walls.if none is present, check the reeds,and crank seals for leaks.also look for any other leaks like at the head,head gasket,base gasket and even spark plug. Any signs of oil will indecate leakage.

[tazland001]

This aint gonna be perty.

Taz

[iceman77]

Post pics of the piston and jug. If the bike died like you said what happened and there was a seize,there are going to be lines on both the piston and cylinder walls.if none is present, check the reeds,and crank seals for leaks.also look for any other leaks like at the head,head gasket,base gasket and even spark plug. Any signs of oil will indecate leakage.

I put it back together yesterday and drove it about a mile this morning to see how it did. runs pretty good except if i cruise at 30 then it wants to sputter.
I'll try to take it back apart here in a little while and get some pics.



Thanks:
TJ

[Dio89Elite]

ooh. pics. Dio89 loves pics.

[Wheelman-111]

Greetings:

Quoth Mike of The Motor:

I sure did....and the Bear's answer accomplished in two lines what i haven't been able to grasp in 40 years..... ....thanx fred......

(Cue Marlon Brando voice...) Santino, whad've I done to you, that you should show such disrespec'? Da Bear, he took two lines to do what I did in one:

When the piston descends, some gas blows out, so less goes up the transfer ports.

Don' evah disrespec' da family in public again.

And don't make me come down on you for over-utilizing the periods. An ellipsis takes three (3) dots. Your period ration will be docked.

[motormike]

I credit the silver-tongued Bear because I didn't know what a transfer-port does. Wheelman did say the same thing with less words, but his statement failed to "pull the trigger" of understanding. I have fallen to the floor with shame and humility before the paternal icon of scooterdom. As required by ancient custom, I have taken a pizza-cutter and repeatedly sliced every fingertip to serve as a reminder of this grave injustice and insult. Tonight, I will share my bed with the head of a mule. Periods will no longer represent pause, but will be an indicator of the many tears I have shed under this veil of dis-respect .

[iceman77]

sorry guys, my two little girls weren't being so great yesterday evening so i didn't get anything taking apart on my back. so no pictures yet. I'm going to try to get it apart today.



TJ

[Wheelman-111]

Greetings:

Quoth MotorMike"

Wheelman did say the same thing with less words, but his statement failed to "pull the trigger" of understanding. I have fallen to the floor with shame and humility before the paternal icon of scooterdom. As required by ancient custom, I have taken a pizza-cutter and repeatedly sliced every fingertip to serve as a reminder of this grave injustice and insult. Tonight, I will share my bed with the head of a mule. Periods will no longer represent pause, but will be an indicator of the many tears I have shed under this veil of dis-respect.

(Brando again:)And for these obviously sincere acts of penitence, the Dawg-Father will show mercy. I will not call out the Ellipsis Enforcement Team.

Back to IceMan's issue - there are actually two:
1. How much damage has been done, if any?
2. What caused the failure altogether?

For 1., I suspect at least some. Unless the result of inconsistent measurement methods, the compression has decreased considerably. Whether the result of a faulty ring/bore seal or some other Unauthorized Air Entry, there's still a problem somethere for it to sputter at 30.

For 2, I've had some weird reasons for poor running on my various "Builds". Usually the result of my own failure to assemble with due care. A loose carb mount, a leaky exhaust flange, iffy seal at the reed block, and of course, incorrect jetting. It's de-Gumptionating to have to disassemble and start all over, but it's the only way to be sure sometimes.

[iceman77]

piston has some scratches. and jug has about the same. they are not very deep but they are there.

[iceman77]

i was wanting to keep the bike running b/c i need something good on gas to ride around. so i put a 51mm bore on and i only have 75psi of compression.
I'm having some bad luck.



TJ