Engine 'seized' yesterday

velardejose

New Member
Sep 9, 2008
120
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Lima, Peru
Hi
After a very short trip yesterday riding at low speed the engine 'seized' and I almost fell
I tried to move the engine pushing the bike but it didn't move
I decided to take the bike to my mechanic, thinking about a rebuild or worse...
Today my mechanic looks at my bike, readjusts the chain slack to an inch and reinstalls the master link with the round end in the direction of rotation, then without a word starts it and goes around the block
When I found my voice and asked what happened he tells me 'These things never break'
I am new to two stroke engines, and after lots of broken type 1 vw engines I thought it was engine damage
What happened?
Thanks in advance
 

velardejose

New Member
Sep 9, 2008
120
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Lima, Peru
Yesterday night, on my way home from work
At medium speed the engine started that high pitched noise
And seized again
I moved the bike backwards, and started it again
The engine sounds weird, like gears but louder
The exhaust chrome is burned 2 or 3 inches from the head
I ended starting it for seconds to gain speed and some pedaling
Could it be that the mixture is too lean? Or is it an intake air leak?
Can't set the idle speed from day 1, engine dies after a few secs
Thanks in advance
 

velardejose

New Member
Sep 9, 2008
120
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Lima, Peru
Semi synth Repsol 2t oil
Local representant recommends 40:1 mix (claims to have data from the factory)
Oil container recommends 50:1 mix
Printed manual recommends 20:1
I know most of you use 20 - 36:1
I will disassemble my carb today, the day it started to fail when parked in front of a hardware store someone tore off my fuel line (carb end)
Maybe some debris (like a toothpick) got stuck inside the carb fuel nipple
I am sad and upset because of these failures
Jose
 

thatsdax

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Feb 22, 2008
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www.thatsdax.com
It sounds like a lean condition for sure. Do not mix leaner than 30:1 for these motors. Use AMSoil Interceptor and mix 30:1. The wrong mixture can burn an engine up. A fresh air leak will burn it up even faster. Check for fresh air leaks and when you find them, fix them. A fresh air leak means certain death for any 2 stroke motor.

The keys to long life for these little 2 stroke motors are, proper mix and proper oil, no air leaks, and no over speeding of the motors. Enjoy the ride...
 

jasonh

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Jun 23, 2008
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Longmont, CO
To find air leaks: with the motor idling, spray carb cleaner or wd40 where the carb connects to the intake tube, and where the tube connects to the head. If the idle changes, you have a leak.

Remove your spark plug and have a look at the color of the electrode. Should be a deep tan, almost like milk chocolate. Anything lighter and you are running lean. What notch is the E clip set to on the carb needle?
 

velardejose

New Member
Sep 9, 2008
120
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0
Lima, Peru
Hi
Found it
I disassembled the carb yesterday night
I had to push the carb 2 mm to fully seat on the intake manifold and there was a dark oily stain by the clamp over the carb
I disassembled it to see the inside and look for debris (thanks for the carb pics (^))
Found none
When reassembled (carb fully seated on the intake manifold) I started it, idle was way too high
Readjusted the idle screw, idle is more stable at lower speeds
And engine is smoother at lower speeds
There is a mechanical noise, like unlubricated gears, that worries me
I tried it for 15 min, with varying speeds, no wot
No problem
What could be the damage because of this?
Should I drive it till it fails?
Should I hear a second opinion?
Thanks in advance
 

velardejose

New Member
Sep 9, 2008
120
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Lima, Peru
My local representant claims that the gears should work with little lubricant to allow some 'mating' before lubricating
I will do it today
I enjoy my turbo car + SQ sound system (listening mydisc from autosound 2000 today) but bike is more fun, uses less gas and is less pollutant
Jose
 

velardejose

New Member
Sep 9, 2008
120
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0
Lima, Peru
Hi
Took my bike on thursday to my local representant because it 'seized' on wednesday again :(
He took it to his mechanic and found a broken ring, probably caused by a lack of oil
I called today and he told me the repair will be covered by the warranty, but that left me worried
Was that caused because of the air leak I found?
Lack of lubrication...
I am sure I shaked the container for the oil premix
This is the oil I used
http://www.repsol.com/imagenes/pe_es/rm 2t_tcm18-438964.pdf
I use the mb to go to work, flat streets at almost wot with a 220 lbs load
He tells me to keep using 40:1 fuel to oil ratio but I want to use 30:1
Peace
 

velardejose

New Member
Sep 9, 2008
120
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0
Lima, Peru
Sorry there was a confusion
Piston and rings are ok
Seems that the failure is in the bottom end
Local representant offered me to install a new engine
Thanks for your answers
 

Jneff

New Member
May 15, 2011
16
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0
florida
i have a similar problem... If there's not enough oil in the engine, is there an immediate problem? on a brand new engine. this same kind of thing happened to me, the bike pedals will not move without a great amount of force, with or without the clutch pulled back.
 

DaveC

Member
Jul 14, 2010
970
1
18
Boise, ID
you bumped a 3 year old thread.....
Bumping threads is accepted procedure here if it pertains to the problem at hand.

There are two kind of lean in a two stroke motor; not enough oil in the mix or not enough fuel for the air entering the motor. 24:1 is a pretty good ratio for a new motor. 16:1 is just too much oil. Run a gallon at 24:1 then use a 32:1 ratio from then on or for 1 more gallon then if your going to switch to a 100:1 oil that would be the time. Two gallons of of a rich oil mix should have allowed the break-in of all the parts.

Too lean of a fuel/air mix is very bad. Not enough oil for the parts and it makes the motor run very hot. Hot enough to start things melting. The aluminum around the exhause port is usually affected and the piston at the exhaust port will start to melt and transfer aluminum to the ring grooves causing them to fail and it just gets worse from there.

Using a very small skim of RTV Red hi-temp silicone on the intake pipe and the carb mounting lip. when you push the two together a small "o" ring like bead will form in front of the intake lip. This should keep any possible air leak from forming. Do not gob it on, a thin layer is enough. ;) usflg