Sorry if this is a stupid question. I'm a girl. I've been holding onto my blaster sense my dad passed away and it was always kind of our project together. I bent a rod in the crank shaft and had to have the whole thing rebuilt. It sat in a box for about 6 years until I took it to a mechanic who put it back together. Well I just got it back in August and I have under 10 hours on the motor. While riding Sunday the top end blew. Before it happened, it was loosing power and seemed very bogged down. I'm taking it back to the mechanic that fixed it the first time Wednesday. I'm just curious how this could of happened when i had the motor rebuilt. It's still turning over and has some compression. It's not siezed. What are the chances I will have to bore out the cylinder? Could it be the mechanic who fixed it last time fault for this happening?
Blown top end, not siezed, some compression
- Thread starter Yamaha_girl712
- Start date
Welcome to the forum, none of those are stupid questions.
There are a few things that could have caused you to lose compression and do in the top end. Air leaks, wrong jetting, a cylinder bore that's out of spec could all cause that. If the crank was bad, like you mentioned, it could have also helped do it in.
If the cylinder is out of spec's, its going to need bored to the next acceptable oversize. The Builder should have the new piston in hand to make sure that the tolerences are met.
Hope that helps you out some.
There are a few things that could have caused you to lose compression and do in the top end. Air leaks, wrong jetting, a cylinder bore that's out of spec could all cause that. If the crank was bad, like you mentioned, it could have also helped do it in.
If the cylinder is out of spec's, its going to need bored to the next acceptable oversize. The Builder should have the new piston in hand to make sure that the tolerences are met.
Hope that helps you out some.
It could be his fault, but can't say for sure. What do you mean by "the top end blew" It sounds like it was probably not leak down tested, broke-in or jetted properly, which builders don't usually do. 2 strokes take a little work, you can't just hop on and ride. Pretty good chance it will need bored again from the sounds of it. We would all be glad to do what we can to help get your project going again.
After 6 years of standing there is a good possibility that the crank seals got leaky.
If the mechanic did not test the engine for air leaks a lean mixture may have caused piston failure resulting in your problem.
Before the engine is pulled down have some one, or you perform a leak test on it to make sure it is air tight.
If the mechanic did not test the engine for air leaks a lean mixture may have caused piston failure resulting in your problem.
Before the engine is pulled down have some one, or you perform a leak test on it to make sure it is air tight.
Sorry for your loss
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Hopefully you will be armed with enough information that they won't blow you off.
1. You need to ask if it was leak-down tested after assembly.
2. Ask if it was heat cycled and head and base nuts retorqued after heat cycles. Heat cycles are warm up, cool down three times so that parts take a "set" so to speak.
3. Do you have complete list of all parts installed, labor, and machine work on rebuild? Crank seals should have been replaced with new crank.
Not to be condensending as not everyone, male or female, correctly identifies parts. The very top of the engine is the head, the center part that the carb and exhaust attach to is the cylinder (or jug). Do you see ANY oil leaking between the two, head and cylinder ? If so you may be lucky and the head wasn't retorqued after heat cycles.
Don't let them blow smoke up your skirt. If it sounds fishy, it probably is. If possible send them a link to this thread, let them know they aren't getting away with doing their job wrong!! Post up what they say, and ask more questions.
Did they give you any specific instructions as to break-in when you picked it up?
Just know your Father is proud of you for not giving up on it.
Come on guys, ya'll have to do better so that Ben Dover doesn't take advantage of a damsel in distress.
Screen name :check
Avatar : check
Admits being female : check
I bet you're a GIRL !!
WELCOME !!
Hopefully you will be armed with enough information that they won't blow you off.
1. You need to ask if it was leak-down tested after assembly.
2. Ask if it was heat cycled and head and base nuts retorqued after heat cycles. Heat cycles are warm up, cool down three times so that parts take a "set" so to speak.
3. Do you have complete list of all parts installed, labor, and machine work on rebuild? Crank seals should have been replaced with new crank.
Not to be condensending as not everyone, male or female, correctly identifies parts. The very top of the engine is the head, the center part that the carb and exhaust attach to is the cylinder (or jug). Do you see ANY oil leaking between the two, head and cylinder ? If so you may be lucky and the head wasn't retorqued after heat cycles.
Don't let them blow smoke up your skirt. If it sounds fishy, it probably is. If possible send them a link to this thread, let them know they aren't getting away with doing their job wrong!! Post up what they say, and ask more questions.
Did they give you any specific instructions as to break-in when you picked it up?
Just know your Father is proud of you for not giving up on it.
Come on guys, ya'll have to do better so that Ben Dover doesn't take advantage of a damsel in distress.
Thanks for all the replies! There is no oil leaking that I can tell. I did get a sheet of all the work done. He never told me any thing about breaking it in. Oil injector is working. I checked the oil periodically throughout the day. I was planning on blocking the injector this weekend and pre mixing. I'll ask about the tests that were done and I will request that he does them this time. I can hear air escaping from the head when I try to turn it over.
Perhaps you have a bad head gasket? This something you can do yourself! Have faith in yourself. Go girl!
You could start by checking to see that the cylinder head nuts on the top of the head are snug. If not,... snug them up, then try to see if you hear the noise. Could you post a short video of the noise it makes when kicking it over?
Unless you wish to use an oil that will not inject, leave the injection on it, is perfectly reliable and delivers the correct amount of oil for the Blaster engine.
When it blew it made a pretty loud bang sound and started hissing like if you were to slash a tire. It lost all power and died. It was smoking a little from somewhere in the top end. I'll check over the head gasket tonight. The piston and rings are new... Less than 10 hours of ride time on them.
you need to upload it to you tube or tiny pic photobucket ect
and copy and paste the url in here.
that is from the exhaust only if your lucky /or base gasket it happens to alot of them.
on another note in your video it looked like your crankcase vent tube is missing?
if it is it will allow dirt/water in your gears/clutch area.
look up through the cylinder from exhaust and see if it is scored or take pics or summin.
nobody is going to know unless it is taken apart and inspected...
if your mechanic is going to fix it then i dont see why you could not just pull the cylinder off to have a look take pics/then give it to him if not able to fix it
on another note in your video it looked like your crankcase vent tube is missing?
if it is it will allow dirt/water in your gears/clutch area.
look up through the cylinder from exhaust and see if it is scored or take pics or summin.
nobody is going to know unless it is taken apart and inspected...
if your mechanic is going to fix it then i dont see why you could not just pull the cylinder off to have a look take pics/then give it to him if not able to fix it
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