should i rebuild my engine

[blastermodder]

ive never had any problems with my engine till more lately i have weakish spark and the reeds have too much clearance. so i was thinking i would change. but i decided to take the top end off this thing looks brand new except the rings may need to changed. i bought an '04 blaster and parted out the old engine and 04' roller in 06' with less then 100 hours on it!!! but hey i made $1400 over retail price I:I with an old but good engine and i got a new engine for my '98. would it even be worth it to rebuild, or should i just spend 60 bucks and get it running as is.

 

[super noober]

if all is well just hone it and get some new rings, no point in boreing when its not NEEDED.

 

[sheeblast]

i am a little confused. what is going on in your post?
you start talking about your engine then about you selling an engine, then about spending money on an engine.

so i have this straight, you have a blaster with a weak spark. you are going to spend $60 on what?

 

[slickerthanyou]

if all is well just hone it and get some new rings, no point in boreing when its not NEEDED.

For sure!

i am a little confused. what is going on in your post?
you start talking about your engine then about you selling an engine, then about spending money on an engine.

so i have this straight, you have a blaster with a weak spark. you are going to spend $60 on what?

Head scratching?!?!?!?

 

[sheeblast]

i am just making sure i understand what is going on before i give out my advise.

 

[hotrodaj_2]

Ya, I'm a little confused. Do a leak down test on the engine and see how many pounds she will hold. You should be around 120 to 150psi, any lower and she is not 100 percent. If it holds good pressure then I would leave it alone and run it.

 

[sheeblast]

^^^ that isn't a leakdown test, that would be a pressure test. a leakdown test is something else.

 

[BugsBunny]

Friends don’t let friends post drunk :-/

 

[little3mil]

LEAK TEST !!!!!!!!!!!!!!!1 ALERT pm me for one bro

 

[little3mil]

Ya, I'm a little confused. Do a leak down test on the engine and see how many pounds she will hold. You should be around 120 to 150psi, any lower and she is not 100 percent. If it holds good pressure then I would leave it alone and run it.

wow you should buy one from me two man it comes with detailed instructions bro lol
you totally wrong dude and that would prob mess your motor up I:I

to me it sounds like your mixing up the two important tests

1 leak test

2 compression test

 

[brandoz28]

yup. he's definitely mixing up a compression test and a leakdown. you only want to go to 7ish psi for a leakdown


you need to be a little clearer about what you have going on with the motor.

 

[hotrodaj_2]

Oops, ya I mixed it up. You can call a compression test a leak down also, ( I grew up racing 4 strokes and you dont pressure test the crank case in those, ever. My mistake. You know what I ment with those numbers though, I want to know what p.s.i. the combustion chamber will hold. He's getting metal in the spark plug, I am going to look first at the piston area and second everywhere else. Damn one mistake and people jump all over it like their experts. Chill out people, just help the guy!

 

[2stroke4ever]

pretty sure they're just trying to clear up what was said before someone makes a mistake testing or a wrong diagnosis, but your right if you were a 4 poke guy you wouldn't be concerned about your crank case holding pressure, either way i'd check your end gap on your rings or if you jug looks worn do a hone and rings, don't waste time and money on a bore and piston and all that if you don't need to, hell if compressions good why even mess with it at all

 

[scotj77]

yeah I was just about to say hotrod usually seems to know what he is talking about, he must have just mistyped what he was trying to say

 

[sheeblast]

a compression test cant be called a leakdown test ever.
leakdown test is trying to find a leak somewhere. and yes, you should still do a leakdown test on a 4-stroke. you could find a leak in your intake system or your head. something a compression test won't test for.
compression test is finding the static pressure inside the cylinder from the piston compressing the air.

and yes hotrod, i am an expert.

 

[hotrodaj_2]

Hold on guys, were in the presence of a expert! First of all, I have never seen anybody do a "laekdown" on a 4 stroke. From 1 cylinder to 8, I've never seen it. There's more than one way to do a compression check. You can spin the engine over to get it or like in our sprint car engines ($40,000) we blow air into chamber and see what percentage we loose with valves closed and at BDC. That is a far better way to do it. That is where I got my terms mixed up. Second, as far as the crank case goes, what are you gonna do? You gonna test it like a Blaster engine. That's crazy, lmao. The blow test will check everything in combustion chamber including the heads. A intake problem would be found a little like the blaster method in that you would spray soapy water on it while the engine is running. You have breathers, intake , exhaust and probably a couple more things to plug up to test a 4 stroke crank case with a 100 percent seal everwhere, that's crazy. Your thinking small dude. Think V-8. If you wanna continue, bring it. But I'm calling this dead. Mr. Expert

 

[sheeblast]

Hold on guys, were in the presence of a expert!

yes i am an expert

First of all, I have never seen anybody do a "laekdown" on a 4 stroke. From 1 cylinder to 8, I've never seen it. There's more than one way to do a compression check.

It is LEAKDOWN

You can spin the engine over to get it or like in our sprint car engines ($40,000) we blow air into chamber and see what percentage we loose with valves closed and at BDC. That is a far better way to do it. That is where I got my terms mixed up.!

how can forcing air into the chamber give you static compression? i can force over 300psi in an engine with the valves closed and it hold.
static compression is how much the air and fuel is compression from BDC to TDC.

Second, as far as the crank case goes, what are you gonna do? You gonna test it like a Blaster engine. That's crazy, lmao. The blow test will check everything in combustion chamber including the heads. A intake problem would be found a little like the blaster method in that you would spray soapy water on it while the engine is running. You have breathers, intake , exhaust and probably a couple more things to plug up to test a 4 stroke crank case with a 100 percent seal everwhere, that's crazy. Your thinking small dude. Think V-8. If you wanna continue, bring it. But I'm calling this dead. Mr. Expert

you can go ahead and run your engine and put soapy water on it to find a leak. i rather not want to put soap and water into my engine. and how would the find a leak anyways? do to the cheap ass leakdown test, you use carb cleaner. if there is a leak, it will cause the engine to rev up.
also as far as doing a leakdown test on a v8, it isn't that hard. but we are talking about a 4-stroke quad. all you need to do is make sure the intake valves are closed. put around 6psi into the intake system. this will check for anything leaks on the intake. you spray soap water on this as it will make bubbles because air is being pushing out through the soapy water, not being sucked it.

 

[hotrodaj_2]

So you can call a compression test a leakdown, we do all the time when checking things like I said. He does'nt even have a 4 stroke so why did you even bring it up. I was trying to tell him to check the combustion chamber and got my terms mixed up. Who cares what the compression is, If you put 300 psi in combustion chamber and you "leakdown" or can only hold 150psi then your leaking 50 percent and need a rebuild, if you leak 10 percent you need a rebuild. All he cares about is does he need to look into thing further. We use only the highest quality gaskets on my big engines and we never have leaks but if it happened then a spray of carb cleaner or soapy water is the way to find it, not to pressurize the crank case. You said there's no way and basically I do'nt know what I'm talking about. I did'nt come at you like that and frankly your wrong. you can call it that and you do'nt have to pressurize your crank case on 4 strokes. Why are we talking about this on a 2 stroke Blaster forum. Just help the guy!

 

[sheeblast]

I am helping the guy by giving him good info.
and you are the one that brought up 4-stroke engine.

 

[hotrodaj_2]

You have given no good info, all you have done is bust my balls and I have 'nt seen anybody check a engine your way yet. You might know your sh_t but unless you make a living building engines your not a expert, even the engine builders on this site do'nt call themselves experts. Chill out and tell the guy what he should do, I gave my advise.