Started Smokin Alil?

[rooster300ex]

Today i was romping around in the sand pretty good, and i noticed my 300ex started to smoke under deaccelaration, so i rode back to the campsite to load it up, then when i got home i fired it up let it idle for a second and seen if it was smoking like it was it it wasn't doin it anymore. what do ya'll think? And it was rebuilt very recently. probably doesn't even have 20 hours.

[rooster300ex]

bump

[bwamos]

What color is the smoke?

Black or blue?

Black, you probably just need a jetting adjustment.

Blue, you probably didn't hone your cylinder before installing the new rings.

If it is deceleration my bet would be valve seals. when u let off the gas extra oil goes up into the valvetrain. just a tho. about a 5 $ part.

[rooster300ex]

it was blue. and its not doing it now. i think it starts doin it when it gets too hot. i'm going to stop running 110 fuel, and check into the valve guide thing. When the engine gets hot can it make the valve guides leak more, and when i replace the valve guides is that all i need to replace them. And the sleeve is brand new the piston,rod everthing is, except for the valve train(new cam though)

[bwamos]

Leaky valve guides usually causes smoking at startup not high rev.

Blue smoke on decleration is a tough one.

It can do that if the rings didn't seat right. Sucking oil up past the rings.

I'd try switching to premium pump gas first. 11:1 is fine on premium pump. Mix 25% race if you're worried about it. But, there's no way you need 100% 110 octane.

[rooster300ex]

I'm still not sure what it is. hell i'm afraid to build it up anymore. hell its still kinnna stock just a cam,stock bore 11:1 piston and its already ****ing up on me after prolly 10-15 hours. i hope its just in the valve train.

[fitethesystom]

The answer:

Do a leakdown test. You'll know what it is.

[rooster300ex]

Originally posted by fitethesystom
The answer:

Do a leakdown test. You'll know what it is.


What is a leakdown test?

I think it is like checking the compression but u leave it at tdc and see how long it holds the psi.

[rooster300ex]

I doubt it is the compression. all i have to do is bump the starter button and it busts right off healthy.

[fitethesystom]

A Leakdown Test:

-----------------------------------
What does it diagnose?
-----------------------------------
1. Compression loss for one.
2. Leaky valves.
3. Leaky rings, bore
4. had headgasket
5. and general condition of the motor.

--------------------------------------
How is it done?
--------------------------------------
Leak down tests are done with a device known as a leakdown tester, which can be purchased at an automotive store for 60 dollars and up.

Next you need shop compressed air.

-Set your compressed air level to 100 PSI
-Set engine to TDC (Top Dead Centre)
-Remove the spark plug
-Screw in the appropriate threaded nose end
-Connect tester.
-Watch the reading (make sure your at 100psi), if it drops from 100 to 90 you have 10% leakage, if it drops to 80, you have 20% leakage, and so fourth.
-Next is to secure the motor from spinning (put it in gear) and open the valve to let air freely flow into the cylinder, if you hear a hiss or noise, you and your leakdown is more than 10% you have a problem.
-Now we need to find out where. Listen with your ear. If it's coming out of the exhaust port, you have a leaky valve. If it's coming out of the intake, you have leaky intake valves, if you remove the breather hose on the engine bottom end and you feel air or hear hissing from lower end you have bad bore/piston damage/piston shrunk/bad rings/taper.
-Now you can tell what you will need and how much it will cost.
-All shops use this method and 99% of the time it can be narrowed down without even having it apart.
-Your local dealer may also offer this for aprox $70.

Hope this helps.

[fitethesystom]

Try this, too.

With your compression tester, take a cold compression test, record your result, now, add 1 table spoon of engine oil. Now test it. Did your reading increase? If so your rings/bore/piston are worn and will need replacement. If not, it's your valve seals or other.

[Dave J.]

I Have to ask, have you changed the oil after break in? If not that is what I would do. With only 20 hours on it if, its a hour here and a couple of hours there you might want to change the oil. It might be just that. Just my thoughts with out much history of the motor and the break in piriod.

[fitethesystom]

Another likely possibility is your ring's didn't seal that well to the cylinder during the break in...

[fitethesystom]

do leakdown before u decide anything.

[rooster300ex]

Originally posted by Dave J.
I Have to ask, have you changed the oil after break in? If not that is what I would do. With only 20 hours on it if, its a hour here and a couple of hours there you might want to change the oil. It might be just that. Just my thoughts with out much history of the motor and the break in piriod.


The motor is already broke in, And i change the oil in it regularly. As soon as it was broke in i change the oil, i use HP4 10 40 in the cooler months and 20 50 in summer.

[rooster300ex]

Originally posted by fitethesystom
Another likely possibility is your ring's didn't seal that well to the cylinder during the break in...

How long after break in can you tell. cuz its been broke in for awhile and hasnt smoked a drop instead on start up a few times.

[rooster300ex]

Originally posted by fitethesystom
do leakdown before u decide anything.


How much do you think somebody would charge for that. There is noway i have the tools,know how and patients.

[fitethesystom]

Call your local honda dealer right now for a look-over, it's about $70 (1 hours labor). They will do a leakdown and all that and tell you exactly.

As far as telling how well the ring's have set, that isn't a real obvious thing if they didn't, however you may have a little more kick with a tighter ring seal, sometimes the cylinder gets overheated and the oil burns on the cylinder wall causing glazing and this causes the rings to improperely seal to the wall. Many things could be the case, call honda, take it in, pay 70 and it will save you alot of headache.