300cc Loncin eng

[DesertDog]

well b-4 i knew anything in this business it was assembled and delivered , the customer called me up the next day complaining, and the complaints never stopped , so i apologized,

picked it up to work on it and see what it was doing , it never dawned on me back then to do a compression test, i messed with the carb for 2 wks , :evil: confused, changed the oil , tore the side covers off, looked at what i could at the time of no experience,
some one mention to me on TT to do a valve clearence check, did that no clearence, you could'nt have put any tool between the valve and lifter,
still no thought of a compression test yet.


after two weeks when delevered to the customer and he gave me plenty of time to fix it and i refunded the guys money back,
my distributor has refused any help .
now that your up to speed.


so it is a high possibility the valves got bent , to me anyrate, cause when i adj. them it finally started easier and you could go with out it dieing when you let out the clutch.

i'll do the wet test as well, leave no stone unturned

thanx guy's for the input

[katoranger]

I would suspect a damaged valve. You may be able to replace just the valve, but it is also possible the cam is damaged.

Best possible solution is a replacement head/valves/cam.

Is this a pushrod engine?

Allen

[DesertDog]

no all is moved by the cam, ie: chain down to crank from cam, i've go some old pics see if i can link it here. the lifters are bolted down to the valve cover, no push rod to actuate the lifters
DD


http://i273.photobucket.com/albums/j...2/IMAG1363.jpg

http://i273.photobucket.com/albums/j...2/IMAG1371.jpg

[katoranger]

Okay, OHC engine then. The cam may have flattened lobes and you would need the spec sheet and a dial indictor to tell probably.

Possible the the valve stem is bent too.

After the wet compression test let us know the results. That will get the problem narrowed down further.

I am suspecting a bent valve/flat cam from the valves too tight. Most likely an exhaust valve.

Allen

[DesertDog]

okay,
do that when i get off of work , thank you
DD

[DesertDog]

Originally Posted by DesertDog

okay,
do that when i get off of work , thank you
DD

did the wet test b-4 leaving for work , squirted about 3 pumps of oil in the cylinder, put the tester on , cranked it over, it went up to 115lbs, did that twice, same both times 115lbs stedy,
so leave a post for me on what to do next and i will check it out tonight, i am late for a date ( my j.o.b.) gotta go
DD

[katoranger]

That indicates rings. It may be that a hone job and some new rings might fix it. It may just need a light hone and then a proper breakin.

If it was broke in with synthetic oil the rings probably didn't seat or it wasn't heated up enough then let cool etc.

It could be that the wrong rings were used etc.

Either way you will need to pull the top end.

This will give you a chance to inspect the valves, cam and head.

Allen

[DesertDog]

hey thanx Kato
some friends at work say the same thing , one told me i may have put to much oil in there and caused the oil to set up on the valves creating a seal , thus giving it better compression, since it did not smoke,

but none-the-less i need to break it down as mention and then i can tell
thanx a bunch.

hey kato can you leave me a post for where to get valves and rings, if and when needed,

DD

[katoranger]

I don't know about parts for a loncin.

Might be a Bruce question.

You would need to call him.

Allen

[DesertDog]

well i found out that this engine (300cc Loncin ) is a look-a-like to the DRZ250 (05), dont know yet on the internal parts per say, Saturday is the break down day, to see what the ? went on inside this motor
could pics be wanted for everyone ? nah!
DD

[katoranger]

I would like pics. If it really is an DRZ copy or relation I may be able to use one.

Allen

[DesertDog]

anyone got a good camera 8O ,
a steady hand ,
this is'nt gonna be like my old 327 chev i take it, that was one of the most simplist motors to work on.

hope this one does'nt give me fits.....

going to brkfst , see ya

[VinceDrake]

Hey there!

Just thought I'd jump in here with some useless info-- If the valves were that tight, 0 clearance, more than likely, the problem is not bent valve, but *Burnt* valve, most likely exhaust. Bent valve would more likely result in 0 compreshkin, normally they hang badly. Burnt valve can kind of seal at low speeds/pressures, especially with a little 10w30 in there filling in the gaps.

If you're interested A couple ways of checking without tearing it apart--

If you have a smoke-machine (Usually only works best on *very* burnt valves)
--Turn cyl to TDC.
--Pull plug and Insert Smoker outlet into the spark plug hole.
--Crank the smoker flow rate up as high as it goes.
--Pull oil dip stick and air filter (Put this step up 3 spots, k?)
--Watch for where the smoke comes out.
--Dip stick hole=Rings/piston/bore
--Carby=Intake valves
--Exhaust=Exhaust Valves

If you don't have a smoker, you can use a cylendar leak down tester, of just hook up shop air to your compression tester, with it in the sparkplug hole, only thing is the crank has to locked in place. This level of air pressure, will tend to move the piston/crank, etc. in gear with the park brake on should work.

--Same set up as previous, But now instead of look for smoke, listen for air escaping, in cases of small leakage,, I've used soap bubles over the carby and exhaust (How to make a China-ride blow bubbles!)

Final Possibility-- The Good Ole Boy Way
I'm Sure I'm going to catch he11 for this but!

--Remove Sparkling Plug.
--Remove Exhaust and Intake Manifold.
--Roll the pistom Before top dead centre about 1 to 1.5 inches
--Fill Combustion chamber with diesel fuel
--Re-install sparkling plug
--Turn Crank by hand towards TDC. *NOT* hard-- Don't want to bend the conn rod! I'm thinking Maybe 15-20 Ft. Lb Torque, max.
--Hold under pressure until diesel drips out somewhere.
-- A crank case full pf diesel indicates rings, and is very messy.

Checking Timing Chain The Good Ole Boy Way!

As Long as we know where there's a 0 mark on the flywheel, that's really all you need.

--So! At TDC We know Both valves are closed, right!
--At 180 degrees of cam rotation (one full crankshaft revolution) The engine Goes from exhaust stroke to intake stroke, correct? Therefore! If you can find TDC, and go one complete crank rotation, as the 0 mark on the crank just passes, the valves should go from exhaust to intake (Flip over, whatever) The point at which both valves are slightly open, should line up with 0 on the crankshaft (Can be measured with screw driver in plug-hole too.) IF it's not, the timing chain is out of time.

So yeah, that was really, really long. Sorry about that. Hopefully you can use some of it, maybe it'll hlp isolate things without having to tear the thing apart. Best of luck man!

--Vince

[DesertDog]

either way i have to take the head off, and i just busted the clutch cover, looks like a round thingy with flat fingers and the clutch plates go on the inside, i have to take this off to remove the nut that holds the timeing gear on the bottom, to get to the chain and remove the chain,,


but i do appreciate all that info and i fallowed it very well, thanx V/D

[VinceDrake]

Yeah, either way you're going inside, shortly after I posted, I kinda realized that would have been useful about a week ago-- Kinda Useless now... Sorry About that.

I'll try to be more useful in the future

Just for my curiosity, would you be willing to take a couple of shots of the engine when you're in there? I know like, zilch, about the 300cc engines-- Is it about the same thing as the 200cc OHC?

Best of luck with the thing, hopefully it starts treating you decent, man!

--Vince