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Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 4:43 am
by ghpiaggio
I've just completed a major tidy up on the NQ50 - 1985? model. But it has 'issues' that I can't seem to find covered
exactly in other posts here.
It starts great when cold, Idles really fast though. The bystarter then leans it out and slows the idle to almost stall it as it warms up. It blows lots of (very blue) smoke.
It won't rev to max - even on the stand, and needs help to move from a standstill with wide open throttle. On the road it will do 20mph max. and that takes wide open throttle and approx 30 secs to get to that. It only seems to be running about 1/2 revs. When warm, it struggles to maintain idle and frequently stalls.
HELP!!
I have cleaned petrol tank and fuel. Cleaned carb twice with aerosol, checked float and float level - OK, reset air and idle screws. Checked CDI, Bystarter and rectifier with meters - All OK. Checked air filter - OK. It has strong spark and new plug, but plug is wet and oily. Compression is 90psi. Muffler is clear, no soot build up.
WHAT AM I MISSING???
HELP!!
Can the inlet reeds play a part in this???? WHAT DO THEY
ACTUALLY DO?
Cheerz
GRAHAME
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 9:05 am
by Wheelman-111
Greetings:
Reeds can do this if they're starting to gap. Before you delve in there, first try replacing the filter element with a new one. The foam changes its properties over time and resists airflow. It sounds like you're simply running very rich and a soggy old filter could to that. Easier to reach and no messy gaskets to scrape.
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 9:50 am
by noiseguy
Ooo, I hope you looked at that air filter b/f you fired it up. They disintegrate and make a mess of carbs and reeds.
Sounds like a plugged pilot jet. Clean clean clean. Also sounds like you're running lean. Check for air filter condition as well as leaks around the manifold.
I don't suppose you installed the thermal decoupler (brown piece) in one of the 3 wrong of 4 ways that it can be installed? Look for the arrow on the side, should be facing forward. If you don't see the arrow or it point backward, that's a problem.
Excessive smoking is normal after long storage; the oil pump dribbles and fills up the bottom end, smoking like crazy and fouling plugs. Speaking of plugs, you should check yours.
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 2:26 pm
by Wheelman-111
Greetings:
Agree with Noiseguy in all but this: How'd ya figure a wet oily plug sounds lean? Running on bystarter until it hands off to the plugged pilot circuit?
I missed one question:
Can the inlet reeds play a part in this???? WHAT DO THEY ACTUALLY DO
??
They ensure that the inhaled mixture doesn't simply blow back into the intake tract and out the carb. A 1-way valve upon which the engine tuning is predicated. If they go bad, there's no way to tune the engine to run clean. My Aero behaved similarly when one of its reeds developed a crack.
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 2:33 pm
by Bear45-70
Wheelman-111 wrote:Greetings:
Reeds can do this if they're starting to gap. Before you delve in there, first try replacing the filter element with a new one. The foam changes its properties over time and resists airflow. It sounds like you're simply running very rich and a soggy old filter could to that. Easier to reach and no messy gaskets to scrape.
If the reeds are staying open (Gapped? That's a new one on me) then starting would be an issue long before they would cause a problem while running. I've seen and engine run with one of 4 reeds missing, starting required a 3/4 drill motor on the flywheel nut turning the motor at 1800 rpm, wouldn't idle below 1200, but it ran. Beside at higher RPM the reeds never close (at least according to a degreed 2 stoke design engineer I know). I would suspect one of 2 things if it is not the old filter. Super high float setting or a throttle slide not opening all the way or both.
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 4:58 pm
by ghpiaggio
Thanks for the tips so far. UNFORTUNATELY I'm hearing OPPOSITE OPINIONS here guys, and don't know what to follow. Great advice and TRULY appreciated, Thanks. I just don't wish to make things worse, or spend time unnecessarily.
MORE INFO for you to go on:
I tried the motor with no air filter foam - it didn't alter the lack of revs or lack of 'crispness'.
The filter is spongy and springs back into place when depressed. I
can blow through it.
It's had
a NEW plug twice, but they fouled after only 30 seconds running. Wet with black oil/gas mix.
Throttle slide has
been checked for movement - approx 25mm (1 inch?). Needle is set on the middle leanness notch.
Re assembly of decoupler, bystarter and jets etc
all checked. OK
CAN THE FOLLOWING BE OF IMPORTANCE?
There is always a
smell of petrol coming from the carb area - even after 2 thorough cleans. Gakets and 'O' rings
look perfect. I'm yet to see any gas leaking from anywhere, but it smells!!!
Could this be a FLOAT SETTING issue?
Thanx again
Here's hoping
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 5:44 pm
by Bear45-70
You are obviously too rich. So it could be a bad float, to high a float setting or a leaking needle and seat that the float operates of a combo of all three. I have never seen bad reeds make you too rich. I don't remember and I'm too lazy right now to reread the whole thread, have you done a compression check?
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 5:47 pm
by Wheelman-111
Greetings:
At this point you have little to lose but the reed block gaskets. You've done a remarkably thorough job of checking everything else with this possible exception, unlikely though it may be:
Sometimes the flywheel on the alternator side can become misaligned with respect to the crankshaft. The little sliver o'steel called the Woodruff Key can be missing or broken. If that happens, you get very early or very late spark and ensuing mayhem.
Pull the reeds first and have a close look. Flash I actually ran with this one:
That was an attempt at 0.25mm thick straight carbon material. Not strong enough.
It needed full throttle and cranking for several weeks to fire, but once started it was almost normal as long as the revs stayed above 5000. Black wet plug and no low end for sure! If your reeds look fine and still feel springy, see above.
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 6:04 pm
by Bear45-70
Wheelman-111 wrote:Greetings:
At this point you have little to lose but the reed block gaskets. You've done a remarkably thorough job of checking everything else with this possible exception, unlikely though it may be:
Sometimes the flywheel on the alternator side can become misaligned with respect to the crankshaft. The little sliver o'steel called the Woodruff Key can be missing or broken. If that happens, you get very early or very late spark and ensuing mayhem.
Pull the reeds first and have a close look. Flash I actually ran with this one:
That was an attempt at 0.25mm thick straight carbon material. Not strong enough.
It needed full throttle and cranking for several weeks to fire, but once started it was almost normal as long as the revs stayed above 5000. Black wet plug and no low end for sure! If your reeds look fine and still feel springy, see above.
Like I said a broken or bad reed makes a single cylinder 2 stroke next to impossible to start. He says runs poor but does start and runs rich. Reeds don't cause that.
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Wed Sep 02, 2009 6:04 pm
by ghpiaggio
Thanks guys.
Compression is 90 Psi, so not too bad? Probably indicates the reeds are doing their job??
The float - floats and has no holes. The stop needle seats properly, but I haven't measured the cut-off point height - may be too low.
Just one other symptom.
The idle screw is only 1/8 turn from all the way in when engine is warm. Must be a carburretor issue - surely?
Will check the flywheel alignment and prescence of the shaft 'key' after having another go at the carb.
Thanx heaps...
Any more ideas?
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Thu Sep 03, 2009 12:34 am
by ghpiaggio
OK.
Took the day off work and 'played' in the garage all day.
Tried all suggestions and still the same fault when its warm.
Will try a new thread. Thanx................
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Thu Sep 03, 2009 12:58 am
by Wheelman-111
Greetings:
Not for lack of trying, GH! It sounds like the float is your very last option, but I'd still examine the reeds directly. 90 sure sounds pretty good, but unless you look, you won't know for sure. The float isn't adjustable, so if it's off it's probably broken. Imagine, 25 year-old plastic soaking in gasoline failing like that!
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Thu Sep 03, 2009 5:08 pm
by ghpiaggio
Hi.
I got some surgical tubing and put it onto carb drain fitting. Turned the tube into a "u" bend and opened the release screw. Petrol level is just below the join of the carb halves. So, its not over filling. So, float is OK and shut-off is operating fine.
While I was there, I added a paper gasket to the carb body as the 'O' ring was a little compressed and allowed a small mist of gas to exude. Perhaps that was the gas smell I had before?? Dunno.
Physically inspected reeds and manifold gasket - all Ok there, too.
FRUSTRATING!!!!@!!!!!
What else?
GRAHAME
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Thu Sep 03, 2009 8:12 pm
by noiseguy
OK guys. The way you get a wet plug and a lean engine is 1) lots of goupy oil in the bottom end of your long-stored engine slinging around 2) Some lean-causing thing on the air side (like maybe too much oil) I had one old engine (10+ years) so full of oil it was hydrolocking. I had to pull the jug and turn it over into a pan to dump all the old oil out. Ran much better afterwards
Need to ask: Is it 4-stroking up to 20 MPH (shaking, hitting every other revolution) or just not going any faster than 20, but staying in two-stroke firing, then it's lean.
If this runs with the idle screw nearly seated, there's an air leak of some sort making up for it. That's the main reason I think it's lean.
That paper gasket should not be there in the carb circuit. You'll need to run down some nitrile o-rings at the hardware store.
What size is your main jet? Should be #65 or 68.
ghpiaggio wrote:Thanks guys.
Compression is 90 Psi, so not too bad? Probably indicates the reeds are doing their job??
The float - floats and has no holes. The stop needle seats properly, but I haven't measured the cut-off point height - may be too low.
Just one other symptom.
The idle screw is only 1/8 turn from all the way in when engine is warm. Must be a carburretor issue - surely?
Will check the flywheel alignment and prescence of the shaft 'key' after having another go at the carb.
Thanx heaps...
Any more ideas?
Re: Spree (Nifty 50 here in NZ) - POOR RUNNING!! HELP!
Posted: Thu Sep 03, 2009 9:17 pm
by ghpiaggio
noiseguy wrote:OK guys. The way you get a wet plug and a lean engine is Some lean-causing thing on the air side (like maybe too much oil) I had one old engine (10+ years) so full of oil it was hydrolocking. I had to pull the jug and turn it over into a pan to dump all the old oil out. Ran much better afterwards
Thanx for the response, it really is challenging me as to what/where to head - other than the dump!!!
Need to ask: Is it 4-stroking up to 20 MPH (shaking, hitting every other revolution) or just not going any faster than 20, but staying in two-stroke firing, then it's lean.
No obvious shaking or anything else. Just not crisp running, like bogging down. Takes forever after twisting throttle for any response and needs to be pushed to move from standstill.
If this runs with the idle screw nearly seated, there's an air leak of some sort making up for it. That's the main reason I think it's lean.
That paper gasket should not be there in the carb circuit. You'll need to run down some nitrile o-rings at the hardware store.
Will try, but what difference will it make its only a few 1000ths (maybe 0.4mm?)thick
What size is your main jet? Should be #65 or 68.
Its a 68.
Thanx again
GRAHAME
ghpiaggio wrote:Thanks guys.
Compression is 90 Psi, so not too bad? Probably indicates the reeds are doing their job??
The float - floats and has no holes. The stop needle seats properly, but I haven't measured the cut-off point height - may be too low.
Have measured - is corrrect height.Just one other symptom.
The idle screw is only 1/8 turn from all the way in when engine is warm. Must be a carburretor issue - surely?
Will check the flywheel alignment and prescence of the shaft 'key' after having another go at the carb.
Thanx heaps...
Any more ideas?
