slow runnning problems

[Mutineer]

The last bunch of times I've been out sailing my longshaft clutched weedless prop (for id purposes) 40 plus has not wanted to run slowly consistantly
As I mostly use it to power into my slightly awkward slip area, I really need to have it working well at slow speeds.
When throttle down it'll run for a bit and then start to get slower and almost quit unless I increase the throttle dramtically. And then it responds slowly, then starts running very fast...It doesn't seem to like any middle ground, or runnning really slow. I did just put a new (slightly longer cable I got from SOS on it) and that seems to work fine though to get it up to full throttle I had to adjust the cable all the way out (on top of the carb)
Any ideas?
I can't quite remember the ideal mixture setting and I've misplaced my shop manual..grrr

[Horsley-Anarak]

It could be a crankcase leak.

Tighten the bolt, including the ones that hold the crankcase and cylinder together.

Also look for a leak where the tiller stub is, quite often they leak there.

H-A

[Ian Malcolm]

It could also be carburettor flooding due to a slightly leaky needle valve making the mixture too rich.

[Mutineer]

What is the correct mixture setting (needle screw height on the carb piston) on the villiers carb for a 40 plus anyway
I knew there was a kind of average setting to start from...where's my %#@%#@ shop manual?

[Taspiper]

Needle screw flush with top of slide to start with. Rich up, lean down.

[Mutineer]

Thanks
I've had some exciting new developments
For the first time it started and then cut out on me
I was runnning it slow at the dock with the clutch disengaged. I pushed off, emgaged the clutch , increased the throttle and was going to motor out of my slip ,
It wouldn't respond to the throttle and then died. Tied up to the other side and spent a while trying to get it to go with it starting, running for a short while not responding to the throttle and then dying. Finally it started running normally so off I went.
I tried to start it leaving another dock in an tight position in strong wind and it started but died shortly after, necessitating some quicxk paddling to stave off disaster
Then in the same high wind, hove-to , started the moptor so I could head into the wind , take down my sails and motor back into the narrow marina , when it stalled again after seeming to run normally and had me drifting backwards towards a barge with my sails all ahoo and no power. I managed to steer into the marina on the jib, narrowly missing a dock and another doat and get into my slip in the lee of the barge...almost had a ^#@#%$ aneurysm!!
I did notice a little dripping from the villiers storm cowl , but I closely examined the crankcase and the block while I was running the carb dry at the dock (acting $#^$#@ normal ) and I couldn't see any of the telltale leaks and or air bubbles.
I set the mixture to minutely above flush prior to heading out today
This motor has been really reliable up to now
Any ideas ?

[Taspiper]

Crap in the fuel, tap or banjo gauze blocked? Shitty fuel? Even if the mixture screw is out a couple of turns either way it should still run. I'd flush and check the entire fuel system first then while your at it points, plug and lead as all is easy to check and doesn't take that long.
Leaking head will allow starting but then stops almost straight away but if you got it to run continuously sounds like fuel problems.

[Mutineer]

Well.
I took checked all the lines, the tank filter, the fuel, the hose,the banjo bolt screen, there might be a bit of crap in the tank. Then I took off the carb and dismantled it and what do you know there was some crap in the bottom of the float bowl so I cleaned that all out, and the jet going up into the business part of the carb. Then I swapped in a long range tank (removed the small brass one) I wanted to be using and filled it with gas minus the crap.
It started better and ran well at the dock. So I took it for a spin in the dead calm of the early eve.Seemed to go Ok but started having a wee bit less power after a bit and then was finicky slow running back to the dock and was slow to respond to the throttle again. (perhaps another cleaning is in order.

I did however remember that when I had a throttle cable failure whilst fighting a mild tide in a narrows a while back that I quickly swapped in a spare cable that had the piston with needle attached and forgot about it.
So I took it out and it and checked it and it had the No. 3 needle in it
I'd been running it 25 to one since I got it cause it said I could on the tank. I checked the needle of the original 'piston' and it was a No. 2 so I swapped it back in but didn't take it for a spin as it was getting dark
Could the wrong needle in there with a 25 to 1 mix be the cause of the slow running problem and a slight power problem...would it be too rich because the fuel is thinner at 25 to 1 ?

[1650bullet]

Run the jet needle on the very bottom clip and see how you go. If you have an air compressor, Blow out all the carby bowl and jets. and anything else that you can blow air threw. Have you tried using SAE-30 4 stroke engine oil. Mix it at 16-1 and see how you go. The SAE30 engine oil mixed at 16-1 produces a good amount of pressure in the crank case, and therefore wont have any vacum leaks coming threw the crankshaft bushes.

One more thing. Take the fuel tank of and flush it out with the hose, and tip a bit of metho in there to disapate any leftover water inside.

[Taspiper]

Well.
I took checked all the lines, the tank filter, the fuel, the hose,the banjo bolt screen, there might be a bit of crap in the tank. Then I took off the carb and dismantled it and what do you know there was some crap in the bottom of the float bowl so I cleaned that all out, and the jet going up into the business part of the carb. Then I swapped in a long range tank (removed the small brass one) I wanted to be using and filled it with gas minus the crap.
It started better and ran well at the dock. So I took it for a spin in the dead calm of the early eve.Seemed to go Ok but started having a wee bit less power after a bit and then was finicky slow running back to the dock and was slow to respond to the throttle again. (perhaps another cleaning is in order.

I did however remember that when I had a throttle cable failure whilst fighting a mild tide in a narrows a while back that I quickly swapped in a spare cable that had the piston with needle attached and forgot about it.
So I took it out and it and checked it and it had the No. 3 needle in it
I'd been running it 25 to one since I got it cause it said I could on the tank. I checked the needle of the original 'piston' and it was a No. 2 so I swapped it back in but didn't take it for a spin as it was getting dark
Could the wrong needle in there with a 25 to 1 mix be the cause of the slow running problem and a slight power problem...would it be too rich because the fuel is thinner at 25 to 1 ?

Yes. The number two should see you going with 25:1
The needles adjust for fuel viscosity. No3 = 10:1 more viscous fuel so 25:1 with a 3 would be rich as the fuel would flow past easier.
Your funny slow running was probably from four stroking on the rich mix. Lean down low it would probably spit, backfire and stall.
Swap needles before adjusting anything else.
Funny beasts old two strokes.... No wonder more than a few went overboard... I've been tempted...

[Mutineer]

Thanks
It has a different tank(long range) on it now (no no more tank gunk) and the proper # 2 needle re-installed and set flush
I'm going to take it for a test drive and see how it runs before I do anything else

[Mutineer]

Well it ticks over better now with less inclination to stall.However it still seems a little slow to repond to the throttle.
I do have a good 304 inches in the water above the cavitation plate, but even like that if I go on the foredeck to change sails it gets enough out of the water that I can hear the exhaust!

[skyetoyman]

"304 inches above cavitation plate" That's not a yacht it's a submarine - mine would run slow in those conditions

[Taspiper]

I'm guessing you mean three to four inches above, should be fine. Try turning the needle down half a turn at a time, may still be rich.

[Mutineer]

On my first printing of the last cd I made(happily a small printing)
My bass player read it over and spotted 5 typos immediately.
I guess I'm not great shakes at editing
yes 3-4 inches.
Damn zero key is right beside the dash
I'll try adjusting it a little leaner