tewitt1949

Seems like I've read there are some diesel guys here. I bought a paw .09 diesel a while back and it runs great. The question I have is, should I have to readjust the carb or compression before starting. I try not too, but it does start hard. Needs slight priming. I was hopeing once I get it running and starting good, thats about it, no more fiddling with it. Maybe a little carb tweeking but that would be it. Do you diesel experts contiunuely have to adjust? Thanks Terry

mylamo

My Feedback: (1)

You may have to increase compression a little
when cold but that should be the extent of it.
Great engine have fun.
Ralph

LittleRock

After it is fully broken in the starting procedure becomes easier. I have a MP Jet .061 that needs no adjustments. Fuel, choke, flip and go.

Steve Staples

tewitt1949

So far the info sounds encourageing. I know you have to be careful when choking/priming not to get a hydrolic lock and bend the rod, so I'm very careful when using a starter. I can't get it to start by hand. The only thing I'm not sure about when adjusting the fuel mix on the carb, after its running, do you rev it up and adjust like a glow engine? Is it better to run rich then turn leaner a little or run lean and open until it smooths out. It appears it likes to run better on the rich side. Terry

gcb

Terry,

You've probably heard it before, but I would encourage you to learn to start it by hand, on a bench. You did not say how much running time on it, but you should be giving it some "heat cycles" for break-in. Heat cycles mean to start it, run it at max for a minute, then shut it down by pulling the fuel tube, then let it cool = one heat cycle. This procedure also helps you get familiar with starting it.

Once it is broken-in you can start it, let it "warm up" to normal operating temp, which takes a minute or so, before you make tinal adjustments. Approach final compression by lowering it a bit, then increase until it runs good. The fuel needle should be set for peak. Note where the needle and compression are...this should be your initial setting.

If you need to adjust compression for starting, fine. After it starts, move it back to your known-good setting. I try to alter my starting procedure to start without making compression or needle changes. This does not work for some engines. Try different types of prime, ie. exhaust, choke, or drop a couple of drops in the intake. One will work best for you. If you need to lower compression to start, sometimes it's because your prime is a little heavy.

I'm sure others will supply alternatives...we all develop our favorite method. Good luck with yours.

George

Edit: I did not comment on the throttle part because all but a couple of my diesels are for CL, and I don't have much experience with running the throttled ones. I have read some comments that some adjust the compression just a little higher if you throttle down a lot. Otherwise some will cool down and are slow at regaining peak.

steve111

I've had a number of PAWs over the years, including two 09s, and the one thing they have in common is that they don't like starting with excess compression. This goes against what you often hear about increasing compression to start, then backing it off to a normal running setting. Mine generally seems happy to have the comp backed off about a quarter of a turn for the first start; hot starts can then often be done at the previous run setting. Trying to start them with compression higher than the normal run setting is just a recipe for frustration, in my experience.

One of my 09s has a looser initial piston/liner fit as the piston starts its upward stroke (evidenced by bubbling past the piston) - perhaps a bit of extra taper in the bore or something. This engine needs very generous priming/choking (beyond what I'd normally consider necessary), with the compression backed off considerably, to get it going. Once it's running, however, it's really strong.

Can't help with advice on carbys as I have no experience on them with PAWs. Hope this helps

buzzard bait

I discovered the same thing with my PAW .06 - it often did best when I backed off compression for starting.

Ether content is very important on the small diesels. If it becomes hard to start, it's probably because you've lost some ether. I restore periodically with John Deere starting fluid, which is mostly ether. I think my .09 started at the running setting once it was broken in, but it's been awhile. In any case, it was easy after break in. I don't think I touched the needle once set.

Jim

Jim Thomerson

I've only run PAW's on the bench, but agree with the two comments above. I've been flying diesels in CL stunt. Ideal is to get the running settings and start with the running settings, using a starter if need be. I generally leave the needle alone once set, but I'm not using an adjustable carb. I will tweak the compression setting if the exhaust is too dark to suit me (overcompressed) or if the engine misses in level flight (undercompressed). In CL stunt, one needs a reliable length of engine run. Others have had problems with this; I have had very little problem, because I leave the needle alone once set. The general advice on diesels is to run them as lightly compressed and as lean as they like to be.

tewitt1949

Thanks for all the info. Sounds incourageing, maybe I can get it to run better now. Does the black exhaust only apear if over compressed?
Another question, will CL diesels out run RC version's?

build light

I don't profess to have any real knowlege regarding diesel engines but in my experience:
White 'smoke' is water (steam) indicating a cracked head or block allowing water into the combustion chamber. Water cooled engines of course.
Blue smoke is oil being burned due to worn or cracked rings.
Black smoke indicates a 'rich' condition where not all the fuel is being burned completely.

I would say that this would be not being leaned out properly. How this can be remedied regarding increasing or decreasing compression I do not know.
I would like to hear more about this as one day I hope to try diesel!

Robert

SGC

The black exhaust will apear when running at high compression settings but not nesesarily over compressed, ie if set to produce maximum power the exhaust is almost allways dark/black, some prefer to run at lower compressions to give a lighter exhaust colour- this also reduces stresses on the engine and prolongs life.
From my experiances it seems the black comes from the parcial combustion of the castor oil or its lacqures, as my runs useing olive oil as lube have no sign of colour in the exhaust (clear), this is due to olive oils higher combustion temp (hence its favoured use in cooking) This fuel also has a much different and less offensive exhaust smell.
Note due to olive oil diesel fuel's ability to flush any acumulated carbon and lacqures from an engine its use in well run engines is not recomended as loss of compression may result.
Stewart

colingw

Oil colour seems to vary from engine to engine. My two PAW 19s both produce very dark oil when peaked, but my CS olly produces only a honey coloured oil when running flat out.

I agree with previous comments about PAWs liking the compression backed off a quarter turn or so to start. When I got my first PAW 19 back in 1981, I began by trying to start it according to the instructions, and found it to be quite "bitey". Once I'd gotten used to the thing, I quickly found that a slightly undercompressed setting leads to much easier starting.

The way I now start a PAW 19 is to back the compression screw out 1/4 turn from the last running setting. Choke through a couple of times and then start flicking hard. It will generally fire fairly quickly and run a little rough and undercompressed. Turning the compression back in restores smooth, powerful running. Starting at the running setting is also relatively easy, but going to higher compression than that makes the process harder than it needs to be.

Stewart - do you run olive oil for all your lube, or a blend of olive & castor?

cheers,
Colin

SGC

Colin,
I am only running the olive oil in 2 new engines, I still use castor in others till the judge rules on the olive - ie till i have results as to wear rates etc. I run only olive in these 2. Olive oil seems to act like synthetics in reguard to cleaning out laqure/carbon so as stated is not recomended in well run engines. Results to date show no bad signs, engines are slightly easier to start and give a few hundred rpm more on olive oil.
Olive oil has 2 things going for it, 1 it mixes readily with kerosine etc without ether, 2 it has a higher viscosity at running temps than castor, plus a higher flash point - hence the cleaner exhaust. I will warn that it probably will not protect like castor in a lean run as it doesnt form laqures, but its high flash point ( about double that of synthetics) gives some room for error.
Stewart
I have run 50/50 castor/olive oil in fuel and found it runs similar to all olive and due to flushing out the burnt castor/carbon deposits will probably prevent laqure formation.

vauxhall

Why use olive oil? Castor seems to have proven to be the best available lubricant for model engines. Perhaps you should save the olive oil for the garlic prawns and salad dressing.
Maybe the black exhaust is also coming from the kerosine content of the fuel mix, we've been getting some low grade, high sulphur content stuff imported from Indonesia lately, or so I've read on the Barton Forum. Has anyone tried the new low sulphur distillate ( car diesel fuel ) instead of kerosine in their fuel blend as yet?
I currently mix my own fuel to the PAW specifications.
I've found PAW's to be very user friendly and easy starters, especially if the fuel is fresh.
Ditto the PAW start up comments re a surprisingly low compression setting.........John

AndyW

My Feedback: (1)

Some diesels are easier to start than others. This Norvel .074 conversion starts with the prime provided by blocking the muffler along with using a spring starter.

http://www.youtube.com/watch?v=af4dQNa60_w

I had trouble with small diesels at first until it was pointed out to me that the small ones like lots of ether. Much like small glow engines like lots of nitro. I mix my own fuel with 39% ether, 39% kerosene, 20% Castor and 2% cetane booster. Ether, from John Deere is expensive but for small engines, .09 and down, that's not such a large problem. Not much more than high nitro fuels.

It can help a lot to make up a special prime mix with 60% ether and 40% Castor. This allows for easy starts without any adjustments from running settings. After a few prime bursts, the engine warms up enough to keep running and as it warms up, it transitions into a solid run. In fact, using a high ether prime can allow for running your diesel engine with no ether at all in the fuel.

http://www.youtube.com/watch?v=zkNb6...e=channel_page

I used an electric starter here but this one is custom made. Note how easily it stalls. This saves you from breaking a rod,, or crank,,[:@]

Hand starting is far safer, glow OR diesel but with diesel you can get in trouble a little more easily when using a starter.

AndyW

My Feedback: (1)

The use of a modified olive oil was covered in the thread, "Substitute for Ether" some two or more years ago. I made a batch that I hope to test out this summer along with some commercially made, Biodiesel. I'm hoping to run a no ether formula using 90% Biodiesel and 10% olive oil. I'll be adding 2% up to 10% cetane booster. I'm speculating that the Biodiesel being made of oil in the first place will not need much oil.

Here's a run of 100% Biodiesel. It was a *&%$#* to start but it did run.

http://www.youtube.com/watch?v=PgxIy...e=channel_page