Hello all,

I am coming to you guys, being conversion nut myself, because I am having a problem that the "gas engine" forum boys seem to know nothing about. I am tired of dealing with the buy it and flip it type anyway!

OK, this concerns an old Quadra 35 without breaker points. This engine will pop a few times, but will not sustain a good run. All carb positioning is correct in regard to pulse pressure holes and the engine has spark and compression. I have gone so far as to replace the ring, but to no avail! The bearings are also in tip top shape.

I have a homemade muffler in place. Can this be too restrictive and causing me my grief? I think it would run, although poorly, if this was the case. Am I wrong here?

What in the world is going on here. This engine looks ten times better than some of the conversion engines I have made run like tops. I am at my wits end!

I have also tried different CDI units - same results. What in the world is happening here?

I know this is not a true conversion, but this truly is nothing more than an adapted saw engine.

Thanx in advance,
Tom

Don’t have quite enough information to help.

Does the above mean that the original magneto ignition is being used?

It would be helpful if you could more fully describe the running symptoms. Does it actually start and run for a few seconds or does it just pop when attempting to start?

Ok, the original magneto ignition is being used.

The engine will run for about 1 second and then not sustain running. It is as if it runs out the prime. I have used two different carbs, thinking that the carb was not pumping, and both did the same thing.

Does this help?

Tom

No fuel delivery is a carb or pulse problem...If you have done everything else you might look at the crank seals, a leak there will cause a weak or no pulse, and no fuel flow.....
I just had an old Q35 here, so old it came in the original box with the original price, $85.00...
It was a points ignition type..I rebuilt the carb and put a G38 ignition coil on it...Ran like a top, hand started very easily...Old Q35s never die...
All Q35s descended from a chainsaw..My neighbor has 2 of these, at least 30 years old..Only difference I can see is the saw engine has the spark plug coming straight out on the front, about 2 inches from the ignition coil...He still uses the saws....

What I have done is make the gasket where the cylinder meets the case out of a gasket making goo! It is locktite brand something or another. This is what us engines recomended for this job. When you say the crank seals, do you mean where the crankshaft exits the case? I am not sure if fuel flow is the problem.

You decide: when I close the choke on the carb, I flip the engine over until it runs for about 4 pops and dies. I then open the choke and set the throttle a bit above idle. Next, I proceed to flip the engine over. It will pop-pop-pop-pop for about 3 or so flips and then will do nothing unless it is rechoked.

I have made sure the pulse hole out to the carb is open and I believe all else is tight.

Just a thought. How big should the spark be when the engine is turned over? I removed the plug and touched the engine with it while turning over the prop. The spark is tiny and blue. The spark on a US 41 I have seems to be much larger and brighter. The spark on the q-35 is tiny even when I use another mag unit and another compatible flywheel.

Thanx,
Tom

Tom it sure does help.

A gas engine that runs the prime out has a fuel delivery problem. I like to start by looking at the clunk especially if it is a filter clunk like the originals used in saws and weed eaters. Also the fuel lines are easy to check and/or replace. Next there should be a small brass screen somewhere in the diaphragm area. The screens clog up easily and they are important filters to the operation of the carb. Most small engine mechanics replace the diaphragm when they are there but I don’t usually have access to a diaphragm in the middle of the night so … I spend extra effort looking at it under a magnifying glass.

Incidentally engines will usually start easily after spraying WD40 in the carb inlet.

You will probably find a fuel delivery problem. Carburetors that have not been in use for some time easily gum up.

I will check the fuel system and the carb stem to stern. Will you believe it if I told you I just ran another engine on the same test stand I was using for the Quadra? If it is the carbs fault, why does the engine act the same with both carbs I tried? Lastly, I flew the airplane that I had it mounted in two weeks ago with a friends older Quadra 35 with breaker points and it performed flawlessly. I guess it is not the fuel sytem behind the carb anyway. Is it possible that the flywheel is designed for a breaker point ignition and I am trying to run it on an ignition designed for no points. Does this add up to a hill of beans, or am I just dreaming up impossible solutions out of desperation?

When I say run out the prime, I am not talking about a short powerful burst, I am talking about pop-pop-pop. (I don't know how else to describe it!)

I just replaced the ring on this engine. Can this make it unable to be started by hand until it is re-broken in? My symptoms did improve after the ring change. Before, the engine would kick back and forth until the prime was gone. At least now I have it turning in the right direction.

Just a note: I just ran a Kioritz 22cc from an echo trimmer........man it runs sweet. At least I have had one success this day!

Thanx, and keep the possible solutions coming. I ain't givin' up till that darn Quadra runs. Being a conversion nut, I don't know how to give up!

Tom

A points flywheel will not run with a no points magneto coil..,If you look at both flywheels you will see that the keyway is in a different location relative to the placement of the magnets...
If you want to run the engine with no points, I can send you a new G38 coil that works with the original flywheel, better than the original setup...$40.00 shipped, bolt it on and run..This will NOT fix the fuel problem....
There is no gasket between the bottom and the top of the case, just sealer..
The crank seals are on both ends of the crank, outboard of the bearings...Check out the parts drawing on the B&B website, page 11, part #100027, one on each end....
www.bennettbuilt.com

I experienced the same problem with a US 41 which is essentially the same design as your Quadra 35. It just wouldn't take the gas. You could prime and get about four pops and sometimes a little more but that was it.

Finally with the needle way out and a big fast starter instead of the spring, we got it going. It quit up in the air unexpectedly and I then found the crank sqeeked when you tried to turn it over.

Upon dissassembly, of the spring starter area, the spring had bound up and turned the crank blue. I just knew that the seal was toast and that was the reason for the engine starting poorly. I found a seal for the rear bearing at the local auto parts store and the engine ran like it was supposed to. No more problem. Bye bye spring because the crank was gaulded where the one way dog clutch for the spring rode on the crank.

Enjoy,

Jim

Sprague clutch needs to be lubed once a year with white lithium grease although they don't tell you that when you buy the engines.

Tom,

If/when the seals where the crankshaft exit the engine go bad, the engine cannot develop the pulse that operates the fuel pump. It will also have difficulty drawing the fuel/air mixture into the engine. The engine creates a vacuum at the carb when the piston is on its way up, draws the fuel/air mixture into the crankcase area, and when the piston is on its way down, (after it closes the intake port), it pressurizes this mixture and sends it into the combustion area once the transfer ports open. This is the pulse that operates the fuel pump, and this is how the engine draws the air/fuel mixture into the crankcase and then sends it to the combustion area. If there is a leakage in those seal(s), this whole process cannot occurr properly. This is of course, completely different from four stroke car engines that you might be familiar with, whereby a leaking crank seal only leaks oil, and doesn't affect engine operation. I plug all outlets on a two-stroke engine and use a vacuum/pressure pump and gauge to check crankshaft seals, but they are so easy to replace, that is what I would try in your case. This is of course assuming, that you have no air leaks whatsoever in your fuel tank/supply system.

Good luck,
AV8TOR

AV8TOR,

I was waiting for you to chime in! I am going to replace the seals and give her another go. I have the fuel delivery system secured, now the hunt continues. This whole thing really puzzles me. This engine is as clean and free of wear as any I have tinkered with, but it will not keep a goin'. I am very hopeful that the seal deal will change my situation. I guess these seal leaks are not too obvious if you are using a vacuum pump to diagnose them. Anyway, can these seals be found at auto parts stores as the above post mentioned? That would make things easy!

Thanx for the help,

Tom

You will need to take an old one with you and see? A industrial bearing supply house may have one too. Auto Zone is not going to have one. You will need to go to a old established independant auto parts store.

They are readily available from B&B the main distributor of Quadra and US engines. The are in Indianna. Find them with Google.

Enjoy,

Jim

take out the spark plug ,take off the carb and the insulator and gasket till you see just the bare intake port. now take some dish washing soap and with your finger wipe across the small hole till you see that you have created a bubble cover now rotate the engine crankshaft in the normal direction do you get a bigger bubble? if not that gasket goo that you mentioned earlier has plugged this passage way!!!! also take some more soap and put around the crankshaft where the seals meet , turn the crank does it bubble ? if so then proceed to replace the seals and or the bearings that might be sloppy.

tom

Another way is to take the carb and isolator block off, bring the piston down till it just closes the intake port. Put a piece of fuel line over the pulse hole. Grab a smoker friend and get him to blow smoke into the fuel line. Where the smoke comes out is where the leak is.

MikenLapaz... re your PM.

Hi Mike,

Not sure what I could add to what I already said. Fuel draw problems just need to be traced out like any problem. If a person is absolutely sure that his tank and lines are 100% air leak proof, then you look to the carb. If the screen and passages in the carb are good, and the diaphragms are in good shape with the inlet needle lever set properly, then you have to look at the pulse situation. First here is to make sure nothing has been done that could affect the pulse, such as accidentally closing off the hole, etc. If you turn the engine over briskly with the carb off, you should be able to sense a puff of air at the pulse hole. If there is a pulse problem, you have to look at what creates the pulse. If the seals are leaking, (or bearings with covers), or the compression is poor, it will affect both the ability to pump fuel with a good pulse, and the overall starting and operation of the engine. Remember, a two stroke has both primary and secondary compression; a worn engine will affect both, and fuel draw.

As far as getting a good prime to start, I have run across chokes that don't seal well, and then you can't get the engine "wet" to start. In this case, a finger securely closing off the carb while you prop it over works well. On your Ryobi, this would be difficult. I saw a picture here once of a popsicle stick with half of a small rubber ball glued onto the end. Looked like a good idea for a Ryobi choke to me!

For finding parts such as seals and bearings, it's like the guys said above. Here in Arizona, if I couldn't get parts from the OEM, I would first try Napa, then Merle's Auto Parts, then a bearing supply house. Bearings and seals are not as specialized as many people think. It is much cheaper, faster, and easier for the designer of an engine to spec an existing, common bearing and seal for his new engine, than make a new one from scratch. Just whatever you do, don't bother going to Autozone, Checker, etc. Those places are only good for normal, "look it up on the computer" applications, and the low paid personnel are generally uh.. not very astute nor motivated.

Good luck,
AV8TOR