saito 100 wont idle
 

i have a saito 100 that today while flying just died. I brought it in and filled the gas tank and restarted the engine. The engine starts fine and the in about 5-10 seconds it starts to die and then idles up and trys to die again very erratic idle then dies. I put 2 new type f plugs in because it sure acts like a bad glow plug (didnt help) The engine runs fine at the top end. Anything past the 1st few clicks of throttle and it runs fine. I removed the fuel tank and all looks good. I will try new fuel line. Is there anything im missing that could cause this problem. The engine is only 1 season old and has had the valves adjusted once a month since new. Has run great untill today. Acts to me like maybe a piece of dirt is clogging the carb on the low end??? when the engine is cold it idles a lot better than when its at operation temp.

thanks

RE: saito 100 wont idle
 

I thinkI would have to agree that it sounds like there is something in the carb. Completely remove the high speed needle and flush some fuel through it and see if that clears up the problem.

Ken

RE: saito 100 wont idle
 

Ok i removed the high end needle and flushed fuel through it both ways.(carb inlet and through the threads on the high speed needle) It didnt help. Is there a way to remove the entire needle and housing. I cant get the gold threaded portion of the needle to come out to inspect the spray bar part. Does this screw out or pull out? I can keep it running if i leave the glow ignighter on it but it still runs erratic, but if i remove the glow driver it stalls soon after, but only at idle if you open it up a little it runs great. I tried a 3rd known good type f plug and it didnt help. I also put new fuel lines on the tank to the engine. I looked at the klunk line and it looks good. I was thinking of putting the engine on a test stand to eliminate the plane as being the problem.


thanks for your help
travis

RE: saito 100 wont idle
 

Hi Travis,

How many gallons of fuel have you run through the 100? What type of fuel are you using? How large is your valve gap? Also, what prop are you using? I assume you have a fuel filter installed? The 100 is a great running engine

RE: saito 100 wont idle
 

This problem is almost always the adjustment of the low speed needle. It took me some time to figure out that since our field elevation is 3200', the low speed mixture needed to be leaned out. I kept adjusting the screw inward 1/4 turn at a time until the idle was smooth and I still had good transition to full throttle. I have not had any further idle problems since.

RE: saito 100 wont idle
 

cbr954rr.... The spray bar is lightly pressed in... If you pull it be very careful, or you will
need to get a new one.... I just changed my bearings on my 100 to ceramics, and I had
to get a new spray bar, "because I wanted to clean it out good"..... Check out the engine
section... Club Saito.... All the info./help you will need

I would also insure that your low end is rich enough, Saito IMO likes to be a tad on the
rich side on the low end

RE: saito 100 wont idle
 

As panhandledon said, it is your idle screw.
Open it about 1/2 to 1 turn and try it again

RE: saito 100 wont idle
 

Ahhh, if he hasn't adjusted the low end since he bought the motor then the low end is too rich. Have you tried the pinch test yet?

RE: saito 100 wont idle
 

It sounds to me like just the opposite is needed... Unless I am interpreting what you are saying incorrectly - which is always possible. [:-]

If the engine keeps running at idle with the glow igniter attahced that sounds to me like the low end needle is too rich and needs to be closed (idle screw turned clockwise) to lean it out a bit. If it were running too lean at this point the presence of the glow igniter wouldn't make any difference - the engine would simply lean out and quit when you try to get it to idle.

cbr954rr, the low-end needle is more sensitive than the high-end needle on most engines - I suggest you only turn it about 1/8 turn at a time. If it still dies give it another 1/8 turn and try again. You will find it doesn't take much to see some results.

Saitos ship from the factory very rich so I would think most people would have had to lean out the low end at least once in a years time but maybe at your elevation the engine will run on a relatively richer setting than where I live due to different elevations and air density.

Has the tempature started dropping where you live recently? That can require a change to your carb settings as well.

One trick I have learned over the years with four strokes is the low end and high end needles can affect one another a small amount and once you tune one you will sometimes find the other one isn't set just right. I bought a used OS .70 FS once and the needle settings were so out of whack I was pulling my hair out because I thought I would get it set right then it would quit on me. I was pretty new to four strokes and one thing that experience taught me is when you can't nail down the settings it can be helpful to simply set both needles extra rich (engine will be spitting fuel out the muffler like crazy) to the point that you have to keep the glow igniter on to keep the engine running. Then at that point, starting with the high-end needle, lean out one needle at a time until the engine will run without the glow igniter attached.

Once you have reached that point both the high and low end needles will be set fairly rich. This is beneficial because it gives you a place to start and it avoids the possability of running the engine too lean while trying to chase down the "sweet spot" where the engine is tuned just right. Once you are at this rich setting you can start dialing in both needles. Using a tach, I always start with the high-end needle (adjusting with the throttle full open) and get it to the point where the RPMs peak then turn the screw back to richen it a bit. Next, do the same thing with the low-end needle only this time you want the carb set so the engine will idle fairly low but keep running reliably. Now repeat the process - readjusting the high end needle then the low end. The goal being to get as low of an idle as you can get without the engine quitting on you.

It takes time to get it right - especially the low-end needle because you need to shut the engine down while making the low-end adjustments then fire it up again to try it. Following this process you will find that you get both needles set just right and your transition will be dialed in as well.

RE: saito 100 wont idle
 

I have about 5 gallons of fuel through the engine. wildcat 10% nitro 18% oil. valve gap is .003. Using a 16x4w prop, and have been using this prop for the last 2 gallons, i dont have a fuel filter installed, should I. The enging peaks out at 9300 and i run it at 8900.the engine was running great for the 1st 2 tanks of fuel that day then on the 3rd it deadsticks, and now wont idle? I would rule out low end adjustment for that reason, but i did try to turn the low end in and out to see if it helps and it didn't seen to make much differance. It acts like the low end is super lean like there is dirt in the carb to me but flushing it out didnt help. That is why i was wondering how to pull out the spray bar. The engine is still under warranty 1 year old. I think i will try to run it on a test stand maybe this weekend.

thanks for the help

any other suggestions???

RE: saito 100 wont idle
 

It sounds like you had it tuned and running pretty well before the problem started. Do you recall if the engine regularly died at a certain throttle setting? If it were me I wouldn't bother pulling the engine from the airframe to test run it in case the tank is actually the problem. I'd just hook up an extra fuel tank with the engine still on the plane. You can either rubber band the tank to the side of the fuselage or simply set it on top of something approximately the right height next to the plane. I always do what takes the least amount of time first. If the engine still quits with the alternate tank you have then eliminated the tank as the problem. Then I would pull the engine and inspect it thoroughly. I would shy away from pulling the spray bar until I have checked all the o-rings, carb, bolts, etc. to make sure an air leak hasn't developed somewhere.

If the engine runs better on the new tank then I would pull the old tank out of the plane and test it to make absolutely sure there isn't an air leak. After making sure as much of the fuel is out of the tank as possible, plug one line then blow in the other. You can even submerge the tank in water and watch for bubbles while you do the same for an even better test.

Use a process of elimination when tracking down the problem and you should be able to narrow it down pretty easily. If all that doesn't lead you to the answer then send it in and take advantage of the warranty.

RE: saito 100 wont idle
 

The 16x4W might be a little too much prop for the 100, especially with 10% fuel? Also, try a valve gap of 0.0015. Once you've set it there, you only need to check it once a year. It might be worth it to also check your low end as it might be still too rich. Also check the if the intake manifold is sitting well on the cylinder as an air leak there can cause erratic behaviour. Is your fuel tank level with the carb?

RE: saito 100 wont idle
 

Yes the engine has been broke and was tuned rather well before this condition started. The engine died on the 3rd flight after a vertical climb then a throttle back to enter a harrier. I will get another fuel tank and try what you suggested Flyerbry. I will then try replacing the o-ring on the intake stack. If all else fails i will send it back for repairs. My understanding is that the newer saitos have quieting ramps on the cam and the valves should never be tighter than .002?

thanks for the help
Travis

RE: saito 100 wont idle
 

The height of the quieting ramp above the base circle is 0.04mm, which converts to 0.00157 inch. If you don't have a 1.5 mils shim, a 2 mils shim would do just fine. But I prefer to keep the gap at the minimum to reduce the hammering on the cam and tappets and consequent wear.

RE: saito 100 wont idle
 

Have you pinched the fuel line when the engine is idling to see what it does?

RE: saito 100 wont idle
 

cbr954rr, just an extension of my previous reply, I have 6 saito engines and they have all required leaning of the low side. I have always broken in the engines first, and then leaned the low side, being careful not to get it too lean. They all idle smooth as silk, have good transition, easy to start. Just really good engines.

Panhandledon

RE: saito 100 wont idle
 

Ok i got it. I was a piece of dirt in the spray bar. I closed the needle valve and pumped fuel into the fuel inlet and opened and closed the carb several times and a small piece of dirt came out.

thanks

RE: saito 100 wont idle
 

That answers the question about needing a fuel filter.

RE: saito 100 wont idle
 

This is exactly the thread that I was looking for. I am having almost exactly the same problem. Except my motor was not ever tuned as well as cbr954rr's. It runs fine as long as it is a few clicks above idle (w/o glow heater), if I leave the glow heater on it will idle but erratically. From what I read above it sounds like I need to play (lean) my low end needle........would you guys agree? Or should I be looking for a piece of dirt?

cbr954rr, since you flushed out that piece of dirt does the engine run fine now?

RE: saito 100 wont idle
 

rc-sport, what is the pinch test?

Thanks.

RE: saito 100 wont idle
 

Hi Diavolo,

Sounds like you need to adjust the low speed jet. On a Saito this is usually with the head of the idle screw just 1mm below level with the throttle arm.

The "pinch test" is to pich the fuel line to the carby. If the engine dies immediately it is too lean. If it keeps running it is too rich. If it speeds up and then dies it is close to the correct mix (only very minimal adjusment neede for good transition).

Cheers,

Colin

RE: saito 100 wont idle
 

all is good. runs great since i flushed out the spray bar. I would agree seems like you need to lean the low end on yours. saito engines come very rich on the low end from the factory.

RE: saito 100 wont idle
 

Well......I just spent about half a day and a half gallon of fuel trying to get this 100 to idle. It still won't idle, sometimes I think I got it close but then when I'd move the low end needle either way it always got worse. And my "close" wasn't ever good enough to fly.

I decided I would just let it run at about half throttle to get some fuel through it but it would ALWAYS die after about a minute.[>:] I tried adjusting the high end needle but the it would still die if I let it run in the middle. Am I right to say that the low needle has little to no effect on the mid range speed? Only has an effect on the idle and transition from idle, right?

Any ideas on what I should try? Other than just tinkering with it, cause I'm all tinkered out!!:eek:

RE: saito 100 wont idle
 

If flushing the spray bar doesn't remove the dirt, I have removed both needles and run a piece of fine wire through the spray bar to remove a foreign object.

RE: saito 100 wont idle
 

Any suggestions on what may be causing it to die in the mid-range?