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| Engines Discuss engines |
Topic Review (Newest First)
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| 05-15-2010 03:30 PM | ||
| Cougar429 |
Re: Saito Backfire Can report the stock Saito gear and richening both high and low needles made a big difference. In fact, I was able to maiden flight the Skybolt this afternoon  . Just have to lean out the low speed a tad as it was gagging when I landed. Still ran, though. |
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| 05-15-2010 09:04 AM | ||
| moo |
Re: Saito Backfire Quote:
http://www.harryhigley.com/EngineAccessories1.htm 
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| 05-14-2010 10:24 PM | ||
| leopard1 |
Re: Saito Backfire Cougar, I just looked at my Saito 72 and 100. The grooves are fairly agggressive but if your prop slips a few times then you can get a buildup of prop material that fills the grooves. Causing more slippage of course. I had this occur on a 40 size two stroker. Worth a try for you to clean the hub and maybe try a new prop. Deven, Sorry I did not think of that, the other day. Glad to hear you got it running ok. See ya at the field clean-up tomorrow  Cheers, |
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| 05-14-2010 10:09 PM | ||
| Cougar429 |
Re: Saito Backfire I'm bringing it with me to the local club season opener tomorrow and we'll see what happens when we fire it up. I would think with the requirement for the prop to carry the motor up and over TDC if slipping were the issue Saito would have recognized this earlier and machined a more aggressive bite into the drive flange. |
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| 05-14-2010 08:13 PM | ||
| DVO |
Re: Saito Backfire I came across this thread while trying to solve my own backfiring issues.(saito 72). I got the engine used with a plane and it ran great the first time I tried it. I took the prop (13x6W) off to check out things under the cowling and when I put it back on and it ran max 5 seconds at idle and backfired as I throttled up. I knew the problem wasn't the mixtures. This thread made me think of the prop. I tried tightening the prop as much as I could but it would spin against the thrust washer. I even put pliers on this sucker to tighten it but nothing changed. As it turned out, the prop was spinning and wouldn't turn the crank past TDC with power applied, and backfired. When I held the throttle open a little to start it, I got nothing but constant backfiring. Long story short...I pulled the prop, cleaned off the thrust washer with a little windex and put a new prop on it(very-tight)...problem solved. NO backfiring at all, throttled up and pulled hard (for a 72). I left the field the other night, totally frustrated that this wouldn't run, thinking that maybe I'd busted a valve spring or something. Who'd a thunk it was a loose prop. Just my .02, but it sounds like your problem too. Deven |
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| 05-12-2010 07:12 AM | ||
| 1THEPALMER |
Re: Saito Backfire Follow the instructions that came with the motor. Yes you are too lean on the low end, BUT have you followed the directions and ran your first couple of tanks through rich? On these motors you need that rich run time. Your two stroke fuel is fine, I run mine on 2 stroke mix all the time with no trouble up to and including 35% nitro. As you are finding out this engine is a different cat. |
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| 05-10-2010 09:31 PM | ||
| Cougar429 |
Re: Saito Backfire I'm waiting for the stock locking nut and washer setup. Did not realize Higleys had the same type rig till I looked tonight. Next time I order that will be included. |
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| 05-10-2010 09:10 PM | ||
| YoungestPiperCub |
Re: Saito Backfire and make sure a 4stroke prop is very tight! if you have room another nut on the shaft may help it from throwin |
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| 05-10-2010 09:09 PM | ||
| YoungestPiperCub |
Re: Saito Backfire High speed needle is out of whack. Try brining it up to full speed then richen it up till there is a noticable drop in rpms. 500-1000 rpm you should see lots of smoke and oil comin out then run the motor a few tanks good and rich. Richness helps keep it cool and washes the metal flakes away from brake in. Then after a few tanks new glow plug and lean it out to to peak rpm. Back it off 200 rpm (rich) . Once thats done adjust the low end let the motor idle for 30 seconds and punch it. If it hesitates and lots of smoke comes out its to rich and lean it out. If it revs and quits its to lean. Another way is to let it idle for 30 seconds and pinch the fuel lne the engine should rev up slightly then quit. Hope this helps!!! |
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| 05-10-2010 09:05 PM | ||
| Flypaper |
Re: Saito Backfire If you don't want it to kick loose, ever, here's the fix. Give it a shear pin. Had a new big 4 stroker a guy in the club gave me to fix for him. Said he set the carb to the specs. and he left the paper at home. Anyway, all it would do was kick the prop loose with any throttle up at all. I drilled a 1/16 in. hole in the prop thrust washer, about 1/8 in. deep. drill a hole in the back of the prop about a 1/4 in deep. Cut a piece of 1/16 piano wire long enough to bottom in both pieces, 5/8 in. in this case. It will no longer kick loose. The reason the motor kept kicking the prop loose is being to lean. One of the new Saito gas motors I recently worked on, said to set the carb high speed at 2 turns, 30 seconds and the low speed at 1 turn 45 seconds. I think the guy could only read a digital watch. |
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