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It's a good question about the tooth out cam timing thing.Only time i ever came across that was when i mistimed an xr350 honda by one tooth and it behaved as ian says his 150 is doing,just a thought.
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Nah don't bother with the vid we've all heard flat engines and wondered why sometimes.If you keep them at full throttle while you make your mind up they go bang sometimes.
It's a good question about the tooth out cam timing thing.Only time i ever came across that was when i mistimed an xr350 honda by one tooth and it behaved as ian says his 150 is doing,just a thought.
It's a good question about the tooth out cam timing thing.Only time i ever came across that was when i mistimed an xr350 honda by one tooth and it behaved as ian says his 150 is doing,just a thought.
Missing the timing on a Saito by one tooth will result in timing being off by 15°. Timing shifts to bump the torque curve via (automotive) custom timing sets are usually limited to + or - 4°.
4° variance in cam timing either way from "straight up" is substantial. 15° Is way to much for the engine to run W/ any resemblance to normality.
The one time I did try to start a Saito that was off by a tooth, it kicked back against the starter, popped & refused to even start. That was W/CDI too.
It's a good thing it wasn't my HC 180 or I fear valves would have gotten way too "familiar" W/the piston.
The point is, being off "by a tooth" on cam timing won't result in a few thousand RPM of lost power or tradition problems, it will result in the engine barely running if it starts @ all.
Advising people to check cam timing in those instances of moderate loss of power will only result in unnecessary dismantling of the valve train.
Of course doing the overlap check @ TDC would verify any cam timing issues (or lack thereof) but many less experience folks might just tear into the valve train W/O the easy check.
Last edited by SrTelemaster150; 04-14-2015 at 05:42 AM.
Thank you very much.
Sincerely, Richard
Club Saito #635; Saito 56, 100, 120abc, 130T, 180
YS F 120;
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As the crank throw goes over TDC, the exhaust valve will be closing while the intake valve is opening. At TDC, both valves will be open slightly & a near equal amount. I hesitate to say equal as there appears to be a slight difference in the open/close as far as degrees before/after TDC.
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My sole experience with an out of time engine, my fault of course, was on an Enya .46MKII. I pulled the cam box to investigate a rusty oil coming out of the vent problem. The rust was not nearly as bad as I thought but I installed the intake cam one tooth off time. It would only turn 6,900 rpm and a great amount of fuel danced around the carb intake.
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Ian, from your description of the engine suddenly kicking back and the subsequent difficulty, I would strongly suspect you have contamination blocking fuel flow. Saitos DO NOT like to run lean and that backflip sounds like the cause. That would also cover the symptoms of slow pickup, etc.
I would recommend pulling the fuel line from the carb and blow into the exhaust pressure line to see if you have strong and consistent fuel flow. If so, the next step would be to remove the HS needle, install a length of fuel line to the inlet, open the throttle and blow into the tube. You should have a relatively good air flow either with or without your finger over the end of the HS seat threads. If not then your inlet and/or fuel bar are plugged. Time to pull the carb and go through it to find and clean that out.
Frequently, new fuel systems or ones fed with contaminated fuel can have what we call "Schmigglies" floating around or picked up from agitation. Any can plug up the very small ports used to feed and meter fuel.
I cringe when someone suggests the timing may have jumped a tooth. Unless the engine is in such bad condition, the cam cover is physically loose and lifting away from the case or suffered physical damage to allow for this and still run the likelihood of timing shift is low.
First off, to "Hop a Tooth" would require a physical jump between the cam and crank gears. Only way that could happen is for there to be so much wear or a broken tooth (or more). If either case exists then that change should occur repeatedly every two revs as the cam timing comes around to the same location. I would imagine that would be evident if the crank is rotated by hand,
The other case, and one I had handed to me by a friend, was a 56 that would not start. There the cam was missing a couple of adjacent teeth that luckily had not gone into any other bits to cause destruction. Suspect the sudden stop when the prop hit the ground and the fact it would not start saved it from further damage. The gap had aligned to the crank and the cam would not turn at all. Easily seen as no valve action once the covers were removed.
ps. Just got the bits to put the last 100 together and finished that yesterday. Good compression and smooth action, but one thing a bit weird. Had to adjust the lash and the intake was considerably shorter than the exhaust, to the point almost no threads were exposed above the nut or below the arm. Still had the pocket and no apparent wear to the pushrod. Cannot remember if this was the case with the previous 3 engines and will have to pull one from storage to have a boo.
I would recommend pulling the fuel line from the carb and blow into the exhaust pressure line to see if you have strong and consistent fuel flow. If so, the next step would be to remove the HS needle, install a length of fuel line to the inlet, open the throttle and blow into the tube. You should have a relatively good air flow either with or without your finger over the end of the HS seat threads. If not then your inlet and/or fuel bar are plugged. Time to pull the carb and go through it to find and clean that out.
Frequently, new fuel systems or ones fed with contaminated fuel can have what we call "Schmigglies" floating around or picked up from agitation. Any can plug up the very small ports used to feed and meter fuel.
I cringe when someone suggests the timing may have jumped a tooth. Unless the engine is in such bad condition, the cam cover is physically loose and lifting away from the case or suffered physical damage to allow for this and still run the likelihood of timing shift is low.
First off, to "Hop a Tooth" would require a physical jump between the cam and crank gears. Only way that could happen is for there to be so much wear or a broken tooth (or more). If either case exists then that change should occur repeatedly every two revs as the cam timing comes around to the same location. I would imagine that would be evident if the crank is rotated by hand,
The other case, and one I had handed to me by a friend, was a 56 that would not start. There the cam was missing a couple of adjacent teeth that luckily had not gone into any other bits to cause destruction. Suspect the sudden stop when the prop hit the ground and the fact it would not start saved it from further damage. The gap had aligned to the crank and the cam would not turn at all. Easily seen as no valve action once the covers were removed.
ps. Just got the bits to put the last 100 together and finished that yesterday. Good compression and smooth action, but one thing a bit weird. Had to adjust the lash and the intake was considerably shorter than the exhaust, to the point almost no threads were exposed above the nut or below the arm. Still had the pocket and no apparent wear to the pushrod. Cannot remember if this was the case with the previous 3 engines and will have to pull one from storage to have a boo.
Last edited by Cougar429; 04-16-2015 at 04:28 AM.
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I can see that during assembly, but would think less chance of that occuring from the manufacturer. Still, mistakes happen.
Last edited by Cougar429; 04-16-2015 at 03:23 PM.
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Well old fart (and others) our section of the nats is over. My mate got a 3rd in Nostalgia (by dint of an exception last flight, 3 minutes at less than 200ft, which for a 4 pound model in the glide is great). In Texaco we have CD supplied fuel, 15% oil (either castor or synthetic) and either 5% or 10% nitro. You can use your own but incur a penalty of 1 ml per pound). We use Enya 4 strokes in this event as they don't mind the 15% oil, but the Saitos (especially the modern ones) do not like the mix at all and add it the lean runs for max fuel "efficiency" and that reduced the competition by 3 I think. Competing at these levels against quality fields is really god and I recommend that attendance either as a competitor or "helper" is a good way to "get to see what the others are doing" Invaluable experience. But I am really glad it is now over. It was a good comp, great weather great competitors and organisation. Now to Canowindra next year and wopping that West Australian mob that seem to think they can beat us every couple of years.
Would one you guys that has a Saito apart or have some broken engines measure some valve for me. I am working on a 4 cyl old time engine. Looking for a valve with a head dia of around .430. The length would need to be close to 1.375 in length. Sharing this data would be great for those building cast kit engines. Thanks Very much in advance. John PS any other brand valve sizes too !
Well old fart (and others) our section of the nats is over. My mate got a 3rd in Nostalgia (by dint of an exception last flight, 3 minutes at less than 200ft, which for a 4 pound model in the glide is great). In Texaco we have CD supplied fuel, 15% oil (either castor or synthetic) and either 5% or 10% nitro. You can use your own but incur a penalty of 1 ml per pound). We use Enya 4 strokes in this event as they don't mind the 15% oil, but the Saitos (especially the modern ones) do not like the mix at all and add it the lean runs for max fuel "efficiency" and that reduced the competition by 3 I think. Competing at these levels against quality fields is really god and I recommend that attendance either as a competitor or "helper" is a good way to "get to see what the others are doing" Invaluable experience. But I am really glad it is now over. It was a good comp, great weather great competitors and organisation. Now to Canowindra next year and wopping that West Australian mob that seem to think they can beat us every couple of years.
Got the duke back after a major cambelt service and we are riding in the hills tomorrow along with thousands of competition cyclists on narrow windy double white line roads with hundreds of frustrated car drivers,us bike riders trying to trickle through too.A riding mate pinched this all over the road female cyclist on the rear end as we went past last year out of shear frustration,they had back up trucks following behind so slowly that thinking about performing brain surgery on yourself with a black and decker drill and a blunt bit was a realistic alternative.
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Would one you guys that has a Saito apart or have some broken engines measure some valve for me. I am working on a 4 cyl old time engine. Looking for a valve with a head dia of around .430. The length would need to be close to 1.375 in length. Sharing this data would be great for those building cast kit engines. Thanks Very much in advance. John PS any other brand valve sizes too !
FA-150 valves are .542" in diameter. The bad news is that they are only 1.252" in OA length. This is the smallest valve head in the big block series (same as the FA-120S) and yet the OA length is too short.
You might find medium block valves W/a diameter that is close enough to grind to spec, but then the OA length will be even shorter.
Would one you guys that has a Saito apart or have some broken engines measure some valve for me. I am working on a 4 cyl old time engine. Looking for a valve with a head dia of around .430. The length would need to be close to 1.375 in length. Sharing this data would be great for those building cast kit engines. Thanks Very much in advance. John PS any other brand valve sizes too !
I have tried to get a Stihl 4-Mix with no luck, even though the shops said they were not a commercial success. Seems the customers thought that since they were 4 stroke that they did not have to add oil to the gas mix. And they burned them up. Still the shops would not give them away (Stihl Co. policy?).
Sincerely, Richard
Club Saito #635; Saito 56, 100, 120abc, 130T, 180
YS F 120;
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Richard, I had a 26cc Ryobi trimmer for about 2 years, the thing was pure junk. I gave it to my neighbor and it has hung on his garage wall ever since. I bought a 55cc Stihl and it is nearly always a one pull starter.
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I would have to go look for which engine, but one of my Saitos has a muffler that has never been cleaned off and it is thick with bumpy dried castor. Looks kinda good. There used to be a kid who would ask me if I was going to clean it every time he came out. Too bad they grow up eventually.
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Ryobi 4 stroke engines were very available for free at my strimmer repair/sales shop three years ago.. I had 3 of them, but moved and gave them away. You might check that source, although maybe by now they have been purged even from the junk piles.
I have tried to get a Stihl 4-Mix with no luck, even though the shops said they were not a commercial success. Seems the customers thought that since they were 4 stroke that they did not have to add oil to the gas mix. And they burned them up. Still the shops would not give them away (Stihl Co. policy?).
Sincerely, Richard
Club Saito #635; Saito 56, 100, 120abc, 130T, 180
YS F 120;
I have tried to get a Stihl 4-Mix with no luck, even though the shops said they were not a commercial success. Seems the customers thought that since they were 4 stroke that they did not have to add oil to the gas mix. And they burned them up. Still the shops would not give them away (Stihl Co. policy?).
Sincerely, Richard
Club Saito #635; Saito 56, 100, 120abc, 130T, 180
YS F 120;
I bought an FS-90 years ago not even knowing it was a 4-stroke, but the operating characteristics soon caused me to investigate.
In addition to trimming around the yard/garden, I use it to clear shooting lanes in the woods. W/the 3- blade steel cutting head, it will slice though 1 1/2" pine saplings in 1 swipe. Hardwood & larger pine saplings can still be whacked off W/several swipes.
It starts easily & has never missed a beat.
Last edited by SrTelemaster150; 04-17-2015 at 11:25 AM.
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Old Fart, thanks for the comment, Good to be back in the competition scene seriously. Gets the juices flowing and my mate and I do get the others bothered. Just apply the lessons learnt as aircraft engineers. Roll on June 2 major comps then our own. Now where are those tricked up Saitos.
I would have to go look for which engine, but one of my Saitos has a muffler that has never been cleaned off and it is thick with bumpy dried castor. Looks kinda good. There used to be a kid who would ask me if I was going to clean it every time he came out. Too bad they grow up eventually.
This 82 muffler is about three years old,i'm sure there are people with grungier one's than this but just in case there is'nt,i've added a grunge benchtop background for your viewing pleasure.
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I ran this Saito .50 today for the second time to make sure it is ready to fly, I put an additional 30 minutes on it. 80 minutes total now.
Fuel====WildCat 10% 2/4, 18% full synthetic.
Plug====Enya #3
Prop====Graupner 12x6
Max rpm one click rich==9,751
Idle================2,050.
Exhaust=======improved version of the cast muffler for .50, .56 and .62.
Fuel====WildCat 10% 2/4, 18% full synthetic.
Plug====Enya #3
Prop====Graupner 12x6
Max rpm one click rich==9,751
Idle================2,050.
Exhaust=======improved version of the cast muffler for .50, .56 and .62.
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CR
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Wouldn't ya Know it?
Sooo,
Last Tuesday I took my Saito .80 powered Ace Cloud Dancer 60 off the wall and ventured to the field in mid-afternoon. It was the first sunny day we'd had since 2 April. Hadn't flown the model since last fall.
Sooo, the engine wouldn't start & run. It would start & quit after about a one second run. I thought it was running out the prime. I figured I had a fuel feed problem, so I packed it in & went home. Don't like taking things apart in grassy pits.
Sooo, today, the first sunny day since last Tue, I got a chance to get the model out & troubleshoot the fuel system; tank, lines, filter, carb for clogs, poured out the fuel, checked the can for corrosion, etc, etc. Could find nothing wrong.
Sooo, I filled the tank, tethered the model down, turned on the radio & tried to start the engine. It would start, run for a couple of seconds & quit, even though the glow battery was still attached.
Sooo, in desperation I changed the glow plug; put in a used Fox Miracle plug.
Sooo, the thing started and purred like a kitten!
Wouldn't ya know it?
At least I know all the plumbing's OK.
CR
Last Tuesday I took my Saito .80 powered Ace Cloud Dancer 60 off the wall and ventured to the field in mid-afternoon. It was the first sunny day we'd had since 2 April. Hadn't flown the model since last fall.
Sooo, the engine wouldn't start & run. It would start & quit after about a one second run. I thought it was running out the prime. I figured I had a fuel feed problem, so I packed it in & went home. Don't like taking things apart in grassy pits.
Sooo, today, the first sunny day since last Tue, I got a chance to get the model out & troubleshoot the fuel system; tank, lines, filter, carb for clogs, poured out the fuel, checked the can for corrosion, etc, etc. Could find nothing wrong.
Sooo, I filled the tank, tethered the model down, turned on the radio & tried to start the engine. It would start, run for a couple of seconds & quit, even though the glow battery was still attached.
Sooo, in desperation I changed the glow plug; put in a used Fox Miracle plug.
Sooo, the thing started and purred like a kitten!
Wouldn't ya know it?
At least I know all the plumbing's OK.
CR
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Ah the old plug problem, Charlie I have been having the same problem myself and in the process filling the local hobby shop owners wallet. Do you store your models nose down? My biggest problem lately is forgetting that I have run 4:1 fuel through the engine and adding ATF prior to storage which usually means the plugs are oiled up. Not a big problem with synthetic but a ***** with castor.
Maybe store with a burned out plug? Suggestion is as much to me as any one!
Heck I found I removed the plug and did not have a plug in an engine I had stored a month or 2 ago with ATF.
Why wont this sucker suck fuel and start. And then the OH DUH moment!
Ken
Heck I found I removed the plug and did not have a plug in an engine I had stored a month or 2 ago with ATF.
Why wont this sucker suck fuel and start. And then the OH DUH moment!
Ken
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All my stuff is stored nose down and i use a healthy dose of A.F. and no probs with plugs . Mine last for ages especially in 4 strokes . If you have plug issues I would look else where . Cheers the pope