Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines
The Regular Stuff: Chat, Buy, Sell, Off Topic, etc. => General Discussion - Scale Model Gas Engines - Hit & Miss - Throttle Governed - Non-Compression – etc => Topic started by: MadeForThat on October 29, 2022, 11:13:47 pm
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Black and shiny is odd I really doubt it would be the oil additive though because of the engine was overheated the O. rings should let go long before any serious temperature is reached
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Odd thing is it's not the typical soot. It's a thin layer of baked on black shiny stuff. I am suspecting the Lucas oil added got overheated and caused this. I ran the engine around 20 times and only thing came up was this. Had to spent a good amount on adjusting valves on all cylinders first but it runs beautifully
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Dark and sooty looks like a rich mixture to me.
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My h75 has been working exceptionally well and it's a joy . However few days ago I noticed a very rough andnintsable start، idling and lack of throttle response. As usual I checked the carb , and intakes , compression and spark plugs to make sure they are all fine and they seemed to.
What I noticed on the spark plugs were this black shiny deposit and I didn't think much of it as it wasn't a soot or wet, until I during my tests I replaced the plugs and engine worked perfectly again.
I'm surprised on how short lived the plugs were, specially as I replaced the PK ones with RCEXl which has been working amazingly and without the black deposit on my R90s .
Has anyone else with H75 noticed low life span of plugs ? I must add I'm using mixture of coleman fuel and Lucas oil treatment which is same as MMO. I believe the carb setting is correct . I do noticed that it's quite hard to get all 4 cylinders to run on low idle . Could this be caused by over heating of spark plugs ?
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One thing I noticed with these engines is the grounding can be flakey, resulting in inner spark in the CDI unit and burning the hall sesnor. I extended the ground point to under one of the base legs with a wire. Now the misfiring issue has been resolved and no more dead hall sensor
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I've only ever purchased through eBay, and I will just send him a message with some pictures of the issue. I have only requested action from him twice regarding parts, and he/his team responded in a day or two. Pictures are the important part, I fear the translation tools may not always translate technical words correct and pictures skip any losses from it. I worked for a valve manufacturer who had a plant in China. The guys I was communicating with were very smart, but neither of us could properly communicate technically. Drawings and pictures cut right through the fog, we all understand when we see it.
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I definitely have to agree, Mr Jin is great about replacing parts when someone has an issue.
I swear I don’t know how Mr Jin has the time to design and build so many beautiful creations.
Every single engine he engineers and builds are so detailed.
-It’s easy to see that He takes so much pride in each of his engines.
Gotta applaud him 👏👏
How do you communicate with him to replace parts? Only way I could get something was to open a dispute. Their response was zero.
His creations are amazing but let down but a poor assembly and quality control processes which is a big shame
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I definitely have to agree, Mr Jin is great about replacing parts when someone has an issue.
I swear I don’t know how Mr Jin has the time to design and build so many beautiful creations.
Every single engine he engineers and builds are so detailed.
-It’s easy to see that He takes so much pride in each of his engines.
Gotta applaud him 👏👏
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Can't say for certain, I'm not sure I understand how you have things connected to the multimeter when it fires, but if you connect the sense wire to ground it should cause it to fire, the hall sensors are so cheap and easy to break it is certainly worth picking some up, I suspect it will do the trick
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I discovered something bizzare. When I connect the multimeter to the ground and output (black and blue) of the hall sensor when power is connected to it. I can hear the spark when I rotate the flywheel. As soon as I take the multimeter connectors off it stops. It happens even with the multimeter off. On the continuity setting It only shows 0L even when the magent passes the hall sensor
Is this the hall sensor or something else ?
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Just saw this . Very useful. I tested my hall sensor with multimeter. On connection to black and brown I get the 4.5v which seems the input voltage. When I connected blue and black I have 4.0v and when magnet passes by I get 3.71v, is this working okay?
Could I ask where you got the hall sensor from? Might worth the try before buying a RCexl CDI
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@engine-man you will see above how I repaired my hall effect sensor, I am sure it is the same, but you may want to compare.
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I appreciate that he is willing to send parts for a machine that he has no obligation to warranty. I do fear that if something else in the ignition circuit went wrong I would probably not be able to repair it because it is all potted, (epoxy filled box) but perhaps after a few good years of producing this and earning his profit, Jin will release a circuit diagram so someone with sufficient knowledge could fix/rebuild these circuits.
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I spoke with Jin and he is sending me a prewire sensor.
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Great to hear it worked for you as well! I have messaged Jin referencing this thread, I think that a lot of us would probably like to have a few spares of these already wired and laying around and I suspect that would be a lot cheaper for Jin to send replacement sensors rather than the whole ignition. Perhaps prewired will be a product soon :)
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Just wanted to say i did the replacement on the pick up sensor that MadeForThat posted here and it worked perfect. Got the sensors on amazon. Have to take your time soldering them but works great.
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Great info, gents. Thank you!
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Thank you!
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I've attached an image of the sensor with the colors of the wires as they should coordinate. Take note of the writing on the chip facing up when wiring. Also not sure how this engine is timed, I don't think the chip went all the way into the plastic cover that holds it on the cam gear, so it will be a little retarded (or advanced?) from normal. This was because I used a waterproof heat shrink tube to cover it all, and that added a bit of extra thickness. Won't know if it is an issue til I fire it up!
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They are quite small, but if you have a set of "spare hands" it isn't very bad at all, the hardest part for me was keeping some of the heat shrink on the center pin. These are what I have (but the harbor freight version) https://a.co/d/jaMUMx9
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How hard a job to solder in are these?
Thanks for the links.
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You can buy 10 for about 5$ shipped from china here: https://a.aliexpress.com/_mPUBLtE
Or if you want replacements quick from Amazon: https://a.co/d/2oEP1qq
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Well I went ahead and bought replacement hall effect sensors, as I noticed that the ignition circuit would fire when black was connected to the blue wires (replicating hall effect pulling down when activated) So far what I am noticing is that it works with the replacement sensor, but 2 wires fire at a time. I suspect it always did that and I just didn't know/observe it. So I just need to get the new sensor all soldered in and make sure it can't short out. I don't know what caused the failure, if it might have been a stray water drop or jolt from the ignition that fried the hall effect sensor. Not sure, but for 8$ I have 9 more replacements.
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I have had an issue with my h75 on the ignition. First turn it on no spark. If you leave the switch on for about 1 minute it will have spark and runs fine. I've tried new batteries, different brands of batteries, same thing. So now I turn it on, put fuel in tank and oil it and by then it's ready to run. I've had this issue from the start. I've got a new ignition for it but figure run this one till it stops working completely then I'll change it.
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Recently I experinced the same thing with my engine. After a great deal of investigation I found the problem. The Hall pickup sensor is located in a plastic housing on the side of the gear case. The sensor had slipped part-way out of the plastic housing in a postion where it could not get triggered by the magnet inside the gear case. I pushed the Hall sensor back into the plastic housing and secured the wire with a wire tie. Problem solved.
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Hi all, have one of Jin's magnificent creations, and have run it a number of times without issue. Today I attempt to fire it up and have no spark. Try new batteries, verify voltages after the switch etc. And all looks right. I don't know if anyone has gone down the road of repairing the ignition system of these engines, but any input would be appreciated. Not really excited to buy a new ignition system, this failed after a handful of runs, and likely is made identical to the replacement. If I am going to buy a new one I need to know exactly what I did that caused it to fail (so I don't have to keep replacing them) and if it is something I did, why wasn't it more obviously warned about.