69LikesOS FS26S-C 4-stroke development
08-04-2018 | 04:36 PM
#1891
After a month of waiting, a tiny but crucial bit of progress:
I sent the crankshaft from my FS-40S-CX to a machinist who's done work for me several times in the past, and I asked him to grind-down the last 5mm of the crankshaft from an 8mm diameter to a 7mm diameter. This will allow a normal nitro flywheel collet to fit the crankshaft.
I sent the crankshaft from my FS-40S-CX to a machinist who's done work for me several times in the past, and I asked him to grind-down the last 5mm of the crankshaft from an 8mm diameter to a 7mm diameter. This will allow a normal nitro flywheel collet to fit the crankshaft.
08-04-2018 | 06:42 PM
#1892
Tech Addict
Joined: Jun 2015
Posts: 746
Hey, right on! Should be pretty slick. Keep us updated, so this thread keeps going. I've been running mine quite often and have also made changes but I have neglected to update this thread.
I'll have to take some pics...ect when I get a chance.
I'll have to take some pics...ect when I get a chance.
08-04-2018 | 07:40 PM
#1893
The other major obstacle is the need for a custom-CNCed engine mount. I needed to get the crankshaft modded first though, so I could fit a flywheel, clutch, and bell to the engine so I could see how the engine would line-up with the rest of the chassis. I'll have to learn 3D CAD to design the engine mount, because I have so much spare time with a full-time job and a pregnant girlfriend.
Quick question regarding camshaft timing: There's a small nick on the side of the camshaft that is clearly used for properly aligning the camshaft and crankshaft. I think that nick is supposed to point directly at the pushrods when then crankshaft is at TDC. Am I correct about this?
Quick question regarding camshaft timing: There's a small nick on the side of the camshaft that is clearly used for properly aligning the camshaft and crankshaft. I think that nick is supposed to point directly at the pushrods when then crankshaft is at TDC. Am I correct about this?
08-05-2018 | 05:19 AM
#1894
Tech Addict
Joined: Jun 2015
Posts: 746
The other major obstacle is the need for a custom-CNCed engine mount. I needed to get the crankshaft modded first though, so I could fit a flywheel, clutch, and bell to the engine so I could see how the engine would line-up with the rest of the chassis. I'll have to learn 3D CAD to design the engine mount, because I have so much spare time with a full-time job and a pregnant girlfriend.
Quick question regarding camshaft timing: There's a small nick on the side of the camshaft that is clearly used for properly aligning the camshaft and crankshaft. I think that nick is supposed to point directly at the pushrods when then crankshaft is at TDC. Am I correct about this?
Quick question regarding camshaft timing: There's a small nick on the side of the camshaft that is clearly used for properly aligning the camshaft and crankshaft. I think that nick is supposed to point directly at the pushrods when then crankshaft is at TDC. Am I correct about this?
08-05-2018 | 01:11 PM
#1896
Nope, I had no idea that product existed. Wouldn't that design make it impossible to adjust the engine position for different-size pinion gears, though? You'd have to drill new holes each time.
08-20-2018 | 01:32 PM
#1899
A tiny bit of progress:
The clutch fit just like it would on any other engine, no tweaking necessary. Unfortunately I probably won't have time to finish this project before D-Day, but at least one of the two big hurdles is done.
Interestingly, this engine is actually less tall than a TRX 3.3. It is much, much longer, however.
The clutch fit just like it would on any other engine, no tweaking necessary. Unfortunately I probably won't have time to finish this project before D-Day, but at least one of the two big hurdles is done.
Interestingly, this engine is actually less tall than a TRX 3.3. It is much, much longer, however.
08-20-2018 | 03:01 PM
#1901
Losi 2-speed clutch bells fit with no modification, though they are slightly larger-diameter than I think these shoes are designed for, and I only need a single pinion gear anyway. HPI clutch bells are a little too short, but I can shave down the butt-end of the pilot shaft to make an HPI clutch bell fit. I've done that once before already, on my HPI Bullet that has a Losi 3.4 engine in it. I stupidly attempted to tap the crankshaft in that engine a little deeper, broke the tap in the crankshaft, and had to cut off the end of the crankshaft and install a pilot shaft instead.
08-20-2018 | 03:46 PM
#1902
Tech Addict
Joined: Jun 2015
Posts: 746
Losi 2-speed clutch bells fit with no modification, though they are slightly larger-diameter than I think these shoes are designed for, and I only need a single pinion gear anyway. HPI clutch bells are a little too short, but I can shave down the butt-end of the pilot shaft to make an HPI clutch bell fit. I've done that once before already, on my HPI Bullet that has a Losi 3.4 engine in it. I stupidly attempted to tap the crankshaft in that engine a little deeper, broke the tap in the crankshaft, and had to cut off the end of the crankshaft and install a pilot shaft instead.
08-20-2018 | 06:44 PM
#1903
Tech Initiate
Joined: Nov 2017
Posts: 32
Update
So I was on vacation there for a while so I wasn’t able to get much done but just before I left I got my bump box. I bought a used ofna pink box, I lucked out and got it for I think $30 shipped if I remember correctly. I had to rewire the whole thing though because the current gague wire couldn’t handle the 4s power. I got the engine primed up well and tried to fire it. I finally got it to fire but it seemed to only be a few revolutions. It seemed that the engine wasn’t getting any fuel because the carb was just dumping fuel all over the chassis. So I turned the intake header upside down and put the TRX 2.5 carb on. I tried again and got it to run for a few seconds but it died again. But before I got it to run and now after the carb is spitting fuel back out like the timing is off or something. I checked the valve clearance and it was fine. I can’t figure out what the issue is. Also does anyone have any idea what I should set the high and low speed needles to on he carb? I’m worried that I may not be gettin enough fuel and I obviously don’t want to kill the engine. And finally does anyone know where to get replacement wheels for the ofna pink box. I cannot find any anywhere, and although mine is in good shape, it’s eventually gonna wear out. Thanks
08-20-2018 | 08:45 PM
#1904
08-21-2018 | 04:02 AM
#1905
Tech Addict
Joined: Jun 2015
Posts: 746
So I was on vacation there for a while so I wasn’t able to get much done but just before I left I got my bump box. I bought a used ofna pink box, I lucked out and got it for I think $30 shipped if I remember correctly. I had to rewire the whole thing though because the current gague wire couldn’t handle the 4s power. I got the engine primed up well and tried to fire it. I finally got it to fire but it seemed to only be a few revolutions. It seemed that the engine wasn’t getting any fuel because the carb was just dumping fuel all over the chassis. So I turned the intake header upside down and put the TRX 2.5 carb on. I tried again and got it to run for a few seconds but it died again. But before I got it to run and now after the carb is spitting fuel back out like the timing is off or something. I checked the valve clearance and it was fine. I can’t figure out what the issue is. Also does anyone have any idea what I should set the high and low speed needles to on he carb? I’m worried that I may not be gettin enough fuel and I obviously don’t want to kill the engine. And finally does anyone know where to get replacement wheels for the ofna pink box. I cannot find any anywhere, and although mine is in good shape, it’s eventually gonna wear out. Thanks
You've got more than one of these engines, right? I've got a FS-40S-CX and a FS-20; the FS-20 is basically useless to me because it's bump-start only and it has an airplane-spec valvetrain. The only reason I bought it is because it was the first one I was actually able to get my hands on.
Here a link to a video. https://youtu.be/p-A5QFQ1CT0
Its faster now than in the video.
My other project uses an airplane spec fs26s.