Kyosoho USA-1 Nitro Rebuild

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Woo Hoo! Look what my awesome USPS letter carrier, Angie, brought me today to finish off my USA-1 rebuild! First LRP engine, but have heard great things about these engines! Can't wait to get it broken in and start ripping!

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Well, a very quick dry fit is looking discouraging. I may need advice on getting this mill installed to work. May have a an engine with nothing to run it in!

Pics to come.
 
Well, a very quick dry fit is looking discouraging. I may need advice on getting this mill installed to work. May have a an engine with nothing to run it in!

Pics to come.
That sucks. Share your problem and maybe we can come up with something.
 
Yeah, this engine isn't going to work :mad:. It's just too big for this rig! The pull start case won't allow it to sit on the engine mounts. If I made new mounts, then the CB would be way too high to engage on the counter gear and the crank looks way longer than I'm used to seeing.

Too bad, we've got a warm-up here in SW Ohio and I was hoping to at least get it broken in.

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Well, I got a Dynamite .21 engine that fits, but just barely. Problem is, I need to create additional mount slots to bolt the engine to the chassis.

This rig has two plates that attach to the chassis with fixed bolt holes. The plates have oval mount slots to bolt the engine to the plates.

Problem is, the oval mounts don't allow enough play to mount the engine.

I need to figure out how to cut ovals perpendicular to the existing mounts, so I can slide the engine North/South in addition to the existing East/West.

Thinking I can fashion something with my Dremel.

Other challenge is finding an exhaust header that clears the pull start since the pipe breaks to the driver's side of the rig. Can't flip it because the fuel tank and servo tray is on the passenger side.

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Well, the good news is the pipe and header arrived today and looks like it'll fit nicely while allowing ample room for the P/S. Just need to mod those mount plates, get everything bolted on and see what happens! May be a slight rub against the shocks, but I think manageable.

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Cool. Maybe put a slightly shorter shim behind the shocks, or file them down slightly.
 
Once you get the header fastened to the engine and the pipe securely it may just have enough gap.
 
Made some progress this evening.

Managed to get the new mill mounted and lined up. Everything spins freely, so happy with that.

As @Greywolf74 mentioned, once i mounted the pipe and put the spring on, it did pull the header away from the shock tower. Still close, but it doesn't rub.

Put the fuel lines on. Not 100% happy with it, so may mess with them a bit more, but it works.

Got the throttle linkage connected (still need to put the throttle return spring on) and have it trimmed out so that's set.

Steering servo seems weak, but again, it's throwing some substantial tires around. I may upgrade the battery to a five-cell NiMH battery, see if a bit more power may help. Could be the servo is just not strong enough, we'll see.

Next step is to see if this thing runs without coming apart on me! :D

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Well, tomorrow's the day! Started the engine on my work bench just to see if it would fire up and make sure I had the idle set reasonably. Fired up on the third pull. Didn't run it long as it was in my basement.

Supposed to be 47 degrees tomorrow (which in Ohio in February is considered warm) so going to start the break-in on the Dynamite and see what this old rig can do!
 
Can't wait man. I see the body peeking out back there 😉
 
When they were working on the new release of the USA-1, I was dying to get one. But after it came out, I saw people were having some problems with it, so I held off. But I'd still love to get one some day. We have a Mad Crusher that I got off Tunepipe on here, so that is close enough for now. It needs a new body, but that is the only thing really wrong with it.
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I am digging that body! At some point, I'll need a new one for sure. That original body has taken a beating for sure! I actually have a Spider-Man monster truck body that fits as well, but really want the Chevy body at some point. May have to find something close and mod it.
 
I have been looking for a new Mad Crusher body for awhile now. I missed a brsnd new one for $89 ,on ebay 🤬

Might have to say hell with and just do a custom body, or grab the new USA-1 bidy, but I really want to keep it original.
 
Well, first run on the rebuild went so-so. Got about 1/2 tank in and the fuel pick-up line broke. Need to adjust the linkage on the throttle/brake servo. Anytime I put the brakes on, throttle opened for some reason and the thing ran WOT with no TX input.

Steering servo is way too weak for this thing, so please, any suggestions on a high-torque servo will be greatly appreciated! These tires are way too beefy and the turning radius is negligible at best.

Need to do some tinkering, but I at least got it running for a bit!
 
Just look for a good standard high torque servo with at least 350oz/in or so. Savox is my go to brand, but Hitec also has great servos. If it has a terrible turning radius, you'll probably want a fast servo as well. So look for something close to .12 speed or lower. But these will get pricey. If you don't mind pricey, grab a Tekin high torque servo. If you want to go cheap, look at the 35kg servos on Amazon. Just make sure whatever you get it has metal gears.
 

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