I bought 2 of the close out HPI Nitro King RTR's and to make a long story short I sent one back to HPI because the engine/clutch bell was not aligned with the spur gear so the gear got chewed up during break-in, the second one's one-way bearing became loose so I had to remove the engine and I put it back after tightening it. The problem now is I cant line the engine/clutch bell up with the spur gear. When I tighten the for engine mounting screws/bolts it doesnt line up and becomes I dont know...jerky and sounds like its stripping the gear. Any secret to this, thanks.

Chris

Take a strip of paper, fold it double and put it between the spur gear and the pinion gear. Notebook paper works good. Tighten the motor down. You should be able to pull the paper out without tearing it and it should look like an acordian (sp?). If the paper is not crinkled by the gear mesh, its too loose. If the paper tears when removed, you got it too tight.

Lightly snug the engine mount bolts when you set the lash....to make a final adj, see if you can put a small flat-bladed screwdriver in one of the elongated holes closest to the CB and gently twist it to move the CB closer to the spur, or away. Then do the final tightening and re-check the lash. The CB and spur should spin freely through a complete revolution of the spur. If you hold the CB form moving and try to rock the spur, you should feel a barely perceptible movement due to the lash.

Thanks for the tips; I tried both with no success due to the spur gear having some teeth partly shaved off. I know I'm gonna need a couple of spur gears but I can’t find one anywhere in stock after looking all day. No wonder it was $99

Chris

Ok so I got a new spur gear after a hard search and a tip from a fellow RCU user. I put it on but now I am reluctant to run it until I am 100% positive that the engine/clutch bell and spur gear are aligned perfectly as they should be. I have put the piece of paper between the gears and tightened the screws, it feels ok but when I roll it it makes a noise like ringing and gears meshing, if I roll it back and forth about a foot really fast the tires lock up eventually making me think its wrong again. I'm sure that this isn't really rocket science but I don't want to spend another $10+ and wait weeks for them to be in stock. Are these noises indication of a tight or loose fit and need of another adjustment or should I just say screw-it and run it?

thanks again
Chris

The little ringing sound it normal, that's the clutch bell spinning. The wheels locking up while rolling it, I don't think is normal. I just tried mine and I can roll it on the carpet pretty quickly and it free wheels. When you removed the paper from between the gears, were you able to pull the paper out without it ripping? Or did you rotate the spur gear to get the paper out? You should be able to gently pull the paper out from between the spur gears without it tearing. It will be crinkled like an accordion, but in 1 piece. This is because there has to be some play between the gears.

When I pull the paper out I'm holding the spur gear so it does'nt move right? I can get the paper out without it ripping it if I pull slow and now it seems that as hard as I try I'm unable to recreate the wheel lock problem.

Chris

Well I got my Nitro Monster King back from HPI this week but was unable to run it because of 3-day rain. Yesterday I finally take it out of the box and fire it up. It took alot of pulls but finally got it running for about 20-30 seconds then it shuts off. Then I try it again and it starts for about one second then stops, startss,stops,starts,stops.... you get it. I took it inside and figured out the same exact problem had happened,the spur gear had been striped again. Im so friggin pissed, this came straight from HPI and still doesnt work right. I dont want to spend another $20+ on shipping and wait another month+ for it. Is there really a difference in quality on the Nitro Monster King and the Savage that parts break this often or what? What would you do?

Chris

Did you check the mesh before starting it? A spur gear isn't worth sending it back to HPI. A new one will only cost a couple bucks. There are a few things you must do to any new nitro RC before starting it.

1) Check the mesh
2) Check for loose nuts, bolts and screws
3) Check the factory carb settings

I also seal the motor, oil the filter, add a failsafe, add a hump pack and add a charge port before ever starting it. But you can skip these steps for break-in.