I need help figuring out why my engine is revving high!!? 😭

[HPI savage x knowledge]

So my HPI savage x for some reason wants to rev high when I get it started and soon as I got the breaks it shuts off the engine ? Should I check the clutch shoes or do you guys think it could be I need a new glow plug?

 

[ohsnap]

It's probably not the glow plug but swapping in a new one can easily test that.
More than likely, your problem is linkage and trim and / or idle gap related, but the clutch is still a suspect too. The fact that it revs high leads me to suspect the linkage as the culprit over the glow plug or clutch. Get your idle under control. Engine tuning doesn't really start until you got an engine that holds a decent idle.

Engine off - Can you spin the spin the clutchbell - does it spin freely or do you feel shoe drag?

Engine off - transmitter and receiver on - hit the brakes - does the carburetor linkage move causing the carburetor slide to move?
It really shouldn't. That should be your "sitting at idle" idle gap position.

Release the brakes and roll the truck - do you feel any brake drag?
You just need to go progressively step by step through things to identify the problem or problems.

It can be difficult to diagnose a truck when it's not in your hands, but if you check potential issues off the list, you'll eventually figure it out and this site has a lot of good advice.

 

[HPI savage x knowledge]

So i found out why it was revving high.. it was because my clutch my shoe was bad literally i used my finger to check the spring and it was a bad spring in the clutch shoe because it flipped open when i check it.

 

[HPI savage x knowledge]

Another thing the flywheel wont snug up against the the engine and collet. Like there's a little gab between the flywheel and engine. I'm Just waiting for the new flywheel and collet hopefully itll fit perfectly when i slide the flywheel on to the collet. I remember taking it apart and there wasn't a gab before

 

[ohsnap]

I may be wrong in my opinion on this (wouldn't be the first time), but I wouldn't worry about it if the collet is up against the bearing and the flywheel snugs down to it when the clutch nut gets tightened down (and holds).
There may be different slope angles involved (the collets and flywheels) that can exist and become a concern, but generally...

I'm more interested in how the clutch-bell fits and lines up with the spur gear.
Shims come to the rescue here in moving the bell forward or back as well as taking out the excess play.
I test fit the arrangement (including the mounted engine) and if things line up and the bell spins unimpeded, Loctite the crankshaft screw and then mount the engine to the chassis and go.

 

[guinnessdublin]

Another thing the flywheel wont snug up against the the engine and collet. Like there's a little gab between the flywheel and engine. I'm Just waiting for the new flywheel and collet hopefully itll fit perfectly when i slide the flywheel on to the collet. I remember taking it apart and there wasn't a gab before

Photos of set up would help here! 👍🏻

 

[HPI savage x knowledge]

Photos of set up would help here! 👍🏻

Ill send pics soon as i get my new flywheel and collet for the axial .32 engine. Which will be by next week and i will show you all how it sets hopefully flush because its new parts but we'll see maybe its fine the way it is. Just gotta wait for it to come in from amain hobbies

 

[ohsnap]

I'm not saying that I'm disinterested in seeing the look of the new parts and your build in general, but I'd like to see pics of the arrangement/setup that sparked the question.

 

[Easy rider]

I don’t own near as many nitros as a lot of these guys. Or, have the experience a lot of these guys do. But, outside of Traxxas 3.3 motors and clutch setups, I have zero setups that the flywheel sets flush against the front bearing. And, I’m happy about that.


As long as it’s the correct collar ,flywheel, and flywheel nut, I wouldn’t give it a second more thought.