Hpi Savage 21 rebuild and restore thread.

[Starfox2005]

This is the first (nitro) RC truck or (nitro) land vehicle that I've owned so any advice or suggestions are appreciated! @cbaker65 & @STONER RC might need your help with tuning. I have gotten the engine loosened and unstuck! Here's what's happened so far.

Header before polishing with a Dremel tool.

After

 

[Greywolf74]

My 2 biggest pieces of advice would be run nitro fuel that has 12% or less oil in it and make sure and use THIS nitro tuning flow chart. The flow chart is a tremendous help for people just learning how to tune nitro engines. Also read up on glow plugs so you know how to select the proper temperature plug.

 

[Tunedfrog]

I would install new fuel line. A pinhole can be a nightmare.

 

[cbaker65]

Carb needle o-rings are dried out!..

 

[Starfox2005]

Carb needle o-rings are dried out!..

I've gotten it to start and run up to operating temp. How would you fix that?

 

[cbaker65]

I've gotten it to start and run up to operating temp. How would you fix that?

First turn the needles all the way in ,as you do so ,count each full turn as you do so ,make note on the turns!
After you do that ,pull them out an rub some thick sticky grease on the o-rings ,then run them back in until
they bottom out an count your turns back out that you noted!

If the engine runs better ,then your carb o-rings are rotted an is leaking ,that will throw a tune off an you be
able to tune it!
Grease temporarly thing an will let you know that the o-rings are bad!

An engine will never tune or hold a tune with old & rotten o-rings in a carb!..

 

[Starfox2005]

First turn the needles all the way in ,as you do so ,count each full turn as you do so ,make note on the turns!
After you do that ,pull them out an rub some thick sticky grease on the o-rings ,then run them back in until
they bottom out an count your turns back out that you noted!

If the engine runs better ,then your carb o-rings are rotted an is leaking ,that will throw a tune off an you be
able to tune it!
Grease temporarly thing an will let you know that the o-rings are bad!

An engine will never tune or hold a tune with old & rotten o-rings in a carb!..

Can I replace the o-rings or are they engine specific? I'll check em this weekend if I get a chance!

 

[Starfox2005]

Should I get High temp copper RTV gasket maker material for the engine and carb to seal the air leaks? That's what the engine tuning thread recommend doing I'll post a link to it.
https://www.rctalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/#post-726317
Check post #5

 

[tudordewolf]

Can I replace the o-rings or are they engine specific? I'll check em this weekend if I get a chance!

Should I get High temp copper RTV gasket maker material for the engine and carb to seal the air leaks? That's what the engine tuning thread recommend doing I'll post a link to it.
https://www.rctalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/#post-726317
Check post #5

The gasket maker is kind of a last resort, it can cause problems instead of solving them in some cases. O-rings can be found "generic", or in a carb rebuild kit, you might need 2x1mm or 2.5x1.5mm NBR O-rings

 

[Greywolf74]

Should I get High temp copper RTV gasket maker material for the engine and carb to seal the air leaks? That's what the engine tuning thread recommend doing I'll post a link to it.
https://www.rctalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/#post-726317
Check post #5

I use high temp RTV for sealing the backplate and the manifold where the carb connects to the engine. Replace the o-rings with o-rings and then I use some Associated green slime on the o-rings to keep them moist and add an extra layer of sealant around the needles. If the o-rings that are on there look ok, Id just periodically treat them with some green slime and use em. If they look dried out then definitely replace.

 

[Starfox2005]

This engine manual says that I need 20-30% nitro fuel for this engine would anything bad happen if I just run on 15% that I have? I've already ran it off the fuel and it seems fine. I think it's got a higher oil % though and I'll need to try and tune it up right....

 

[gandalfnz]

The gasket maker is kind of a last resort, it can cause problems instead of solving them in some cases. O-rings can be found "generic", or in a carb rebuild kit, you might need 2x1mm or 2.5x1.5mm NBR O-rings

What are the issues gasket maker can create?
Been using it always, to seal the engine back plate and on exhaust manifolds instead of gaskets.
Never had an issue.
I have stopped using it to seal the carb, as I found that o-rings on those seal just fine and am yet to find an air leaking carb.
In my opinion if an air leak is not big enough to detect while blowing into the engine fuel intake, it is NOT a problem.

 

[tudordewolf]

What are the issues gasket maker can create?

I've used it myself on exhaust gaskets, but I'm cautious of using it where it could squeeze into the crankcase.

It's only anecdotal advice that I've read elsewhere, so I may be speaking a bit beyond my experience.

It's probably soft enough that it wouldn't matter if a few crumbs wound up going through the engine anyway, but I'm not willing to risk it as long as I can avoid it.

 

[cbaker65]

I've used it with out issues!
When I do result to using it ,I only use a little by applying it with a toothpick ,an I only set the part in place an wait 24 hrs
or overnite before I tighten the part down!..

 

[Starfox2005]

I think that's a head shim? I'm not sure what it is exactly.

 

[NCNitro]

Wth! That looks like someone tried to make a head shim. That's absolutely terrible!

 

[cbaker65]

LOL.. it looks like someone one didnt properly install it ,the piston & sleeve looks
descent ,an that shim caused leaks ,install a new one an the engine still maybe good!..