2019/05/10 Savage X Tuning the LRP30S2...

olds97_lss

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Most of this footage is just me trying to tune the thing. After my last outing, I wanted to set fire to it.
https://www.hpisavageforum.com/threads/2019-05-04-savage-x-lrp30-grass-bmx-bash.19327/

Had a myriad of issues, noted in that thread.

This is the first run after tearing the engine down, cleaning it thoroughly (found a bit of plastic in the HSN), checking o-rings, throwing some associated slime on them and RTV'ing the backplate/carb/carb banjo fitting. I replaced the fuel/pressure lines as well as installed a new associated primer bulb. Have always had good luck with those. I also put on a new set of dynamite 7075 shoes and relatively heavy springs.

When I put the engine back in, I had set the needles to at least 1 turn richer than stock, but I think even more so on both. The HSN was flush with the brass housing and the LSN was a turn out from flush with the inner tube the needle goes in. Out of the gate, it was acting/sounding lean.


By the end of the video, I had burned 625cc's of fuel.

It's better now than it was during the previous run, but still iffy at times. I've geared down to 15/47 to run the trencher 3.8's. The bell is already toast. Was a tekno hardened 15T. It lasted 1500 cc's of run time. I had issue getting the engine over enough to mesh it as tight as I wanted, so it was a touch too loose. That probably contributed to the bell dying so fast. I'm not sure if I was hitting the end of the motor plate slots or what. I couldn't see the engine making contact with anything, but it wouldn't move closer. I had raised the engine 2mm with spacers as the bell was making contact with the brake disks.

I think I'll try replacing the tires/wheels with something a bit smaller OD and lighter, like the traxxas maxx 3.3 tires/wheels. The tune seems relatively stable, but it just seems to labor so much, especially in 2nd gear. Just feels a lot more sluggish than I think it should be and if I tune a hair more lean, it becomes marginally more responsive, but then I get lean bog when I punch the throttle from a stop and a hanging high idle.

It's acting kind of how I remember the LRP28S3 acting back when I had my aftershock and I installed a set of a buddies muggy tires/wheels on it. Just caused the truck to work really hard.

I do have a brand new set of revo talons somewhere that I never ran on my ERBE, maybe I'll give those a try and see how it does, when I get a new bell and engine plate. I noticed when putting the engine back in that the engine plate is cracked right under the PS. Should be getting those parts this week.
 

olds97_lss

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Set of traxxas talons should cut down on rotational mass... and forward traction... and top speed. lol! Will just have to stay away from concrete with these tires as the sidewalls do not hold up well at all on traxxas tires, especially the talons. The rims cut right through them after a few hard landings. Should do ok offroad and at the grass bmx track.




The notches traxxas puts in their 17mm hubs worked perfectly with the 17mm hub adapters I'm using, so at least I didn't have to cut those out like I usually do.
 

Seanthemechanic

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Really weird issues you’re having. My LRP .30 runs like a top on my xl with big trenchers. Your motor is still acting as if it has an air leak still but who knows where
 

olds97_lss

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Really weird issues you’re having. My LRP .30 runs like a top on my xl with big trenchers. Your motor is still acting as if it has an air leak still but who knows where
Yeah, I know. Doesn't make much sense. I even pressure tested the tank with vacuum and pressure, doesn't leak either way.

What pipe, fuel, glow plug are you running? Did you change your head shims at all?
 

Seanthemechanic

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I run an o.s r5 plug with Byron’s 30% nitro 11% oil. Cold plug. For pipe it’s an RB TM-01. Also ran great on the stock hpi polished pipe. Never changed head shims. I also run the same fuel and glow plug on my o.s .30vg and that one is on the hpi polished pipe. Runs perfectly as well. I’ve found the magic for the big motors is high nitro content on a cold plug
 

olds97_lss

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I run byrons 25%/8% with odonnel medium/purple temp plug. The LRP28's I ran in the past worked well with that. I run a losi LST2 pipe, which is quite a bit more restrictive than the HPI polished pipe and appears to be more restrictive than the one you run. Smaller stinger ID. It worked well with the LRP28 on my aftershock and BB revo when I ran a side pipe. Maybe I'll dig out the old HPI polished pipe I have and give it a try.

I ran the hpi polished pipe with the 28 and it left it a bit muddy in the middle of the throttle range. Would run fine for the first 1/3rd and last 1/3rd, but blubbery in the middle.

I recall one of the guys I ran with back in the day ran an LRP30X on his LST2 (after getting a different crank, owb, backplate for pull-start, pretty much negated any of the exter performance of that version of engine). I think he ran the OFNA JP3 pipe. No idea what fuel/glow plug. Although, it spent most of it's time WOT or not running, wasn't the most "finesse" kind of driver. More like "ricky bobby".
 

Seanthemechanic

Active Member
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The polished pipe works very well! My o.s for example loves that pipe and hates the RB. Try it and see what happens. I would try a cold plug too with that pipe and re tune of course. Give it a shot, that combo works well for me
 

D3MON

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what you are going through is kind of what my axial was doing when i bumped from 20% to 30 Nitro, almost to the T. wont idle/start when LSN was set how it should, acting super rich right until it was lean bogging out.
i swapped to an A5/#10 plug from a #8 and it runs really well now. just for S&Gs don't happen to have an A5/#10 plug around do you? or any straight 20% fuel?
given that it was the same truck with both engine problems, id definitely swap out the pipe to test that as well.
 

D3MON

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i know they are both cold plugs, but you never know. R5 is for on road, so don't really know if that would be a difference. have used #8s almost everything until now, also just a thought, how many head shims are you running?
 

olds97_lss

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Well, I ordered an A5. So, first I'll throw on the HPI pipe, see what that does. If it's still overly fussy, I'll try the cold plug to see if delaying the timing a bit does anything.

The #8 is a medium-hot plug I think. I used to run those too, then tried the odonnel medium/purple and it worked better in the LRP28. That's what I have in the 30 now and the 28 in my BB revo. I run an LC4 in my 21TM in my other revo. Longer plug, but also medium temp.

I have whatever shims came in it stock, 3 of them. The manual says to use 3 for 20-25% fuel. It aslo suggested 25% fuel to be used, which is all I've run in all my trucks since my first LRP28.
 

D3MON

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i did just just realize i had been running a SIG plug, for some reason it was what the hobby shop gave me, must have been the only long plug they had? it is a SIGGP003, has an idle bar too which i thought was strange, i think its a med/high heat plug, then i tried the #8 then the A5. which were both short plugs.
the SIG plug worked fine for 20% fuel, but 30% was no good. don't know if it was the reduced compression becuase shorter plug or the temp itself which caused it to run so bad.
 
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