Need help with my troublesome first nitro truck

[ohsnap]

That is definitely a problem!

Here's the part that you need.
The HPI part number is 1481 and correct for the S-25 engine.
Currently available on eBay.
https://www.ebay.com/itm/126550198254

You also need the 2 orings (HPI part number 1469 - comes as a pair).
One fits in the groove at the bottom and the other rests at the top of the neck (seals the top of the throat).

All the videos I saw from you said that hsn and lan are both flush with their housings to go to factory.

Don't know, don't care what youtubers say...
Same goes for AI responses while I'm at it.
I quoted you the HPI NItro Star S-25 manual HSN and LSN settings.

To complete the manual's guidance - here's what it says about the LSN.
"After break-in, the needle setting can range from 2 1/2 to 3 from fully closed depending on humidity, elevation, fuel, and glow plug."
Yes - it is the same statement as the HSN's setting...

 

[Zombotomy]

That is definitely a problem!

Here's the part that you need.
The HPI part number is 1481 and correct for the S-25 engine.
Currently available on eBay.
https://www.ebay.com/itm/126550198254

You also need the 2 orings (HPI part number 1469 - comes as a pair).
One fits in the groove at the bottom and the other rests at the top of the neck (seals the top of the throat).



Don't know, don't care what youtubers say...
Same goes for AI responses while I'm at it.
I quoted you the HPI NItro Star S-25 manual HSN and LSN settings.

To complete the manual's guidance - here's what it says about the LSN.
"After break-in, the needle setting can range from 2 1/2 to 3 from fully closed depending on humidity, elevation, fuel, and glow plug."
Yes - it is the same statement as the HSN's setting...

Yeah j saw the eBay ones but it'll take a month to get to me. Was hoping to find something faster but no such luck. I already have a full o-rong kit to rebuild it.

I would never trust a YouTuber for tech specs. The videos I saw were made and published by hpi, they specifically say it should be flush. But when I open the manual for the engine it says the hsn is 4.5 and the lsn is 3 turns. That's conflicting data from the same source and not sure what to believe. It also says nothing about idle screw, where is factory for that?

 

[CreepyQuarryCrawler]

I would never trust a YouTuber for tech specs.

There are plenty of excellent YT videos out on the interwebs for whatever topic you are after and we have plenty of excellent YT personalities in the RC space who work hard to bring knowledge and experience forward to help or share with others.
I can think of many YT videos I watched where I learned something.

I mean you mentioned yourself that you're having trouble finding consistent information from the manufacturer. This is where first hand accounts on forums, Reddit and places like YT step up to fill those education gaps.

Glad to see you found the problem, hopefully you can now get it up and running and enjoy some of that sweet brapp brappp

 

[CertifiedMike]

Yeah j saw the eBay ones but it'll take a month to get to me. Was hoping to find something faster but no such luck. I already have a full o-rong kit to rebuild it.

I would never trust a YouTuber for tech specs. The videos I saw were made and published by hpi, they specifically say it should be flush. But when I open the manual for the engine it says the hsn is 4.5 and the lsn is 3 turns. That's conflicting data from the same source and not sure what to believe. It also says nothing about idle screw, where is factory for that?

Buy some oring lube while you're waiting!

Sounds like you're well on your way to getting fired up! Congrats on finding the carb issue.

 

[ohsnap]

Yeah j saw the eBay ones but it'll take a month to get to me. Was hoping to find something faster but no such luck. I already have a full o-rong kit to rebuild it.

... The videos I saw were made and published by hpi, they specifically say it should be flush. But when I open the manual for the engine it says the hsn is 4.5 and the lsn is 3 turns. That's conflicting data from the same source and not sure what to believe. It also says nothing about idle screw, where is factory for that?

A month, that sucks!
I'm guessing that you are not located in the USA given that my purchases usually arrive in less than a week.

Under those circumstances, here's what I would do.
I'd bite the bullet and buy the body and spend the time experimenting.

You know that a vacuum leak is your prime concern - so try and make your current carb servicable.
I previously mentioned Luck 7 sealant - but any sealant that is heat and oil tolerant can work for the purposes of your test.
You just don't want air bypassing the venturi and causing it to lean out.

The main spot that you are concerned about is where the carb and throat meet,
Adjust the needles, reinstall it and seal the heck out of that area (and let it cure).
I would set the HSN and LSN 3 turns out from fuilly closed.

Idle gap - The manual says "Approximately 2mm) gap.
That's the gap at the widest part of the arc.
Personally, that seems a tad large to me, I'm guessing about 1.5mm, but you can easily adjust it.
You want it wide enough to keep the engine running without engaging the clutch.

Note - Prior to reinstallation, I would glue or epoxy that large chunk back in place and let it cure.
I think you'll need that chunk back in place to cinch the carb down.
I'm guessing that at some point someone had really cranked down on the lock pin and caused the damage.

Glad that you already have the o-ring kit.

Videos:
Back when this engine was produced and dinosaurs roamed the earth, there were very few instructional videos.
Was the video that you viewed specific to the S-25 or was it produced with newer designs in mind?

I already gave you my reccomendations as to the adjustments.
Note - On my S-25, I can tell you that the LSN is recessed from flush and it has the exact same carb as yours...

It sounds like you are on the right track and making prudent decisions.
Have fun and experiment...

 

[EJMOPAR70]

Hello, this is my first nitro and I really need help. It's beyond frustrating. It's a hpi savage I believe it's a savage x, it has a hpi .21. 3.5 engine. I think it's the s25. I've been out 12 or 13 times and only gotten it to start 2 times and have yet to be able to get past 40 percent throttle. I've reset all the carb settings to factory with both lsn and hsn. I've used up 3 glow plugs, 2 new and I've verified it gets nice and hot before trying to start. I've tried leaning the needles and richening the needles. I tried pre hearing with a hair dryer. I'm using 25 percent nitro. I have a good losing ignitor that's always fully charged. I've only got it going 2 times.when I do it's super finicky, randomly stops a lot and then I have to restart, give it any gas when you start and it dies. The most recent time I had it going I had it going the fastest yet at 40 percent throttle which is still slow. It got warmer than it had before but randomly died and hasn't started since. Sometimes it sounds like it might but never actually does. I don't know what else to do at this point. Something has to be wrong. There is no way nitro guys are messing with starting this much, takes all the fun away from it. I hope I have enough info

Is this a new engine? If it is you need to set it at factory. Then idle first two tanks. Plipping the throttle occasionally. Don't start turning needles.

 

[EJMOPAR70]

NEW ENGINE?

Is this a new engine? If it is you need to set it at factory. Then idle first two tanks. Plipping the throttle occasionally. Don't start turning needles.