How to remove the primer from LST fuel tank

[Coach Z]

The tanks that come with the Losi LST / LST-2 / Aftershock / Baja STINK! They're very prone to air leaks through the primer setup so its a good idea to remove the primer and its come up a few times recently here and I happen to have a few tanks I was doing the other night so I thought I'd take some pics of how to do it:

Step 0 - Curse Losi for the bad design!

Step 1 - Using your hands or pliers pull the black primer knob off of the tank

Step 2 - Using a small machinists pick or the like pull the primer post out of the fuel outlet at the bottom of the tank

Step 3 - Next push the portion of the post that is still sticking out where it was attached to the knob all the way into the tank, again a small pick is useful but you can use a hex driver or anything small enough to get it done

Step 4 - Using small needle nose pliers remove the post from the tank as well as the washer and o-ring from the top of the tank

Step 5 - Last is to seal the hole in top of the tank where the primer was. The most common thing to use is JB Weld, I'm trying out a new 1 minute epoxy to see how it does. The only problem I ran into with this epoxy was that it was a bit thin and wanted to drip into the tank which the jb doesn't do.

And here is your new primer -less tank: (the only reason I removed the filler cap is I was dying this tank, its not necessary for removing the primer

 

[RCnut]

what would you think about dropping a small piece of an acrylic rod into the hole THEN epoxying it in place ?? i was wondering if the fuel would possibly eat away at the acrylic ??

this would also help to keep the epoxy from dripping into the tank.

 

[Coach Z]

Most adhesives have a hard time bonding to acrylic, the epoxy was one minute stuff so I just kept moving the tank until it had set so it didn't drip but if you don't want the hassle just use the jb, it has more of a playdoh texture.

 

[MrClean]

I tried a 5 minute epoxy, same brand I think and had a few drips in the tank. A little bit of nitro fuel removes them quickly....... but it also apparently softens the epoxy too. I might not have got it mixed up well or something, but it didn't seem to hold and ended up leaking fuel. I removed it and used jb weld.

 

[neobart]

If you keep your hands of the primer from the get go, it won't be a problem.

 

[olds97_lss]

I just used RTV...

 

[hpinitromt]

back in the old days of the savage21, we used to take a screw put an oring on it and then ca or shoe goo in the hole, worked like a charm, i still have a tank from back then, its about 5 yrs old and still holding up
congrats on the excellent post, the pics really help explain the procedure

 

[camaropunk16]

Nice post man, I just did this to my Baja about 4 days ago and it worked like a charm to get it running good!!! With your procedures though, i am sure that next time it will be a bit easier that the way that I took the primer out, I will not get into that story since I still have to get part of it out of the tank. I have those same needle nose though so I should be able to get it out pretty easy I hope.

 

[RC Addict]

Day one and I am already learning about mods. I appreciate this one as my tank is already leaking after 1/2 gallon. Now I have the fix!

 

[olds97_lss]

Be gentle when doing step #3 or you may end up with a tank like mine:

I attempted to pull mine out when the tank was cold... working on it in January immediately after the UPS guy dropped it off... $16 down the toilet! I just got excited... olds97_lss=moron.

 

[chuck3]

I'm surprised you even made it that far with the tank olds!! if your anything like me, you tend to break it just getting it out of the packaging. damn those "new part" jitters

good post!! i might have to try this. what is the best way to pressure test a tank though?

 

[jackel]

good info on primer removel

got mine out today with out brakin nothin but mine still runs for about 3/4 min then quits agin hard to start temp only 160 to 165 then stalls any idas?

 

[chuck3]

it might be flooding, try to lean it up 1/12 a turn.

BTW you can start your own thread so this one will stay on topic.

 

[echelon6]

i dont get it, whats the benefit of removing the primer? Even if it leaks, isnt it just a minor loss of backpressure?

 

[MrClean]

They can allow too much air into the line which may result in an engine that is hard to tune, runs too lean.

 

[alpinehyperlite]

i dont get it, whats the benefit of removing the primer? Even if it leaks, isnt it just a minor loss of backpressure?

With that minor loss of pressure, and the 29,000-35,000 rpms of these little motors, the little bit of air in the fuel, can cause dramatic high temperature jumps.

 

[RC Addict]

They can allow too much air into the line which may result in an engine that is hard to tune, runs too lean.

+1 My leak leaned out the mix and caused the engine to stumble under load.

 

[aftershocked205]

i know this thread is old but i didnt want to start a new one. I used red RTV and i filled it up to much and it went through the small hole and got on the top of the tank , it didnt drip to the bottom though , anyways i was wondering if i should try to remove it or just let it dry and maybe the fuel wont brake it down
thanks

 

[taz1175]

If you keep your hands of the primer from the get go, it won't be a problem.

EXACTLY, I haven't had any problems with mine either !:goodpost:

 

[MOPAR MESS]

Does anybody have a tank for sale? My tank is junk. Unfortunately I could not reseal it. Anybody has a fix or a tank for sale please let me know. I know you can get one on eBay or on a main for about $129. Unfortunately I don't have that kind of money right now so I would like a used tank which is Affordable. Thanks again! Mark