MGT Fuel tank issues?

[olds97_lss]

I'm posting this here due to how many guys run the MGT tank in a mid-tank savage.

I'm not sure if my recent problems are due to the MGT tank or just new engine woes. Kind of hoping it's the latter, but I'm not sure.

Setup:
LRP28S3, savage extended 1", MGT tank, 16/49 gearing, 3 speed trans, standard savage tires, Losi HT LSTXL pipe.

I don't even have probably more than 1/2-3/4 gallon on the new LRP yet, but it seems to be tuning very inconsistent. Seems to always have decent power, but will either load up on me really quick at idle or I get the lean high idle sound when I let off the gas from a few seconds of WOT running. Periodically, it will act like the HSN is way too rich and bog really bad.

Like I said, not sure if it's just a new engine having fits as things wear in, or if maybe the tank is leaking causing an air leak. I notice the fuel pickup line is very softly sealed to the tank, which could make the tank prone to air leaks when engine vibration is going on. Or if it's something else completely.

I have sealed the carb neck/cinch bolt, but that is really all the maintenance I've done on the engine so far.

I don't remember having these issues with my first LRP a few years ago, but it was a long time ago, so it may have been weird for the first gallon or so, but I know it ran cleanly and very trouble free the last time I ran it. It probably has about 4 gallons on it now.

 

[ohmygahitscoby]

Yeah, when I first got the tank I noticed how easy it was to twist and pull on the fuel pickup. I was thinking the same thing if this would have caused an air leak. Another thing I noticed is that when the tank isn't mounted, you can shake the tank and the fuel filter jumps up and down inside. I'm not sure if this is for everyone or if I received a bad tank though.

 

[Scrogg]

That is called a clunk scoby, it's what keeps the truck running when the truck is upside down.
Olds those tanks are very leak prone, check it close.
My LRP would not let me lean the top end until about 1 1/2 gallons was through it.
i had that same run on issue you did. I just leaned the LSN until it went away.
That engine sounds lean when in fact it is actually rich on bottom.
A friend of mine bought a LRP the same time i did, he had to show me what i was doing wrong, talk about embarassing. I taught the guy how to tune! It was his 3rd engine and mine was like the 15th nitro engine I have owned!
i had never heard an engine sound like that from being too rich on bottom.

 

[frickenjoey]

Yup Scrogg +1 on that, I got my arse handed to me the same way I could not figure it out. I had a budy who is pretty intuitive on the suckers and he played around with it and got it going pretty good. But the low end torque was good at take off was good and the fuel line pinch test was ok...tad bit longer than normal but still good. I have heard those tanks could be a PITA.

 

[olds97_lss]

Well, I ditched the tank for the time being until I get things sorted. Went back to a 125cc buggy tank on the savage... won't get a lot of run time, but at least then I'll know it's not the tank causing the issues. The old OFNA tank has always ran good for me regardless what engine was strapped to it. Very consistent top to bottom.

I tried leaning the LSN a bit, but then temps went up. I think it's just been a while since I've had a "new" higher dollar engine. The last engine I broke in was last year and was an XTM 24.7. It was pretty well broken in by the time I hit half a gallon. I think your right on that one scrogg, the LRP needs around a gallon before it stops acting up.

I'll be taking out my aftershock with an LRP in it as well to give me a better base line. Will be the first time I ran that truck this year.

This was then: http://home.comcast.net/~olds97_lss/movies/2008-1019-HinkleyBashAllHighQualLarge.wmv

On a side note, anyone know of a 150cc tank with a similar footprint to the MGT tank? Since I run a primer bulb, the running on the roof time is pretty long anyway. I only really went with the MGT tank because so many have used it and it was a decent size/dimension to slap on the side of a savage even without the mid-tank mod.

Thanks for the tips fella's.

 

[olds97_lss]

Well, after ditching the MGT tank, tune was noticebly changed just from yesterday and the weather was pretty much the same. After leaning out the LSN about half a turn and richening the HSN about 1/4 turn, it was 10 times better than yesterday. Temps were more stable and the WOT -> idle "run on" dropped to almost gone. The more I ran it, the less the high idle thing was happening.

I guess the MGT tank is nice in theory, but sucks in application? Kind of sucks that I wasted $25 on it at my LHS... oh well, live and learn.

Now I just need to find a stable/predictable 150cc tank that will fit on the side of the savage. Running an LRP28S3 on a 125cc tank is only giving me about 6 minutes of run time between fill ups... I guess on the other hand, it gives me more of a chance to check temps and wheel nuts...

 

[frickenjoey]

I had been tossing the mid tank idea around but I think I am just going to stick to the 'ol stock side mounted tank. I need to finsh up the project on mine and get it running. I just hope the Sirio .30 is a good mill....still think I shoulda got another LRP though.

 

[olds97_lss]

I don't get how guys fill up with it up there. Do they just punch a big hole in the hood of the body? To me, that kind of defeats the purpose of looking good. Or do they pull the body off every time to fill up? Would be pretty inconvenient I would think.

I moved the tank up front on a t-maxx I had, but that was more out of being tired of trashing stock tanks. I moved the OFNA 125cc tank I'm running now up by the front tower. Worked fine, but required a decent sized hole in the hood for fill ups. Which looked kind of goofy.

I didn't care for the stock savage tank. To prone to breakage and busted the snot out of my knuckles when starting. Also had a bad tune change from full to empty that I didn't care for.

Found a few 150cc tanks on tower that look promising... just wish they were a little better with their photo's and more precise with their measurements. Would be nice if I could find a tank just like the OFNA tank that was a bit taller for more capacity. If need be, I could make a skid to protect the bottom of it from stuff.

 

[Scrogg]

The Hellfire tank can be made to fit in a midtank nicely. You refuel through the side window or windshield with a midtank. The Mugen MBX5T fuel tank is the best for a midtank mod but it is too long to mount it on the stock location. I have been where you are buddy, either do a nice custom midtank or run the Ofna tank you have with two extra fuel filters, or keep a stock tank.
Put a carb insert in that LRP and it will pick up another minute or two of runtime with very little loss of power.

 

[olds97_lss]

I don't have a carb insert... neither of my LRP's came with any extras. Maybe those come with the truggy version of the engine? With the kind of power it has... limiting it a bit wouldn't hurt my feelings much anyway. May actually prolong diffs/spurs and axles!

I really want a side mount. WIth the extra inch of room in the rear, it should make it easier to mount something. I mean, the MGT tank fit there just fine. It's quite a bit fatter/taller than the OFNA tank.

 

[frickenjoey]

I had thougt about an aircraft tank behind the engine or on the servo plate....I just wish they were more heat resistant and not such a PITA to fill. Right now I have the side mount and it sucks becuase I can't use the side mounted throttle/brake servo now. Everything is a trade off. I have an extra Jammin CRT tank.....hmmmm..I wonder if I could make that sucker work?

 

[ohmygahitscoby]

I don't have a carb insert... neither of my LRP's came with any extras. Maybe those come with the truggy version of the engine?

I think so. I accidentally bought the truggy version of the engine and it did come with the inserts.

 

[Scrogg]

Olds if you have an extended chassis you can put the Mugen 150cc tank in the stock location no problem. I did on my chassis that is only 1/2" extended in the rear so it should be no problem for you.
Fabbing mounts is the bitch, you just have to sit down and brainstorm. That is the most consistent fuel tank I have ever used.
I did not take a picture of the way I mounted it, and i am back to a stock tank.

 

[olds97_lss]

Why are you back to a stock tank if the mugen tank was so awesome?



Just jerk'n your chain.

Is this the tank of which you speak?
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRYV8&P=ML

 

[frickenjoey]

That looks like that same tank one of the guys here is running for a mid tank. That sucker is damn well not cheap is it? I need to go ahead and get the servo plate so I can do the same. There has to be the perfect tank out there. I am surprised some one has not jumped on-board and made a tank specifically for the application.

 

[olds97_lss]

Yeah, didn't notice the price on that. $28 for a fuel tank? Maybe I can find another like it.

 

[ohmygahitscoby]

I was definitely considering running that tank. The problem is that the CEN radio box requires modding to fit onto the FLM chassis. Plus that tank is a bit expensive. But hey it's Mugen. They haven't let me down so far.