Rotary carb probs

[granjer]

.15 trx rotary carb in my sons Maxx has about .003" lateral movement which is enuf to effect tuning accurately. Anyone know of any fixes? Or do I put up with it until this engine craps out and I get him his 2.5? It still runs like a champ so I'm not willing to junk it yet. Thanks in advance.

---------- Post added at 8:46 PM ---------- Previous post was at 8:41 PM ----------

I fixed the title for you.

 

[pipisugbo]

EDIT: I'm assuming you mean the whole carburetor will wobble inside the crankcase.

First link is Green Slime...you should get some to seal around the neck of the carb. Second link is for the o-ring set for the TRX.12/TRX.15 carburetor. That might fix the problem, and if it doesn't, you're only out about $5

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSF70&P=ML
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJL90&P=7

If neither of those work, it may be that the neck on the crankcase is worn out, but I think that's pretty unlikely.

 

[mtaylortank]

look for any hairline cracks..... does anyone else think if there happens to be a slight crack that would let it have extra room to wiggle??????????? just throwing an idea out there.. just something to watch out for...

 

[granjer]

It's not the carb body but the rotary valve inside the body. I don't know the technical term for it, sorry. Basically its the valve that rotates and houses the lsn. This movement is enough to cause tune issues due to the lsn moving in and out of the orifice. I resealed the engine and the pinch bolt that holds the carb body so that's all good there. Perhaps i'm being to picky and accept this as a design flaw? Thanks for the title edit rolex.

 

[vmswimfan21]

you can get a new carb like 35 bucks http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJF52&P=ML

 

[w bill]

If that carb has a slot in the barrel were the idle stop screw rides in try replacing the screw sometimes they wear it retains the barrel also if theres any o rings involved replace them if all else fails get a new carb.

 

[Rolex]

There's a good possibility that the idle screw is out of the track allowing the barrel to move. Make sure it's in the groove or you will not be able to adjust the idle.

 

[granjer]

Thanks for the input and links gents. Gonna look into putting a very light weight spring in the rubber boot to keep outward tension on the valve. The only bad part about that is pushing in on the lsn when I adjust it. I'll have to be more patient I guess. if this don't work, I think I'm going to buy a carb for now. I want my son to get more wheel time before I turn him loose with a 2.5. Thx again. Btw , I checked and rechecked the idle screws and barrel per your advise, all appeared in good condition. No burrs or any major sings of wear. This has always had traxxas ran in it so it has been WELL lubricated.

 

[mtaylortank]

I would switch fuel I am !!!!! after talkin to a bunch of people on here I figured out almost all my problems originated from that oil..... I mean fuel....
switch fuel and it will last even longer!!!!!!!!!!!!!!!!! I have had 2 3.3's with maybe a gallon (if I am lucky) ran through them and traded in the first and rebuilt the secound cause everything else was fine except the conrod......... I had alot more luck with trinity monster horsepower I was running that in dead of winter and had no problems..... as soon as I switched to traxxas I have had nothing but problems with my rigs.............. Just some friendly advise...

 

[vmswimfan21]

i had been running traxxas top fuel for 2 gallons. couldnt figure out why i could pull the wheelys and blogged on take offs and over heated all the time switched to byrons gen 2 racing fuel and its like a whole new truck. id get ride of the fuel

 

[granjer]

I ditched the spring idea after deep thought and debate. Took it to my lhs and he helped me adjust some of it out which helped a little. I'll give ya a run down. We loosened the throttle arm on the "valve", then opened the valve all the way, with the LSN backed out, we took a plastic pick I use to clean my guns and pt outward pressure on the valve, not very much mind you. He then held the throttle arm against the carb body and tightened the set screw. It lessened the play and helped on the tune, but it still slightly idles poorly and goes high when I adjust the lsn. Oh well I guess, inherent problem. Curious if I'm the only one.
As far as the fuel goes, I switched my 3.3 to sidewinder and love it. I have it set not to do wheelies, but when I tighten things up it will loose traction instead of wheelies. I only have 1/2 gal of Crapsas to burn then I'm done. Just can't get my self to dump $20 worth of fuel.