Carb Keeps popping off.....

[MotoGod]

OK so this LRP motor RIPS. Only problem....no matter what I do...the carb keeps popping off of it and wiggling loose creating an air leak. I have taken the pinch bolt completely out to inspect it and it looks fine. The carb fits nice and snug inside the sleeve in the crankcase...but the pinch bolt doesn't seem to pinch well enough.

When I have the carb mounted, and the pinch bolt secured, I can take a center punch and gently tap it with a rubber mallet and the entire pinch bolt will slowly slide out of the hole. The pinch bolt doesn't look damaged at all here, neither does the crankcase or the carb sleeve.

Attached is the exploded view of the motor, with an actual pic of the carb pinch bolt (stock photo)

Anyone have any ideas? This is the only thing keeping me from racing this weekend....and at this point I may just tighten some zip ties around it before each heat just so it won't pop off!

I can always bolt up the OS21VG, but I have at least one....or possibly both sold pending payment...so I'd rather not chance ruining them before I ship them out. Only other motor I could use as a backup is the Force 26 out of my buggy...and that is a snail.

So if anyone has any ideas....let them rip.

 

[KROGOTH]

Sounds like you're in the same boat I am. Engine issues keeping ya from racing. Might just have to take the hit and not race? Or try and get something from a LHS if ya have that luxury.

 

[crk]

Could seal it in with some copper gasket sealent and a zip tie to hold it in place?

 

[MotoGod]

That's what I'm thinking as well. Worst case I zip tie it. Nylon shouldn't melt with the engine temp....but I think I'm going to have the LHS take a look at it before Saturday. Might go drop it off at lunch time if the boss lets me take an extended lunch ;-)

 

[MotoGod]

Dropped it off at my LHS at lunch time. We'll see what they can figure out ;-)

 

[hardmikke6996]

i dont know but would some thread lock work

 

[MotoGod]

Nope. Locking the bolt to the pinch portion won't help when the whole pinch assembly slides out of the crankcase when fully tightened ;-)

 

[DuckStang]

Teflon tape around the carb.

 

[hardmikke6996]

Nope. Locking the bolt to the pinch portion won't help when the whole pinch assembly slides out of the crankcase when fully tightened ;-)

o ok wasn't sure

 

[MotoGod]

Was thinking Teflon Tape, but won't that cause it to slip?

 

[bigjay]

I would think a little silicone or thread lock would help.

 

[MotoGod]

The pinch bolt is NOT backing itself out at all. It's still just as tight as I left it in there. I just think it's not grabbing the carb sleeve properly. LHS should be able to get it fixed. I was short on troubleshooting time...so I just dropped it off at lunch time. He said he's seen that problem on a bunch of motors in the past and can fix it up for me in the AM with a little grinding and maybe some shimming. I'll see how creative he gets.

Worst case there is always JB Weld! ;-)

 

[Scrogg]

Sounds like it was overtightened, the carb may be warped. Silicone the carb neck to the block, tighten the bolt and use red loctite on it. Then silicone over the pinch bolt on both sides. It should stay put. Make sure your throttle/brake linkages are not stressing the carb. If you set the endpoints too far it will push on the carb when you apply the brakes. Also there should be some play in the slide when the throttle is wide open.

 

[yeroc1982]

I just went through this with my savage. The neck on the carb has sum kinda special sheild on it, if it gets damaged, its toast. I tried permatex ultra copper on mine and it holds abit, depends how u drive. I like nailing jumps so it dident hold long.

 

[Racer 1966]

I just went through this with my savage. The neck on the carb has sum kinda special sheild on it, if it gets damaged, its toast. I tried permatex ultra copper on mine and it holds abit, depends how u drive. I like nailing jumps so it dident hold long.

Your Savage carb is different, this carb doesn't have that sleeve on it.

 

[yeroc1982]

Your Savage carb is different, this carb doesn't have that sleeve on it.

Ahh i see. Is there a carb i can get like that for my 4.6?

 

[Scrogg]

Stick with the stock carb for your engine. Just be sure to install and remove it properly. You'll never have any more trouble from it.

 

[MotoGod]

So it looks like the carb that was on it has a plastic sleeve that goes around the carb base. Well that plastic sleeve was somehow mangled inside the crankcase....so the LHS replaced the carb with another model that doesn't require a sleeve. Kind of odd though since I don't recall seeing a sleeve at ALL inside there. He gave it back to me, and it's certainly mangled.....but I'm pretty sure I would have seen this rather LARGE piece of grey plastic. So he charged me $50 for the work and the carb. Not a bad price....but if it was just a sleeve...I would think replacing the sleeve would be a cheaper route to take...

Oh well....it's fixed....but of course whatever tuning work I had done has now gone to hell. lol I ran 2 tanks through it tonight at the track...and it's running hot now. Oh how I love Nitro......

 

[crk]

So it looks like the carb that was on it has a plastic sleeve that goes around the carb base. Well that plastic sleeve was somehow mangled inside the crankcase....so the LHS replaced the carb with another model that doesn't require a sleeve. Kind of odd though since I don't recall seeing a sleeve at ALL inside there. He gave it back to me, and it's certainly mangled.....but I'm pretty sure I would have seen this rather LARGE piece of grey plastic. So he charged me $50 for the work and the carb. Not a bad price....but if it was just a sleeve...I would think replacing the sleeve would be a cheaper route to take...

Oh well....it's fixed....but of course whatever tuning work I had done has now gone to hell. lol I ran 2 tanks through it tonight at the track...and it's running hot now. Oh how I love Nitro......

Why didn't they just replace the sleeve? Did the give the old carb back too?:\

 

[Scrogg]

That plastic was your heat shield. Sounds like he gave you a lesser quality carb IMO.