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Throttle linkage help...

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A

AC48

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Hey all,

I need some serious help with my throttle linkage. SOme of you may know that when I had the 3.3 engine and stock servos it wasn't opening my carb all the way, but just about. Now I have an RB TM523 mounted in my Revo, along with a Hitec HS-5625MG servo. Now my problem is much worse.

With the engine out of the truck, the carb opens smoothly. The throttle linkage also works very smoothly when not attatched to the carb. As soon as I mount the engine up and slide the linkage on, it comepletely jams at half throttle. From idle to half throttle everything is perfectly smooth and quick, then it just jams. I am completely stumped. This makes no sense to me.

I broken in my engine with it like this cause I didn't need WOT anyway. Even with the carb only opening half way it has just as much power as the 3.3 did. Just doesn't have the top end obviously. It even wheelies, which as me worried, it must be insane once I get WOT haha.

Anyway I think I need to completely redo my linkage. I have always hated linkages...so a step by step would be good haha.

Thanks.
 
When it jams, is the servo still pulling, or is it at the end of it's throw? If it's at the end, then you need a servo horn with a longer arm. If it's still trying to open the carb, you need to find out why it's jamming. Possibly a bad angle from the servo to the carb.
 
bad angle on the carb is what I'm thinking also rolex.


could be anything though.
carb brand new?
add some Wd-40 to the slide, loose'n it up a little bit
 
the 523's are notorious for not opening all the way. you can turn the carb so that it pulls farther. i put the aluminum pivot on mine and it helps alot to. i can get pics if you need them. mine opens up almost all the way, and yes it is INSANE
 
Tekno or what ever it is now sells a really nice throttle linkage for revos. I have wanted to pick one up but havent got a list big enough to buy something off the internet. O ya if your still running stock return spring may want to try a differnt one too, the stocker is really stiff, I like the associated, they provide just enough and give me the best response.

Bryson
 
The servo still wants to open it farther, and if I push the carb open with the servo helping it will open all the way. I've tried many different angles on the carb, and the best I could do was half throttle. At one point I had it opening almost all the way, but it would stick at half throttle and the return spring was not strong enough to pull it back to idle. So that was no good haha.

Thanks for the info Bryson, I'll check that out.

Z400, the carb has seen 3 tanks of fuel.

Rolex at one point I had it so that it would jam and the servo kept going and bent the linkage rod. I just don't get why it gets so stuck, when if I pull it with my hands it opens smoothly.

http://www.amainhobbies.com/product_info.php/products_id/14365

I think I will pick up one of these.
 
The only bad thing about that techno linkage is that it runs the wire outside the roll bar.

How do you have your TRS hooked up? With a TRS I've never been able to get the linkage to work right. Regardless of the engine. I redid how the linkage connects to the servo with springs/collars so the servo was holding the carb shut instead of the TRS. Granted, this isn't as safe as running with a TRS, but I do run with a electronic fail safe.

2005-1201-RevoThrottleLinkageHiRes.jpg


Also, if you turn the little arm on the carb so it angles towards the front, it makes it contact the plastic arm further out so you get more throw.

Notice how my arm on the carb is almost straight up and down. If you angle it forward like the yellow line, it will give you more movement.
2005-1201-RevoThrottleLinkageEdit.jpg


I also use 4x6 bearings on the throttle pivot to help avoid wear induced slop.
 
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I'll give Mallanaga's a shot, looks pretty much the same as old's.
 
you can kinda see my setup in this pic

DSC02049.gif


see how the carb is turned? i had to do that to mine so it would open all the way. (well very close, it still doesn't open ALL the way.)

i also opted for the aluminum pivot, it has bearings in it and seems to be a touch longer. plus the notch is angled. not sure why, but i got no binding. i run out of throw befor it binds...

i can get better pics if need be
 
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Not a problem I ever had with a rotary carb, but after the 2.5 conversion, the slide carb had a very picky lineup.
Just as Beason says, same thing I had to do, set it at an angle. It might take a while to get it right, and your linkage adjusted accordingly, but once I found the happy spot for mine, I never had another problem with it.
 
I've angled the carb. I tried many angles and the best I could get is half throttle. Most other angles would open most of the way, but would stick when closing, and the spring did not close it. If I pushed even very slightly the carb would spring closed. Where I have it set now, it opens and closes up to half way smoothly and reliably, which is why it is where it is. I'm gonna try a set up like old's and see how that works out.
 
Disconnect the linkage from the servo, and with your fingers, pull it open from different angles, and also different heights. At some position, you'll find that it slides very cleanly. That's the point you have to realign the carb and linkage to. Even an odd bend to adjust the height might be necessary.
 
Well I got the linkage from Mallanaga and mounted it all up. It works much better than the stock. With the 523 I can get about 90% throttle now, which is a hell of a lot better than 50%. The 523 is nice, I like it. Makes my Revo feel like its got some power behind it haha, which is what I wanted.

Thanks to all who helped.
 
I modified his set up to work for mine, but I'll post up some pics when I get a chance. Its basically the same as old's set up, cept I have fuel tubing instead of a spring because the spring was too long. Also it has a ball joint on the pivot.
 
Have you run it with the fuel tubing yet? I can't believe tubing has enough give to let the servo kick in the brakes.

The spring on mine is holding the carb shut, that's it's only purpose. If TRS's didn't put so much side load on things, it wouldn't be necessary.
 

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