carb not closing

[ibanez890]

hey guys, on my old engine when i go to full throttle and then let go the carb stays open about .5mm however if i brake it closes the rest of the way, i have a return spring on it and its pretty tight but it still doesn't close fully, when i put two springs on it closes fully but then it only opens half way, I'm not sure as to whether its they way my ofna linkage is set up since ive never used it before but i set it up like hypnotiqs picture of his ace servo.

 

[ibanez890]

forgot to mention, I'm not too bothered about it since the picco is coming next week, but it would be nice to learn how to fix it.

 

[SwampDawg]

people still use return springs? wow!
i use no such thing but use a fail safe for preventitive measures.

as per the carburetor not closing completely, this is prob cuz its set up incorrectly and/or something is binding in the linkage/carb throat/slide.

simply remove the link off the carb arm, and manually slide it in and out. Check for the gap in the opening to make sure when its closed is no more then a creditcard in thickness. When its opened all the way that indeed the opening is wide-open and clear.

With the link on the carb arm, make sure your trim is set at neutral and with the truck not running, check to see that it opens and closes properly - in your case, not..... so then make adjustments to the linkage until the desired opening is achieved.

 

[SwampDawg]

forgot i was attempoting to make a new forum long ago.....found this thread for ya

http://rcmotorsports.50.forumer.com/viewtopic.php?f=56&t=33

 

[Londoner]

hey guys, on my old engine when i go to full throttle and then let go the carb stays open about .5mm however if i brake it closes the rest of the way, i have a return spring on it and its pretty tight but it still doesn't close fully, when i put two springs on it closes fully but then it only opens half way, I'm not sure as to whether its they way my ofna linkage is set up since ive never used it before but i set it up like hypnotiqs picture of his ace servo.

Probably something wrong with your linkage somewhere, also check the idle screw is set correctly.

people still use return springs? wow!
i use no such thing but use a fail safe for preventitive measures.

A throttle return spring is just as important as your failsafe, I never run without it.

If you have total power failure, i.e your battery falls out or a cable is cut, snagged or whatever then your failsafe is totally useless, the failsafe needs power. If this happens at WOT without a return spring, your truck will stay at WOT totally out of control!! :bad driver: happened to me once and as I say I'll never run without it again.

I also test my return spring before every run to ensure its doing what it should, as they get weak over time and can't pull the throttle back to idle, just switch your radio gear on without the engine running, go WOT and hold it there, then switch off Rx power or disconnect the battery pack and watch the spring pull the throttle back to idle position.

 

[ibanez890]

i have a failsafe, i just used the return spring to see if i could get it to close fully, the carb opens up fully and closes fully when the brakes applied, if i don't aply the brakes it does close but its still about .5mm open from where the idle is set unless i apply the brakes in which case it closes that extra .5mm

 

[Londoner]

Your carb shouldn't close totally, it should remain at at ~1mm open at idle and when full brake is applied to maintain idle, if your carb is closing altogether with no gap then your engine will stall at idle or when the brake is applied.

 

[Londoner]

IMO you should always use your throttle return spring, as I stated if you lose power suddenly or your linkage comes loose or breakss then your failsafe is useless, it won't help you at all.

Failsafe's only protect against low power and/or signal loss, not total power loss or linkage failure.

 

[ibanez890]

what I'm trying to say is, my idle is set up right its open about .7mm with the idle screw BUT when i accerlerate and let go its stays open another .5mm in this case it would be 1.3mm open unless the brakes are applied bringing it back down to the idle screw. i hope this makes sense

 

[Londoner]

Yea I understand what you mean now. Sounds like you need to adjust the linkage slightly or adjust your throttle/brake trim closer to the brake side, so when the carb slide returns to idle position it sits on the idle screw, takes a bit of fiddling but you'll get it.

What linkage set-up are you using?

 

[ibanez890]

I'm using fastrax sliders, hellfire knurled collars and the IRC wire thingys that came with the chassis lol

 

[Londoner]

Could you post a pic of your linkage? I can probably help as to where it needs adjustment.

 

[ibanez890]

 

[Londoner]

Try moving both the linkage stoppers circled to the right about 1mm and make sure there is no slack where I put in the 2 red lines.

 

[ibanez890]

thanks, that solved it. cheers =]

 

[Londoner]

thanks, that solved it. cheers =]

Cool!! :rock: