Is it possible to have carb too small

[REVO-5309]

my carb is as closed as possible i think. i have richened up the LSN so that it idles, but when i come off WOT it idles up after a sec or so.... should i open the carb a bit and lean the LSN... the HSN is set so it runs around 105-120 degrees C which is about right. and it doesn't hold revs when i come off. only after a sec or so...

ps motor is out atm, will prob have it back in over the weekend to test the new settings. its also a new motor, 10 tanks or so thought it. sealed everything expect the carb neck but it has 2 seals there and i pushed the carb in when tightening the bolt so it should be fine.

 

[Metalhead Matt]

If it's hanging coming off a high speed pass, richen the hsn an hour at a time until it stops. Remember to drive for a couple minutes between adjustments.

 

[REVO-5309]

wont richening it make it hang more? and can the carb be too small? it wont close any more.

 

[Metalhead Matt]

What won't close any more? Richening means opening... If it's hanging after a high speed pass, the hsn is a little lean. It's starving for fuel until the feul flow catches back up.

 

[REVO-5309]

the carb opening... the 0.5-1.5mm gap. its like 0.5mm or smaller and it wont close anymore. and i have the LSN around 1 turn rich from factory to get the revs back up at idle.... launches decent. but should i open it up to 0.5-1mm and lean the LSN a bit?

 

[Metalhead Matt]

The hsn has to be set before the lsn. I'd get it to quit hanging up then see where your at. All engines are different. If it runs right, let er rip.

 

[REVO-5309]

well i did have the HSN correct. wasn't getting too hot and pulled pretty hard. then i tried making the idle screw as low as possible as i thought the lower the better. and its all the way to the point i can pretty much take the screw out and it doesn't drop the idle. and the LSN is richened up to keep it idling fine... but should the idle screw be that far out or should i open up the carb a touch more and lean the LSN to correct the higher RPM.

 

[2revo1maxx]

Make sure the idle screw is touching the carb slide and try leaning the lsn some more. Any idle is a good idle as long as it responds without hesitation and doesn't try to drive away at idle.

 

[REVO-5309]

so i took it out this avo. i think the glow plug was the cause for all this... but... went back to factory, 1/2 turn rich again. LSN back to factory and idle screw around 1mm. so i go WOT and it just starts to rev up, down, up, down and settles and is reving kinda high. so check temp... yep near enough to 300F, so shut down, richened up another 1/2 turn... still high temp. so we took it home and stuck a new glow plug in. took it outside while it was still warm and gave it a quick blat up and down the street and seemed to be a fair bit better. havent tuned it at all yet, but at least from that quick 3-4 WOT pass's it seemed better.

any ideas why it was doing it? the glow plug was still glowing and intacked but was a little bit wobbly.

 

[2revo1maxx]

Never trust a funky plug. I think you need to keep richening the hsn until you KNOW it's too rich, then tune it back from there......your plug is funky from being too lean. Remember to warm it up first, and a well tuned engine will act rich until it warms up.

 

[REVO-5309]

yeh k, might give that a go this avo...

 

[REVO-5309]

after todays run, video to come

 

[geno22]

Suggestion

I would like to make a suggeston please, blow all the dirt off the engine before you go for your inspection. i small grit can cause trouble, the car belongs to you and you can do as you please is why I said suggestion and not tring to be a know it all.

 

[2revo1maxx]

That looks pretty good. Just remember this simple rule....if you're unsure about your tune, richen it up, don't go leaner.

 

[REVO-5309]

yeh i generally keep it pretty clean. in the next week or 2 it will be getting a bit clean. everything apart and inspected before the picco goes in. and yeh i went 1.5turns or there abouts rich on the HSN past factory and then leaned it 1/2 turn or something before it started running good. but i have an idle issue... ill post up vid soon

---------- Post added at 10:05 PM ---------- Previous post was at 9:55 PM ----------

http://s72.photobucket.com/albums/i163/peachey87/?action=view&current=510f2775.mp4

 

[2revo1maxx]

I would try richening the lsn a tiny bit to control that idle. Richen the lsn as much as you can (in 1 hour increments) while still having that nice snappy throttle response.

 

[REVO-5309]

ok ill give that a go this avo or tomorrow. my cousin and his work mate both have nitro's so we might take em out tomorrow.

---------- Post added at 12:26 PM ---------- Previous post was at 12:25 PM ----------

and richening the LSN will stop it from idling up and down like it was at the end of that vid?

 

[2revo1maxx]

I think so. Just get it warmed up real good like it was and slowly richen it. It's got plenty of snap in the video, I'm sure you can richen it some.