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-   -   NOVAROSSI Engine thread.... (https://www.rctech.net/forum/offroad-nitro-engine-forum/353301-novarossi-engine-thread.html)

invrtd 07-25-2016 12:21 AM

Try richening the low end. Good rule of thumb to use to know you are in the ball park for low speed needle is the pinch test. Pinch the fuel line and engine should die in about 4 seconds while idling. Longer than that too rich, shorter too lean. This is just to get in the ball park for low needle. Sounds like the typical low end lean and high end too rich to compensate for low end being too lean. Also set idle gap with a paper clip to start. These are tricks I have been shown and have worked for me. Set you high speed needle to factory which should be close to flush. Hope this solves some of your issues. Did you get a lean bog going down the straight or gurgling bog like the car doesn't want to get out of it's own way?

Jhafler 07-25-2016 08:36 AM


Originally Posted by invrtd (Post 14612567)
Try richening the low end. Good rule of thumb to use to know you are in the ball park for low speed needle is the pinch test. Pinch the fuel line and engine should die in about 4 seconds while idling. Longer than that too rich, shorter too lean. This is just to get in the ball park for low needle. Sounds like the typical low end lean and high end too rich to compensate for low end being too lean. Also set idle gap with a paper clip to start. These are tricks I have been shown and have worked for me. Set you high speed needle to factory which should be close to flush. Hope this solves some of your issues. Did you get a lean bog going down the straight or gurgling bog like the car doesn't want to get out of it's own way?

Lean bog at high rpms. Idle gap is set correctly. I've tried many times going back to factory needle settings and staring from scratch but it barely runs and is extremely lean when needles are flush. Could be an air leak or maybe my pipe is clogged. I'm going to seal the carb and change pipes and see what happens..

HaulinBass 07-25-2016 11:06 AM


Originally Posted by Jhafler (Post 14612898)
Lean bog at high rpms. Idle gap is set correctly. I've tried many times going back to factory needle settings and staring from scratch but it barely runs and is extremely lean when needles are flush. Could be an air leak or maybe my pipe is clogged. I'm going to seal the carb and change pipes and see what happens..

I have a nova that's the same way the hsn needle wants to be run so the bottom of the slot for the screwdriver is almost flush with the top of the brass hsn housing

mblgjr 07-25-2016 05:21 PM

Yall have air leaks in the lines or tanks. Also maybe a fuel volume issue.

I've never seen a Nova carb have an air leak. Should be no need to seal it.

HSN usually about 1/2 turn in from flush (approx)

LSN always flush or slighly in when idle gap is correct.

If you have the LSN too rich & HSN too lean; you can get a midrange bog.

If you're on 30% ensure you're running a c6tgc plug or OD97t.

For the low cg heatsink/heads they can run up to 290*F without issue.

cczjordan 07-25-2016 10:00 PM


Originally Posted by Jhafler (Post 14612545)
My bt4 plus bogs on the straight and runs super hot yet my HSN is way rich like 6 turns out from bottom. I replaced the exhaust gaskets and checked internals and nothing looks broken. No fuel leaks through front bearing. Still feels like I have lots of compression. Less than 2 gallons on it. Any suggestions?

lsn way too lean, richen it and lean hsn

skrichter 07-26-2016 07:47 AM


Originally Posted by mblgjr (Post 14613508)
Yall have air leaks in the lines or tanks. Also maybe a fuel volume issue.

I've never seen a Nova carb have an air leak. Should be no need to seal it.

HSN usually about 1/2 turn in from flush (approx)

LSN always flush or slighly in when idle gap is correct.

If you have the LSN too rich & HSN too lean; you can get a midrange bog.

If you're on 30% ensure you're running a c6tgc plug or OD97t.

For the low cg heatsink/heads they can run up to 290*F without issue.

Agree w/HSN needle -- flush or slightly in.

LSN needle, I'm not sure flush (or slightly in) is accurate (at least from the Nova's I've seen). Depending on motor/buggy/truggy, I have seem most Nova's a couple turns (or more) in (with an idle gap of 1mm or less). It's super rich/bogging when the LSN is flush (stock setting: 5 -6 turns out).

But Maybe we are missing the boat...

Just my 2 cents.

bash bros 07-26-2016 10:54 AM

Just don't get too hung up on where the needles are. I've got a p5 xlt where the hsn sits about a full turn in from flush and on the Elite 8 it's about a half turn out so it can vary quite a bit especially when you factor in different fuels, pipes, venturis, etc.

Getting the correct idle gap is probably the most important imho. If you don't have anything to measure you can remove your carb insert and back the idle screw out just where the carb closes. From there you can open it up 3/4 to 1 full turn and that should get you pretty close to .5 or .6mm.

Run it for a tank until it's fully warmed up, get the hsn in the ballpark aka not blubbering rich and not screaming lean either. Just a decent top end will do on the hsn to start with.

Once it's warmed up and your hsn is fairly close, throw it on your starter box and give it a good wot squeeze and keep leaning the lsn until the idle doesn't drop but stays up high and steady, clearing it with a good wot burst everytime you make an adjustment. Once you get the high and steady idle then you can drop your idle down. After that you can double check the hsn and make sure you've got it dialed in for good performance and plenty of smoke when you accelerate. You can usually lean it a couple hours if needed for your final race tune without having to mess with the lsn.

That's the quickest foolproof way I've found to tune a Novarossi.

If you watch that Bernard Durand video, that's basically what he's doing... also keep in mind when fine tuning the lsn you only need tiny adjustments. 1 hour is often enough to overshoot your mark.

mblgjr 07-26-2016 12:44 PM

LSN always winds up in but not "couple turns" until the engine is considerably older...

But. As you said, all that is greatly dependent upon insert size; clutch & vehicle.



Originally Posted by skrichter (Post 14614127)
Agree w/HSN needle -- flush or slightly in.

LSN needle, I'm not sure flush (or slightly in) is accurate (at least from the Nova's I've seen). Depending on motor/buggy/truggy, I have seem most Nova's a couple turns (or more) in (with an idle gap of 1mm or less). It's super rich/bogging when the LSN is flush (stock setting: 5 -6 turns out).

But Maybe we are missing the boat...

Just my 2 cents.


qstorm777 07-26-2016 08:03 PM

Bash, I actually watched that video again last night. I have a few questions that maybe you all can clear up.

I'm running the elite8. That's a short needle carb right? Lsn only comes into play when idling and first part of take off right?

If I go by the video, do I start the process with an idle gap of 0.5-0.6mm or should I start with a wider idle gap? If 0.5-0.6mm is about the right gap, to me, it seems like I need to start with a little wider idle gap to dial in the correct idle gap.

What is the cause of a temporary hanging high idle after wot? I've read it can be the idle gap is too big (what the video dials out) or the hsn is too lean. If both are true, how do you distinguish between the two (no boggin when wot). Any other causes of a hanging high idle after wot? People around me have said a lean lsn can cause this, but I haven't read anything credible that says this is true.

When leaning the lsn to get a high idle when setting the idle gap, how long should that high idle last? I think I read it should remain high for at least 20 secs. If less, keep leaning lsn.

Thanks, in advanced, for your help.

mblgjr 07-26-2016 09:19 PM

........



Originally Posted by qstorm777 (Post 14614950)
Bash, I actually watched that video again last night. I have a few questions that maybe you all can clear up.

I'm running the elite8. That's a short needle carb right? Lsn only comes into play when idling and first part of take off right?

If I go by the video, do I start the process with an idle gap of 0.5-0.6mm or should I start with a wider idle gap? If 0.5-0.6mm is about the right gap, to me, it seems like I need to start with a little wider idle gap to dial in the correct idle gap.You can start with the gap larger & LSN richer so that as you lean the lsn the idle rpm will increase & stay steady until you lower/close the gap

What is the cause of a temporary hanging high idle after wot? I've read it can be the idle gap is too big (what the video dials out) or the hsn is too lean. If both are true, how do you distinguish between the two (no boggin when wot). Any other causes of a hanging high idle after wot? People around me have said a lean lsn can cause this, but I haven't read anything credible that says this is true.

most often I see this with the idle gap is slightly too large & lsn is slightly too rich. So post WOT its hot & momentarily too rich thus you get a hanging idle

When leaning the lsn to get a high idle when setting the idle gap, how long should that high idle last?

it will maintain a high steady rpm until you close the slide via stop screw

I think I read it should remain high for at least 20 secs. If less, keep leaning lsn.

Thanks, in advanced, for your help.


cczjordan 07-27-2016 12:43 AM


Originally Posted by qstorm777 (Post 14614950)
Bash, I actually watched that video again last night. I have a few questions that maybe you all can clear up.

I'm running the elite8. That's a short needle carb right? Lsn only comes into play when idling and first part of take off right?

If I go by the video, do I start the process with an idle gap of 0.5-0.6mm or should I start with a wider idle gap? If 0.5-0.6mm is about the right gap, to me, it seems like I need to start with a little wider idle gap to dial in the correct idle gap.

What is the cause of a temporary hanging high idle after wot? I've read it can be the idle gap is too big (what the video dials out) or the hsn is too lean. If both are true, how do you distinguish between the two (no boggin when wot). Any other causes of a hanging high idle after wot? People around me have said a lean lsn can cause this, but I haven't read anything credible that says this is true.

When leaning the lsn to get a high idle when setting the idle gap, how long should that high idle last? I think I read it should remain high for at least 20 secs. If less, keep leaning lsn.

Thanks, in advanced, for your help.

Elite 8 comes with 24069/63 carb, long lsn needle. Just start with bigger idle gap, flush lsn/hsn. Lean lsn slowly n decrease the idle gap

Kenhbd8 07-27-2016 01:44 AM

this is from novarossi
 

Originally Posted by Jhafler (Post 14612545)
My bt4 plus bogs on the straight and runs super hot yet my HSN is way rich like 6 turns out from bottom. I replaced the exhaust gaskets and checked internals and nothing looks broken. No fuel leaks through front bearing. Still feels like I have lots of compression. Less than 2 gallons on it. Any suggestions?

Factory standard and reverse carburettors settings .21-.25-.28



Screw clockwise the high speed needle "A" until it will stop. Do not force it otherwise
the tuning tip will be damaged. Once you reach the stop, unscrew counterclockwise
for 3 and a half turns.
WARNING: if you have to turn the fuel intake pay attention to:
- close the fuel tube
- change the aluminum rings (cod. 11016)
- tighten the high speed needle support with a torque of 2.3 Nm

Screw clockwise the low speed needle (LSN) "B" until it will stop while keeping the
carburetor barrel fully open, then unscrew the LSN for 5 turns (6.5 when using the
carburetor 24066 and 6 turns with the 24067).

WARNING: This guide will help to start your engine and could be used as a starting point for the
tuning, however keep in consideration that the tuning could change according to the carburetor that
you are using, to the operating temperature, to the track style and to the driving style.

The screw "D" is the medium speed needle. You can use it to have a finer tuning of
your engine. To restore the factory settings you can screw it clockwise until it will stop
and then unscrew counterclockwise for 1 and a half turns.

The idle screw "C" is used to set the minimum air passage between the barrel and the
carburetor body. This passage will control the rpm your engine will have when idling.
This screw must be screwed until the gap between the barrel fully closed (pressed as
shown by the arrow on the picture) and the carburetor body is approximately 0.6mm.
Before measuring this distance remove the Venturi.

qstorm777 07-27-2016 12:06 PM


Originally Posted by cczjordan (Post 14615195)
Elite 8 comes with 24069/63 carb, long lsn needle. Just start with bigger idle gap, flush lsn/hsn. Lean lsn slowly n decrease the idle gap

Thanks. I see that on the exploded view manual now too. I'm going to try this again going by the video. I thought I had it running good this winter. Than pnb came along and pit man said it was running 290-300 in practice. I significantly richen the top end (at least 1/2 turn) and it still was running hot. I prob should have richen the bottom, but I thought it was a short needle carb so as long as it would idle and takeoff good, I thought lsn was good. I've never got it to run good since pnb.

qstorm777 07-27-2016 12:07 PM


Originally Posted by mblgjr (Post 14615093)
........

Thanks for the help. I'll try tuning this again hopefully this week.

qstorm777 07-27-2016 12:10 PM

So how do I tell the difference in a long needle and short needle carb if looking down into the carb? Everything I read described what I was seeing with the 24063 carb as a short needle. Maybe I should have actually looked the needle up to see...smh.


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