RC Monster Trucks Discuss rc monster trucks in this forum

Genesis, something strange...

Reply

Old 05-15-2006, 03:51 PM
  #1  
Neo9686
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Italy, ITALY
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Genesis, something strange...

Hi, i want to introduce myself first, this is my first post here 'cause i'm Italian, in Italy, and i found this forum only some dayse ago...

Here's my problem: i'm trying to tune the Nx-76, but it's really strange... it change when the fuel decrease! when it is full it's so, when it's half it's different, when it's almost empty it's more different... is it normal?

Is normal that this engine is really really nervous? my engine is really unstable, and in my fuel line there are many air dots, is it normal? can it be because my fuel line pass too close to the engine?

and the last thing (for now), when i give gas when my Gen is stopped, and it is going forward, sometimes finish into a weelie, but if i do this in reverse it ALWAYS finish in a wheelie and then make a backflip! is it normal that going in reverse gives more power to the front train? or it is only a fact of weight or wheels orientation? i have the central differential locked, 25% nitro, front transmission in plastic telescopic shaft and rear transmission is with a dogbone...

Thanks men.. I hope you'll reply...
Neo9686 is offline  
Reply With Quote
Old 05-15-2006, 04:41 PM
  #2  
MTS
Member
 
Join Date: Nov 2005
Location: Afton, VA
Posts: 82
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

The bubbles in the fuel line means that you have an air leak in you gas tank or in the fuel line itself. First test the fuel line. Clean the line and pintch one end. If you are able to blow into the line and feel or hear air come out than that is part of the problem. If it was bad, get some new fuel line. Once you have a good feul line you will have to check the fuel tank itself. there are 2 lines that come of the tank. Take the gas tank and both lines off too. After the fuel is out of the tank pintch one line and blown into the other until you build up pressure. While blowing, pintch the other line while still holding the other. Hold that for ten seconds. Put one of the lines to your ear, let go of the line, if you hear air come out, then the tank is okay. If you don't or was not able to build pressure in the first place look at the o-ring on the fuel tank. Flip the top of the tank and there should be an o-ring, if the ring is torn at all or if there is no ring, than that is the problem. Either get a new ring or rig up the tank so that you can put one in there. Also check the tank for any cracks or holes. Hope this has been helpful.
MTS is offline  
Reply With Quote
Old 05-15-2006, 04:45 PM
  #3  
Neo9686
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Italy, ITALY
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

Thanks, i'll check soon... But i don't think there's an hole on the fuel tank, it can be on the lines... Can the lenght of the lines create some problem?

Can you help me with my other problems?

Thanks for the reply
Neo9686 is offline  
Reply With Quote
Old 05-15-2006, 05:12 PM
  #4  
snowbl!nd
Senior Member
 
snowbl!nd's Avatar
 
Join Date: Jan 2005
Location: Manchester, UNITED KINGDOM
Posts: 3,779
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

"Here's my problem: i'm trying to tune the Nx-76, but it's really strange... it change when the fuel decrease! when it is full it's so, when it's half it's different, when it's almost empty it's more different... is it normal?"

This sounds like a "half tank leaning" issue. As the amount of fuel in the tank decreases, the backpressure into the engine is altered and this changes the "tune" of the engine. Unfortunately, i don't know of any solution, although replacing the fuel tank on the HPI Savage (the original had the same problem) for a different one solved the problem. A search on this site for "new era tank mod" or "half tank leaning" should give you lots of information.

"Is normal that this engine is really really nervous? my engine is really unstable, and in my fuel line there are many air dots, is it normal? can it be because my fuel line pass too close to the engine?"

This is probably the result of an air leak. It could be in the tank, filter, tubing etc. Remove the tank and tubing and place underwater. Hold one line closed and blow into the other one. Bubbles will appear of there is an air leak. If your tubing is passing VERY close to the engine try to move it somewhere else.

"and the last thing (for now), when i give gas when my Gen is stopped, and it is going forward, sometimes finish into a weelie, but if i do this in reverse it ALWAYS finish in a wheelie and then make a backflip! is it normal that going in reverse gives more power to the front train? or it is only a fact of weight or wheels orientation? i have the central differential locked, 25% nitro, front transmission in plastic telescopic shaft and rear transmission is with a dogbone... "
This is weight distribution - my truck does the same thing.

Oh, and the length of the lines should not cause problems (unless they are VERY long - 1m+)
snowbl!nd is offline  
Reply With Quote
Old 05-15-2006, 05:17 PM
  #5  
dracy69
Senior Member
My Feedback: (1)
 
dracy69's Avatar
 
Join Date: Jul 2004
Location: Port Jefferson Station, NY
Posts: 1,000
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

the half tank leaning on the savage can be tuned out. my savage 25 and savage x have never given me this problem. the genesis should be no exception. just richen the low end and maybe the idle. tuning takes ALOT of trial and error and it will seem like everything you do worsens the situation. just keep trying to make adjustments until you get it tuned good. you may want to start from factory settings and just try again. tuning comes along with experience
dracy69 is offline  
Reply With Quote
Old 05-15-2006, 05:25 PM
  #6  
Neo9686
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Italy, ITALY
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

Thanks... i'll try to find if it's a tuning problem or a leak problem soon...

For the distribution of the truck, it seem to be lighter on the front, so how can the back go up better than the front? is there something to do to have a quick wheelie going forward?

Thanks for the great replies...
Neo9686 is offline  
Reply With Quote
Old 05-15-2006, 05:27 PM
  #7  
snowbl!nd
Senior Member
 
snowbl!nd's Avatar
 
Join Date: Jan 2005
Location: Manchester, UNITED KINGDOM
Posts: 3,779
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

...unless it's geared differently in reverse? That would explain it...
snowbl!nd is offline  
Reply With Quote
Old 05-15-2006, 05:45 PM
  #8  
Neo9686
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Italy, ITALY
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

I think the same thing... now i'm searching in the manual for the transmission ratio..
Neo9686 is offline  
Reply With Quote
Old 05-16-2006, 10:54 AM
  #9  
silverman1
Senior Member
 
Join Date: Jun 2004
Location: rural valley, PA
Posts: 1,160
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

Its a fairly well know fact that many maufactures reccomend you tune your engine at about 1/2 tank of fuel to get your engine tuned properly. This should be done with the engine warmed up. As the fuel level changes in the fuel tank you have fuel pressure changes thus sometimes causing the engine to lean out somewhat.

why they reccomend the 1/2 tank of point to perform the fine tuning I don't know maybe someone could better answer that question. I also know that many persons have had good luck running OS 8 glow plugs with this engine.

Its always good to start with the simple stuff first and proceed to the more complex. Checking the fuel lines is a very easy thing the 2nd thing Id check also.

Good luck
silverman1 is offline  
Reply With Quote
Old 05-16-2006, 10:58 AM
  #10  
Neo9686
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Italy, ITALY
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

Thanks, i will change to the n° 8 plug soon, first i will check for a leak in the system... Now i'm using a Novarossi n°6, that i think it's almost the same of the original from the cen... Thanks for the reply...
Neo9686 is offline  
Reply With Quote
Old 05-16-2006, 11:12 AM
  #11  
ThermalRD
Senior Member
 
ThermalRD's Avatar
 
Join Date: Aug 2003
Location: Who z\' whats it, YT, BOTSWANA
Posts: 7,133
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

I went thru some of these same issues with the Gen. I had e-mailed back and forth with CEN for quite some time. That .46 engine has a really long warmup time. I learned that if you tune the truck after you've run about 3/4 tank of fuel thru it, then you'll get consistant performane. It sucks you're essentially warming up the truck for almost a full tank, but thats honestly how i tune mine. And the OS 8 plug silverman reccomends, is right on. Thats what Andrew Smolnick told me to try, and its helped alot.
ThermalRD is offline  
Reply With Quote
Old 05-16-2006, 11:21 AM
  #12  
Neo9686
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Italy, ITALY
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

So i have to:

- check for a leak somewhere (fuel tank, fuel lines)
- change plug with an OS 8
- tune the engine when it has run 3 or 4 tank of fuel, when it will be at the right temp (right?)

Thanks to all, i'll try soon...

Did anyone knows anything for the "reverse" problem? i want to pull wheelies like that, but going forward!!
Neo9686 is offline  
Reply With Quote
Old 05-16-2006, 11:23 AM
  #13  
snowbl!nd
Senior Member
 
snowbl!nd's Avatar
 
Join Date: Jan 2005
Location: Manchester, UNITED KINGDOM
Posts: 3,779
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

Scuffing the clutch shoes, tightening the slipper clutch and a good tune should allow you to pull wheelies in fwd.
snowbl!nd is offline  
Reply With Quote
Old 05-16-2006, 02:31 PM
  #14  
silverman1
Senior Member
 
Join Date: Jun 2004
Location: rural valley, PA
Posts: 1,160
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

Correction, What thermal was trying to say is trying tuning your carburator in after you used 3/4 of a tank of fuel. Thats when you you want to tune your carb. Now if your motor is not broken in, i would not mess with the carb to much, and i would follw Cen's engine break in porcedure first, but if you have done the break in then follow the tuning instructions first given in in this post.

During break in engines usually run crappy, idle poorly etc. Like i said if its broken in forget about the 2nd part of the post and proceed to the beggining part of the post. You might want to set your idle screw a little lower to take care of the idle issues when your truck is supposed to be sitting still.

Here try this site www.cenracing.com for more tips on tuning

good luck
silverman1 is offline  
Reply With Quote
Old 05-17-2006, 02:42 AM
  #15  
Neo9686
Junior Member
Thread Starter
 
Join Date: May 2006
Location: Italy, ITALY
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Genesis, something strange...

Thanks... I've already burned 2 1/2 bottle of fuel, but the model has been stopped for tuning most time... it has run 4 or 5 tank of fuel in motion... so i think that i can tune it now... so, let's try! thanks...
Neo9686 is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service