raceman17

I just a bought a new Rex P5 for my buggy. I am having a terrible time getting the temperatures down below 240 (with the body off) All the settings are set way fat. I get a great deal of smoke but, the performance sucks. As soon as I go to lean the motor , the temps shoot up. I have run probably 15 tanks of fuel through the engine. I have seen them at the track and I can tell that mine is not even close to where everyone eleses is at. I dont have a clue what type of pipe is on the buggy now, its just one I had that came with a RTR buggy. Would this cheap pipe make the engine run hotter. I have an 086 pipe coming in the mail. Any suggestions?
Thanks

Dawman

My Feedback: (33)

A pipe can make a big difference on how an engine runs . I assume by the number you have an Ofna based pipe coming . It should run better with that pipe.

raceman17

Im also running sidewinder 20 percent. Should I switch to 30 percent? I just want the motor to last longer thats why I am using 20 percent.

Dawman

My Feedback: (33)

20 % will work great . I run 30 only in engines that have been modded .

kx250ryder

Your low speed needle may be too rich (hiding an overly lean high speed needle), causing the engine to gain temperature the longer you run. All engines should heat up, but after reaching the point when the chassis gets hot, the engine should not continue to increase. Try leaning your low speed needle a bit and also richening the high speed needle.

raceman17

It seems like the engine has no top end (It reaaly doesnt have that high pitch when it reached the higher rpms. Im assuming this is because of the cheap pipe. The 086 pipe is suppose to fix this. I will be putting the new pipe on when I get home from work today. Can I set the lsn first by doing the pinch test on it before I set the HSN?

gubbs3

My Feedback: (1)

No, never adjust the low end before the high. That will just get you into trouble. I would wait until you get the pipe because so many of the engines availible today are extremely pipe sensitive. One other thing, your engine may not be fully broken in quite yet. I know many motors take at least a gallon of fuel before they really sing. What plug are you using by the way? An extremely cold plug may share some of the blame.

raceman17

The plug was a super cool plug. I just pulled it out and changed it to a regular one. I dont know the number because they are cheap plugs. The plug that i put in is another cheap plug (megatech mtc16192). I got the pipe in and put it on the buggy. The temp are down just slighty. It still doesnt have the top end. Could it be gear ratio? I play around/race on a very small tight track. The overall gear ratio that I am running is 11.71:1. The spur/cluctch is 3.642 (51/14) and the ring and pinion is 3.14 (44/14). Should I drop a tooth on the clucth bell? It seems like I have to hold down on the trottle along time (a couple of seconds) before it really gets up there in rpms and it still doesnt seems as high. Also if I lean it out on the HSN, it will get there but the temps just get to high. I am still running without the body on also. Thanks for all the help

o.s. power

you want to run a cold plug in .21 and larger engines. Go out and get yourself some o'donnell 99 plugs. They are not cheap, but they are the best on the market. The 086 pipe will help. Like what was said above, the high speed could be to lean and the low end really rich. A common misconception is that the high speed needle determines how much fuel gets to the engine, so there is a good possibilty that it is too lean.

raceman17

I just went outside and ran another tank through it. I think the LSN is adjusted fine. If I pinch the line with a pair of needle nose pliers, it revs up and dies in about 3 seconds. I will go back out side and riched the HSN 1/2 turn and see what it does.
Thanks

RcRacer37E

Save a bit of time, check out the bearings in the bell. I fought my buggy for 2 tanks of gas, I new I was fat, never ran lean, turned out one of the bearings was shot. Double check the fuel tube fitttings, all nice and tight? Then I start messing with needles.

raceman17

The clutch bearings are new. I just replaced them with the new motor. I richened the HSN up 1/2 trun and it seemed to rev alittle better. But, that was short lived. I stripped out the ring gear on the rear diff so, I will have to fix that. I will be messing around with it on Saturday. If anyone has anymore suggestions, please feel free to comment. I will let yall know what happens.
Thanks

SManMTB

Running a cold plug is not a rule and nothing to aim for either. To make max power you should run as warm plug as you can without blowing it up.
A plug that is too cold will have a problem keeping the 'glow' when you go down the straight. The engine sounds like it's 4-stroking and you immediately think: 'Aahhh... it's running rich, let's lean it out'.
That's as wrong as it gets. The engine will start to sound OK again but you are now running lean just to keep the plug lit ----> engine runs hot.
A warmer plug would have taken care of that.

Turanden

I almost never see anyone with overheating problems given the advice that they may have an air leak on RCU. Do you guys just never get them, or do they never happen on a Novarossi motor. This is a very common problem on many of the larger motors, especially the ones with rotostart backplate like we have on our LST's, but the carb throats, HSN and LSN needles, and even the bumpstart backplate can leak also. I dont even start a motor up before I have sealed all of the above listed.

raceman17

So, Your saying I need to run a hot plug. Will that help the temps go down? I think the Rex motors are sealed up pretty good with orings instead of gaskets. But, to be sure, I guess I will take the backplate and carb off and seal that up just to be sure. I have also got new lines on the car along with changing the gas tank. This should take care of any air leak issues. I will let yall know. Any more info would be appreciated also.

SManMTB

At least try a warmer plug and see what happens. Richen up the HSN until it runs real rich and lean it until it runs with a clean 2 stroke cycle. That's the best tune.

Drifter240

the pipe may have something up with the backpressure that pushes the fuel into the tank. A new pipe would change the performance

nurch

Correct me if I am wrong in saying this, but doesn't the low speed needle control the take-off aspect of the engine? Usually if the LSN is set too rich, your vehicle will have a sluggish take off. If the LSN is set too lean, it will take off like a rocket, but as soon as you go WOT, the engine will choke out.

One rule of thumb I had learned was once I am satisfied with the take-off setting on my LSN, I should then play around with the HSN and make sure not too much fuel is bogging out the engine at high revs.

enginemugen

That pipe is defenetley not working at all you should go to a local hobbie now and ask for seggustions. The pipe controls three things. It throws your fumes out of the engine, it can give you a better low on your motor or a better high and it can also affect in temparature. I just got a RB ws7 3 engine with a jp 1 jammin pipe. Change the pipe you will see the difference instantly. Tjen just open and close the needl depending on the temparature. I like my engine to be around 210 to 230 the maximum temparature is about 260. After that you are in trouble.

raceman17

Well according to Amain hobbies, they suggest the 086 pipe for this engine combination. That is the pipe I bought for the engine because it is reccommended. I will be out in the morning retuning and seeing what I can do.

axisrc

i have something wrong with my duratrax axis. after i run it for about a half a tank my car dies. i have adjusted the high speed and low speed and still dies. i am thinking about getting a Hot Bodies Powerhouse .26 Engine w/Recoil it $140 off of tower hobbies. but i also want a tiger drive too which one do i get. that is also one tower. i am also thinking about getting a cold air intake for the new engine. thanks

mike

nedMX

why so worried about temps?
every engine likes to run at a different temperature, even two of the same engines will run at different temps. why not try tuning to power, sound and smoke and then see where the temps are. you never know, full power could only be another 10f away.

SyPTo1

the LSN has nothing to do with WOT , you have to understand that the LSN is physicially locked to the valve and when you open the throttle the needle will pull away from the carb opening ...if it bogs down at WOT your HSN is set too lean... most people don't understand that a LEAN LSN on the track is sometimes more of a contributor to high temps then the HSN is , i know on my track 80% of the time you are in idle - 1/3 throttle range so if your LSN is set lean on my track you will get higher temps then when it would be rich with a lean HSN...

ALOT of people use the hosepipe/nozzle story...well this is great EXCEPT it only work from idle to about 1/3 throttle once you open the throttle more then that you would need to take the nozzle off the hosepipe and then you would controll the fuel flow ONLY with the faucet.. once you go down to 1/3 throttle or lower you would have the nozzle back on the pipe and you can adjust both for fuel flow..

understanding the physics of the carburator will make you a better tuner...

do this :

highspeed runs , set the HSN to the right temps... then do a few HS runs and let it idle count 8 seconds and sqeeuze the trigger to WOT , it should have a bit of hesitation in it like maybe a sec orso...if it bogs down longer then that your LSN is set too rich , if it picks-up immediatly it's set to lean..

you engine should NOT be able to idle all day long... there's a thing behind it... when in idle you have no air flowing thru the cooling head , so how do you get rid of the heat ?... you use the fuel/oil to transfer the heat out of the engine , so by loading the engine up a bit (giving it more fuel then it needs) it will have excess fuel that will transfer the heat from the engine into the pipe...

my racers only idle for no more then 15 seconds... most of them will die at about 10-12 seconds

axisrc

no my engine is trashed i think it just turns off after a half a tank it is getting too hot but the lsn and the hsn are set right then it takes forever to get back started then when it does start it dies then i start it back up then dies it keeps doing this then when i go to start it the next day it will go for a half a tank then do it all over again thANKS

mike

Da Smak

Sounds like your way too lean in all areas. Think youd better strip the carb and check the seals old bean.