Some problems with my revo 2.5R

The stalling when you hit the brakes is because your idle is set too low. When you put your brakes it applies pressure to the carb in a closed position. If your idle is too low it will stall the engine.

I would imagine that you are too lean when it dies at the shift point. Try resetting to factory settings and retuning.

I agree, idle is too low. Check your linkages as well. It sounds like the carb doesn't close all the way when you're off the gas. You want to set up the linkage so that the carb returns all the way to it's idle stop position when the trigger is at neutral.. not just when you hit the brakes. So...

1. Set your idle screw so that when the carb is closed you have about a 1mm gap at it's widest opening.

2. make sure that when your trigger is at neutral the carb returns to the point you set up in step 1.

3. return the HSN and LSN to factory setting and tune your engine from there starting with the HSN first.

Thanks for the info, so since my idle is too low then turn the screw counter-clockwise correct?

No your idle screw is just like a regular screw. Tighen it and your idle will go up. Loosten it and the idle will drop.

When adjusting the idle remove the airfilter and look at how much the opening is. You should have around .016-.020" Work it from there but it's a good starting point. As VB stated, your probably lean on the top end too, richen the top end. Since it sounds as though you guys may be new to this nitro thing, make sure you understand that a little is actually alot on these engines. Think of the needles as a clock and turn them in one hour increments when adjusting. Make sure your up to temp before making adjustments.

Thanks again, I will get an infrared temperature gauge from work. We do turn the pins in little increments. When I hit the brake all the way, when i look into the hole that the air filter covers, it's completely closed. Else, there is a small opening in idle position. I think this is what JetMech was talking about.

I will post more about what has happened tomorrow, thanks again!

I would follow all of the advice above, but first, I would suggest centering the throttle/brake servo first.

Take the servo horn off the throttle/brake servo.
Turn the RX and TX on.
Set the trim on the TX to zero for the throttle/brake.
Set your idle screw to the right point as indicated above.
Replace the horn so that the carb barrel is against the idle screw.

After that, hitting the brakes should not kill the engine, then you can start tuning.

Start by setting the needles to factory, then tune the HSN first, then the LSN.

You should be good to go from there!

Okay, well, we did that, now when we drive the car the engine bogs down when we punch it starting stopped. But when we richen it the engine gets very hot and when you put liquid on it it will evaporate in 2 seconds or less.

Any ideas from here? And yeah we fixed the brake problem. And still when we go FOT (fully open throttle, not sure if that's right) it just dies.. like usual..

The engine should not get hotter as you richen it, but cooler.

I think your needles are out of whack, big time. My suggestion is to pull the mill off and seal the backplate and carb throat with RTV sealant (sensor safe).

Once you get the engine buttoned up, set the needles to their stock positions.

Make sure the O-ring in the tank lid is in good shape and make sure the fuel line is in good shape.

From there, start tuning. You need to get a temp. gun. Water on the head is a very general idea of temperature and you want to get the engine up into the 230-250 range.

Start running the truck and tuning. As mentioned, adjust the HSN in 1 hour increments only and adjust only ONE NEEDLE AT A TIME. If you try to tune both needles, you'll drive yourself nuts.

You want to get the HSN dialed so that you are getting a temp. of 230-250, a nice smoke trail and good top end performance. Once you get that, tune your LSN.

It takes a little time and, most importantly, patience. You want to make several high speed passes after each adjustment of at least 50 or so feet long.

One step at a time, my man.

I'll say this just to be sure, you turn the needles to the left (unscrew) to richen.

For a starting point return both needles to factory settings

HSN is 4 turns from closed
LSN is flush with the carb body (approximately 1 3/4 - 2 turns from closed)

At this setting you shouldn't get the real high temps. If it's a little sluggish thats ok, you just want to make sure it can run without overheating. If you can run without overheating slowly start to tune the engine for better performance. For someone new to nitro a temp gun is your best friend!


Good Luck

Well, once again it wont start.. It's sucking in gas, engines heating up, HSN is in the position it was when I put the easy starter in a and turned it on for about 2 seconds and started right up. Now the wont even start at all.. When the fuel wasn't flowing we took out the HSN completely and checked to see it was gummed up, and I guess it was because we cleaned it and the gas started moving again.

I swear this thing decides to start and not start all by itself..

I guess you do need alot of patients for this hobby, right now it just crazy how much tunning is needed for a $500 car that you expect to work fine, although it does.. sometimes..

Is this a brand new Revo or used? If new, did you perform the engine break-in process exactly as described in the manual?

The not starting issue sounds like a glow plug, which is common. Put a fresh one in.

Yes, it is a $500.00 truck, but it's not a $15,000.00 truck. It takes a little time and patience to learn about these things, so it's key to stay patient. If you tru to rush things, chances are you'll end up ruining the engine and then you'll be really pissed!

Traxxas' manual's and DVD's are actually very informative and make it simple. I suggest, if you haven't, you take the the time read and view them. Once you understand how these engines react, it'll make it a lot easier to tune.

Best thing to do is take a deep breath, set the needles like SMaxxin suggests and go from there. Get yourself a temp. gun and a couple McCoy MC-59 glow plugs and go from there.

Okay, I took my time, 1/16th turn at a time. It starts now! Now I'm just going to have to slowly adjust the LSN so I can go faster than 25 mph .

LSN has nothing to do with speed. You need to tune the HSN first. Get the right temperature and smoke trail. LSN controls quickness off the line and needs to be tuned last.

You are going about it wrong. Without hearing it myself, it sounds what you are describing as a lean bog. Richen the LSN to stock or even slightly richer and don't touch it anymore. Richen the HSN to stock (if your flaming out after a high speed pass it still sounds lean). Only work the tune from the HSN first. Once you get the HSN where you want it, make very minute adjustments on the LSN and I will explain the pinch test, but only after you get the HSN set. Pull your plug and look at and describe what it looks like, or take a picture and place it here. You plug will tell you a story about how your tuned. If you feel adventureous, pull the head and look at the button and top of the piston and describe it here or post pictures.

Okay, now after completely tuning my car it hits second gear with-out any problems at, runs at around 230 -240 with 33% nitro.

Unfortunatly I have another problem, and it has to do with my transmission

For some reason this part -> http://www.buytraxxas.com/product_info.php?products_id=2124 keeps on braking!

I went to my local hobby shop and bought a new one, then the next day I went to drive it and I made some good high speed passes, no problems, then I give it gas after a high speed pass and I the egines rev'ed up but the cars not moving!

I drove all the way back to the hobby shop and they said it could be the opti-drive switching into reverse then forward for just a second and its killing your gears. Also, what I also found out was that the spur gear is suppose to slip and sure enough, it was tight as ever.

So they recommended that I get a forward only conversion kit and that your transmission should never be a problem again.

So, what should I do? Reverse is extremely helpful espically when your against a tree or in a bush, but if this is a known problem that opti-drive pops into reverse for a second and kills 3 or 4 gears would it be better to just get forward only?

Thanks!

It's your call. Many will say ace the reverse and go forward-only. I have the forward-only in my Revo, but it's a racer primarily.

I doubt, seriously, it's the OptiDrive failing as you are the first to ever mention the OptiDrive may be the culprit. You state that the slipper was tightened all the way and my guess would be that is why you are tanking gears.

Replace the stripped gears, then tighten the slipper all the way and back off 1/4 turn.

It's good practice, personally, to make sure you are at a complete stop before switching to reverse and vice versa. Even with the OptiDrive, better safe than sorry.

Okay, that seems like a plan, except I can't get that clip thing off the first speed gear! I guess i'll have to wait until I get my backwards pliers.

Ok, I've heard of optidrive's going Tango Uniform before. It's also known that the Reverse gear is weak, in turn having reverse the forward gears are smaller (not as beefy). Another problem is the micro servo. One thing you may try that will not cost you anything is to re-set the optidrive. Two, you can remove the optidrive, you will have to be completely aware of your truck though since nothing will prevent the transmission form shifting into fwd or rev when you select it. If you can make sure your completely stopped before selecting fwd or rev, then really there's no need for it. I'd have to agree with the LHS, dump reverse all together and go FOC, it'll elimate the weak point, get rid of problems and believe it or not, you'll get a little better punch off the line.