i've got an os.18cv-rx that i put in my smaxx. i've got about 12 tanks through it now, but i'm still trying to tune it and it never seems to hit second gear on the straights. it just whines on the top end. it'll finally shift into second when i lean it out, but at that point it's running at about 270-280. will adjusting the shift point effect top speed and bring down my temps??? i wasn't able to do it because the track closed at that point. thanks.

In my opinion, you should tune you motor for optimum performance, and never mind the temp at that point. Adjust the two speed for proper shifting, and get that OS running great. And then, when it seems you cant improve the performance any more without running into a lean condition, back out the high speed needle about an 8th turn, maybe even 1/4 turn, make a few high speed runs, and note the temperature at this point. Say its 270 degrees, if it runs great, GO WITH IT! In future runs, kinda make that temp your goal. KEEP IN MIND THE WEATHER! Also, temperature gauges or guns are tuning aids, its not a really a tool, by that I mean, nothing is set in stone. Your screwdriver and your ears are your best TOOLS. Temperature is a good reference. There is no magical temperature, at least in my experience. Again, this is purely opinion. Good luck, cya.

i hear ya and do agree with you, but it just seems a little too high to be running at that temp. i'm also fairly new to tuning engines, but i'm going to try to adjust my shiftpoint to see if my temps go down any. on the straight, it just whines and goes like two miles and hour. i'm going to try to bring those temps down first. if nothing else works then i'll just run it at 270, but that was just an average. at some times that temp ran to 299. i didn't run it long at that temp. i just richened it a little and saw my performance go down and started over. the one thing i hadn't touched was my tranny shift point. a guy at the track said that when it whines like that it means it's running at high rpms and he said i could end up stretching my rod. i definetly don't want that!!!

280 might be a little high but not excessive.
If that's where the engine likes to run and you've got good smoke and good performance then I'd say you're ok.
Tuning by temp alone is a poor way to tune. Heck, nitro motors have been around since at least the '40s and temp guns less than 10 years. I continually wonder why people think they're so indespensable now. They're a great tool but not having one sure isn't going to stop me from running nitro engines.

i understand the temp controversy, but since temp guns are available, why not use it and run an engine for 10 gallons vs. 5 gallons worth of fuel. like i said, if i've exhausted all my tuning capabilities, which aren't many, then i'll run it at 270-280. i also just bought new clutch shoes, i'm thinking that may be why it's revving so high and not picking up speed and shifting. maybe one day i'll be able to go to the track and just drive and not tune or fix something.

I think I missed something, you mentioned that the motor is revving high, but the truck " whines and goes like 2 mph "? Did I read tis right? If so, give us a rundown, that sounds like a driveline problem. [sm=confused.gif]

Don't make the mistake of thinking that one method of tuning ( temp vs sight/sound) will in and of itself affect engine longevity. I have an OS.10 that has never had a temp gun pointed at it and it is 19 years old - yes, 19 years old, that's not a typo. But , I do have and use a temp gun. The thing is, if you practice and learn to tune w/o one, you'll be a better tuner AND better able to tell when something's not right.
On the reving thing, check the slipper clutch too.
For the record, I've never taken my nitro toys out w/o having to at least tweak something.

just back from the track. i think i'm set, temps down to 240-250, hittin' second halfway down the straight. it even has a distinct sound to it. i changed my spur gear and yes, in the process i noticed it was not tightened down all the way. should it be tight, i never can tell, some people say it should slip a little, some say tighten it all the way. anyways, i can't exactly say what did it, but a combination i think of starting over with needles at factory settings, changing tranny shift point, and tightening my slipper seemed to do the trick. i didn't stray too far off those factory settings but i did increase the idle a little too. i won't give myself on the pat on the back just yet because now i've got a little problem upon acceleration, like a winding noise that disappears when hitting second. i did shell it out a couple days ago and replaced all the gears except one. has anyone ever had one day at the track where you didn't break anything and just ran your car from start to finish. another problem for another topic........

Just to touch on something I mentioned before. If you feel your truck was running great, and was shifting properly, take note of the temp of the engine as well as the ambient temp. So later, you can say, "well, at 60 degrees, my truck runs well at, say, 240 degrees". Use this as your REFERENCE. Im glad some folks agreed with me earlier, your best tuning tools are your screwdriver and your ears. O yea, I forgot about the eyes, LoL. Also, take note of other ambient temperature situations, such as, "its cold out today" and tune accordingly. And note that temp. It'll help you get a feel for your engines particular temperature characteristics.

your slipper setting is up to you but they work well if you bottom it out then back it out 1/8 to 1/4 turn depending on surface you running on. and as far as the shift point still sounds like its taking to long to shift it shouldn't take half a straightaway to get into second gear should be shifting about 10 feet or so out of the turn the .18 has enough power to pull that second gear with ease. my o.s. .18 runs around 210 to 220 depending on weather

Hmmm,

280 celsius or fahrenheit? If fahrenheit, I thought that was pretty much frying your engine?

I run my TRX 2.5R engine around 220 (per specs) and it runs great. I understand that TRX engines run hotter than other engines, and that the OS engine should be around 160-180?

I'm working on a OS-CV .15 that hit 280 and was smoking. Not "fast" smoking, but smoking from the head. Still trying to work that one out.

wow, 220 on the 2.5? isnt it supsto run at 270? and not go below 200

moork550,

I guess it's a matter of opinion then. The manual says it's overheating if it's hotter than 270. I guess my engine may last a little longer running around 220. It still puts out plenty of power.

Thanks.

Can anyone tell me where the OS CV .15 should be running at?

Anyone got an answer for my engine question?

"Bueller? Bueller? Has anyone seen Bueller?"

Thanks.

220 is great if your getting your full potential of power. is it accelerating quickly and hitting that second gear??? is there alot of fuel coming from the exhaust, if yes, then that's awesome, but sounds to me like you may want to lean it out about an 1/8th of a turn and see if your performance goes up, temps may go up a little, but i think you'd be ok with that engine. just mess with your high speed needle at this point.

sk8z27,

I know that about the 2.5R engine on my Revo. Our track has a 120ft straight. The engine has no problem reaching 2nd at about 1/3-1/2 that length. It keeps up with most of the other trucks, and for those that are faster I get them in the turns. I do appreciate your words on that though. I was actually asking about my OS engine.

I've been tinkering with it (my OS) for 2 days now and am having major problems. There's no power (doesn't reach second in my TMaxx) unless I lean it out so much that it gets over 300. Then it's literally smoking. There doesn't seem to be a happy point. It's either 220 and puttering, or 300 and smoking, but flying. And that's all within about a 1/8 turn. You're probably thinking "only turn it 1/16", but trust me I've been there. Can't find that happy place. This is the way it's been since I got it 3 years ago.

I don't think it's an air leak, as the engine's hardly been run and I just replaced the exhaust coupler and reseated the carb.

I think I'm gonna have to give up and replace it, unless you can tell me what else to check.

believe it or not, but i just went through that with my os.18 last week. i had the same exact problem. here's what i did, i ended up going back to factory settings, i think 1.5-2 turns in on the low side and 2 out on the high side. then i didn't adjust much more from there. i think i just did the high speed. and it was very little turns like you said. i also tightened my slipper and adjusted my shift point. it's funny, but it was exactly the same problem. oh and i think what helped the most was i turned my idle up a little more then what i thought was normal. it absolutely screams now and sounds great. it's running at about 245, but now i blew out my rear diff so i haven't been able to drive it for a couple of days. it took me about 2-3 days to tune it, but i finally got it. good luck.