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Old 09-18-2007, 08:08 AM   #1
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Default OS CV-R Promblems

I have an OS CV-R on my RC10GT and for some reason i just can't seem to get the engine to run at full rpm. I've checked to make sure the carb is opening all the way, took the engine apart and resealed it, changed all the fuel lines, took carb off and cleaned it up, replaced the fuel nozzle on the needle valve, took the needle valve out and cleaned it, changed glow plug, and tried two different fuels with two different nitro contents, all with the same results, seems like the engine is only reving up halfway to two thirds its rpm. Any other suggestions?
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Old 09-18-2007, 08:29 AM   #2
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Did you check the throttle linkage? (from another forum)

Did you try bringing all of the carb settings back to factory tune and starting over? Otherwise I'd look at maybe a crank bearing going bad or possibly some debris stuck in the pipe. Or if there's a gasket between the block and the header, perhaps it's the wrong one or in upside down and it's restricting exhaust flow.

Yeah I know, you got this truck used. Never know what you'll find in other people's stuff sometimes.
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Old 09-18-2007, 02:09 PM   #3
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Im thinking the exhaust gasket. ya see the associated one has a smaller opening than the exhaust port.. try enlarging that hole to be the same size or get some of the losi gaskets

that is if you are sure on the tune
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Old 11-04-2007, 06:45 PM   #4
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alright, i checked the exhaust gasket and that's not the problem, anyone else have any other ideas?
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Old 11-05-2007, 09:36 AM   #5
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Check to be sure the throttle arm on the carb is tight and not just rotating freely(if it has a rotary carb) Also check out your gearing , should be running 16/66 0r 15/66 .If all this stuff checks out ok Then someone may have put the sleeve in wrong and the ports are not lined up correctly.
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Old 11-05-2007, 09:42 AM   #6
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arm was tight, i put the sleeve in myself before and i took it out yesterday and put it back to make sure the exhaust port was lined up and it was and i'm pretty sure it's a 66/15 gearing (i know it's a 15 on the clutchbell, and i'm pretty sure it's a 66 spur) so i'm not sure what else it could be. I took the carb completely apart last night but didn't have any motor spray to clean it up with so i'm having the woman get some on her way home from work tonight so i can try to thuroughly clean the carb and see what that does. If that doesn't work, i'm at a loss.......
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Old 11-05-2007, 05:35 PM   #7
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Make sure the piston is in correctly as it has a front and rear. This will really make the engine run like a real bag of A$$
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Old 11-05-2007, 06:48 PM   #8
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How old is this motor? How much fuel has been ran thru it, what fuel were you using and what temp is it running at? It could just be worn out.


Does it have a fuel filter? If so, have you tried bypassing it?
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Old 11-07-2007, 07:14 PM   #9
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I'm not sure how old the motor is. I've disassembled it and made sure that all of the bearings and what not are still good. Engine still has all kinds of compression, including the little lock at TDC when the glo plug is out. The piston was in correctly, so now i'm back at square one. As far as fuel and fuel filter, i've tried with and without, same results. i tried %15 Byrons and %20 Byrons with the same results as well, but temps were kinda high....270-290 at some times. Thought it might have been an airleak, so i sealed up the back plate and the carb with the same results......any other ideas?
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Old 11-07-2007, 07:25 PM   #10
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How deep is the pressure line into the pipe??

Now sure what you've got but back on my Losi NXT is had a motor that wouldn't run and it wound up being the pressure line had slipped into the pipe enough to block the stinger.

It's kind of random but you never know...
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Old 11-07-2007, 07:26 PM   #11
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Quote:
Originally Posted by AssocRacer View Post
I'm not sure how old the motor is. I've disassembled it and made sure that all of the bearings and what not are still good. Engine still has all kinds of compression, including the little lock at TDC when the glo plug is out. The piston was in correctly, so now i'm back at square one. As far as fuel and fuel filter, i've tried with and without, same results. i tried %15 Byrons and %20 Byrons with the same results as well, but temps were kinda high....270-290 at some times. Thought it might have been an airleak, so i sealed up the back plate and the carb with the same results......any other ideas?
What plug? I use Odonnels 77 or o.s.#8 in my 1/10 motors.
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Old 11-08-2007, 04:26 AM   #12
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I know that's not the problem either, i checked that as well. I mean, if i gotta get a new piston and sleeve for it or even a new engine i'm not gonna cry, This engine came on an RC10GT that i paid 80 bucks for that also came with two servos and the truck itself turned out to be a full Factory Team, so if i gotta drop 100 bucks on a new motor oh well, i just got a full Factory Team truck with engine now for $180. I'm using the recommened O.S. A3 plug which is new as well.
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Old 11-08-2007, 08:13 AM   #13
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It sounds to me like you are really lean. I have two OS CVRs and they run great at about 200 to 210. Reset your needles to factory settings:

Rotary-- Top- two full turns out from all the way in. Bottom- 1/2 turn in from flush.

Slide-- Top- two full truns out from all the way in. Bottom- 2 1/2 turns in from flush.

1. reset your needles to those settings. (it will be rich.)
2. start your truck and warm up the engine.
3. drive your vehicle down the street to observe top speed.
4. turn the top end needle clockwise (lean) 1/8 of a turn untill you acheive the highest top speed your engine will make.
5. richen your engine about 1/8 to 1/4 turn after you have acheived the highest speed possible.
6. Your top end is set.
7. now adjust your bottom end so that you get good throttle response and a consistant idle.
8. with your engine idling, pinch your fuel tubing about one inch from the carb. your engine should run for about 3 to 5 seconds then speed up and die.
9. your bottom end is set.


Try that and tell us how it goes.
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