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-   -   RB Concept Engine Thread.. (https://www.rctech.net/forum/offroad-nitro-engine-forum/251409-rb-concept-engine-thread.html)

t4mania 04-25-2009 03:19 PM

Hey guys getting ready to order my D8 and would like to know if there are any parts I should stock up on. How about upgrades. Heard there were some problems with the driveshafts. Fix available?

Midnight 04-25-2009 05:32 PM


Originally Posted by 8&stuff (Post 5730865)
I hear of guys running jp3's(some get lucky and are efficient)but that 2020+short header outta be nice..I read somewhere somebody was getting more than 13 minutes and it might have been with an insert. if i remember right it was on a ws7.

Well a buddy has a jp4 and a 2045 for sale cheap. Would one of those work?

8&stuff 04-25-2009 06:36 PM


Originally Posted by Midnight (Post 5731613)
Well a buddy has a jp4 and a 2045 for sale cheap. Would one of those work?

I tried jp4 a month ago for a couple tanks and it ran strong but hot. 2045 is the ticket. with the s5 2045 lacked top end just a little at end of straights. id say your gaurenteed 11 minutes. I used a 2045 for second half of 1st gallon on break in. 2045 or 086 are the only pipes iv liked on my s5. wish i still had my 2045 being that my rb is pipe limited...

putterx 04-25-2009 07:02 PM

I personally have been using the Odonnel 099 plug in my S5. I have about a gallon on the plug in there now. I have used the 099 in cold weather and hot weather and it works fine.

Shooky 04-25-2009 09:30 PM


Originally Posted by 8&stuff (Post 5730865)
I hear of guys running jp3's(some get lucky and are efficient)but that 2020+short header outta be nice..I read somewhere somebody was getting more than 13 minutes and it might have been with an insert. if i remember right it was on a ws7.


Originally Posted by Midnight (Post 5731613)
Well a buddy has a jp4 and a 2045 for sale cheap. Would one of those work?

I have a WS7 III and I am currently using a JP-4 pipe with a 6.5 restictor. I can almost get 13 minutes on a tank (120cc). This is with 25% fuel and a OS P4 plug. Runs like a grape ape and temps at 235 degrees.

8&stuff 04-26-2009 05:52 AM


Originally Posted by Shooky (Post 5732408)
I have a WS7 III and I am currently using a JP-4 pipe with a 6.5 restictor. I can almost get 13 minutes on a tank (120cc). This is with 25% fuel and a OS P4 plug. Runs like a grape ape and temps at 235 degrees.

only thing different is your ws7 would put my s5 in the dirt lol. id see parts of the track(or off track) thats unchartered with a ws7. do your temps go over 235?

aaron joy 04-26-2009 07:05 AM


Originally Posted by Midnight (Post 5728974)
THanks for the info. SHould I run the #7 on my new S5, during break in and after break in. Thanks for the response, atleast there is one person out there showing love. I also run odonnell 30% after break in. I run 20% sidewinder during break in. Also, where did you order that new Hobby 5? I wanted to wait for these but got to jonesing after I ran that s3 last weekend.

Hello Midnight,
I ordered them directly from the RB importer in Texas. I work at my local hobbyshop and I do the RB orders for him. I was told they should be on their way from France very soon. I got four on order. I will let everybody know when we get them in.

Midnight 04-26-2009 07:28 AM


Originally Posted by aaron joy (Post 5733429)
Hello Midnight,
I ordered them directly from the RB importer in Texas. I work at my local hobbyshop and I do the RB orders for him. I was told they should be on their way from France very soon. I got four on order. I will let everybody know when we get them in.

Thanks bro.

Shooky 04-26-2009 07:57 AM

8&stuff, I think I had temps up to 255. That usually happens when the tank is empty and leaning out. I will see the temp vary from the morning to evening. Might touch the needle mid day.

8&stuff 04-26-2009 10:12 AM

right on. sounds similar here

8&stuff 04-26-2009 10:23 AM

when i ran my s5 with jp4 it was rockin. i ran it for 3 tanks at crcrc about a month ago. i got off the stand after a 7 minute heat and several minutes of practice so tank was about empty and temp was 260 exactly. i walked out of pits and another guy running a couple c6's said it smelled hot and to put a jp1 on it. well the jp1 was crap. it could make jumps but no top end and i didnt have time to tune so i switched to jp4 for main. last weekend i ran a re11 and it was pushing 270+ degrees. the smooth powerband on an rb is hard to get used to after running vspec type engines.

OfnaJoe 04-26-2009 03:04 PM

How much difference in run time would I get with a 6.5mm restrictor instead of a 8.mm one in a WS7 II ? I have the 8.mm now and only get a little over 6 min. I know my pipe is a gas hog (JP-3) and will be changed soon to a 2045, but I need runtime now? I am going to add another filter and some fuel line, but need to make a 7 min heat, so I am looking to gain another min. or so.
Thanks Joe

Semple 04-26-2009 03:15 PM

Well, after chasing a tune for over a week I decided I'd go to the track today anyway. I had some good guys helping try to find the tune. We would find what we thought to be a good idle, and good bottom end, put it down on the ground for a few minutes and it would start to lean out and struggle to move at all. After about 30 seconds, it would get this horrible lean bog at half throttle or more. It would spit tons of smoke for those 30 seconds, then there would be a lot less, and the temps would soar up above 260. Same problems I've been having for a long time now. It got to the point that the bottom end was out so far that it just didn't make any sense to keep going. Then one of the guys noticed that the o-ring that sits at the top of the carb neck had been pushed out and was no longer seated in between the case and the carb. I couldn't explain this as the engine had never been taken apart. At that point we just assumed that was the problem, an air leak at that point. I packed everything up and spectated for a few hours.


On the way home I stopped at Canadian Tire(Department store specializing in automotive, outdoors and tools/hardware) and picked up some gasket sealer. I began to take the engine apart and quickly realized that there was in fact, still an intact o-ring on the carb neck. The o-ring wrapped around the case below the carb is beyond me. I noticed as I took the engine off the chassis that there was a puddle of raw fuel under the engine mounts, and a steady stream of it coming from the front bearing/crank area.


I guess the big question is, could my bearing be leaking THAT BAD as to render my engine completely and utterly un-tunable and incapable of holding a tune/not leaning out regardless of settings? It's weird, the engine is not very old, and has not seen much fuel. Less than a gallon, still.

putterx 04-27-2009 12:23 AM

I had to change the front bearing in S5 after about 2 gallons. It was leaking pretty bad but it wasn't really causing my tune to lean out. I would say change it if for no other reason than the mess it makes.

RCmayor 04-27-2009 10:13 PM

Did you turn the fuel inlet where the main needle is? If yes you gotta be careful to turn the whole assembly. If you turn it and mis-align one of the soft gaskets it will leak. This will look like a front bearing leaking but it is really the main needle assembly. This is very common.



Originally Posted by Semple (Post 5734637)
Well, after chasing a tune for over a week I decided I'd go to the track today anyway. I had some good guys helping try to find the tune. We would find what we thought to be a good idle, and good bottom end, put it down on the ground for a few minutes and it would start to lean out and struggle to move at all. After about 30 seconds, it would get this horrible lean bog at half throttle or more. It would spit tons of smoke for those 30 seconds, then there would be a lot less, and the temps would soar up above 260. Same problems I've been having for a long time now. It got to the point that the bottom end was out so far that it just didn't make any sense to keep going. Then one of the guys noticed that the o-ring that sits at the top of the carb neck had been pushed out and was no longer seated in between the case and the carb. I couldn't explain this as the engine had never been taken apart. At that point we just assumed that was the problem, an air leak at that point. I packed everything up and spectated for a few hours.


On the way home I stopped at Canadian Tire(Department store specializing in automotive, outdoors and tools/hardware) and picked up some gasket sealer. I began to take the engine apart and quickly realized that there was in fact, still an intact o-ring on the carb neck. The o-ring wrapped around the case below the carb is beyond me. I noticed as I took the engine off the chassis that there was a puddle of raw fuel under the engine mounts, and a steady stream of it coming from the front bearing/crank area.


I guess the big question is, could my bearing be leaking THAT BAD as to render my engine completely and utterly un-tunable and incapable of holding a tune/not leaning out regardless of settings? It's weird, the engine is not very old, and has not seen much fuel. Less than a gallon, still.



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