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Old 10-11-2009, 08:24 PM   #1
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Angry my first .21 engine.....

Well, i've buy a used Kyosho MP7.5 Kanaļ 3 with an RB S7 World in it. It's not a recent RB, this engine is 5 or 6 years old, but it only have 2 gallons on it. They've not heat button, the plug is threaded directly in the cooling head, and it's my first .21 engine. I've always run .28 and .30 before. And you want to know what???

I'am realy disapointed I can't compare the power of this .21 with what i've the habit to run.
It's slow on take off, and can't push this buggy like any of my .28 did it.

And more, this .21 don't have the RPM that i suspect.

So i've two choice, sell it and buy another good .28, or make it modify, but i'am realy not sure that this .21, even with a good mod on it, could be as funny to run that an LRP .30 X
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Old 10-11-2009, 08:27 PM   #2
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Old motors=old technology. By any newer motor (Nova, Ninja, Speed) and you won't want any more power.

I may be wrong though. If an RB expert chimes in and says the motor can make more power then it probably isn't tuned right.
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Old 10-11-2009, 08:39 PM   #3
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Sounds like a tuneing/engine problem. I'm assuming yor .28's were RTR engines and not a .28xz. That engine should have decent rip.

6 years old with only 2 gallons?? Can it and get a +4 or WS9.
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Old 10-11-2009, 09:50 PM   #4
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The WS7 was a wonderful engine.

Square bore/stroke; had a real mild bottom, excellent mid and didn't give up on the top; but no it didn't rev to the moon.

Pipe choice is important; you should run one of the RB pipes or a Novarossi 9853.

WS7 wasn't 'excessive' anywhere, but was/is a favored buggy engine for all around use. Mine also gets pretty good mileage...

If you're racing, I'd suggest looking further into your pipe/header and clutch setup.

IF you're bashing...then yeah, ditch and and go buy a 28 or something if that makes you happy.

Make sure the car is geared correctly as well. The prev. owner may have gone up on the clutchbell's tooth count and you need to go back down for your needs probably.
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Old 10-12-2009, 07:33 AM   #5
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RB S7s are great engines. I dont know that your ever going to get the same power as a .28 though.

You should try using stiffer clutch springs. The S7 is a bit soft on bottom and the stiffer clutch springs will let it spool up a bit more before engaging.

You didnt mention what pipe your running either. That can make a big difference. I always ran a JP-1. It gives a bit more bottom end compared to a 086 style pipe.

Are you racing? Most places would frown on running a .28 in a buggy. Usually they only allow engines larger than .21 on buggies that came RTR with larger engines just so they dont have to exclude guys with new RTRs.

There are other .21 engines that have more power than the S7. If your racing or planning on racing I would get a different .21 engine like a V-Spec or JX Ninja.
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Old 10-12-2009, 09:02 AM   #6
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The pipe i get with this engine is the RB EFRA 9863.
I'am geared with the stock 13T clutchbell.

When my GO GX-5R will be totaly brokin-in, i'll can compare two engine.
But for now, i don't realy like the power of this RB.

Anyways, probably that i'll let this buggy to my 7 years old son, so it'll be probably enough for him
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Old 10-12-2009, 09:22 AM   #7
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May be I missed it but do you race
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Old 10-12-2009, 09:31 AM   #8
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Thumbs up It's a great engine.

I think you would be happy with the 9853 pipe. the one you have is a torque pipe, but it limmits the engine and doesn't let it breathe. the ws7 is a great engine, and probablly needs to be tuned better. I will admit it lacks bottom end, and the guy above said it could use stiffer springs. The buggy you have is heavier than the newer cars, that engine would work great in a lighter car. I had a s7 in a 7.5 and it was slower on bottom end too. I know exactly what your saying. It's irritating. For that buggy I would get a Novarossi p5. You could send the ws7 to get it modded and that might help. On the plus side the w7 is really reliable and will last for a long time. Good luck. I suggest getting an xray 808 buggy and putting that ws7 engine in it. Perfect combo.
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Old 10-12-2009, 12:30 PM   #9
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Quote:
I suggest getting an xray 808 buggy and putting that ws7 engine in it. Perfect combo
I have a brand new Mugen MBX6 with a GO 21-5 in it.

But i've bought this MP7.5 for my son, he want to start racing.
And i only look for a way to make this S7 pull a little harder.

I'll try my GO 2072 pipe on it tonight.

Thank you
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Old 10-12-2009, 12:43 PM   #10
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Thumbs up I see.

When I ran the ws7 I remember leaning the low speed needle a bit more than normal to get better bottom end, but watch the top end. It likes to be close to flush. with the 7 port it needs the extra fuel on top. I hope that helps...
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Old 10-12-2009, 03:27 PM   #11
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Quote:
Originally Posted by merdith6 View Post
I think you would be happy with the 9853 pipe. the one you have is a torque pipe, but it limmits the engine and doesn't let it breathe. the ws7 is a great engine, and probablly needs to be tuned better. I will admit it lacks bottom end, and the guy above said it could use stiffer springs. The buggy you have is heavier than the newer cars, that engine would work great in a lighter car. I had a s7 in a 7.5 and it was slower on bottom end too. I know exactly what your saying. It's irritating. For that buggy I would get a Novarossi p5. You could send the ws7 to get it modded and that might help. On the plus side the w7 is really reliable and will last for a long time. Good luck. I suggest getting an xray 808 buggy and putting that ws7 engine in it. Perfect combo.
I just used to run WS7 as well. Very nice engine. RB is very high quality and it would last a lot longer than 2 gallons. The question I would ask is, is it really a 2 gallon old engine? If yes, then I would invest in a NovaRossi 9853 or 9886. If you are unsure, I would rather spend the money on a Nova Plus 21-4
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Old 10-12-2009, 04:18 PM   #12
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I say 2 gallons, but is probably less than that.
I have a novarossi 9886 pipe on order and i have a short conical manifold tu put with it.
Hope that this pipe will wake up this mills a little more. And i'll order a set of Mugen 1.1 clutch spring too.
Here,s a pics of the engine, if somebody could realy tell me the aprox year of this RB please?
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Old 10-12-2009, 11:32 PM   #13
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That car and engine was the worlds winner around 2000. I had the same setup and it won more races than my 777.
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Old 10-13-2009, 06:55 AM   #14
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2000
So i think to send it for a mod, but i think i'll run it as it is, and simply buy a new and better engine when this one will be dead
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Old 10-13-2009, 07:02 AM   #15
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dont put a short manifold on it, that will kill the bottom end even more..... you need a long header to get that motor into its powerband sooner !
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