How is the Japanese RG 500 restricted?

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insignis
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Joined: Sat Feb 06, 2016 1:29 am

How is the Japanese RG 500 restricted?

#1 Post by insignis » Sun Apr 17, 2016 7:17 pm

Hi, first post here with a request for information.

I'm after some advice regarding the Japanese RG500s. I live in Australia and it seems the only RGs to be offered for sale are the 'grey imports'. So I went ahead and purchased a Japanese import RG 500. It is 'restricted', apparently reduced down to 75hp from the full power versions (94hp I believe). My initial ride certainly confirmed (seat of the pants) that it is restricted.

My request for information on how to de-restrict has resulted in confusion. I've asked on the various forums but people are providing conflicting information. Some say the restriction is based on the use of RG 400 exhaust system which have a reduced diameter (where the exhaust meets the muffler). On an RG500 this is approx one inch, and just 3/4 inch for the 400. Other people say it is jetting, some say it's a different CDI, and yet others talk about block off plates at various points in the induction and/or exhaust systems. All explanations seem valid, but surely it can't be restricted in all 4 ways?

So I'm wondering if anyone has a definitive answer, or a promising lead? I'm keen to restore my bike to a full power version. Not after a fire-breathing dragon (though that would be nice), just after a little more excitement. Certainly happy to purchase some of your mods/improvements to successfully undertake this process.

Thanking you in advance for your wisdom
Frank

begbie
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Joined: Fri Sep 02, 2011 7:02 pm
Location: UK

Re: How is the Japanese RG 500 restricted?

#2 Post by begbie » Mon Apr 18, 2016 4:30 am

As far as I'm aware, the 500 was never restricted,the 94 hp you speak of is an exaggerated number taken from the crank. A good tight stock engine makes mid 70's bhp.
Just like the rd500 in the context of modern bikes they are not by any means fast.

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Rick Lance
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Location: Leicester, NC
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Re: How is the Japanese RG 500 restricted?

#3 Post by Rick Lance » Tue Apr 19, 2016 1:59 pm

The export RG500 was rated at 95 hp at the crank and commonly dyno'd in the low 70's in stock form. My filter kit typically brings this up to mid 80's hp.
The Japan 500's were de-tuned to 68 hp by the use of the RG400 exhaust. To de-restrict, simply fit the export 500 exhaust (or any aftermarket system) and adjust jetting to suit. The ignitions and airbox components are all std issue RG. If you would like to discuss your RG's development potential, I can be reached at (828) 777-4076 or through my website http://www.lancegamma.com
If I disagree with everyone, that doesn't make me right. If I take the side of only one, it doesn't end the fight. If my position's strong enough from exposure to the light, you may see things my way when we share the same highway.

vdrive
Posts: 63
Joined: Fri Mar 18, 2016 2:17 am

Re: How is the Japanese RG 500 restricted?

#4 Post by vdrive » Sun May 08, 2016 5:01 am

yes indeed , Rick Lance Gamma Filter Kit on my RG 400 Gamma Really Runs Crisp +1 .

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