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Discussion Starter #1
Anyone know of and cam upgrades for sp2? Or stroker kits? Just wanting to know if anything like that is possible. btw love the site!
 

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The weak point of the RC51 is the stock cams.
They're cast and have been known to break in half if welded and re-ground with higher lift and duration profiles.

For performance cams, insist on billet cams, preferably with adjustable cams gears to dial in perfectly.
And if you're going for performance cams, use performance springs and lighter retainers in the valve train.

And since the higher lift and longer duration cams will lower your effective compression ratio at lower RPMs, you may consider higher compression pistons.

JE pistons are advertised as 12.8:1, but have an effective compression ratio of around 11.5:1 with performance cams. That combination can live on 93 octane pump gas.

So for pistons, look at JE or Wiseco.
For cams, you can inquire at Kent Cams Ltd in the UK.
For titanium retainers and performance springs, try Kibblewhite Precision Machining, Inc. in Pacifica, CA.

For stroker cranks, you might check out Falicon.
However, since a stroker crank is going to put your deck height totally out to lunch, you'll need shorter rods or pistons with offset holes.
So that would mean Carrillo titanium rods.

Or, you could learn to love the RC51 as it is and take all that money and place a down payment on a Ducati 1198S with 170 HP or KTM RC8R with 180 HP.

As Clint Eastwood (as Dirty Harry) said, "a man's got to know his limitations".
 

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To clarify a bit.
The JE (and probably Wiseco) piston's 12.8:1 compression ratio was derived by use of HRC valves that had smaller volume than OEM valves (flat valve heads vs. dished valve heads).
The larger volume of the OEM valves drops the compression ratio down to 11.5:1 or so.
 

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Discussion Starter #7
I got some prices from that guy..... I need to learn how to build Honda motors..
That guy was not cheap, lol..
 

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If you have the tools...
Pistons and cams you can do yourself.
Although if you're doing pistons and cams, you'll probably need to use stiffer springs and lighter retainers to control the valves at higher lifts beyond stock.
Porting and polishing heads is a job best left for experts at flowing heads.
All said, you might be able to push it up to 150 HP.
That's what they called a Stage 2 setup.

Beyond that, it gets very expensive and hard to obtain parts as the RC51 is no longer supported by HRC.
For example, here's a site that lists HRC parts.
https://www.slipstreamperformance.com.au/store/index.php?cPath=1_26
Check out the prices on some of those parts, if you can even get them anymore.
 

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My RC is a mild superbike motor. Makes about 136 or 7 rwhp.
Was originally built by EDR in Portland. Blew up shortly there after. The guy I bought it from got no satisfaction from Eric at EDR so took it and had SDS in Portland build him another one. It now has about 350 race miles on it and is doing fine.
I have enough parts ot do another motor and am thinking about sending them off to Sage at SDS. He does nice work.
 

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My RC is a mild superbike motor. Makes about 136 or 7 rwhp.
Was originally built by EDR in Portland. Blew up shortly there after. The guy I bought it from got no satisfaction from Eric at EDR so took it and had SDS in Portland build him another one. It now has about 350 race miles on it and is doing fine.
I have enough parts ot do another motor and am thinking about sending them off to Sage at SDS. He does nice work.
Looking for someone who is reputable and still in business to work on an RC51 racebike engine. Prefer somewhere in Canada. :)

I tried looking up SDS Performance but it seems they no longer exist.
 

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Hi guys. Someone buggered around with the one head of my sp1. The agents say that I need to replace the head and cams, even though there is nothing wrong with the cam. Only the head. They say that you can't use different cams on a head, that they are a set. Is this true? Or are they trying to take me for a ride?...
 

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You should be able to swap cams from one engine to the other.
The cams on the SP1 and SP2 are the same.
The exhaust port shape however, is different between the two heads.
However, inlet runner size is also the same size for both SP1 and SP2.
 

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Thanks, that makes me feel alot better in the wallet. Just have to find a head now. The dealer I went to only wanted to sell the complete head with cam and the lot.
 
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