SP vs SPR

[Aradune]

Here is what I've been told: SP has bigger carbs and one power valve per cylinder. SPR has smaller carbs (same as RS?) but 3 power valves per cylinder.

Is this accurate?

Which bike de restricted makes more HP?

Also any other differences?

Thanks!!

[Jakes]

SPR has 32mm oval carbs if I remember correctly. The other SP's are 32mm or 36mm for the 3XV2 and 3XV5 (I think). The SPR is restricted to 40hp, earlier models are 45hp. It has like you say 2 extra power valves per cylinder that operate the exhaust auxilary ports.

Although it has the other SP bits (adjustable suspension etc) it actually shares its parts book with the R/RS models so I guess it's less special than say a '92 SP..

It's also the heaviest at 132kg

[Neal]

In the end , you can put bigger carbs on and get the hp you want .
I guess it depends on the price of either bike available and the cost to boost up the power .

[maccas]

The 32mm oval bore carbs are very good. Bigger carbs are not necessary.

Dan

[Warwick]

Have you experimented with the 32s, Dan? I have a pair of SPR Oval bore 32s here, but I've never got round to trying them out myself. If I can set them up to broadly match the settings of the 38s I run on the track bike it'd make an interesting back to back dyno experiment I reckon (though logic would suggest their advantage would be at part throttle really). Might try to do that this summer though anyway  - if the motivation fairy pops by...  .

[Neal]

Come on Warwick , you can do it !

i would be keen to see the changes ! 

[maccas]

I haven't yet Warwick but it is something I'd like to do in the future possibly. The jap's were very clever with the oval bore giving a lot of area and still staying within the 32mm bore rules of F3 racing at the time. (which was brought in to try and reign in the 3xv for the nsr's etc.).

I've read (looked at the pictures) a few japanese blog posts and some of them running the SPR 32's have good results.

Dan

[Warwick]

Yeah, that's much my understanding too, Dan. Kind of why I picked the 32s up in the first place. They are really earmarked for one of the road bikes, but I've just never got round to testing them yet.  As noted, I suspect there would be more likelihood of any noticeable advantage at part throttle than at WOT - hence the idea of bagging them for the road bike. But the oval 32s use different internals again to the earlier 36 (and the round 32mm) SP carbs, so that's an added complication... It'd perhaps be a more illuminating test of the outright performance to test them back to back on the same motor though of course. If I ever get round to it , I'll let you know how it goes... 

To try to get this thread back on track, The SPR was in some ways a little over-complex for my own tastes (the electronically controlled oil pump and 'triple YPVS') - and carried a bit of extra flab compared to the earlier, more focused, SPs. Also, as the sole model from 95 on it was a bit of a hotch-potch of R and SP bits, so my own preference is for the earlier bikes. TBH though any 3XV is a fine piece of equipment and I'd take a well set-up R over a ropey SP or SPR myself anyday.

Basically, any of the models are only as good as the set-up of them is my take on it. And in view of the lack of them that are properly 'de-restricted' it's hard to definitively say which is 'best'. or has the most potential etc.

My own favourite 3XV is my own shonky R model track bike. I loves it, I do... 

[Aradune]

Wow these bikes are rare. I wonder if anyone has ever dyno'd a properly de restricted SPR and SP?

I didn't know about the SPRs oval 32s. Thanks for all of the replies and info.

If anyone in SoCal has a de restricted SPR let me know and I'll bring my SP and we can compare notes.

-Brad

[Neal]

I should be ready to dyno my SPR in April . What i have read before is that the last bikes raced in the Asian champs were pushing +70hp .

Is this for road use or track use ? Mine is a track only bike 

[yorkee]

I thought there are more difference between RS and SPR other than the carb.  I thought the crank, the head and the cylinder are different as well. 

I don't have the cylinder, but I have a crank which I thought is a SPR crank:


Can you guys tell the difference?  or I should take the picture in another angle?

[ybk]

That looks like a parallel twin's crank? 3XV cranks are a lot more compact..

[Need4speed]

2MA - standard - you can compare here...
http://pure2strokespirit.net/forums/index.php?topic=390.0

[eyrey1]

[epa police]

This is a (3XV) SP crank