Bigger Power Valve?

rc46 · Post by **rc46** » Fri Jun 01, 2007 7:01 pm

Has anybody seen or tried to use a Bigger power valve. one where the port or hole in the power valve is made bigger to match a bigger port in the barrell? I ask as im starting to dig through Box number 2 of the bits i got with the ebay bike and guess what i found? 1 power valve (no idea if this was a test bed or the other 3 went missing) but this power valave compared to the standard ones i have sitting about is very diffrent the port is much larger!!! i guess it allows more gasses to flow... but i have no idea if it was sucssesful!

Ill post some pics if there is intrest but right now no point unless its gona be of use....

Cheers

mr_bungholeo · Post by **mr_bungholeo** » Fri Jun 01, 2007 7:42 pm

b good to see the standard n modded ones side by side.....

the-elf · Post by **the-elf** » Fri Jun 01, 2007 7:48 pm

Has it got a flat one one side of the valve? Be good to see a pic.

the-elf · Post by **the-elf** » Fri Jun 01, 2007 7:50 pm

BTW are you just comparing a KR1 and a KR1S valve?

rc46 · Post by **rc46** » Fri Jun 01, 2007 7:54 pm

Elf, thats a good point I havent actually seen any KR1S valves are they bigger anyway?

this one is the same dimensions just bigger hole!!!

Ill go and get some pics, ill be back in a few hours with pics

rc46 · Post by **rc46** » Fri Jun 01, 2007 8:48 pm

Right, I think Elf Has pointed out a silly error, I didnt realise there where that many diffrences in the KR1 and S barrels and Power valves, But! i do have a pair of both Kr1 and S barrels, and from what i can see the diffrnce is not that great on the Exhaust side, compared to that of the power valve... here is what i have....soz for the crap pics

Power valve KR1 Vs what is probally a S valve..

the other side

And then i took some pics of the ports fron the exhaust side, again soz for the crap shots,

KR1

and then the S ( im correct that the S has only one inlet port on the inlet side vs 2 of the KR1?

Next question is, Can you still buy these power valves? if indeed they are KR1S

mr_bungholeo · Post by **mr_bungholeo** » Fri Jun 01, 2007 9:39 pm

yup i think so...i got one from fowlups...sorry fowlers about a year ago n it was in my hand in two days...think it was around 28 quid?

rc46 · Post by **rc46** » Fri Jun 01, 2007 9:46 pm

Yikes!!!! over £100 for 4!!!

Oh well, ill have a look!

So you think this is indeed a KR1S valve then?...

To optomise the engine ill have to try and Get it to KR1S spec!!

Ho Hum.... Mind the Bike now goes real well and thats just KR1!!!!

mr_bungholeo · Post by **mr_bungholeo** » Fri Jun 01, 2007 9:48 pm

i may have a couple of 1s pvalves if it'll help.......pm me if you need em.....

the-elf · Post by **the-elf** » Sat Jun 02, 2007 11:20 am

RC looking at the pics of the cylinders. Yep the KR1 has a lower boost port at the back, The KR1S has only one. The exhaust port is also different as the 1S has larger power valves.

The main visual difference between the ports is that the KR1 has a bridge across the KIPS port in the exhust port behinh the valve and the 1S dosn't. However the KR! cylinder you've picture is missing it and the KIP port looks to small, so I guess someone has modified it to 1S spec at some time?

The thing to remember is that the KR1 Race Kit cylinders and power Valves became the standard KR1S parts. A case of racing development getting to the road bike

rc46 · Post by **rc46** » Sat Jun 02, 2007 3:19 pm

The top pic, (KR1 Tunned Barrels) came from the motor but had standard KIPS, Im not to worried as the Baby you sold me makes me happy and if the new engine goes as well as that (KR1 Tune at the MO) ill be happy, just wana make sure i take advantage of everything i have... to get the best motor..

KR-1R · Post by **KR-1R** » Wed Oct 22, 2008 10:23 pm

the-elf wrote:Has it got a flat one one side of the valve? Be good to see a pic.

.
.
.
pics pinched from...
http://www.geocities.jp/fake_dimension_ ... nance.html

stock standard powervalve 12005-1132
Cylinder Formula 3 'F3 KIT' powervalve left side 12005-1135
Cylinder Formula 3 'F3 KIT' powervalve right hand side 12005-1136

Who has done the power valve mod thing - any dyno tests?
certainly helps with the alignment issues and although it might compromise low end power with standard linkages/rotation? - ONLY because i went whole hog and single sided all four

I think it must improve the flow from the main exhaust port because it opens up a larger area and the left and right auxilliary exhaust ports merge sooner - it certainly looks cool looking up the exhaust port seeing the flush floor across the entire ports.
.
.
.

mgtkr1 · Post by **mgtkr1** » Thu Oct 23, 2008 6:37 pm

i have done the powervalve mod, basiclly turning the 1s valves into f3 copies and matched em all best as possible. only did it for the benefit of the alignment issues with std gear and really to try and make best of what i had by removing the step you can (usually) get. they look cool aswell. the main reason for the genuine f3 pv's is for that reason aswell irc. easy to do. does it work? i have no dyno proof as yet and its such as small mod on its own that i cant really say ive noticed anything for that mod alone. its all those tiny bits that make the diffrence together, working in unison. oh, and i was bored at work!! if someone has a rotary/porting tool and needs 1s valves, its easy enough to use kr1 pv's to make 1s valves. just copy the genuine 1s valve and while yer at it match em all. a bit time consuming but i reckon its worth it., if you have 1s barrels/pipes.

TwoStroke Institute · Post by **TwoStroke Institute** » Fri Oct 24, 2008 7:05 am

There is an easy 2HP gain per cylinder in the exhaust duct outlet.

vincbr900 · Post by **vincbr900** » Sat Aug 15, 2009 4:24 pm

Care to elaborate?

KR-1S.co.uk Forum

Bigger Power Valve?

Bigger Power Valve?

Powervalve Modification - Single sided exhaust valve mods