KR-1S.co.uk Forum

Forgetting about the KIPS subchamber which works better than a power valve.It matters if you want the most HP/torque available to you, simple fact that main open first makes the best mid range and top end,you DO NOT loose mid range(because you add so much more Blowdown angle area). Open together you loose mid range and no gain on top, Subs open first is what you have now probably in between the 2.The main open first/sub next has been tested and proved by the best there is utilised ad nauseum in just about every triple port cylinder there is except the KR-1.

With Avgas advance maybe the extra comp adds heat to combustion, reality is less advance more comp and leaner with avgas the reverse for ULP.

I point you in the direction of Krazy-Katts dyno room Krazy-Katts dyno room

Show me where one of your conventionally ported engines makes more torque than the incorrectly ported KR engine

So we really need to see what actually happens when we Mod the KR the correct way,any takers?
Interesting take on the fuel/ignition requirements,i hadnt factored in the Compression increasing the Combustion temp.
Interesting to see Krazy Katts dyno curves,are they compareable to DynoPro?

Dave they are dynopro

Barry Booths VJ22 made 74~75hp on a dynojet. On Krazy-Katts dynopro the same bike made 66~67hp.

James (Krazy-Katt) is worth a visit, he likes two strokes

A fair number of F250 machines have been on James' dyno though not all owners will allow him to post the curves.

KR is a stonking motor which out grunts any other proddy 250 but lacks horse power as nobody has played with getting them to rev.

With cranks NLA I can't see the point in chasing RPM (HP). I am investigating an alternative two piece crank design that joins underneath a modified balance gear. This would effectively be like two single MX cranks so rebuild costs will be lower and maintenance easier. It also makes the webs much cheaper and easier to make.

mj43 wrote:I point you in the direction of Krazy-Katts dyno room Krazy-Katts dyno room

Show me where one of your conventionally ported engines makes more torque than the incorrectly ported KR engine

Right here "off ther street"



KR-1 crank looks like it needs thicker thrust washers and a 18 roller big end bearing, the same bearing as a TZ 250/125(and anything else that revs it's tits off).

I knew you would post that one - but got it covered as the TZR and NSR had non stock ignition and pipes so don't count

Ignitions don't make that much difference to mid range, peak power is within 200rpm, so that doesn't account for 3-5HP2-3ftlbs better everywhere. Especialy without power valve control

yes and what do pipes do

Just which brand of off the shelf aftermarket pipes add HP across the entire rpm range?

The 3xv and nsr250 mc21 are restricted to 45hp in stock form whereas the rest of the bikes on that chart aren't restricted.

Below is a graph showing a stock 3xv (green line) and a blueprinted 3xv with aftermarket pipes and stock ignition (powervalve stays low for a long time):



James will no doubt improve on the above curve when he gets a programmable on the bike.

The stock pipes are designed to do one thing and that is to make the best of the 45hp limit that the jap legislators imposed.

Dan

TwoStroke Institute wrote:Just which brand of off the shelf aftermarket pipes add HP across the entire rpm range?

Lomas did a pretty good job on the KR