So close, 1bhp per 1kg......

[muttsnuts]

I was asked to build a bike for a customer, its a race/road bike, its first outing will be tomorrow at Donnington, the remit was pretty simple, make the bike as light as possible and give it 100bhp or more

So a rolling chassis was delivered and then months of hard work and head scratching began, the chassis is a Kawasaki KR1S, but that is about it, everything else is different.

While I can't go into the finer details of the build, the end results I am pleased with, and nearly achieved 1bhp per 1kg, if I push the engine and fit bigger carbs I am sure I can get it to 1bhp/1kg, but for now and reliability's sake, I am leaving it as is while I get some data from its maiden runs and races this coming weekend (its racing R6's and the likes !)

So here is the bike at its final weighing, that's a full tank of petrol on there, it came in at 120kgs, so say 125kgs fully clothed





Next it was ready for the dyno, so it was loaded on and 12hrs of mapping, fuelling and steady heat cycling and it was done, I am pleased to say it lived up to what I hoped.......

Here it is on the dyno.......





So I suppose you all now want to know what it did, well below is the dyno chart..........







I am expecting some teething issues with this, especially around cooling (custom radiator required really) and fuel consumption issues, but they are all solvable.......

Anyway, I'll just leave that there for you to think about.........



PS: I am now on with an even bigger more powerful engine, details to be published at a later date and also got a few others in the pipe line...... watch this space

[petenofear]

Far play that’s some nice horses out on that

[reedpete]

Presume the gear ratios will keep working band within less than 2K rpm ? In which case those R6s are going to be spectators out of the corners....

[dusty350]

Great work Dave, very impressive. There could be some very embarrassed diesel owners this weekend !!

Dusty

[muttsnuts]

Mar 20, 2019 19:52:37 GMT 1 reedpete said:

Presume the gear ratios will keep working band within less than 2K rpm ? In which case those R6s are going to be spectators out of the corners....

Hi Pete, lots of work done on the gearbox, its a close ratio affair and has been geared to match the R6's, so 4th gear it does 115mph, 5th it does 138mph and 6th is 162mph

The RPM drops between 1600rpm and 1800rpm between gear changes, so its always in the power above 6500rpm and has a 3500rpm power band and loads of torque, an R6 full race unit kicks out around 120bhp and 45ftlbs of torque, this is kicking out 33% more torque and revs much quicker, plus its a whole 40+kgs lighter than the R6's !, the triumph 675's are even heavier !

It will be interesting for sure, although I think we will have fuel issues as the tank only holds 17lts, which won't be enough for 12 laps I don't think, but its all part of the learning curve !

[Tobyjugs]

This is really nice to see and puts a bit of reality to my target weight of 100kg. With the power peaking higher up in the rev range how long do you think the crankshaft will last? or what is the plan for maintenance? I am also worried about the cooling as i have been told they can get hot around the exhaust ports.

Good luck with the testing over the weekend.

[muttsnuts]

Mar 20, 2019 21:46:23 GMT 1 Tobyjugs said:

This is really nice to see and puts a bit of reality to my target weight of 100kg. With the power peaking higher up in the rev range how long do you think the crankshaft will last? or what is the plan for maintenance? I am also worried about the cooling as i have been told they can get hot around the exhaust ports.

Good luck with the testing over the weekend.

The crank is rated at 10k rpm, so its just over, so reliability should be fine, if I took it to 10500/10750rpm I could have hit 120bhp, but its too far into the red for me on such large pistons, the next phase will be to bring the power in below 10k, not too much work to do for that, but 200rpm can be hard at times, but a few small tweaks should sort it

Cooling is key, I have a guy who makes me custom radiators, this should have had one on, but the time frames didn't fit, so we will run with what we have for this time, but then I am sure it will have one made to sort it out

The exhaust temps around the ports can be critical and they don't like being cooked (I say if you cook it you fook it), but this has a few things on it to help, plus a very low temp fan switch, which will help to a point, but the fairing scooping etc is also a big part funnelling the air through the radiator, there is far more to it than meets the eye, hence why i've been fairly quiet on here for a good while as I am not only busy work wise, I am spening alot of time developing this stuff which means lots of thinking and research !

[marrcel]

Wow how many cc? Cant be 250🙈

[veg]

Finally got it finished then Dave that’s going to be an absolute monster. Let’s hope he likes wheelies and high sides .

[marsbar350]

Mar 20, 2019 20:22:39 GMT 1 muttsnuts said:

Mar 20, 2019 19:52:37 GMT 1 reedpete said:

Presume the gear ratios will keep working band within less than 2K rpm ? In which case those R6s are going to be spectators out of the corners....

Hi Pete, lots of work done on the gearbox, its a close ratio affair and has been geared to match the R6's, so 4th gear it does 115mph, 5th it does 138mph and 6th is 162mph

The RPM drops between 1600rpm and 1800rpm between gear changes, so its always in the power above 6500rpm and has a 3500rpm power band and loads of torque, an R6 full race unit kicks out around 120bhp and 45ftlbs of torque, this is kicking out 33% more torque and revs much quicker, plus its a whole 40+kgs lighter than the R6's !, the triumph 675's are even heavier !

It will be interesting for sure, although I think we will have fuel issues as the tank only holds 17lts, which won't be enough for 12 laps I don't think, but its all part of the learning curve !

if hes doing the no limits races its on the national circuit which is only 2.1 miles x 12 =25.2 miles.17 litres is 3.77 gallons
that equates to 6.6 mpg.i hope he completes the race

[4l04ever]

Are you reversing the water flow as some of the Southern big bore boys have done? I seem to remember chatting with one of them at the Aircooled rally and they said it lowered temps quite a few degrees...

[shaunthe2nd]

Bloody hell Dave, you do some amazing stuff, no wonder you needed a dyno upgrade!

[oldbritguy]

Impressive Dave, that is a lot of go in a very light bike.
A few track miles will as you say, identify a few niggles which you will no doubt iron out in jig time.
I imagine there will be a few surprised R6 boys at the weekend as well !

[Tobyjugs]

Revenge of the two stroke 

[mouse]

That is truly amazing! Well done Dave, please keep us posted as to how the bike runs on track

Mouse

[muttsnuts]

Mar 20, 2019 23:35:16 GMT 1 4l04ever said:

Are you reversing the water flow as some of the Southern big bore boys have done? I seem to remember chatting with one of them at the Aircooled rally and they said it lowered temps quite a few degrees...

Hi Rob, yeah Johnny Corin did the reverse water flow first (Southern boys copied him a few years later !), this is not running it yet as I am making a reverse flow water pump as well to make it all work properly, but I suspect it will end up revese flow, I am also working on a slightly different head design to stop short circuiting which can occur when you reverse flow as well, although itsnot a major issue, but if I am going to do it, I want it right from all aspects, but then that's me all over, over engineering things as usual !

[beardy]

I can’t add anything technical to this post
Just awesome that people love 2 strokes like I do

[muttsnuts]

two sessions completed, one small issue, easily fixed, best comment so far is "its fooking savage" !!!

[steven]

Hi,
Very interesting post.
I will look forward to hearing about "the savage 2 stroke" humpin the R6,s !
Good luck withh the testing etc, Im sure we will all look forward to hearing how things go.
Steven.

[4l04ever]

I bet he is leaning over the front wheel most of the time to keep it down! :-)

[mark69]

Mar 21, 2019 13:26:20 GMT 1 muttsnuts said:

two sessions completed, one small issue, easily fixed, best comment so far is "its fooking savage" !!!

That's awesome. Best of luck for the weekend. Look forward to the updates.

[muttsnuts]

Mar 21, 2019 14:22:51 GMT 1 4l04ever said:

I bet he is leaning over the front wheel most of the time to keep it down! :-)

yeah, its lifting in 3rd on full chat, so that's around 80mph, on the plus side he's just out dragged a TL1000s on the start/finish straight, the bloke wasn't too impressed by all accounts - its getting lots of attention in the paddocks, he says he can hardly get to the bike for people taking photo's etc of it - I've told him to cover it up, I don't want all my secrets nicking !!

[marrcel]

Mar 21, 2019 14:22:51 GMT 1 4l04ever said:

I bet he is leaning over the front wheel most of the time to keep it down! :-)

I did a lot of laps on my 98gixxer 130rwhp.
When i jumped on my 147kg ypvs with modern suspension and brakes i found it difficult to get used to stopping power and other lines on the track. The R6 riders are already comfortable to their bikes. Very interessting what will happen. 👍👍🤗

[reedpete]

Perfect world would be that if the heavier bikes don’t cover their lines they will naturally come in wider giving light bikes ambush space to shove up the inside, block the apex and then rat out of the exit....

Then there’s the real world ....fast guys getting punted into the bushes by the less capable unable to stop !

[muttsnuts]

unfortunately a high side has stopped play, he has broken his ankle I am told, but was the first lap of a session, so I am thinking cold tyre issues, but until I see the bike I won't know for sure, but I am told it wasn't engine related, still, got some good data and fuel consumption has been miniscual, for a 20min session he has used 4 litres, which is bloody amazing TBH and he was giving it some berries on the last session so I think we will be good for a 12 lap race once he is sorted. Temps stayed good and never went above 57c so bang on target temp as well

The bike isn't badly damaged, few scuffs and broken lever (usual bits and bobs), so easy fixes, and it certainly was fast from what I understand, no racing this weekend, but gives me time to fix a few things and make some improvements while he gets sorted

Also I've been told a lot of people have been taking great interest in it, including non other than Ron Haslam !!

[veg]

Erm I wasn’t being mystic meg, hope he’s ok.

[Mad Biker]

I hope the rider mends soon. Looking at how rapidly the engine makes power, high siding it wouldn't be that hard!

[muttsnuts]

Mar 21, 2019 18:49:06 GMT 1 Mad Biker said:

I hope the rider mends soon. Looking at how rapidly the engine makes power, high siding it wouldn't be that hard!

yeah, he seems ok, your not wrong Martin, it certainly makes big power very quickly and it was detuned for today down to 105bhp while we got some data etc, but even so, it was very fast by all accounts

[donkeychomp]

What engine is it? Or better yet, what engine did it used to be?

Looks the mutts nu....oh

Alex

[mellow]

i wanna see video of it