Dakar Dazed II - the return! Part 1: Project LC4-50

Why be just one of the sheep?????


Why not be the Lead Dog!!!!!!
I love the " thinking out of the box !!!!!!"

A clear solid tube with calibrations down the side of the tube.
Out the bottom of the tube is a hose with a screw in adaptor on the end of it.
In the tube is a plug that cam move freely up and down the tube.

Pull a spark plug, screw the hose from the tube into the spark plug,
crank the motor over.

http://www.precisionmeasure.com/test1.htm

There maybe be slight variations between engines due to running different cam shaft profiles.

But the testing guy after awhile can pick if an engine is not reading how it should.


Funny story:
There was a guy breaking records all the time, NHRA.
he used to come in at the right capacity engine.

Theway the car was built one cylinder was easy to get too,
the other seven were down right pain in the butt to get the plug out.

So scrutineering would check the easiest cylinder to get too.

Not thinking that the other seven cylinders were over capacity :)
Which they were.

Hi Techdutchie, and welcome... don't worry, it is a legitimate question - there are any number of ways to build a Dakar bike - from the Factory teams, to Luis Belaustegui on a 150cc 2-stroke, and everything in between... we are just choosing to do it the way we are doing it...

And your appraisal is pretty much bang-on to the motivation of the whole team:

• For myself personally, yes, I am looking to finish the Dakar... I still have my fully prepped & rebuilt WR450F from 2011, but the offer of a ride on this new project bike means I can sell my WR to help fund the entry and assistance costs for my return.

• For John at Rally Raid - he has built his business around the KTM 690, and is widely respected for the quality and design of his components. It makes perfect marketing sense for him to race a bike that features parts that he has designed and sells - and where better to advertise than to participate in the #1 off-road endurance race in the world? He is no fool though - John and his company are investing a lot of time and effort and money in this project - it is only fair he sees a return for his investment?

• For Martin at Torque Racing, he is an excellent engine builder and A1 rally mechanic, with plenty of Dakar experience - for him, it is the engineering of the bike that particularly appeals - similarly, if he didn't think it was both a challenging yet feasible project, he wouldn't have got involved.

• As for Piglet, yeah - he basically needs a new pair of shoes...

Jx

Sorry, but I see that as the worst of all worlds- lots of expense (450RR motors cost what a good used 690 does complete), none of the benefits (enduro/mx frame, poor weight distribution, etc).

The LC4 project, if successful, will be relatively low cost, won't require a spare motor, and will have at least an approximation of the benefits of KTMs rally experience- Trellis frame, good weight distribution, etc.

I just wonder if a motor engineered from the ground up for 654+, can be made to work worth a darn at 450ccs. There's so much that goes into engineering not only the engine, but airbox volume, exhaust, ports, cams, etc... I have no idea what to expect from the finished product on the dyno.

If i can ask Jenny / John.

What length rod your using ?

And what length is the stock rod ?

+1 A side-by-side comparison pic would be cool!

After reading Ned's post this morning about how much better his 690RR felt in the sand (due to the trellis frame he said), I wondered how hard/expensive it would be to have something similar, i.e. trellis frame, with a Dakar-legal 450cc. It seemed to me there were only two options: 1) Buy a 450RR like Pyndon did, 2) put 450cc engine (like an XC4) in a 690's frame.


Never did it occur to me to convert a 690 engine to 450cc's.


That's why y'all are doing it, and I'm sitting here puttering away at a computer like a monkey.


Well done!! Can't wait to see how this turns out.

If nothing else, changing the piston, rod, and stroke should be a way to make the 690 vibrate like a proper LC4! :)

Stock is 141,5mm centres,new rod is 154,0mm centres.The extra 12,5mm in length will compensate for the reduction of stroke by 25mm.

Hopefully,once we try the first motor,with the welded up & repositioned crank pin,and prototype piston,the next version will have a production piston,and a lighter,billet crank,to suit the smaller motor,to help it spin up quicker.This will mean adjusting the weight of the LC4 balance shaft to compensate.

Hey John,

Good luck with the project - sounds interesting and will be keen to see the dyno charts.

With the valve and port sizes as they are it is going to struggle until it's at high rpm. The domed piston's not going to help either. Not sure it will be that much fun to ride on that big 690 platform.

It will need extensive head work, smaller valves, welded chamber, new exhaust. To make potential it would need cam development - as is you could reduce the lift quite a bit as you won't need the flow.

I think by the time you've got the head sorted out you may as well have left the bottom end alone, sleeved the block and focussed on the head.

Sounds like you have good people involved so I'm sure it's all been considered. If you haven't done so already i'd happily run it through some simulation if you can give me the port dimensions and flow details - must be readily available for the 690.

Are there enough potential customers to recoup your investment time and costs?

Where's that LIKE button around here!

Dirty

"To try is not to fail"

[John Mitchinson]

Hi Mtrehy! - many thanks for your offer of running a few simulations... as you suspect, things are going to be tight in there, and it is not just the physical elements of everything meshing (but hopefully not actually) coming together, but how it effects the power characteristics...

John has already been talking with the development department at Cosworth* regarding the dimensions required, and they will actually be laser-scanning a stock 690 head on Monday, so that we have the most accurate data available.

After John's original meeting with them last year, they are confident it can be made to work - but as you suggest, how efficient and ultimately how suitable the new engine characteristics are going to be, is very dependent on getting a prototype engine running and in a bike...

*Regarding your final question - while it is true there is only going to be a limited market for a complete 450cc conversion kit for these engines, the development spin-off is the ability to create a separate profile for a stock replacement and hi-compression piston option for the regular 690 engine (to be machined from the same batch of blanks, hence the desire to keep the original 690 bore and pin centre) which as you might imagine, has a far broader commercial application - with aging 690s in Enduro, SMC and Duke guises, or anyone looking for higher performance from the original capacity engine.

Should the initial prototype prove sufficiently successful, then it is likely that Rally Raid will be producing a batch of regular 690 pistons (in stock and hi-compression ratio) in conjunction with Cosworth, together with the required number of 450cc piston profile.

Jx

Hee hee - someone has been reading the Jennydakar.com website x

And on that theme, today's picture is of that wise old sage - yep, the Yoda-Pig had indeed gone a bit Orange!



"Dakar. Or do not Dakar - There is no Try."

Jx

Go Yoda and Piglet!!

Lovin' it Shouldn't there be a RallyRaid logo on his upper arm there Jen?

Love it!!

Hee hee - top work Nordie! (maybe he needs the nose as well?)

Jx