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

Hee hee - really? - it must be magnetism drawing us together...

Very much looking forward to the Hellas for sure - see you there!

Jx

Hi Ned! - Yes, we were all set to debunk the 450RR this year after Dakar, only for loads of them to finish on a single engine (doh!) - although I think a lot of that was risk-tactics, especially at the top end of the field with the racing so close this year?

It certainly seems the Factory have got their act together regarding longevity from the 450RR engine now - although I still think it is a brave soul who would enter a bike like that without taking at least one spare engine 'just incase', which makes an extremely expensive bike even more expensive!

Taking a spare engine also means you are not eligible for Marathon class - which as you point out, and I'm sure many would agree, is very much the privateer spirit and the original ethos of the Dakar as a long-distance endurance event - where traditionally you stand or fall not just on your speed and/or navigation prowess, but on the very fact you can get your vehicle to the end of the rally without breaking it...

As I say, we are not setting out to prove we can engineer a front-running race bike, rather provide an excellent (in our opinion) platform for the clubman level rider who wants to race a whole season [or a Dakar] on the same engine, with low maintenance - essentially, as you suggest, something that would be an ideal Malle Moto machine - which in turn makes even the Dakar look a lot more affordable to enter?

Jx

ps. Final chassis spec is still to be decided, but John & Martin have a lot of experience setting up the 690 for rally racing, and I imagine they would prefer to keep as much of the bike as stock as possible (if only to retain the 'budget' ethos of building it around the 690E/R).

That said, as John alludes to above - we will be race-testing one of these new TracTive shocks on the Tuareg this year, with a view to incorporating it into the Dakar bike spec for April onwards... There is another version which is still in the development stage at the moment, and I'm sure John will be along with more info when they are in a position to release the final spec, but suffice to say, it has a very innovative damping set-up, which could revolutionize dirt-bike suspension!

Hi Matt! - thank you for the vote of confidence!

To be honest, the 450cc conversion is not really designed to be a commercial venture as such - I'm sure Rally Raid will sell a lot more 690 hi-comp pistons they they ever will 450cc conversion kits!

However, as I mention in reply to Ned's comments above, what the 450cc kit does now offer is a serious option for those riders who would like to enter Malle Moto in Dakar (or any other 450cc event) without the almost universal requirement to take a spare engine with you, or to even have to change the oil more than once or twice in an event!

Jx

It will be interesting to see what way they decide to go with the engine to get 450cc seeing there keeping to same size bore.

Great to see guys / girls thinking outside of the box

Good luck Jenny

102x84.5 is 690 specs

so 102 bore with 55 mm stroke is 450 cc

so they will lengthen the rod and drop the wrist pin to make up 30 mm in stroke. It sounds like they are doing mostly rod lengthening because they are going to use the same basic piston as a hi comp 690 piston (close to stock wrist pin location therefore)

This should keep the scrutineers scratching their scalps

Yer that is one way of doing it.

As i said it will be interesting.

Scrutineers should have a capacity checker.

Surely they could sleeve it a little without being too small for the valve layout.
But hey what do we know!

To me, this is where it's getting very interesting for an armchair engineer/noob like me. It's been established that the bore will remain the same (no cylinder change). I think it also means no change to cylinder barrel length, and the piston top comes to the top of the cylinder at the top of the stroke - it sounds like the stroke is the only variable factor.

Can someone:
1) correct me if I'm wrong
2) explain the considerations between changing the connecting rod length and/or changing the length between the crank pin and the centerline of the crank.

Thanks

Greg

I don't think this machine would be eligible for Marathon in any event- looking at an older rulebook but:

When I studied the book in depth, Marathon has become largely irrelevant to anything but the KTM 450RR- you're not allowed to change anything from standard (down to handlebars), meaning there's only one machine that is capable box stock.

I think they've made the category largely irrelevant, but what do I know.

Long rod motors are cool. The longer rod means a longer dwell time, which can really change (and increase) power characteristics. With that said, that's a pretty darn oversquare motor!

One last thought- the Dakar has become increasingly technical in years past, and I think that trend will continue. Do you think the LC4 based machine (with higher weight than a comparable converted enduro bike) will be a disadvantage in that light?

Our initial donor engine is an 08 motor,so 654cc.This is 102mm bore x 80mm stroke.
Our initial attempt is to keep the std bore,and gudgeon(wrist) pin height,then move the crankpin 12,5mm nearer to centre of crank,giving the 25mm reduction in stroke needed to achieve 102 x 55= 450cc
But,because of the reduction of swept volume,we have to "lose"approximately 20cc from the head volume to maintain the same compression.That will be the difficult bit,as we will be running the rally cam,so there will have to be quite a pronounced dome on the piston to up the compression,but still miss the valves.

Onward & upwards..........

Thanks - I couldn't ask for a more informed response. Please keep posting the progress of the build, and the best of luck!

Greg

This is what I love about this place!!!!
We've got JMo going down the bulletproof 450 route, if a little heavy! (Possibly!) (Discuss?)
And then you've got these two threads!
The 'carry a couple of pistons in your pocket' threads!
Great!


http://advrider.com/forums/showthread.php?t=538827

http://advrider.com/forums/showthread.php?t=858840

Just out of interest, what does the stock 690 motor weigh anyway?

A bunch- I've got one in a crate and also have a 450XCW motor sitting next to it. I'd guess the 690 motor is ~20lbs more, although given I don't have a scale and am guesstimating the weight of the crate, that could be complete malarky.

On the flip side, I believe that weight goes to things that count. A 690 will go, as Jenny said, a very long way with no maintenance at all, where a 450XCW really wants its oil changed often to get decent life from the engine.

Curious about FI vs Carb as well!

That was the other option of course, however, when John stripped the engine down, he realised that the difference between the size of the [450cc] bore and the shape of the original head would have such a pronounced lip, the combustion chamber would be all to cock (to use a phrase pioneered by James May)...

Of course technically you could also machine a new head to mate up to the new cylinder bore, but that is getting way beyond what is realistic both time and expense wise - the idea is to produce a kit of parts using the least number of parts required to change - sleeving the stock barrel would be more complicated (and not a DIY job), while a new head as well would just not be cost effective...

As a bit of background to the project - John was actually on his way back home from seeing the start of the Heroes-Legend Rally in Spain last year (he was due to ride, but had broken his wrist a few weeks beforehand so had to drop out), and stopped off at a vintage bike rally in the mountains. By chance he got talking with an American guy called Drino Miller - who as it turns out is head engine tester for Pro Circuit in the US:

http://motocrossactionmag.com/Revie...-We-Take-You-Inside-Pro-Circuits-Su-5959.aspx

As is the way in Spain, they of course got yakking over a bottle (or two) of red wine about the pros and cons of the various ways to build this engine, and it was basically Drino who pointed John in the direction we are now taking...

Today's nerdy photo is of a shiny new con-rod!



As John explains above, the combination of a longer rod and adjusting the position of the crank pin will give the necessary stroke to retain the standard bore/cylinder etc. As he explains,the trick[y bit] will be to create a piston profile that creates enough compression while at the same time misses the valves when they are extended - the 690 Rally cam (which should help boost power) has a longer overlap than the stock cam, so things could be a bit tight in there - hence the prototype build and bench test before we go to production with the final specification...

Jx

Hi Ned - yes, without getting them side by side and on the scales (which we will do in time, just for the number crunchers out there), I reckon you are probably in the ball-park with around 8-10Kgs, which is what we've factored in.

Otherwise though, the total bike itself (that is the rolling chassis and the Evo2 tank & fairing kit) is near as dammit going to be the same as a 450RR, so the weigh penalty is not all that huge.

Regarding the EFi vs Carb debate - when I was chatting to Niles [Follin] at Scuderia last year about the project, he asked a similar question and suggested using carbs as a preference (bloody old-school mechanics!), but John is confident that he has got the EFi dialed-in on the customer 690 rally bikes he builds already, and again, the desire to keep the bike spec as close to stock (not for any reason other than to minimise the variables of changed parts going wrong) means we're planning on running the stock EFi system with a custom map for the 450cc kit.

Obviously there is (or was) a known issue with the 690 fuel pump, but John has various safeguards in place - and if all else fails, fortunately replacing the standard fuel pump (in the rear tank) is not too much a trial with trail tools, if it ever came down to it...

On balance though, there seems to be far more benefits (not least fuel consumption and automatic altitude/temperature adjustment) to retaining the EFi than trying to make to all work with a carb too?

Jx

These are good points Ned!

I ran my WR450F in Marathon in 2010, as I was fortunate that my bike was built around a European spec WR (that comes fully road legal and most importantly, with homologation papers and a specific chassis number designation compared to the Enduro spec bikes you get in the UK and USA), but almost fell foul as I also presented my spare 'just incase' engine for scrutineering, as you have to do... Patsy ended up sweet talking the officials and they let me stay in Marathon, but also scrutineered the second engine*

*Just for info for anyone else reading this thread (as I'm sure Ned is aware), any spare engine/s you may have with you for Dakar need to be scrutineered as well as the main bike - presumably in an effort to stop people changing out a 450 EXC lump for a 530 engine for example (or a bigger bored version of any other brand).

I think you are probably right that the scrutineers may consider this bike is too far removed from a stock or homologated machine - although that said, the chassis and engine numbers will correspond to the paperwork, so technically it might be eligible - the wheels, brakes, swing arm, forks and exhaust will all be stock (or manufacturer options - we intend to run an Akrapovic end can for example), and you are of course allowed to add tanks and a fairing...

Ultimately though, it is not so much the [Marathon] class as the principle we are trying to follow here - as Doyle says above, the Dakar is continually evolving, with lighter machines and more technical terrain (although to listen to Lyndon's final thoughts video from this year, he said he was [pleasantly] surprised that the stages were not as technical as he had feared), and certainly at the sharp end, it has become essentially a two week series of daily sprints - with a total overall every night, so the bikes are essentially as new again.

As I said in my introduction to this thread, as each year goes buy, the Dakar gets more and more expensive for the privateer to enter, or at least to be competitive. However, to start considering an engine as a 'consumable' still goes against the grain for me, and for many people [outside of a professional racing team] I suspect?

This project is really about retaining a degree of [financial] realism for the privateer rider who wants to use their participation in the Dakar not so much as a race against the other competitors, but more a personal journey of endurance against the Dakar itself...

Jx