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Old 04-20-2014, 03:21 PM   #416
JMo (& piglet) OP
Dakar Dazed
 
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Joined: Apr 2007
Location: Somewhere west of Laramie...
Oddometer: 3,265
OK everyone, a quick wrap up of this thread, in preparation for part 2 of the Dakar Dazed II project - actually getting out and racing the LC4-50!

So John and Martin went back to DWR on Friday, and it was indeed a 'Good Friday' (see what I did there?)...

While in Tunisia we had speculated what might have been the cause of the rough running at certain RPM (albeit while running a guest-imate fuel map built on the fly by Martin Wittering of Torque Racing).

Turns out that fitted with the open airbox lid and free-flow filter that works so well to uncork the stock 690 capacity - the LC4-50 was indeed getting simply too much air for the reduced 450cc capacity to ingest properly, even with a piston profile that closely replicates the draw and velocity of the 690cc version - and it was effectively choking itself on too much air and fuel...

So John elected to fit a stock 690 airbox (and filter) just to see the difference, and sure enough, the result was an instant 1.5hp gain!

A little more tweaking of the fueling, together with fitting the alternative DEP silencer (without a spark arrestor fitted), and the ultimate power and torque figures are below:



Just shy of 50bhp from 450cc! - together with another couple of lb/ft torque from the dyno session last week! - interestingly you can see the effect of the reduced airbox, that the max power and torque is more, and at around 500rpm lower than last week...

With the step in the curve smoothed out too, we now have a very strong engine, with a broad and level torque curve, coupled with some very credible top end power as and when it's required!

Excellent result and top marks to all concerned - John Mitchinson (Rally Raid Products), Martin Wittering (Torque Racing) and Dave Woods (DWR Racing).


With the engine and fueling finally sorted, it was time for John to swap a few bits around prior to the first real endurance test - yep, not only will I be racing the LC4-50 at the Hellas Rally next month, but I shall be riding it all the way from the RRP HQ in the UK, via Austria and Italy to Greece - before racing the Hellas (I'm #155 btw.), then riding it all the way home again!

The intention is to prove it's ultimate reliability, and illustrate that we have finally achieved what we set out to do 18 months ago - which was to create effectively the 'ultimate privateer rally bike' - something you can realistically ride to an event, compete on, and ride home - with minimal preparation and servicing throughout...

SMC wheels fitted for the run down through Europe... just for the hell of it really!


John out testing a new headlight set-up at the weekend:



So to coincide with my visit to Rally Raid Products on Tuesday this week for final prep prior to my departure next weekend, I'll be starting a brand new Dakar Dazed thread here on ADVrider - featuring regular updates as we ramp up towards the Hellas Rally and beyond... then soon after we hope to be able to announce the 2-bike Dakar team for 2015.

Thank you all for staying with us on the journey so far, and welcome at last, to chapter two!

Jenny xx

JMo (& piglet) screwed with this post 04-21-2014 at 01:05 AM
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