CRF based Rally Bike Help

[doyle]

So I know a guy....

Actually Chavo asked me to inquire the minds about either A) putting a carb'd (pre-2009) CRF450R motor in his Team Honda Europe 450X rally bike or B) Adapting the tanks, nav, etc.. from the CRF450X onto a CRF450R.

Anyone familiar enough with the specifics of the motors?

Some drawbacks of the R for rally would be the closer gearing, perhaps too close for the long hours and longer liaisons? Also as far as I know, there is no electric start on the R's, correct? The R is also a higher compression, could lead to detonation problems at altitude and heat, perhaps?

His major mechanical problems in Dakar were mostly stator related. He had a few let him down and is looking from some assurances from Team Honda Europe that they can correct the problem but Chavo is looking to flush out some ideas and asked me to gather the wisdom of the collective. I pondered putting this in Thumpers, but the intent is more rally related so I wanted to keep that perspective on the overall discussion.

Thoughts anyone?

[xr400r]

i am quite sure that the r has a closer ratio transmission than the x. how that would be for rally biking i dont know.

[schattat]

I have heard of many cases where the stock stator of the Honda 450X has failed, I believe the Honda Europe bikes had the Trailetech DC upgrades. Not 100% sure, but I believe a newly made wiring loom is the best solution ot cope with the upgrade. I did that on my WR450F, prior to the stator upgrade, also a Trailtech, there were somethings I wasn't happy about. E.g. the small stock ignition switch would also pass the current that was required for the headlight, so several amps went through the mini on/off switch. Just my 2cents.

Tell him he can get in touch with me, I can sort something out together with him and Henk from Honda!

[Strong Bad]

Many of the D-37 desert racers use the CRFX as a base. Having done it myself allow me to add a couple of things:

The R does not have the magic E button.

The R close ratio gear box is too close for desert usage (and assuming Rally Raid).

Many guys use R cams in the X head and there are different tuned cams that come on different years X & R.

Not uncommon for guys to swap the X head for the R head.

The R uses a 19" rear wheel, the X uses a 18".

Not sure about the newer bikes in the last couple of years, but the at one time the X had larger radiators.

I know that you can't directly fit an R pipe onto a X, how much of that is due to the different shrouds, tank size, or if the mounts on the frames are different or what.

If it was me I would start with the X, and I'm pretty sure that what JCR starts with for their Baja bikes.

[doyle]

Thanks guys, all great stuff and I think just what Chavo is looking for.

[doyle]

Juan Carlos had two main frustrations, the stator, and the fact that he'd push in the technical sections only to get onto some open ground and have the other bikes blow passed. He was topped out at 158kph. He'd like to be up pushing 180 as some of the other bikes are.

[Yellow Pig]

Wow, those are crazy speeds for a 450cc bike.

[Mudguts]

Some of the limitation of using the small 450 mx base engines are the gear box ratio's if you have $$$$
You and get custom gears made . No doubt some of the big dollar teams would have done this ,
Or hybrid MX / Enduro gear box .

[schattat]

Originally Posted by Mudguts

Or hybrid MX / Enduro gear box .

Yep, the factory Yamaha 450s had/have that, some gears from various bikes, 250, 426, 450, ro make a Frankenstein Setup!

[Blur]

I may be getting the 250X and 450X problems mixed up but....from what I understand, you probably want to swap out the valves also. Stock valves don't like long, sustained high rpm. I've heard good things about aftermarket stainless steel valves.

Thumpertalk would be a good resource: http://www.thumpertalk.com/forum/80-crf450x/

[Aussie66]

To be in the top 20 you need a fast bike, to finish you need a reliable bike, strangely enough those two things dont go together too well. The KTM is probably at the moment the more reliable pro rally bike. And the top KTM guys are already calling it an old bike because its heavier than rest of the pack.

We, the followers look at a rally bike and think reliability (more from days gone past), The factory boys need an engine that will last 7 days. A 7 day engine = an enduro engine. Thas what the rally has essentially become.

As an amateur I think the route Jmo Piglet has taken is the route for the amateur. Absolute reliability. Time to dust off a 690RR.

180 km/hr out of a 450X and make it last??? One can only hope.

[rmhrc628]

Originally Posted by doyle

So I know a guy....

Actually Chavo asked me to inquire the minds about either A) putting a carb'd (pre-2009) CRF450R motor in his Team Honda Europe 450X rally bike or B) Adapting the tanks, nav, etc.. from the CRF450X onto a CRF450R.

Anyone familiar enough with the specifics of the motors?

Some drawbacks of the R for rally would be the closer gearing, perhaps too close for the long hours and longer liaisons? Also as far as I know, there is no electric start on the R's, correct? The R is also a higher compression, could lead to detonation problems at altitude and heat, perhaps?

His major mechanical problems in Dakar were mostly stator related. He had a few let him down and is looking from some assurances from Team Honda Europe that they can correct the problem but Chavo is looking to flush out some ideas and asked me to gather the wisdom of the collective. I pondered putting this in Thumpers, but the intent is more rally related so I wanted to keep that perspective on the overall discussion.

Thoughts anyone?

You need to r ify the x motor. I spent $5000 doing that.

Change the head, carb and valves over to r model parts. Radiators. Porting. Open the air box.

You need to keep the x base.

Switch the r model swing arm in too.


Why was the yzf so good - presumably it's gearbox is very tight like the CRF r model? They did fantastic in Dakar 2013.

[doyle]

Juan Carlos will chime in here tomorrow. For this Dakar, he did use the standard battery but still had stator problems. He's been reading through and really appreciates the information.

[rmhrc628]

Is he running genuine rewound stator or aftermarket ?

[Luke]

Originally Posted by doyle

Juan Carlos will chime in here tomorrow. For this Dakar, he did use the standard battery but still had stator problems. He's been reading through and really appreciates the information.

If you could be more specific about 'stator problems' and post up a wiring diagram of the bike (or at least of the stator part) and some details on the stator/regulator/battery/etc that'd be helpful.