WE RIDE A BIG-BORE HONDA CRF469 PROJECT BIKE:

October 22, 2009
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You’re gonna want to read this bike test. This is a story of a project bike that got out of hand. A bike that should have been awesome, and, in fact, had lots of awesome attributes, but turned out to be just average. If only we’d been smart enough to unload the gun before shooting ourselves in the foot.

Read it and weep, because the MXA wrecking crew can promise you that we are?weeping, that is.

SHOP TALK: DISCUSSING THE COMPONENTS

The cylinder on our Honda CRF450 was bored and re-plated to 98mm to increase displacement to 469cc?Millennium took care of the bore and re-plate, while CP Pistons supplied the 13.5:1 forged racing piston.

This engine kit shows that much potential lies inside the 2009 CRF450 engine. As a rule of thumb, bigger almost always means better when it comes to 450cc motocross engines. Need proof? The Athena CRF488 kit was the king of the Honda roost back in 2006 and 2007. The KTM 505 powerplant is much better than the 450SXF engine (and it is only a 470 kit). Our Husqvarna TC510 produces the kind of power that the Husky TC450 can only dream of. And the story of awesome big-bore engine goes on and on.

Amazingly enough, big-bore engines, like our Millennium Honda CRF469, have better throttle response, more torque and the revs are metered out at a very usable rate. That combination results in a bike that accelerates harder out of turns, pulls taller gears and stays on longer down straights. Making the CRF450 into a CRF469 was a win-win engine kit?or at least it should have been.

Before we spent beaucoup bucks flow porting or camming our CRF450, we went big. Bigger is better. Of course, in our case, we not only went 2mm larger on the bore, but had major head work done to increase flow. Along with that, we added in Tokyo Mods valves, valve seats and guides. The new guides were installed and honed to a tighter tolerance than stock. This, along with the better valve seat material and lightweight titanium valves, helped ensure that valve flutter was kept to a minimum.

IT WAS EVERYTHING WE EXPECTED A BIG-BORE BIKE TO FEEL LIKE. THANKS TO THE EXTRA TORQUE, IT COULD BE SHORT-SHIFTED AND LUGGED THROUGH CORNERS A GEAR HIGHER. THIS ALLOWED THE TEST RIDERS TO PULL THE TRIGGER WHENEVER THEY FELT LIKE IT, BECAUSE THE FEAR OF WHEELIES AND WHEEL SPIN WAS GREATLY REDUCED BY THE VERY EFFECTIVE GEAR RATIOS.

The stock exhaust system, which we know from extensive testing is the biggest hang-up in developing competitive power out of the 2009 Honda CRF450, was replaced with a very powerful FMF Factory 4.1 system with a MegaBomb header.

Once we upped the torque we had to do something about the stock, four-spring CRF450 clutch. We went Hinson all the way.

The EFI ignition mapping was slightly changed from the standard-bore CRF450 setting. Fewer changes were made on the bottom end of the curve, with more significant changes in the middle and top areas of the map. Another noteworthy change was the trimming of the rear side panel air inlet snorkels. They were cut 10mm shorter, allowing more air into the air box for increased throttle response.

TEST RIDE: HOLD ON AND PRAY

How did it run? It was everything we expected a big-bore bike to feel like. Thanks to the extra torque, it could be short-shifted and lugged through corners a gear higher. This allowed the test riders to pull the trigger whenever they felt like it, because the fear of wheelies and wheel spin was greatly reduced by the very effective gear ratios. All that said, we thought that it could have run better if the compression had been reduced slightly to allow for less grunt off the bottom (where it had beaucoup beans) and a little more free-rev on top. Virtually every test rider raved about the grunt off idle and complained about decompression braking and lack of over-rev. This is common on big-bore engines that are too hotted-up. In our opinion, less compression would stop the CRF469 from chugging up and chugging down.


Every test rider wanted more power higher into the rpm range?exactly what they wished for on the stock CRF450. While the extra torque made the CRF469 easier to ride, more power higher up would have made it unbeatable. That doesn’t mean we didn’t like the setup, just that we went way too far in hot-rodding the engine. It could have been better, and every MXA test rider knew it?once it was too late.

IF WE STARTED OVER, WE’D PROBABLY SKIP THE TOKYO MODS VALVES (WE JUST AREN’T WORRIED ABOUT VALVE FLUTTER ON AN ENGINE THAT DOESN’T REV HIGH ENOUGH TO GET THE VALVES FLUSTERED), GO WITH A 12.5:1 PISTON, KEEP THE PORTED HEAD AND LEAVE THE IGNITION STOCK.

If we started over, we’d probably skip the Tokyo Mods valves (we just aren’t worried about valve flutter on an engine that doesn’t rev high enough to get the valves flustered), go with a 12.5:1 piston (instead of the high-compression version), keep the ported head and leave the ignition stock (or at the very most go for the low-rpm/minimal-throttle-opening ignition setting that is the most popular with CRF450 owners).

WHAT ABOUT THE SUSPENSION? WE WERE VERY SMART ABOUT THE SUSPENSION ON OUR HONDA CRF469 PROJECT BIKE. INSTEAD OF JUST HAVING FACTORY CONNECTION DO THE SUSPENSION, WE SPENT A DAY TESTING WITH THEM BEFORE WE BUILT THE BIKE (AND WE RODE KYLE LEWIS’ FACTORY CONNECTION-EQUIPPED AMA NATIONAL BIKE, JUST TO MAKE SURE).

What about the suspension? We were very smart about the suspension on our Honda CRF469 project bike. Instead of just having Factory Connection do the suspension, we spent a day testing with them before we built the bike (and we rode Kyle Lewis’ Factory Connection-equipped AMA National bike, just to make sure). After trying out their proposed settings, we made a few suggestions about what we thought would work better and then had the setup put on the Honda CRF469 when it was done. It was a smart move, not just for us, but for Factory Connection. It gave them something to work from, and it gave us a head start on the setup.

Stock Honda suspension is a mishmash of bad ideas. The front end rides too low, and the rear rides too high. Our suggestion, and Factory Connection’s solution, was to install stiffer springs in the front and a slightly softer spring in the rear. In the forks, Factory Connection went lighter on the pressure springs for improved ride on small bumps and square-edge hits. They also added their Works Oil Lock Collars for better bottoming control in the bottom three inches of travel.

In the rear, they used the valving to get more compliance over the stock setup. Also, to get the rear to be balanced, Factory Connection runs a longer link to drop the ride height. This longer shock linkage dramatically lessens rear-end kicking and swapping.

Additionally, MXA had Factory Connection add on their Works Team Remote Reservoir to increase the nitrogen volume, which provides a plusher ride as the nitrogen pressure builds up.

As for the handling, we have never really come to terms with the loose feeling in the Honda’s front end. In stock trim, we blamed it on excessive dive and too steep of a head angle. But once we lowered the rear, kicked out the front and balanced out the suspension, the CRF469 still hunted and pecked over every ripple and ridge on the track. This is a bike that requires constant attention at the bars. Lots of riders are trying 22mm or 24mm offset triple clamps to calm the chassis down, but we tested them and didn’t feel that they offered significant improvements over stock. Yes they felt different in one aspect of cornering, but since we divide turns into three parts (turn-in, center-out and exit), changing one part of the corner isn’t always worth the trouble. The different offsets just made the CRF seesaw in a different part of the corner. Thus, we stuck with the stock 20mm triple clamps (adding only Applied big bar mounts to accept our Renthal 997 TwinWall bars).

In the accessory department, we added parts from a few of our favorite suppliers: perches, levers, a skid plate and guards from Works Connection; a 270mm QTM front brake (awesome stopping power), Renthal TwinWalls, grips, sprockets and chain; FLU Designs MXA graphics; CV4 silicone coolant hoses; Dunlop MX51 tires (we would have preferred 756s, but they are getting hard to come by); and no trick bike would be complete without TCR wheels (the only wheels that are lighter than stock Honda wheels).

CONCLUSION: WHAT DO WE REALLY THINK?

We blew it! We think that if we started over we could do it better. This was a case of not knowing when enough was enough. We jokingly say that “we tuned this bike to a standstill.” That isn’t completely true. It ran impressively, produced tons of torque and was a blast to race. It just could have been so much more if only we had done a little bit less. 

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