October 28, 2010
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You are forgiven if you are a Honda CRF450, Kawasaki KX450F or KTM 450SXF owner and you don’t give a twit about hopped-up Yamaha YZ450Fs. You may be thinking, “Yamaha? I don’t own a Yamaha and don’t want to read about them.” But, you know deep down inside your insecure heart that you do want to know everything there is to know about the 2010 Yamaha YZ450F. Why? Because that is your competition.

The YZ450F was all-new in 2010, and every racer, on every brand, has to wonder if the YZ450F’s backwards cylinder, offset crankshaft, tilted top-end, downdraft fuel injection and creative frame offer a significant advantage over his trusty, but rusty, race bike.

In the 2010 MXA 450 Shootout, the Yamaha YZ450F finished second overall (behind the KTM, but in front of the CRF and KX-F). The MXA wrecking crews thinks that the Yamaha YZ450F is a solid machine with innovative credentials. It has a typically abrupt, low-to-mid, fuel-injected powerband; is relatively flat on top; and does not come near the horsepower output of the KX450F or 450SXF. As for the handling, the YZ450F feels light in roll, pitch and yaw, but since it is heavier than the 2009 YZ450F, some of the benefits brought on by centralization of mass are muted. The front end has a no-bite feel on the entrance to turns, but overall it handles decently. All in all, the 2010 Yamaha YZ450F is a good motocross bike?not a great one, though, because it needs more power, improved top end and a sleeker layout.

To that end, the MXA wrecking crew ordered up four full-race, hopped-up 2010 YZ450F project bikes. We told Hot Cams, AP Racing, Yoshimura and Pro Circuit that there were no holds barred?choke holds, arm bars and knee drops were allowed. They were asked to build the ultimate expression of what a YZ450F could be.

What follows is what the MXA test riders thought about the four YZs.…this is a test of one of them (the rest will follow)?Larry Ward’s Yoshimura YZ450F.



Here are the details, prices and parts used on Yoshimura’s 2010 Yamaha YZ450F:

1. Yoshimura Stage 1 cylinder head modification, port and polish ($675.00).
2. Yoshimura ISF Process transmission treatment ($230.00).
3. Yoshimura PIM-2 (Peripheral Interface Module) fuel-injection tool ($399.00).
4. Yoshimura data box ($429.00).
5. Hinson clutch cover ($159.99), pressure plate ($189.99), inner hub ($309.99), basket ($269.99), FSC kit ($199.99).
6. CP Pistons 13.5:1 piston ($250.00).

1. Yoshimura Pro Series RS4 titanium/carbon fiber system ($1045.00).

1. Noleen J6 fork and shock revalve ($375.00).


1. Yoshimura case saver ($24.95).
2. Yoshimura brake clevis ($44.95).
3. CV4 radiator hose kit ($195.90).
4. Pro Taper Contour Windham bend handlebars ($89.95).
5. Pro Taper half-waffle grips ($14.95).
6. Dunlop Geomax MX51 front and rear tire.
7. Tag Metals rear sprocket ($69.99).
8. D.I.D. 520 size chain.
9. Braking 270mm Batfly front rotor kit ($356.40).
10. Twin Air double-wall air filter.
11. Works Connection skid plate ($69.95).
12. Works Connection Elite clutch perch ($139.95).
13. Lime Nine Grafixs graphics.
14. SDG seat cover.
15. Maxima engine oil.

Yoshimura: www.yoshimura-rd.com or (800) 634-9166.
Noleen J6: www.noleenj6.com or (760) 955-8757.
Hinson Clutch Components: www.hinsonracing.com or (909) 946-2942.
Works Connection: www.worksconnection.com or (800) 349-1475.
CP Pistons: www.cp-carrillo.com or (949) 567-9000.
CV4 Products: www.cv4.net or (336) 472-2242.
Maxima: www.maximausa.com or (800) 345-8761.
Pro Taper: www.protaper.com or (951) 736-5369.
Tag Metals: www.tagmetalsracing.com.
Twin Air: www.twinairusa.com or (800) 749-2890.
D.I.D. Chains: www.didchain.com or (615) 323-4020.
Braking: www.brakingusa.com.
Dunlop: www.dunlopmotorcycle.com.
Lime Nine Grafixs: www.limenine.com or (888) 546-3969.
SDG: www.sdgusa.com or (949) 752-5227.


Yoshimura thrives in the street bike exhaust system market, particularly on sport bikes like the Yamaha YZF-R1 and Honda CBR600RR. So it comes as no surprise that the Japanese-born company’s craftsmanship transcends street bikes, with technological advancements carried over to the motocross market.

The MXA wrecking crew has worked with Yoshimura on many projects, from exhaust pipe tests to engine work to complete bike builds. Their workmanship is second-to-none, which is why we are confident in expressing our excitement for any Yoshimura-built product. After the dust settled on our seven-pipe 2010 Yamaha YZ450F shootout in the July 2010 issue of MXA, the Yoshimura exhaust emerged victorious. The pipe produced the most horsepower and was favored by nearly every skill level racer. Yoshimura does great work.

When Yoshimura dreamed up a 2010 YZ450F bike build, we were all ears. Our interest piqued when the boys at Yosh decided to build a retro-style bike, mirroring Larry Ward’s 1995 Noleen/Sizzler YZ250. The fact that Yoshimura flew Ward out to SoCal from his home in South Carolina for the bike test was icing on the cake.

Larry Ward and cool retro graphics aside, Yoshimura’s race-spec YZ450F wasn’t a puff piece. Yosh invested beaucoup d’argent into their project bike. They ported and polished the cylinder head and utilized a CP Pistons 13.5:1 piston. As for the transmission, Yoshimura used their ISF (Isotropic Surface Finishing) process to remove any surface asperities found in the YZ450F’s machining process. The end result is a transmission that has reduced friction and increased lubrication capability.

It should go without saying that Yoshimura outfitted the YZ450F with their Pro Series RS4 titanium/carbon fiber exhaust system. Attached to the headpipe was a data box (through a sensor) to read air/fuel mixture. It works in conjunction with their PIM2 unit to allow for self-mapping. We were able to plug-and-play into the PIM2 unit to target various areas of the air/fuel ratio. Very cool.

Specializing in engine, exhaust and hard parts, Yoshimura doesn’t focus on suspension modifications. That’s where Noleen J6 came in. Noleen’s Clark Jones owned the company and ran the highly successful race team in 1995 when Larry Ward finished second overall in the Supercross series to Jeremy McGrath. In 1996, Jones sold the company to ski company K2, and then in 2002 Clark restarted Noleen with the modified name of Noleen J6 Technologies. Today, Jones is still tweaking and advancing the performance of stock suspension. For Yoshimura’s Larry Ward YZ450F bike build, it was only fitting that Noleen J6’s Clark Jones be involved. He was in charge of revalving the forks and shock.

“The engine had decent hit off the bottom, similar to what the stock YZ450F is known for. The Yosh engine pulls hard through the mid-range, and from half throttle until wide open the bike screams!”

“What’s best about this engine is that the harder you push and the faster you want to go, the engine will be right there with you. Often, especially with a YZ450F, the engine falls off drastically once it peaks out in the mid-range. That’s not the case with the Yoshimura engine. If you want to go faster, be brave and hold on to your britches.”

“I absolutely loved the oversized Braking Batfly front rotor. The stock Yamaha brake isn’t very powerful or progressive feeling. The Braking unit is exactly the opposite. I could go deeper into corners and stop on a flea if I needed to. Yes, it was that good.”

“It’s hard for an aftermarket company to vastly improve the suspension on the Kayaba-mounted YZ450F. Yet somehow, Noleen J6’s Clark Jones made something great even better. He zeroed in on my skill level and weight, then revalved the Kayaba units to near perfection. I’d love to see what he can do with less-than-stellar suspension!”

“Being on the heavier and faster side, I found that the too-soft stock SSS forks were still too soft after Noleen J6 got done with them. However, the valving was pretty close. The forks soaked up everything, from small chatter to massive G-outs, with relative ease. If I were to keep racing this bike, I would want stiffer fork springs.”

“One of the biggest handling advantages is a longer shock linkage arm. The Yoshimura bike didn’t have one. The bike wasn’t as balanced as the Pro Circuit YZ450F, and it didn’t corner as well. I would love to see how the Yosh bike would handle with a Pro Circuit link.”

“You can’t go wrong with a complete Hinson clutch. The clutch didn’t fade through my incessant abuse, nor did it chatter and burn out. I ride with greater confidence knowing that a complete Hinson clutch is in the bike.”  

“The strangest thing about the Yoshimura bike was that Larry Ward cut about two inches of the clutch side grip flange off so that he could keep his left thumb straight. Since Larry broke his thumb twice, he can’t bend it very well. Guess what? My thumb works fine. A fully flanged grip would have been more comfortable.”

“Overall, I really liked the powerband on the Pro Circuit YZ450F (tested at the same time…and set to run here soon) because it was smooth, quick-revving and flexible, but I think that the Yoshimura engine trumps it. The Yosh powerband is stronger and pulls longer than any other engine in this test. I loved it.”


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