Burris Racing / Yamaha YF200 R1 Updates / Yamaha YF200 Updates

Lite Rod for the YF200

Burris Tech Info — Thu, 06 Mar 2008 17:30:24 GMT

Please note that all YF200 engines shipped after 2/1/08 will feature our new #6257 Lite Rod included in the kit. This replaces the #6259 "Beefy" model and is 25 grams lighter (almost 20%!) and features 8 oiling slots (4 on each side) on the big end thrust cheeks.
Test have shown the new "Lite" rod to reduce stresses (which increases reliability) on the crank and rod bolts in high extended RPM situations and the oiling slots provide for better oil flow to the crank pin under these conditions as well.
The new "Lite" rods are now available through your local Burris dealer and carry the part number F21-201-01.

Gen lll Valve Kit Available

Burris Tech Info — Sun, 23 Dec 2007 17:48:41 GMT

New YF200 Gen lll Stainless Valve Kit Update!

(Pt# F21-415-15)

We are pleased to announce the release of our new “Gen lll” XR stainless valve kit for the Yamaha YF200. The main difference from the Gen ll kit is the changing of the intake valve from the long time 26mm diameter to the (10% larger) 27.3mm, which is the maximum allowed for F200. The new valve is part # F21-402-25 and is made in the U.S. of the high quality forged stainless steel on CNC machines to exacting tolerances and feature hard chrome plated 5.5 mm stems and hardened tips to insure long life and performance. Both intakes and exhaust valves now have the popular Pro Flow stem relief for better low lift flow and are machined for 7 degree radiused locks. The Gen lll upgrades also carry over the tried and true features of the Gen ll kit which include longer valve stems to allow for more clearance between the guide and retainer at full lift and relocated lock grooves that reposition the retainer and gives about 10% more seat and full open spring pressure. The Gen lll spring retainers are made from hard anodized Teflon coated aluminum which reduces the acceleration/inertia loads on the valve train and also allows for more rpm’s without valve float. In addition to the new valves the kit includes longer tubular chromoly push rods to correct the rocker arm geometry from the longer valves which in turn allows the valve to open closer to the .275” maximum lift than in the earlier Gen l kits.

The Gen lll kits contain 2 ea of the following items; valves, retainers, locks, wear caps, tubular push rods, valve springs, valve spring shims and rocker stud spacer washers as well as a step by step installation guide.

Header Brace for the YF Yamaha

Burris Tech Info — Thu, 27 Sep 2007 12:03:19 GMT

Although it is technically not an upgrade we have a photo here of a header brace that RLV has just came out with and feel that it is something everyone should want to consider installing regardless of you application. It was originally designed to support the header from the heavy weight of a silencer we were required to run at a track here in So Cal but we soon found that regardless of the application it all but eliminated the header loosening up or worse yet having a stud pull out. They will be included (along with a clamp) in all future RLV YF exhaust systems that we ship to our customers. The brace is also available as a stand alone item for those who already have anRLV system.

New YF200 Piston Oversizes

Burris Tech Info — Fri, 08 Sep 2006 14:35:22 GMT

Three additional piston oversizes are now available for the Yamaha YF200. With the standard bore at 71.00mm you have a choice of sizes ranging from 71.05mm thru 71.25mm in .05mm (.002”) increments. By having pistons in these small steps you can go to the next size by simply honing a small amount of material out of the bore versus the traditional (and time consuming) method of boring and honing that other brands of engines require. This approach makes the YF a lot more user friendly and easier to keep in top shape.

The kits come complete as shown with piston, rings, wrist pin and circlips. The recommended skirt clearance is .0035”/.0055” and the rings come with an installation and end gap instruction sheet.

Gen ll Stainless Valve Kit

Burris Tech Info — Mon, 21 Aug 2006 16:36:52 GMT

Burris is pleased to announce the release of our new updated “Gen ll” XR stainless valve kit for the Yamaha YF200. Made in the U.S. of the high quality forged stainless steel on CNC machines to exacting tolerances and feature hard chrome plated 5.5 mm stems and hardened tips to insure long life and performance. The 26mm intakes are swirl polished (our experience has shown this size is adequate for current F200 applications) and the 24mm exhaust has a race flow stem relief for better flow and machined for 7 degree radiused locks. The Gen ll upgrades include longer valve stems to allow for more clearance between the guide and retainer at full lift and relocated lock grooves that reposition the retainer to give about 10% more seat and full open spring pressure without the use of shims. (For added insurance the kit comes with hardened steel wear caps for the stem tips.) The kit now includes the tried and proven XR valve springs to compliment the new Gen ll spring retainers which are now made from hard anodized, Teflon coated aluminum (versus chromoly for the Gen l). The lighter weight reduces the acceleration/inertia loads on the valve train and also allows for more rpm’s (approx. 300/400) without valve float. To compliment the longer valves, longer chromoly tubular push rods are supplied to correct the rocker arm geometry which in turn allows the valve to open closer to the .275” maximum lift than with the Gen l kit.

The Gen ll kits contain 2 ea of the following; valves, valve springs, retainers, locks, push rods, wear caps, spring shims and rocker stud spacer washers.

The new kit is a “bolt in” and only requires a slight resizing of the guides. No other machine work required!

Pt # F21-415-10

Fuel Pump Mounting Bracket

Burris Tech Info — Sun, 20 Aug 2006 23:21:50 GMT

Pictured below is our mounting kit for the Mikuni DF44 pump to the YF200 Yamaha block. The kit includes all necessary brackets, hardware and instructions can be installed in a matter of minutes.

The part number is F21-508-00

Side Cover Stud Update

Burris Tech Info — Sun, 20 Aug 2006 22:57:11 GMT

During the upgrade of the side cover gasket we decided to go all out and make that area of the block and side cover “bullet proof” with the addition of new 8mm 4340 chromoly heat treated and rolled thread studs by A1 Technologies (http://www.a1technologies.com ). A1 is the same company that makes specialty threaded products for many of the top NASCAR, IRL and NHRA teams so the improvement to the final product is no surprise that they ended up being an amazing 35% stronger than our previous chromoly studs. Testing with the combination of the new Aramid fiber gasket and A1 studs over the last three months has been very successful and not a single incident of stud breakage or losing tension has been reported. Other problems in that area have also ceased!

It's definitely overkill, but so is the YF!

(The recommended torque for the new studs is 240 in/lbs using a good grade of thread lube.)

Side Cover Gasket Update

Burris Tech Info — Thu, 15 Jun 2006 23:50:00 GMT

For the last year or so there have been some isolated reports of side cover stud breakage. The problem was confined to the stud closest to the camshaft at about 3 o’clock when viewing the engine from the clutch side. Usually if a stud were to break this would be the first one and if it went unnoticed for very long then the two adjoining studs above and below it break which in turn lets the oil escape and leads to more serious engine damage. Since this was a random problem it was difficult to pin point the source of the trouble at first but after going over all the components involved and studying the type of failure they were experiencing we have come to the conclusion that the side cover gasket is the culprit. Several things contribute to the failure of the stud but the main cause is the gasket is letting the joint in that area “squirm” which is flexing the stud from side to side and eventually causing it to fail from fatigue. Since the original gasket had a thin rubber coating (and rubber doesn’t compress), if the load frequency gets too high and/or lubricants with additives that can soften rubber get on the gasket it allows a minute amount of movement between the block and side cover that eventually lead to the stud having fatigue failure. After several months of testing our supplier Cometic came up with a gasket made of an Aramid (Kevlar) fiber material that has shown great promise and so far no stud failures! The new material is highly compressed and is best known for its ability to resist “shear creep” between the mating parts. While testing the material we also tried it on the gasket between the manifold and head which in turn made that joint solid and stable and should help stabilize the manifold flange at that point. These gaskets are now available to all of our distributors and are also included in all engine shipments starting on June 10^th. If you have any questions you can contact us at yf200@burrisracing.com .

Revised YF200 Intake Manifold

Burris Tech Info — Sun, 11 Dec 2005 23:42:03 GMT

YF Connecting Rod Upgrade

Burris Tech Info — Tue, 06 Dec 2005 14:53:17 GMT

Burris and ARC have a new "Heavy Duty" connecting rod available for the YF200 Yamaha engine and it will be included in all engine kits shipped after 11/18/05. While we didn’t experience any problems with the #6260 model, there were several failures brought to our attention and after close examination we felt that either excessive sustained rpm’s, longer than normal maintenance intervals orimproper rod bolt torqueing were factors. Wanting only the best possible for our customers, Burris and ARC got together and went over these issues and came up with a new “Heavy Duty” rod that will add a much larger margin of safety. As you will notice in the photos the new #6259 rod (Burris Pt # F21-201-01) has returned to a more conventional cap bolting arrangement and strengthened the area that makes the transition from the big end to the beam. They also eliminated the “forced” oiling through the dipper and added two oil access holes in the beam area and one in the cap. All in all we feel these updates make an already good product better.

The next time your engine is scheduled for a rebuild or “freshen up” we highly recommend upgrading to the new #6259 rod, its good insurance!

YF200 Tubular Pushrods

Burris Tech Info — Tue, 06 Dec 2005 11:39:19 GMT

New XR Valve Springs

Burris Tech Info — Wed, 04 May 2005 08:39:21 GMT

New XR YF200 Valve Springs

Burris now has replacement valve springs for the Yamaha YF200 R1. They are made by the same company whose valve springs are the choice of most top NASCAR and NHRA engine builders. These are made from heat treated, x-rayed and shot peened alloy steel wire and have much higher duty cycle life than other after market or OEM springs. In addition to their longer life they are progressively wound which allows for low seat pressures and higher open pressures (approx 15%) than symmetrically wound springs and also the progressive springs reduces destructive high rpm valve spring harmonics as well.

The main advantages over the OEM springs are longer service life and increased valve train stability at high rpm’s in unrestricted engines while giving longer life in the lower rpm restricted engines.

OEM Red Exhaust Spring Pt#F21-405-00

XR Orange Exhaust Spring Pt# F21-405-10

OEM Blue Intake Spring Pt# F21-405-01

XR White Intake Spring Pt# F21-405-11

8mm Solid Side Cover Dowels

Burris Tech Info — Wed, 30 Mar 2005 19:31:22 GMT

The early 8 mm hollow side cover dowels need to be replaced with the new solid type (Burris part # F21-106-00) at your earliest convenience. In most cases the hollow dowels are adequate but under certain circumstances such as extended high rpm running, the hollow dowels flex causing the side cover studs to loosen or break. The solid dowels eliminate this. Another suggestion is when servicing the engine be sure that the gasket and mating surfaces are clean and free of oil since this will aid in reducing movement at that juncture.

Note that we are also working on a side cover stud kit that will enable them to be torqued to a higher setting which will add to the safety margin of the solid dowel. Stay tuned for that announcement. Contact Burris Tech at techinfo@burrisracing.com