what to do with a WR400

I have a new old stock wr400 which I would like to build into a road special. Has anybody fitted cast wheels, a full lighting system and changed the body and seat panels? What is best for the engine? My Japan contact told me to junk the carb and use a Keihein flat slide but what size?

Cost is not a problem as I have some funds tucked away from the wife. Another problem is that the bike is set with 14 inches of ground clearance; the norm on a road bike is about 8 inches. How do I cut it down to size?

Send me a PM with your email address and I will send you something.

Are you in UK? If so, tell me where as we may be local to each other.

I can give you tips on cast wheels, brakes, wiring etc.

Thank you for your offer of help.

My name is Mike and I am in Barking, Essex. My email address is: info@newton-equipment.com

Our business involves the manufacture of fuel tank filler caps for many types of vehicles. You can see some of what we do on


A small part of our business is making motorcycle parts for export to Japan. Back in 1998 the Japs were going crazy for the new WR400. They expected this bike to be the forerunner of a road version. They told me that there would be a good market for a road race or cafe racer programme to suit the new bike. They wanted a frame kit with tank and seat as well as all types of go faster parts. To my mind this was good thinking because one of the top selling bikes in Japan is the old air cooled Yamaha SR400. It has been on the market for 21 years and still makes top sales outselling the total of all the four cylinder machines. We ordered a WR400 which arrived just in time for the Japanese market to go into free fall. We still make parts for the SR400. All very boring stuff, such as old type British bike headlamps. We have not been asked to design one new part for any new bike since the debacle of the WR.

The WR bike is one of the original series. It has not even been started. Rather than leave it sit there I had in mind to make a nice Super Motard. As you might imagine we have got machining facilities so we can make the odd part such as an adapter plate for a 4 piston caliper.

I am new to the internet and was astonished that a reply came so quickly. thank you again. Mike

Do you have access to CycleWorld magazine? This month's magazine features a Street Conversion with 17" wheels, custom painted plastics, etc. Sounds like what your looking for...

The carb should be a Keihin FCR 39 mm slant. Ain't nothin' wrong with that.

Starting in 2000 Yamaha switched to a proprietary version of that carb, the Flat CR. But the slant still comes on KTMs, DRZs, CRFs etc., so I don't think it is a stretch to say that is THE carb going for four stroke singles, or is at least good enough.

There are a few small advantages to the Flat CR, but they are over $700 here in the US, and IMO it wouldn't be worth it to make that swap.

For your engine hard parts see these guys.

They are strait up and very serious about r&d.


I believe they are the best in Europe.

As far as chassis conversions go check out some of your local motard guys.

Pm me if you can't find any...

I have been working on lowering my WR400 I have some spacers made up to lower the suspension but havent installed them yet ... let me know any ideas you have come up with as i am interested.

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