Rd400F Daytona

[pdxjim]

Keihin PWK28 are cheaper and better than TM28. They fit the stock airbox boots or y-boot, and are easily modified to work with a standard RD400 cable set (at least they work well with an LC cable, can't imagine the 400 is much different.

Keep the oil pump. It's very reliable, and premixing sucks.

[Hawaii-Mike]

Some advantages of running stock 1A1 carbs:
 - One choke lever (Aftermarket carbs have a lever on both carbs)
 - Stock RD400 1A1 cables work
 - Stock RD400 (2V0 or 1A1) or RZ350 (31K) Intake manifolds work
 - Stock RD350 Y-boot can be used to run either a K&N or UNI filter

Stock VM28's work great, performance will be fine.  If you want to a set of used stockers, I have some. 

[rearwheelslider]

Do you guys install the engine with cylinders and head on the engine or off? Do both ways work? I removed the cylinders with engine in frame so I was curious to the best method of reassembly.

Also, do you guys prefer the oem black cylinders with polished head? I am liking the blasted look and no paint!!

I have the seat pan all done, had to fiberglass over the rusted out portions.

[m in sc]

i mean its all personal preference there.

[rodneya]

Roger Allen is making pipes for the Daytona if you want something with more modern looking silencers.
https://www.wickedatv.com/product-page/rd400-carbon-steel-pipes-and-billet-silencers

[rearwheelslider]

Roger Allen is making pipes for the Daytona if you want something with more modern looking silencers.
https://www.wickedatv.com/product-page/rd400-carbon-steel-pipes-and-billet-silencers

Good to know! I just placed an order with him! Super nice guy who explained everything and sold me on his product. I am sure Spec2 pipes are good pipes, but I really liked Rogers attitude!

[Milan]

Ive got a few Canadian Daytona's.  The 2R9 carbs are great.
If you can find any.
No linkage or EPA stuff

[SoCal250]

The 2R9 VM28 carbs are basically the same as the US 1A1 version, only the jetting is different and if you're doing tuning all that will be swapped out anyway. You'll have a much easier time locating a set of 1A1 carbs.
The 2R9 uses a 169 series primary type needle jet while the 1A1 uses a 175 series bleed type, but interchangeable.

[Alain2]

Reference the 20 thousandths clearance, I assume you mean 2 thousandths (0.002"). It will work but don't expect 20'000mi out of them.

My last set of pro x pistons were fitted with 0,0016" clearance (1.6 thousandth), I was very gentle with the break-in process and now have 3500mi on them. While I may not recommend such a tight clearance for others, i would be confortable recommending 1.8 thousandths clearance.

One of my bike has +0.005 clearance of forged pistons and still has good compression and is quiet once I get cruising, the other website doesn't like it!

[rearwheelslider]

Reference the 20 thousandths clearance, I assume you mean 2 thousandths (0.002"). It will work but don't expect 20'000mi out of them.

My last set of pro x pistons were fitted with 0,0016" clearance (1.6 thousandth), I was very gentle with the break-in process and now have 3500mi on them. While I may not recommend such a tight clearance for others, i would be confortable recommending 1.8 thousandths clearance.

One of my bike has +0.005 clearance of forged pistons and still has good compression and is quiet once I get cruising, the other website doesn't like it!

Yes, I am sorry. I mis-spoke. I certainly dont expect many miles will be put on the bike. I have other bikes for mile munching and dirt riding. I am still trying to understand why the aircooled forum guys are so against using the prox piston. They were going off! They said the metallurgy was different, expands at different rates, etc..

[rearwheelslider]

The 2R9 VM28 carbs are basically the same as the US 1A1 version, only the jetting is different and if you're doing tuning all that will be swapped out anyway. You'll have a much easier time locating a set of 1A1 carbs.
The 2R9 uses a 169 series primary type needle jet while the 1A1 uses a 175 series bleed type, but interchangeable.

I am going to purchase carbs so I am open to ideas! TM, VM, PWK are all options at this point. What would you all recommend for ease of tunability and good performance? It must fit the stock intake manifold and Y-boot!

[rearwheelslider]

Let me ask about reed options. Are the stock steel reeds okay for performance and durability? If they come apart, I dont want them grenading my engine.

[This Old Daytona]

From my experience, Mikuinis are " ultimately" better carbs w greater adjustment capabilities, But the PWKs are pretty darn easy to set up..I beleive that's why so many people like em. I have a set of 33s on a Banshee .there pretty good w great response.
 But in your case I'd recommend 28s! Every RZ I've ever owned..if I went larger than 30 mm was  always a few bikes slower accelerating.  So your perfect w 28s and pipes...even 26s PWKs. 30+s are good on a modified motor & reed cage.
 I'd keep it at 28s and reeds.,👍
 
 

[rearwheelslider]

I am curious if anyone has a PDF of the 400 F repair manual supplement? I am trying to find head torque and points/timing information. Thanks in advance!

[rearwheelslider]

Is this accurate information? Seems a bit light for head torque.

Cylinder Head Torque Specs

MODEL	TORQUE SPEC	SOURCE
RD125 / RD200	Cylinder head nuts torque:  86.8 ~ 130.2 in-lbs (1.0 ~ 1.5 m-kg)	Yamaha Service Manual: RD125/RD200 1975-76 (LIT-11616-10-12)
DS7 / R5 / RD250 / RD350	Cylinder head nuts should be loosened and tightened in a "cross" pattern and in progressive stages with final torque of 180 in-lbs. (2 m-kg).	Yamaha Service Manual: DS7/R5/RD250/RD350 (SVM-360-0800-20)
RD250 / RD350	Cylinder head nuts should be loosened and tightened in a "cross" pattern and in progressive stages with final torque of 180 in-lbs. (2 m-kg).	Yamaha Service Manual: RD250/RD350 1972-75 (LIT-11613-61-02)
RD400	Cylinder head nut torque: 1.9 ~ 2.1 m-kg (13.7 ~ 15.2 ft-lbs.)	Yamaha Service Manual: RD400 1976-79 (LIT-11616-RD-40)

RD400F

Cylinder head nut torque: First:  1.0 m-kg (7.2 ft-lbs.) Final:  2.0 m-kg (14.5 ft-lbs.)

Yamaha Service Manual: RD400F Supplementary (LIT-11616-01-24)