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The Carb Windows and dots on the slides are there to sync them when lined up in the middle of the window. Not the bottom of the window.

Is this one of those situations where the manuals are giving bad advice? The Haynes and Yamaha Workshop both say bottom of window, but I imagine the more important thing is that they're even.

I've had this bike for over 5, and it runs and is fun to ride, but I don't think it's running quite like it should.  I've had the top end done by Chuck, installed a Vape, boost bottle, etc, but still not running primo.  So I can only conclude it's my inability to tune the thing properly or sync the carbs properly that's the problem.  This being my first and only 2 stroke, I don't have the experience to know what it is supposed to feel like or sound like.

And so I turn to 2sw for help.  I recorded a video of the bike running and my efforts to sync the carbs as explained in my Haynes manual.  I'm hoping that someone here can watch and say "your problem is that you did X, you should be doing Y" or "if you listen at 2:02, you can tell it's running rich/lean" or point out something else I'm doing wrong that'll help me get the bike dialed in.

Setup:

• RD400C
• Chuck stage 1 with TSR boost bottle
• Dave F mod w brass ball removed, airjet drilled to 2mm
• Vape ignition @ 1.9 BTDC
• Main: 200
• Pilot: 35
• Needle Jet: P2
• Need: clip at 2nd position from the top
• Air screw: 1.25
• Slide: stock, synced so the bottom of the "dot" as viewable through the hole on the carb body is align to the bottom of the view hole at full throttle

2 spooge diapers ready to go. Filled the space in each flange with hi temp copper RTV about 1/4" deep. Going to wait 30 mins as someone recommended and hopefully my spooge problems will be solved!

Had a drippy leak on that side because I buggered up the seal/cap (Part # 90338-22021-00) at the end of the shifter fork shafts when pushing them in, and fixed it by putting in a new one


I've seen Chuck solve this by filling up those 2 holes with sealant:
https://imageevent.com/supertune/nicks76rd400?p=79&n=1&m=-1&c=3&l=0&w=4&s=0&z=3
https://imageevent.com/supertune/paulsrd400?p=89&n=1&m=-1&c=3&l=0&w=4&s=0&z=3

In any case, removing the side cover should reveal a trail of oil that should lead you to the culprit.

do the Spec ii s require an o-ring or sealant in the flange, or will a spooge diaper doo?

Do you use RTV (1) between cylinder and pipe flange, (2) between pipe flange and pipe, or (3) both 1 and 2?

I ended up returning the TracTech brace.  The part of the lowers under the dust seal are 54mm diameter, and the brace they sent was the wrong size (needed to get the 54mm clamps with 121mm bridge) - since I had to mail it back anyways, I decided to just return it and order the RSW Racing brace since that seems widely used, doesn't require removal of dust boots and more specific to the RD350/400.  I will say that TracTech was very responsive and tried to help to get the brace to work, and when I finally just asked for a refund they didn't give any issues, so high marks for them as a company.

hey all - I ended up ordering a fork brace from TracTech Mfg.  The brace has a lip on one side of the clamp (rather than being the same diameter) so it doesn't fit on the lowers like most braces I've seen.  I e-mailed the company and they said I need to remove the dust boots so that the lip sits on top. This doesn't seem like an ideal setup and I'm hesitant to leave the fork seal exposed on my newly RaceTech-rebuilt forks. What do you guys think?

Here are photos the company sent me of the brace on an RD350.

Ah yes!  We had an Astro van growing up (the Chevy version of the Safari).  It served us well, taking us all over the country and lasted from our childhoods up until we all moved out of the house and my parents no longer needed a van. 

Kind of a sad story, though - growing up in India, my dad always that thought the ultimate sign of success in America was owning a Cadillac. Years later, he moved here, started a family, worked for years and finally got to the point where he could afford a Cadillac.  He had it for all of 3 months before his bratty kids made him sell it for an Astro van because we wanted more room.  No wonder he's a grumpy old man now!

I think my RD has sparked a love for all things that are impractical money pits, and I've become increasingly obsessed with the idea of getting an old clunky, uncomfortable, overpriced, CO2-spewing cage - specifically a 70s era SUV like a Int'l Scout, Land Cruiser, FJ40, LR Defender or Bronco.  I'm undecided whether I want to be talked out of it or encouraged. 

Anyone else have a 4-wheel obsession they're dreaming about or gave in to?

Looks like they have one for a 1976 XS650, which was before they changed the fork configuration in 1977 (according to Wikipedia).  Hopefully that works!

Does anyone know of other Yamaha models with the same tube circumference and spacing between forks as an RD400C?  Tarozzi makes fork braces for 20 different Yam models but apparently nothing for RD400s.  Wondering if I can use one made for another model (RZ350?). http://www.fastfromthepast.com/fork-braces/yamaha 

Replacing the front fender that the PO installed (which looks too chunky and I think is for a CB or some other larger bike) with a new Airtech one to keep the weight down.
(1) What's a good clearance between the tire and the fender? I've read anything between 3mm and 1", but figure 1/4-1/2" would give enough buffer for tire expansion and for pebbles that might get stuck in the treads.  Prefer to keep the clearance on the smaller side bc, you know, it looks cool. Any recs?
(2) Since a fiberglass fender doesn't provide the structural stability of the stock metal fender, is it recommended/necessary to use a fork brace to keep the forks from twisting?  Keep in mind this is a street bike, and I also plan to add a stabilizer, but watching too many tank slapper videos on youtube has me paranoid.

For comparison, here is the sound of a brand new bearing https://www.youtube.com/watch?v=zBVnCVHmGmo

Having never replaced bearings before, I thought even this new one was too noisy so asked 2sw (old site) and was told it's fine!

Sweet, I'll email Matt at RaceTech. 

@Czakky - sorry that 'hole shot' isn't what you were hoping for 

[(what is the difference between this and 'Emulator Valves' below?)]

I'm sending my front forks off to Race Tech to be rebuilt, and was wondering what options are typical/recommended for a street RD400.  Also, are preload adjusters recommended? Doesn't look like Race Tech offers them. From their service request form, here are the different options (red=options I think I should select; orange=options I'm not sure about):

Comp Gold Valves [YES / NO] (what is the difference between this and 'Emulator Valves' below?)
Reb. Gold Valves [YES / NO]
Reb. Holder KYB (Must AX/SX) [YES / NO]
Emulator Valves [YES / NO]
Springs [YES / NO / If Required]
Pressure Springs [YES / NO] (what is difference between "Springs" and "Pressure Springs"?)
Seals [YES / NO / If Required]
Bushings [YES / NO / If Required]
Hole Shot Device [YES / NO]
RT G2-R Cartridge [YES / NO Length+____]
RT G2-R Cartridge caps [YES / NO]
Lower [YES / NO -____mm(@wheel)]