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Yes V force reeds would definatly be a good choice , more reed tip area plus more reactive material , more pedals doing less work , every part of power band will improve . I have another recomendation for you , the carbs I build with venturi dividers , makes for a linear power band  , its like opening 4 small carbs in series . Air velocity stays high throughout , Stronger pull out of corners and basicly  any time the throttle is rolled on .  You might be interrested in checking out my web site  richstaylordporting,com

I've always wondered if those work.

Rob

And always  the use of UFOs is a must . They make a round slide out flow a flat slide carb up to 13/16 throttle opening ,

Rich

The UFO's I ordered showed up yesterday.

Rob

Are the brakes nice and strong on this bike that is going to carburate it's way to the lead?   

I sure hope so.  FZR600 disc, stock RD400 front caliper, Cannondale motorcycle master cylinder.  All stock, OEM rear setup, for now.

Rob

This thread makes me wonder how much is gained by using larger carburettors on RDs.
As far as I understand, one of the main limitations/restrictions in all the 64 mm bore RD350/ 400/LC/YPVS engines is the transfer ports/ ducts. This due to the fairly tight bore spacing.
Next restriction would be the reed valve cavity. It can only be widened so much without a major effort.
So where does carb size become a limiting factor? After all, the RZ had well over 50 rwhp with stock 26mm (?) carbs. And some claim up towards 70 hp with 30 or 32 mm carbs.

I do realize the TZ350F came with 38 mm carbs, but had no reed valves.

Keep in mind, what I'm putting together is a race only machine.  I'm hoping it spends a LOT of time in the middle and upper end of the RPM range.  If I was building something for the street then I would stay around a carb size of 30-34mm.  But the other RD's I'm racing against are running 38's and have engines built by Harry Barlow.  Once this upgrade is complete and tested, I fully expect fuel supply and traction to be the next two hurdles to overcome.

Rob

John is a little over an hour from me.  I forgot to mention, the new chambers going on are Swarbricks.  Lyn was nice enough to sell me a set he had for an RD400.  I just need to weld on the mounting tabs and they are ready to go.

Rob

My biggest worry is that I won't get this combination to run right after spending a LOT of money on it.  The stock motor w/modified carbs and aftermarket exhaust ran great.  It was just much slower than all the guys I race with so getting left behind on the straights was getting boring. We'll see what happens.  Baby steps should get me where I want to be.  It's all for the fun and amusement of racing.

Rob

Hmm pics sure looked like modified stock RD cages with TDR reeds. Ed

You're right.  After I took these pictures I realized I had YZ85 reed cages to use for this engine, so I removed the modified RD400 cages seen in the pictures and replaced them with the YZ85 cages.
For the record, the carb boots in the picture are only temporary.  I plan to replace them with ones that have a crossover.  These were all I had at the time.

Rob

I installed YZ85 reed cages w/new TDR petals with this upgrade.

Rob

I've modded mine in the past like you are suggesting. with 38s you might want to go to some v-force reeds,. thats a LOT of air flow.

I was thinking along those lines.  Trying to do this incrementally. 

Rob

I was in the middle of installing my new carbs/manifolds when I notice there was a LOT of aluminum reed cage material in the air flow path.


So I marked the area that was exposed, removed the manifold and took another picture to show how much of the reed cage was blocking the air stream.


Is this normal, or can I grind away at the upper/lower areas.  I looked at the sides, there isn't enough aluminum to really grind away in that area without creating daylight.

Rob

2/7-9 Laguna Seca; Monterey, CA
2/20-23 Roebling Road Raceway; Bloomingdale, GA
3/27-29 Carolina Motorsports Park; Kershaw, SC
4/17-19 Streets of Willow; Rosamond, CA
4/24-26 Willow Springs International Raceway; Rosamond, CA
5/22-24 Heartland Park, Topeka, KS
6/19-21 New Jersey Motorsports Park; Millville, NJ
7/24-26 Blackhawk Farms Raceway, South Beloit, IL
7/31-8/2 Gingerman Raceway, South Haven, MI
9/11-13 Talladega Gran Prix Raceway; Munford, AL
10/8-11 Barber Motorsports Park; Birmingham, AL

Rob

I turned this into a WORD file, if anyone's interested.

Rob

That's interesting, because AHRMA is going back to Laguna Seca to start the 2020 racing season there after multiple years of failed attempts to reach a deal.

Rob

Start with a track day or training class, rent or borrow a motorcycle (that is already track day/race prepared) for that event to see if you like it.  If you do, then spend a bunch of money getting your motorcycle ready to race and give it a go.

If not, that was money well spent.

Rob

OK, that's funny.

https://babylonbee.com/news/motorcycle-that-identifies-as-bicycle-sets-world-cycling-record?fbclid=IwAR3X1BkGYu0aV-k-kw9MWtCCzDkZzkWm0hL5GwI7zC3_CIOBffPIRyS0IDs