RD350 Carburetors: Flat Slide vs. Round (28mm)

[MRDRcycle]

Hello,

I'm sure this question has popped up on the forum in the past, but I haven't been able to find it. I'm looking to purchase new carbs for my 73' RD350 and am thinking about spending a little more to get flat slide 28mm carbs vs. round. I've read that flat slide carbs provide much better throttle response, power and fuel economy. This seems worth an extra 150$ or so, but I've also heard that they "might be" more difficult to tune. I'm not entirely certain if this is true, but I would rather not have to deal with additional tuning or even oil injection adjustment issues. Also, I'm not sure if the TM 28mm flat slides will fit with my stock intake manifolds and/or y-boot/uni filter. I'm currently using the original 28mm round slide Mikuni carburetors.

Any feedback on this topic would be much appreciated!

[m in sc]

If the rest if the motor is sock dont bother. if you do decide to go with flatslides, tm 28s are kind of a waste of time, at least jump to 30 or 32. 28s intake snout is too small for a stock intake.  but very good performance can be had from the stock vm28s. jusy my .02  not to mention having to rig up oil injection ports, etc.

[Ws76133]

I talked to John at Economy with some questions about fitting larger carbs to my RD350 a couple of years ago.  He said the same thing about performance potential from the OE carbs and told me unless I was planning to race, properly tuned OE carbs were sufficient.  He also pointed out the issue on oil injection and having two choke levers, one per carb.

[SUPERTUNE]

If the stock carbs are in real nice shape, go through them and make them all new. If in poor condition, replace them with new carbs.
Now your choice is how modified are you going with the engine build and performance like Mark mentioned. Drilling for oil nippes is easy, I do it all the time ($30)
If mostly stock, just use new VM28's with a primary needle jet conversion, stock sized 35mm spigots. (dual chokes are not an issue!)
If leaning to performance, modify the top of the cases a little and go with some VM30's for mild builds (carbs can be turned down if wanting to fit stock sized manifolds or go aftermarket manifolds with 40mm spigots, as this will also allow to upgrade to TM32' or 34's flatslides)
Modifying stock cables is required for 30's and all new throttle cables set if going bigger than 30's as you have to have a splitter that offers more travel inside.

Chris's STG 1 RD350 with VM30 's, TSR/Barlow intake system with aftermarket manifolds.

Chuck

[MRDRcycle]

Thanks for all the great information. Looks like 28mm VMs it is!