Bottom end Power

[KANDY]

Hi,
My 1974 RD350 is bit low on Bottom end Power. It picks up after 5500 RPM. I have 27.5 Pilot, 220 Main and Jet needle clip in the middle position.
Air Screw 1.5 opened from seating. Timing is set to 2.0 BTDC. The spark plug is bit dark(its there for past 2000km).
RD is Stock except Y-Boot, K&N Set up and Ignition Relay MOD Done.
Please Advise.

[m in sc]

need more info.

pipes, ignition type, reeds, intake type.


try the airscrews at 1.25 see if its better. these are easy simple things to try 1st.

the way I do it is id try to richen the needle one. if it gets worse, they try it the other way. 

[KANDY]

Thanks,
Will try that and update. More info added in the Original Post

[SUPERTUNE]

Have you removed the log pipe baffles and burned them clean with a torch? (propane or map gas will do)
Has the topend been rebuilt with a fresh bore and new piston kits? How many miles on it? Have you checked the ring end gaps and piston to wall clearances?
Always think...any blowby past the rings kills a 2 stroke 50% more than a 4 stroke engine!
A tired topend will be very lazy, power will be down at slow pistons speeds.
Plug color will suffer also...
It's amazing how many guys complain they can't get the idle and jetting right and I build them a new topend and their jetting problems go away.
Chuck

[Hawaii-Mike]

It's been decades since I rode an RD350.  My old '74 was fast but it didn't have much power on the bottom end until 4,000 rpm and higher.  Maybe you're wanting more power than the bike has available, unless it's Supertuned!

[paul1478]

Yea even my "Super tuned" 400 has little power below 5K. Past 7K hold on tight (and lean forward). Nature of the beast.

[m in sc]

on a bike with stock pipes, it should pull well enough below 5k. 

[quocle603]

on a bike with stock pipes, it should pull well enough below 5k.

yep 

[Organicjedi]

Great advise by Chuck- check the top end and baffles. Fiber reeds and dropping a tooth on the front sprocket and/or going up one in the rear will help. But get those nice chocolate plugs first.