SEF

iTrader: (39)

Still likely too lean on top if it sounds like it is hanging at the end of the straight. Engine is starving for fuel at top speed. Richen an hour and readjust idle if needed. Temps between 215-270 are normal. What is more important is the engine should sound correctly tuned from bottom to top with a healthy idle and good smoke trail.

Graham11

iTrader: (22)

It's not a sound thing, I couldn't hear the motor because it was at the far end of a straight, it was a feel. I would let off the throttle and the car would continue as though I was still on throttle

gt racing

carburator slide stucks?
see that quite often.
check if it stucks and lined up properly.

Andyg01

As an aside, if you are running any venturi insert, the throttle should not open wider.

monkeygrip

how does the B2101 run with the 2060 pipe? About what should I start with as far as needle settings with 7.0 insert?

Thanks

Andyg01

Why 7.0mm?, start with 6mm. Needle settings are in the instruction manual, have a read.

monkeygrip

Its best to breakin an engine with larger inserts to allow plenty of fuel plus tuning window is bigger with a 7mm. It is my experience the factory settings on os engines are nowhere near correct.

I got what I needed in my records from when I ran an xz-b.

lsn=flush and hsn=2mm in. plus I looked at a few top drivers photos of there cars to confirm.

Andyg01

This might be useful, Gord Tessman's running method

https://youtu.be/oViIFCYKA1s

in my opinion for breakin, 7.00mm buy's nothing, heating before start much more....

In use less run time ....

RUDZ206

Hey guys, how many gallons before changing piston and sleeve ?

I am already in my 4th gallon and engine still running great

rallyebmx

iTrader: (21)

My engine was still flawless at 7 gallons but I sent it to RayA for a pinch and I'll put a new rod in after quick break in

Frank L

iTrader: (148)

Usually I get a strong 8 gallons out of my speed mills before I even think about pinching or changing the rod. Around 4 gallons I would listen to the bearings and think about replacing them if you haven't already. These engines run best on less compression that most other engines ever see. Unless performance is an issue change the bearings soon and let it run another 4 gallons.

Sleeper13

I have a Samurai OS 321B with 2090 pipe combo. Tune is good. Idle fluctuates and takes time to come down. Run time of 6 minutes. Not good. Tried another carb. Nothing. Changed fuel tank. Nothing.??.?.?.?.?.?.?.

Maximo

iTrader: (11)

How big is your idle gap ?

Frank L

iTrader: (148)

With 6min runtime 2.5-3mm

pword

iTrader: (30)

likely too lean on top and rich on bottom. not seeing and hearing the motor, i'd reset the needles to flush and retune.