I just recently bought new R21 and I am really liking the performance so far with almost a gallon thru it (30% ODSPBlend plus 2% Bryons Lube Booster). But I am not sure when and if I should remove shim that manual says to remove after break-in. I did use the heat cycle and the motor is really coming around and running first real race this weekend and I will leave the shim in for this race so I don't have to tune it again right now. Should I pull it once I pass the 1 gallon mark or wait until it's had 2 gallons thru it? Also should I add a percent or two of lube booster (castor oil) after break-in is finished to my fuel if I can only get Odonnell Speed Blend 30%/7.5% oil content? One more thing I have noticed a VERY small amount of fuel coming out behind flywheel from front bearing this is normal as long as it's not alot and will hold tune right? I know I ask alot of questions and THANKS for all the info/help that I have recieved here!

I bought a bonito and right now I am having trouble keeping it running. I set the carb to the factory settings and it shipped with the blue venturi. I'm in el Paso tx. Alt is around 3500 ft temp upper 90's durning the day and mid 80's at night 30% fuel. It loads up like an sob. I am thinking of going with a bigger venturi in the carb.

put in a hotter plug a 77t or 87t odonnell plug is perfect. factory seting on the low set needle is to rich to run so lean a bit there until you get a nice idle.
always heat your engine and put it on the ground and start running in with short blips of the throttle heating and cooling cycles is the best way imo just follow the run in guide in the engine section that engine will take nearly 2 gals to run in so take it easy and dont lean to soon.
cheers
ps just run a 7mm carb insert

Am I reading the chart wrong. I would of thought a colder plug for the higher ambient temp

Break in is different

His advice is spot on

Get hotter plug, either odonnell 97t, 77t or novarossi c5tgc, dont be afraid to lean the needles a little to get it to run right and maintain run in temps

Factory settings are fairly rich and I install 8mm venturi for break ins , more air , richer settings means more lubrication

I got it fired up. Hs is still rich. Ls is just ever so slightly below flush but it sounds angry is that ok.

I also added a return spring on the carb is that ok

I have just run a couple of tanks through the Bonito with the 2096/29 combo in an RC8T. Engine is still on the rich side as it has been re nipped by RC renew( 10 tanks prior to tunning ). I had tried a couple of other pipes one of which was the 9901/29. The new pipe has it all over the combos that I tried. One of the lads that I race with was blown away by the difference that the new pipe has made. Unsure of run times but will post some more feed back after next weekends race

I like your description (angry ) thats because this engine is a 7port and has lots of balls just make sure there is plenty of smoke coming out on throttle you should be fine keep and eye on temps as a reference say 100c or 190f there abouts remember you are running in your engine so no full throttle or holding high throttle for long periods of time just blip nice and smooth over the course of the run in your engine tune will change slightly so adjust accordingly and be conservative on the hsn, just keep going with this and your engine should give you lots of life . oh and like houston said keep your temps up running in a a cold engine can do more damage
cheers
carb spring is ok I find because the carb is plastic you can get wear over time where the spring touches the carb housing so I just use rubber hair ties they are very cheap and do a good job without any damage if you need more pull just use two

Head shim question.

High air temps and high humidity. Is it advisable to add a shim under the head button? Add maybe a .10 shim.

i just bought a nova +4. will a sirio 2057 pipe work on it?

I got the bonito broke-in and tuned. This thing is a beast. Going to see if I can get it on the track tomorrow or tuesday for some practice runs. I think I am going to be very satisfied with this mill.

Or remove .10mm

What does this equation equal... torn carb boot + bad leaking front bearing + high elevation + 100 degree weather

My guess is a 300 degree engine temp

Sounds like your having tuning issues.And need some parts