If you turn out the HSN you're richening it. If it's got a load of smoke you can generally lean it. When i used to run the Reedy engines id get the engine somewhere close with the tune. Setting HSN i'd put the car on the box, and when it's hot rev it for 2secs. If near the 2secs it started to choke you've obviously got it to lean. I got it to a point where it would lean bog then back it off about 1/8th to 1/4 of a turn on the HSN (just until it didn't bog). LSN was very much the same, couple of stabs of full throttle, let it settle then full throttle again. Again, i got it to a point where it would hesitate because its lean then richen it 1/4. Idle is easy, once everything else is set turn the idle needle out till it cuts. Restart it, then give it a few full throttle bursts and start to lean the idle (turning it in) until it hangs for no more than 0.5secs then idles nice and low with out cutting. Doesn't take long to do, 2-3mins of tuning once hot and you're done.

I am aware of the process to tune. I just noticed that my HSN was too rich and the engine would not run clean at high speed. I started with a tune on my starter box that was rich enough to have smoke at high speed. I then leaned the mixture until the engine ran smooth and with power. I was turning the needle clockwise to lean of course. When I drove the vehicle it was still not running well at full throttle so I leaned it a little more until it ran good and still have smoke. That is where I am now and I still think it is rich. With head temps at 130degC(266degF) is was fairly hot but I read in this thread that that is a normal temp. I should be pretty good then.

I adjusted the LSN just like you stated. It is running smooth and stable now. I have red that some people set the idle air to a specific dimension. What is that dimension and how did you measure it. I would like to have an idea of what throttle opening people are using for their idle settings with this engine.

I would also like to know what others are using for head shims. Are you measuring them or just picking the stock shims. My engine came with the two thinner shims installed. The shims are supposed to be 0.20, 0.30, and 0.40mm thick. My shims are all about 0.01mm thinner. My local AE/Reedy rep stated that 0.55mm seems to be the best. What are you running?

Measuring idle gap i honestly wouldn't get carried away with. Just set the idle like normal. If Person X sets it at, for example 1mm it could make your engine way out of tune as theirs might be richer or air temp cooler/hotter etc. I always stuck with the 2 shims that came with the engine as standard. I honestly didn't see any need to lower the head but it's worth a try i suppose.

Thanks. I agree that every engine is different due to tolerances which includes the head shims for example. It would be great if people would post their engine settings that would include Head shim thickness, HSN, LSN, Idle air gap, Fuel %, plug type. It would at least reduce the tuning variations and help noobs like me get a good tune sooner.

I was planning to raise the head slightly from 0.49 to 0.55mm. This would reduce the compression ratio slightly. The only issue I have is that my shim combinations are only 0.49 and 0.59 so I will have to see what I need to do to get the desired 0.55mm. I can always go back to 0.49mm if I reduce the thickness of my thickest shim.

Here's where I ended up having the best tune most of the time.

My idle gap is around .75mm measured by using a 1.5mm hex wrench and setting it to the center of said wrench.

HSN is 2 1/2 - 2 1/4 turns out depending on weather.
LSN is 3 1/8 turns out and usually not touched much at all.

Byrons 30% Nitro, 11% Oil Fuel.

Stock head shims, glow plug is Odonnell 97T (Medium), or 77T (Hot) depending on weather. (Hot in cooler weather of course)

So I am very close to your settings today. I will be switching from MK 30% fuel(Brazilian brand) to Byron Gen2 Race 30% fuel. I will stay with the O.S. P3 plug and I have P4 plugs if it gets too hot in the summer.

So I think I should definitly not stick with the 0.59mm head shim selection and reduce the thick shim to 0.35mm from 0.40mm.

Yes, If I remember correctly I believe stock is the 2 thin shims.

...also just to add for reference. My engine temps between 260F and 280F depending on weather and how hard I run it that race.

Under 240F it runs poorly.

I would stay with .50mm for all conditions. DO NOT try and "sand down" your shims for inbetween thicknesses. This will not be precise enough to seal the button to the sleeve.

I start my idle just like Bigwave said, half of a 1.5 wrench tip. If it "won't idle" right, the LSN is too far out of tune, use it before changing the idle screw.

just thought i would let the reedy guys know i have a bunch of good useable parts for sale for dirt cheap

If you considering trying one of these I highly recommend it!! These motors run great and are easy to tune. I have a motor/pipe combo for sale which would be a great way to try one of these out. http://www.rctech.net/forum/r-c-item...l#post11240624

There has been very little action on this thread. I have my 121VR running very well now and am looking for your advice on pipes. I am using the Reedy 2035 pipe right now and I was wondering if there are other pipes that improve fuel economy.

I am using the 7.0mm veturi and P3 plug with 0.50mm shims. What changes would impove fuel economy? I am running my RC8.2 with stock ring gears and 44/16 spur/pinion. It runs great and I am consistantly getting 9:15 run times per tank.

I have a 6.5mm veturi on order and could even increase to a 17t pinion. What will these do for performance and fuel economy?

A smaller venturi will reduce power and increase fuel mileage. I heard people having runtime issue with smaller venturi but you should be fine with a 6.5mm.

A bigger clutch bell will reduce acceleration and increase top speed. In theory, you should also save on fuel.

I have the exact same engine, glow plug, pipe and buggy with the same runtime.

I switched to a 121VR-ST which is a little more powerful version. It increased my runtime a little bit, mainly because I have to control my heavy finger.

I think the best to increase your fuel mileage, is to try to be smoother on the throttle.

Thanks Sylvain. My mileage was great today. My Semi I was able to complete with one stop no issues. 15 minute Semi. I really needed the extra time today. It wasn't enough to make it to the main. I need to improve my driving.

I have done everything to go for "mileage" with the engines and have found that mileage is dependent most on the tune and the driver. Certain engines will get better mileage by design, but pipes can make a difference, plugs, all that stuff makes minimal difference, but not minutes....just a little here and there. A tune that is safe but not rich and a smooth finger is 90% of fuel mileage.

I have been having an issue with my VR-ST's HS needle backing out of the carb body. Anyone else been having this issue? Im gonna try a small amount of loctite..