"the engine tuning bible"
#481
Tech Apprentice
Quick question... My Kyosho KE21R has almost a half gallon through it now, and tune is getting easier each time I run it. Why will the darn thing not start without preheating it first? In the house it stays 72f, and it won't start until I get the heat gun out and preheat to above 160f. The warmer it is the easier it is to start.
#483
Tech Apprentice
Thanks. I kinda figured it may be a plug issue. I run Odonnell 30% fuel and Odonnell #99 cold plugs. How long do you thing it will take to get a (normal temp) start up? In years past I ran hot plugs with 20% nitro with zero issues starting (.12-.15 engines).
#485
Tech Apprentice
Thank you so much for the great replies. It's getting near the total end of racing season here, but with our temps in the south there will be more opportunity to test and practice. The more fuel I run through it the better it runs. I have to turn my radio down to 50%-60% for my aspiring driving skills. Both the buggy and I will get better in time with more practice and tunes both engine and chassis wise.
#487
Tech Apprentice
On a side note for newbies and such. I just came in from trying to diagnose my idle problem. It has had a BAD two stage idle and while keeping the idle high to run, I was never satisfied. A combination of things were my problem. Trying to tune with air filter on. (I know this sounds bad, but this time I ran it on my deck aka wheels off the ground). My radio was quite a bit off, and the one of the collets for the throttle servo was out of adjustment. After a twist here and radio adjustment there, I got the two stage out. She idles fine now after full throttle runs. I put the filter assembly back on and ran on the ground and she purrs great, and does what is expected.
#490
Tech Elite
iTrader: (1)
http://www.novarossi.it/2012/index.p.../off-road.html
This is a subject where those that know don't want to talk, for example colder plugs while harder to tune than hotter plugs have a power advantage, coupled with head shim stack you can get lost on chasing the best setup/tune.
#491
Tech Fanatic
iTrader: (14)
Thanks for the links to the charts. Is the Picco P5 TH a hot plug or is it supposed to be used in hot weather? I am assuming a general rule would be colder plug on a hotter day? The head shimming is another thing I havnt seen much on. I know that having the headed shimmed improperly can damage the motor and hurt the performance. I am trying to find some basic info on when I should add/take away a shim or change the temperature of my plug but it has proven difficult.. I suppose that head shimming and trying different plugs is just something that takes trial and error by the user?
#492
Tech Elite
iTrader: (1)
Thanks for the links to the charts. Is the Picco P5 TH a hot plug or is it supposed to be used in hot weather? I am assuming a general rule would be colder plug on a hotter day? The head shimming is another thing I havnt seen much on. I know that having the headed shimmed improperly can damage the motor and hurt the performance. I am trying to find some basic info on when I should add/take away a shim or change the temperature of my plug but it has proven difficult.. I suppose that head shimming and trying different plugs is just something that takes trial and error by the user?
Up to 0.3mm head clearance is doable, lower than that and you will have lots of issues with thermal expansion and the piston might touch the plug button/deck (research I did years ago I found 0.36mm to be the safest minimum deck height, an engine I religiously followed that was surprisingly powerful). If not mistaken engines are shimmed to cater a specific nitro content (around 25%)and relative altitude (which one IDK, sea level probably). What you want is to fit the most air/fuel in the combustion chamber without pre-detonation occurring by playing with nitro content, plug temperature and deck height.
I don't know much more than this sorry.
#493
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Last edited by damang999; 06-29-2016 at 01:11 PM. Reason: moved
#495
Tech Adept
about to drop the restrictor size in my carb, what changes to the tune should i expect, will the engine run more rich or lean?