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Old 12-22-2008, 05:50 AM   #1
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Default Help with tuning

Losi Eight
OS VG 21 with JP3 Pipe
I just got back into offroad from onroad. Tuning is a little different fron .12 onroad engines.
Anyone got any tips on hot to tune, where to start and what to look for when tuning, temps ect.
Raced this weekend and it ran OK, a little slow on accelertation and it would blow plugs at the worst time. Ran 2 min warm up. Went to the line and the plug blew. Replaced it on the fly and ran a 20 min main and then let my son run two tanks after the races. The plug that blew was replaced before main.

Can anyone offer any suggestions to a Newb in 1/8 offroad.
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Old 12-22-2008, 05:53 AM   #2
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What fuel are you using? I thought I was blowing plugs on my 1/8 Nitro with a .21 Motor in it, using OS8's as they would stop working after a few tanks or a good session, turns out... it was my fuel.

Plugs are fine since I changed fuels from the crappy CoolPower Blue (That I was told was good fuel by my LHS!) and I am reusing "ruined" plugs with no dramas at all, they glow awesomely!

There is a bunch of tuning advice on here, do a quick search and google your engine itself for tuning advice IMO.

Good Luck.
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Old 12-22-2008, 06:54 AM   #3
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Coolpower blue is for airplanes I think. Morgan makes good fuel. Try using Sidewinder from Morgan not Coolpower.

Was the plug coil broken when you say blown glow plug or was the element intact just not glowing when it was on the ignitor.

Too rich and too lean will both kill plugs. I've had good luck with Os's cheapest plug the A3 if I remember right. Never had good luck with OS#8. I use a hotter plug because its easier to tune the motor when you reset to factory (rich) and then slowly lean it out until performance improves. I still run kinda rich just to keep the motor safe as I'm no expert yet.

I've been putting a fresh p3 in my motor every race and save the old plugs for when a plug goes bad on a practice day.
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Old 12-22-2008, 12:43 PM   #4
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Default Tuning from scratch?

I'm trying to get my sons car to run. It hadn't been used in a couple of years so I rebuilt the engine. It's an OPS .21 in a 1/8 buggy. It has a top tuning screw and a bottom one along with the throttle stop adjuster. It will start and idle at times but as soon as you touch the throttle it bogs and dies. I've tried for a long time all different setting on both tuning screws but it just doesnt want to run. Can anyone help with where to start?
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Old 12-22-2008, 12:50 PM   #5
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Quote:
Originally Posted by Monstadrums View Post
I'm trying to get my sons car to run. It hadn't been used in a couple of years so I rebuilt the engine. It's an OPS .21 in a 1/8 buggy. It has a top tuning screw and a bottom one along with the throttle stop adjuster. It will start and idle at times but as soon as you touch the throttle it bogs and dies. I've tried for a long time all different setting on both tuning screws but it just doesnt want to run. Can anyone help with where to start?
I would mess with the low speed needle (bottom needle) first. It sounds like it's running very rich. Lean it out (clockwise) 1/8 turn at a time. You should eventually be able to get on the gas without it stalling. Then, keep leaning it until you get decent acceleration. Make sure you can still see smoke.

Tuning issues are next to impossible to help with over the internet, but this one seems fairly obvious. Blowing plugs, on the other hand, could be numerous things.
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Old 12-22-2008, 12:55 PM   #6
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What fuel are you using? I thought I was blowing plugs on my 1/8 Nitro with a .21 Motor in it, using OS8's as they would stop working after a few tanks or a good session, turns out... it was my fuel.Good Luck.

I had this problem before too. (was not airplane fuel though) .. just what I will now consider crappy.

Without naming the brand, I will just say I am Associated through and through.. and its the opposite of Associated... never a problem since
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Old 12-22-2008, 01:24 PM   #7
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Try Odonnells or Sidewinder and keep using the 8 plugs. That what used with 20% when I had my vg. How much fuel do you have on the engine? What is the weather like where you are racing?
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Old 12-22-2008, 01:44 PM   #8
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Yeah I realize tuning over the net wont be easy. Thanks for trying anyway. I gradually wind the bottom one in until it wont even fire and then gradually wind it out again until it starts but still have the problem of it revving under throttle and then bogging so I wind in the top one and it dies. I think I'll pull the carb apart and see if the correct needles are in it.

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Old 12-22-2008, 02:53 PM   #9
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This thing is driving me nuts. If I richen it up so that it starts the thing bogs as soon as I touch the throttle. So then I start to slowly lean out the bottom end and eventually it wont start. I cant seem to find a middle ground.
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Old 12-22-2008, 04:27 PM   #10
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i would go back to your factory settings and see what happens... make sure to let the engine come up to temp for you start spinning needles
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Old 12-22-2008, 04:48 PM   #11
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SInce you just rebuilt it I'll have to quit thinking the piston/sleeve is worn. That's what it kind of sounds like.

Is it easy to start?

Strange that it stalls at idle. If it raced at idle I'd say an air leak but maybe the air leak is only effecting the top end depending where it is leaking. Have you checked for air leaks??
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Old 12-22-2008, 06:05 PM   #12
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Ok making progress now thanks to you guys. got it running, idling and screaming around the back yard. Temp hit 140 celcius (should be around 110) so started richening top end. Now it bogs at about mid throttle and above??? which would suggest too rich top end screw right? should i keep trying to find the sweet spot or maybe its incorrect glow plug?
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Old 12-22-2008, 06:06 PM   #13
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Originally Posted by Monstadrums View Post
Ok making progress now thanks to you guys. got it running, idling and screaming around the back yard. Temp hit 140 celcius (should be around 110) so started richening top end. Now it bogs at about mid throttle and above??? which would suggest too rich top end screw right? should i keep trying to find the sweet spot or maybe its incorrect glow plug?

what plug are u usin?? most people around here use a p3
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Old 12-22-2008, 06:16 PM   #14
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There is a potential air leak around the throttle plunger. I wont be able to fix it very easily for various reasons. What would that affect?
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Old 12-22-2008, 06:18 PM   #15
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I have no idea what the plugs are I have a small collection of them none of which are in the packet. I bought them several years ago and dont remember.
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