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Old 07-21-2008, 09:48 PM   #1
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Default My motor went rich????

Here is my theory. Five minutes into the main I had a sizable lead so I backed off, and never went above ˝ throttle, even in the straight. Well when I was doing that I think the motor loaded up and cooled off, and it seamed like the motor went rich. (looking back I wonder if I had pulled the trigger to full throttle it might have blown it out, but I was afraid of a flame out) So Bubba (pit man) leaned me out 2 hours at my 2nd pit stop, at that time 2nd was catching up and I started pushing it again. Now with my engine tuned too lean, I couldn’t push it past ˝ throttle fearing a flame out. So if I would have continued pushing it in the beginning, I might not have had the issue. (Being that it was tuned for racing and not putting around) Anyway, I think the motor was tuned correctly in the first place. that’s my theory…. Do any of you agree.

I usually run expert buggy, but this was the first time at this track and I only had two tanks ran before the race started. So I entered sportsman. When I run expert, I'm at the slow end of expert so i push my car the whole time. Running sportsman presented me with being able to back off for the first time. I've never had a motor go rich before. And yes it was spitting out a butt load of smoke when this happined.
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Old 07-21-2008, 09:51 PM   #2
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Replace the o-rings on your carb's HSN.
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Old 07-21-2008, 10:20 PM   #3
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Replace the o-rings on your carb's HSN.
Went threw the motor, it's fine. Plus If I had bad o-rings it should go lean.
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Old 07-21-2008, 10:43 PM   #4
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Went threw the motor, it's fine. Plus If I had bad o-rings it should go lean.
Is it a fresh motor? As in it broke in. They will go a bit fat.
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Old 07-21-2008, 11:45 PM   #5
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Three gallons threw it, plenty broke in. I've had around 20 to 30 motors in 15 years, but have never had this issue. I wouldn't post this question if it didn't baffel me. It's a OS V-Spec
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Old 07-22-2008, 01:37 AM   #6
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Here is my theory. Five minutes into the main I had a sizable lead so I backed off, and never went above ˝ throttle, even in the straight. Well when I was doing that I think the motor loaded up and cooled off, and it seamed like the motor went rich. (looking back I wonder if I had pulled the trigger to full throttle it might have blown it out, but I was afraid of a flame out) So Bubba (pit man) leaned me out 2 hours at my 2nd pit stop, at that time 2nd was catching up and I started pushing it again. Now with my engine tuned too lean, I couldn’t push it past ˝ throttle fearing a flame out. So if I would have continued pushing it in the beginning, I might not have had the issue. (Being that it was tuned for racing and not putting around) Anyway, I think the motor was tuned correctly in the first place. that’s my theory…. Do any of you agree.

I usually run expert buggy, but this was the first time at this track and I only had two tanks ran before the race started. So I entered sportsman. When I run expert, I'm at the slow end of expert so i push my car the whole time. Running sportsman presented me with being able to back off for the first time. I've never had a motor go rich before. And yes it was spitting out a butt load of smoke when this happined.
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Old 07-22-2008, 07:09 AM   #7
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If at half throttle it was fattening up and is totally broken in your mid range needle may be ever so slightly off. It should be turned to flush with the carb body then in one full turn and rest between the 2-4 o clock position. I have had a similar experience with my v-spec but it only has a gallon on it so I attributed most of it to breaking the pinch. However I turned the MSN in just a fraction of an hour and the problem was solved. No gaurantee this is your issue but I hope this helps.
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Old 07-22-2008, 07:12 AM   #8
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So you ran the rookie class just because you hadn't been to the track before?
That's a new one. Wait till all the pros get a load of that theory.
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Old 07-22-2008, 07:16 AM   #9
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I have had this happen, especially with motors that run cool even at race tune. I had a motor that was only running 190F once and leaning it out slowed it down. It was fine unless I came up on traffic and had to back off a bit to work my way around them. Then it would go rich for a lap or two until I got it cleared out. I went to a hotter plug and that seemed to help the problem.
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Old 07-22-2008, 07:34 AM   #10
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Only other thing I can think of is did the temperature out side change drastically?
If your on the verge of running a bit fat to keep the temp on the motor cool it wouldn't take much.
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Old 07-22-2008, 07:54 AM   #11
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Default Fat tune

If you are running a mid throttle most of the time, you may want to talk to some of the onroad folks. They seem to spend a lot of time at mid throttle. I was once told, that they pop the throttle a lot to help with your types of problems. That is also why some of the onroad guys like the mid pin carb to help tune for 50% power. It sounds like you have had that rare case where the midrange needle would have actually helped. My concern is that when I race on a track I get into the timing of the track and the buggy. So If I change the pace I mess up my timing and make more mistakes. Run your race no matter how many people you have beat. I really do not feel like I need to push the car either. As long as I run my race, it seems to work out OK. But a rich system could have come from several things. A lower engine temp is one, but you could have had an air leak in the header that resolved itself with a little oil, or a had something restricting the fuel flow, like a kink that got resolved. during the race. You could have had some oil residue in the motor that broke free. Who knows. too many variables. but go thru your system change out the tubbing, clean the carb and engine and go again. If you are going to lap the field a few times, then do it. Once you get your timming down do not back off to be nice, you could end up breaking something from a missed jump, and you would be out of the race.
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Old 07-22-2008, 08:00 AM   #12
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it happens to me but only when i run in the evening, the weather change a little between 4pm to 8pm so i do little tuning
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Old 07-22-2008, 08:17 AM   #13
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That's good advice from Relay. Another reason to keep running hard is for the practice. When I first started running on road locally I was so much faster then everyone else I could just cruise the whole race. But then when I would travel to run against stiff competition in 30 min or more mains I would often lose focus and break something when trying to push the whole time. I started running local races like it was a nats and pushing all the time regardless of my lead and my driving in long mains under pressure from good competition improved drastically.
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Old 07-22-2008, 08:39 AM   #14
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ya i have seen it happen alot at our track dont know what it is but it sucks
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Old 07-22-2008, 09:31 AM   #15
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Quote:
Originally Posted by ratherBracin View Post
So you ran the rookie class just because you hadn't been to the track before?
That's a new one. Wait till all the pros get a load of that theory.
Cut me some slack, First time at the track, just moved to the state and only the second time I raced nitro in a year. I didn't know anybody here and I won't do it again. I'll run expert next time.
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