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Old 07-21-2006, 01:17 PM   #1
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Default New Engine Time?

Hello all,

I am running a Novarossi 21BF, 3 port. I have about three gallons through it and up until recently it ran great. Now it seems to loose fuel pressure after heating up around 220 F and simply dies. I am unable to restart it until it has cooled back off to around 180F. I use Sidewinder 30% and the Novarossi C6 plugs. My assumption is that as it heats up, something is expanding and I'm loosing compression/pressure to the fuel pressure line. I have also noticed metal shavings on the glow plug...I know that can't be good So am I hosed and just need to buy another mill or is there hope?

Any help would be apreciated!
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Old 07-21-2006, 01:30 PM   #2
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Unfortunately, it would be difficult to diagnose the problem accurately over the net. The best thing would be to remove the engine from the vehicle and perform a detailed-strip; something is definitely amiss if you have metal shavings in there, and they can do serious damage to the piston/sleeve.
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Old 07-21-2006, 01:34 PM   #3
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Best thing is to open her up and take a look. Metal shavings arent good.
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Old 07-21-2006, 01:53 PM   #4
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Thanks for the replies!

I was afraid of that, but since anything I would have to replace internally would be around 1/2 cost of the engine ($150), besides the bearings, I may as well chuck it and grab another one. Still love that engine though and will continue using and recommending it for our local small tracks.

I was afraid it was going to have a short life since it was 30 degrees when I was breaking it in and just as cold during the first couple of races. Not sure if that actually makes a difference but I did have a bad feeling during the process.

I may go ahead and strip it down to see what I can find. I will post the results if I find anything.
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Old 07-21-2006, 05:47 PM   #5
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Well...it was not good that you broke it in at 30 degrees. The purpose of the break in is to heat metals, let them expand, then break them in by rubbing against each other for smooth operation. Since it was 30 degrees outside, i think the engine was a bit cold .

I would tear down the engine, and check for compression and proper fitting. As for the shavings, take a look at the bearings, they are known to go fast in these engines (I have a Hot MOD version of the N21BF), and if it needs it, give the engine a rebuild. Nova suggests a full teardown of the engine after the first four gallons, by then the engine should be properly broken-in.
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Old 08-16-2006, 06:33 AM   #6
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Once again...thanks for the help!

I stripped it down and found that the bushing on the bottom of the rod was coming apart, lots of nice little shiny things floating around.

I thought I would share in case anyone else has these same issues.
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Old 08-16-2006, 07:00 AM   #7
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It shouldn’t matter what the outside temp is within reason when breaking in a new engine as long as you are able to keep the engine up to temp, 200+*. Having a rod bushing go south is not uncommon in any engine. You might have caught this in time though! I would tear it down completely pulling bearings and all and clean everything up real good. If the bearings don’t have any play in them and the crank pin is still round and within spec, (4.97mm to 4.95mm) and there are no score marks in the piston & sleeve do to the metal shavings and is still a tight fit you might be able to just get a new rod and get her going again. IMO if you have to replace more than one item in an engine it is not worth it and is time for a new one like you said.
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Old 08-16-2006, 07:29 AM   #8
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Another thing you can do after you decide to rebuild it, is seal it up really well. We've have brand new motors with air leaks. Just use liquid gasket on any mating surfaces(base of the carb, around the backing plate, ect), and it should seal up and tune real easy, then run like new...
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