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Old 05-04-2015, 08:43 AM
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Old 05-04-2015, 10:31 AM
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Hello all,

I am having a bit of a trouble with my nova 21-4. This weekend I was running in the thirty minute main and it was running awesome, great power everywhere all day and great smoke. About 20 minutes into the main I came in for fuel and everything was great but when I left pit lane I had almost no bottom end. When I gave it throttle it had a flat spot right off the bottom then it would rev out like normal and have great top end. There was still smoke all the way through and the glow plug was new that race. I am running byrons 30% like I always have and my temps were a solid 230-235 all day long. I'm not sure what could be going on. Any help would be appreciated.

Thanks in advance.
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Old 05-04-2015, 01:22 PM
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Originally Posted by gmkiller1967 View Post
Hello all,

I am having a bit of a trouble with my nova 21-4. This weekend I was running in the thirty minute main and it was running awesome, great power everywhere all day and great smoke. About 20 minutes into the main I came in for fuel and everything was great but when I left pit lane I had almost no bottom end. When I gave it throttle it had a flat spot right off the bottom then it would rev out like normal and have great top end. There was still smoke all the way through and the glow plug was new that race. I am running byrons 30% like I always have and my temps were a solid 230-235 all day long. I'm not sure what could be going on. Any help would be appreciated.

Thanks in advance.
Did it continue to do this thru the rest of that tank or just when you left the pits... If it was just the once, I think maybe either the cool fuel hit the carb and acted a little funky or your pit man did an amazing job getting you every drop in the tank and when the lid closed, it may have forced some into the carb and it loaded up.....
If it was a one time thing, I wouldn't worry about it...
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Old 05-04-2015, 06:26 PM
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Originally Posted by Jerm13 View Post
Did it continue to do this thru the rest of that tank or just when you left the pits... If it was just the once, I think maybe either the cool fuel hit the carb and acted a little funky or your pit man did an amazing job getting you every drop in the tank and when the lid closed, it may have forced some into the carb and it loaded up.....
If it was a one time thing, I wouldn't worry about it...
At first I was thinking it was the cool fuel into the carb but it continued until the last minute of the race. I was able to finish the race but without low end power. It makes no sense. I did flame out on the last turn but was able to roll across the line to finish and once I was done my pitman grabbed my car and it instantly started back up. It was still doing the same thing though.
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Old 05-05-2015, 12:59 AM
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Originally Posted by gmkiller1967 View Post
At first I was thinking it was the cool fuel into the carb but it continued until the last minute of the race. I was able to finish the race but without low end power. It makes no sense. I did flame out on the last turn but was able to roll across the line to finish and once I was done my pitman grabbed my car and it instantly started back up. It was still doing the same thing though.
Check your pressure line
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Old 05-05-2015, 04:37 PM
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Sound like weak plug, maybe the tune is very lean, new plug will not last...
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Old 05-06-2015, 12:12 AM
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Originally Posted by houston View Post
Check your pressure line


Replaced pressure line and fuel line just incase. Put new plug clutch bearings and clutch shoes on. Fired it up and same thing runs awesome for a while then just out of no where no low end.
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Old 05-06-2015, 12:56 AM
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Originally Posted by gmkiller1967 View Post
Replaced pressure line and fuel line just incase. Put new plug clutch bearings and clutch shoes on. Fired it up and same thing runs awesome for a while then just out of no where no low end.
I have had engines with severely scored P/S set run pretty well cold then lose all bottom end once they warmed up because all the compression was gone.

Did you lawn dart it really hard?

Wrist pin clip pop out ?

You might want to pull the P/S and check.
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Old 05-06-2015, 01:44 PM
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Originally Posted by JsK View Post
I have had engines with severely scored P/S set run pretty well cold then lose all bottom end once they warmed up because all the compression was gone.

Did you lawn dart it really hard?

Wrist pin clip pop out ?

You might want to pull the P/S and check.
Well it's not that I lose bottom end as soon as it gets warm. It's happens after 20-30 minutes of driving. But I did take the engine apart to have a look. Everything is in tack inside and the piston and sleeve have minimal metal pinch when cold. Bearings are free moving and nothing looks out of normal. I don't think I pulled a lawn dart moment but it could have happened. When I put the engine back together I seal it and performed a leak test. No leaks found so I put it back in the car. Haven't ran it yet due to weather but as soon as I do I'll pass it along.

Thanks to everyone so far that has helped.
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Old 05-06-2015, 05:59 PM
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Originally Posted by gmkiller1967 View Post
Well it's not that I lose bottom end as soon as it gets warm. It's happens after 20-30 minutes of driving. But I did take the engine apart to have a look. Everything is in tack inside and the piston and sleeve have minimal metal pinch when cold. Bearings are free moving and nothing looks out of normal. I don't think I pulled a lawn dart moment but it could have happened. When I put the engine back together I seal it and performed a leak test. No leaks found so I put it back in the car. Haven't ran it yet due to weather but as soon as I do I'll pass it along.

Thanks to everyone so far that has helped.
20-30 minutes is a long time. It may be getting a little low on compression. 4 port novas are kinda weird on torque anyway. Sometimes they feel perfect and some time they feel low on torque. It might be a good idea to get it resized from raya and or you might be a little lean on the top end.causing it to be a bit rich on the bottom and so when it gets warmend up all the way it goes flat or you may be rich all around. 230 is a bit cool for 20 minutes. I would lean the bottom and make top flush. and slightly lean top until iit runs good. Hope this helps. I have had that happen before and its never easy to know exactly what causes it.
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Old 05-06-2015, 07:42 PM
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Originally Posted by gmkiller1967 View Post
Well it's not that I lose bottom end as soon as it gets warm. It's happens after 20-30 minutes of driving. But I did take the engine apart to have a look. Everything is in tack inside and the piston and sleeve have minimal metal pinch when cold. Bearings are free moving and nothing looks out of normal. I don't think I pulled a lawn dart moment but it could have happened. When I put the engine back together I seal it and performed a leak test. No leaks found so I put it back in the car. Haven't ran it yet due to weather but as soon as I do I'll pass it along.

Thanks to everyone so far that has helped.
That's good to hear, hopefully its just a tuning issue.
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Old 05-06-2015, 11:05 PM
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I also have issues with my old keep off 4 , it's perfect from maintenance point of view, no air leakages and new biella is installed also front bearing. I'm getting a good tune in 10 minutes on about 105 Celcius and then after 15 minutes of run on the track i get too lean low end with temp rises 115-120 Celcius. Car is not drivable with lean low end. When i go to rich it out temp is dropping below 100 Celcius and flame out because of too rich low end. This phenomenon is end of life of piston and sleeve, this is how more experienced racers explain to me this issue. Compression is vary after certain time running or if temperature rises a certain point. I think is reasonable after 60-80 liters of consumption and something to expect.
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Old 05-07-2015, 01:42 PM
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I ran my first p5 this past weekend. And I must say you don't need anything else in a buggy (8ight 3.0) . This thing screamed down the straight away with the os and keep offs I couldn't believe it. Granted this is not my first nova (which was keep off 7) but I'm in love with this engine. 9886 41021 combo

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Old 05-07-2015, 02:33 PM
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Check that you clutchsprings are new. It could also be that your engine is slightly lean, so it runs hot after some time.

Test this also:
Take brakecleaner and spray right in front of the enignes front bearing. If it dies, and your front bearing is nwe, you have a worn crankcase/crankshaft. If you do, use the Buku crankcasecap. I have used it on many enignes having problems, but moastly they have a tuningproblem

Please give feedback:-)
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Old 05-07-2015, 04:29 PM
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Hey all! With a fully broken in engine cold, will it still be hard to turn the flywheel/crank over by hand? Right now I still cant turn my Nova over when its cold by hand but everytime I run it I notice its getting a little bit easier to turn when cold each time. Is there a point when it stops wearing in and the turn over pressure needed is the same? Will it ever get very easy to turn over cold?
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