352LikesNOVAROSSI Engine thread....
10-07-2012 | 06:33 AM
#4219
Hey guys, I have a Plus-4btt that has been absolutely bullet proof and been running fine for about 4 straight weekends until yesterday. I am running A Werks #6 plug in it with the stock Mugen clutch with the same OFNA 086 pipe I have been running this combo for 2 months. I have about 4 gallons on it. I was 4 minutes into the second 5 minute qualifier. I really have not touched the needles besides an hour here and there on the HSN each weekend and no flameouts over the last 2 months. The track had a long stretch and we twist the motors pretty good but all of a sudden the thing will die as soon as I let off the gas at the end of the straight 4 minutes into the heat. Motor was running perfect, nice and crisp, and only about 255 when i temped it.
I richened the top up a little bit, set it down to get 1 last lap in, made the whole 40 sec. lap and once again at the end of the stretch same thing when I let off the gas it just dies.
Repleced the plug and richened the LSN and increased idle gap, did the same thing in the 3 heat except earlier and in the 1st lap. Only dies at the end of the straight from being wide open for a good 3 to 4 seconds and then letting off to make sweeper curve? Idles fine, sounds great but keeps dying? I did not check it at the track, but maybe guessing front bearing? Need to tear into it tonight or tomorrow any ideas? We tuned on it the whole 3rd qualifier and the same thing no matter what we did. Also tried a #5 (hot) plufg and still did it?
Any ideas besides bearing or what would cause it to die after wide open throttle would help?
I richened the top up a little bit, set it down to get 1 last lap in, made the whole 40 sec. lap and once again at the end of the stretch same thing when I let off the gas it just dies.
Repleced the plug and richened the LSN and increased idle gap, did the same thing in the 3 heat except earlier and in the 1st lap. Only dies at the end of the straight from being wide open for a good 3 to 4 seconds and then letting off to make sweeper curve? Idles fine, sounds great but keeps dying? I did not check it at the track, but maybe guessing front bearing? Need to tear into it tonight or tomorrow any ideas? We tuned on it the whole 3rd qualifier and the same thing no matter what we did. Also tried a #5 (hot) plufg and still did it?
Any ideas besides bearing or what would cause it to die after wide open throttle would help?
check for dirt in the front bearing........ remove the bearing, pull the shields and do a rinse test on a white paper and see if any dirt flows out......Your at 4 gallons and my guess is your engine needs a little TLC..she probably has a little wear and tear that needs to be addressed...
Ok, the front bearing test failed for one. So I pulled it apart and it looked clean inside and the piston and sleeve look really good. Motor was still pretty difficult to turn over by hand. Clean as a whistle inside but I will pull the bearing tomorrow to see if any fine dirt has made its way in. I think the bearing leak had just started and relatively small.
Secondly, I get the bone head of the year award. I pulled off the air filter assembly and there was no venturi in it! I pulled it all off and cleaned everything and I guess forgot to put the 6.5 venturi back in it. That is the dumbest thing I have ever done. My problem was 2-fold. Front bearing starting to leak and a dumb #$% human error. It was tuned for 6.5 and didn't have it in there so no wonder it was lean. It was not lean bogging though and running great until it flamed once you let off the gas. Anyway, I need to get a bearing and replace it before this weekend. I think I should be good. I feel confident after looking at it everything is okay just a really dumb user error I will never make again!!!
New rule also. All my engines get new bearings no question asked every 2 gallons from here on out, maybe overkill but that is what I am doing.....
Secondly, I get the bone head of the year award. I pulled off the air filter assembly and there was no venturi in it! I pulled it all off and cleaned everything and I guess forgot to put the 6.5 venturi back in it. That is the dumbest thing I have ever done. My problem was 2-fold. Front bearing starting to leak and a dumb #$% human error. It was tuned for 6.5 and didn't have it in there so no wonder it was lean. It was not lean bogging though and running great until it flamed once you let off the gas. Anyway, I need to get a bearing and replace it before this weekend. I think I should be good. I feel confident after looking at it everything is okay just a really dumb user error I will never make again!!!
New rule also. All my engines get new bearings no question asked every 2 gallons from here on out, maybe overkill but that is what I am doing.....
Well, with new bearing, 6.5 Venturi, new c6tgc plug, the motor still did the exact same thing. New bearing and did the bearing test and the idle is completely unchanged. Drop it on the track and the engine is rockin! Running 250 and dialed. Same thing, about 4 minutes into a run it just shuts off at the end of the straight. We richened the HSN, leaned LSN and still did it. Did the opposite and still did it. Idles all day is smooth and crisp and just shuts off. We took it apart, everything is pristine, motor has a ton of pinch. Very tough to turn over by hand when cold, still really tight when warm. We spent 45 minutes with it this weekend and it did it every time after 3 to 4 minutes or running it. As soon as you are full throttle and let off the gas at the end of the straight it immediately dies. HSN really rich, or really lean still did it. Same with the bottom. Any ideas? I am lost with a barely broken in Plus-4btt and have never had a problem with any of my engines like this?
10-07-2012 | 06:41 AM
#4220
Well, with new bearing, 6.5 Venturi, new c6tgc plug, the motor still did the exact same thing. New bearing and did the bearing test and the idle is completely unchanged. Drop it on the track and the engine is rockin! Running 250 and dialed. Same thing, about 4 minutes into a run it just shuts off at the end of the straight. We richened the HSN, leaned LSN and still did it. Did the opposite and still did it. Idles all day is smooth and crisp and just shuts off. We took it apart, everything is pristine, motor has a ton of pinch. Very tough to turn over by hand when cold, still really tight when warm. We spent 45 minutes with it this weekend and it did it every time after 3 to 4 minutes or running it. As soon as you are full throttle and let off the gas at the end of the straight it immediately dies. HSN really rich, or really lean still did it. Same with the bottom. Any ideas? I am lost with a barely broken in Plus-4btt and have never had a problem with any of my engines like this?
what glowplug ?
how many head shims ?
it is possible you have some sort of fitment issue in there somewhere..... one odd one I have sen is where the top of the sleeve has some deviations and it causes the sleeve/head button to lose seal once it is heat soaked....... Flat sanding/stoning the top of the sleeve can correct this issue......
10-07-2012 | 07:49 AM
#4222
did you block the vacuum return port ?
what glowplug ?
how many head shims ?
it is possible you have some sort of fitment issue in there somewhere..... one odd one I have sen is where the top of the sleeve has some deviations and it causes the sleeve/head button to lose seal once it is heat soaked....... Flat sanding/stoning the top of the sleeve can correct this issue......
what glowplug ?
how many head shims ?
it is possible you have some sort of fitment issue in there somewhere..... one odd one I have sen is where the top of the sleeve has some deviations and it causes the sleeve/head button to lose seal once it is heat soaked....... Flat sanding/stoning the top of the sleeve can correct this issue......
Running stock .80 shims
I will try lightly sanding top of sleeve/head button and see what happens.
Sort of weird bc I did not touch the needles for 3 weekends or so. Did not take engine apart and it started doing this. I will find it. I am going to take it to the track and play around more with it. Have not plugged the vacuum port in it but I actually have the stuff from your video to do it....
10-07-2012 | 07:50 AM
#4223
The only thing we have not done is take the carb apart and check the orings...... I think I will take it apart. Maybe I crushed one when I was checking to see what needle settings I am at.....
10-07-2012 | 07:55 AM
#4224
Suspended
iTrader: (7)
Joined: Nov 2000
Posts: 1,012
Well, with new bearing, 6.5 Venturi, new c6tgc plug, the motor still did the exact same thing. New bearing and did the bearing test and the idle is completely unchanged. Drop it on the track and the engine is rockin! Running 250 and dialed. Same thing, about 4 minutes into a run it just shuts off at the end of the straight. We richened the HSN, leaned LSN and still did it. Did the opposite and still did it. Idles all day is smooth and crisp and just shuts off. We took it apart, everything is pristine, motor has a ton of pinch. Very tough to turn over by hand when cold, still really tight when warm. We spent 45 minutes with it this weekend and it did it every time after 3 to 4 minutes or running it. As soon as you are full throttle and let off the gas at the end of the straight it immediately dies. HSN really rich, or really lean still did it. Same with the bottom. Any ideas? I am lost with a barely broken in Plus-4btt and have never had a problem with any of my engines like this?
10-07-2012 | 07:57 AM
#4225
It is not bc CRE P5 ran 30 minutes straight in the main. OS Speed .19 & .21 ran fine for 4 tanks of fuel each early in the morning in practice. New lines, filter, tank is on the buggy.....
10-07-2012 | 09:47 AM
#4227
Have you used the same pipe on all those motors? Check your gaskets and give your pipe the hot anti freeze bath to clean the inside. 3-4 minutes makes it seem like their is something heat related. Maybe an o-ring that is torn in the carb, or varnish in the pipe that it getting hot turning to liquid and running into the pressure nipple and blocking the pressure line. Try a different pipe and see if it still does it. Also is the motor sealed up? Zip tie on the carb boot?
10-07-2012 | 12:10 PM
#4229
Tech Master
Joined: Jan 2010
Posts: 1,628
Well I had a similar problem today at the races.
My 21-4C was running allright in the first qualifying heat, everything was fine.
Then the second qualifying heat, it ran great "on the bench" while tuning, then in the warm up it ran great, and then four laps in it just stalled.
Third qualifying heat, replaced the plug, made sure to get it tuned properly, spent 10 minutes running it warm and all, then sure enough it was running great in the warm up, the first four laps it was awesome, and then it stalled and my mechanic couldn't barely get it running again.
In the seconds before it stalled, on both occasions, it seemed to all of a sudden go very rich, like it was very soft on power, just the kind of symptoms you get when an engine is really rich, soft in bottom, very "progressive" sort of throttle response.
My friend suggested that it could be a bearing issue?
I'm stumped for suggestions.
When cold, if I turn over the flywheel, it seems to have decent enough compression.
My 21-4C was running allright in the first qualifying heat, everything was fine.
Then the second qualifying heat, it ran great "on the bench" while tuning, then in the warm up it ran great, and then four laps in it just stalled.
Third qualifying heat, replaced the plug, made sure to get it tuned properly, spent 10 minutes running it warm and all, then sure enough it was running great in the warm up, the first four laps it was awesome, and then it stalled and my mechanic couldn't barely get it running again.
In the seconds before it stalled, on both occasions, it seemed to all of a sudden go very rich, like it was very soft on power, just the kind of symptoms you get when an engine is really rich, soft in bottom, very "progressive" sort of throttle response.
My friend suggested that it could be a bearing issue?
I'm stumped for suggestions.
When cold, if I turn over the flywheel, it seems to have decent enough compression.
10-07-2012 | 12:22 PM
#4230
Well I had a similar problem today at the races.
My 21-4C was running allright in the first qualifying heat, everything was fine.
Then the second qualifying heat, it ran great "on the bench" while tuning, then in the warm up it ran great, and then four laps in it just stalled.
Third qualifying heat, replaced the plug, made sure to get it tuned properly, spent 10 minutes running it warm and all, then sure enough it was running great in the warm up, the first four laps it was awesome, and then it stalled and my mechanic couldn't barely get it running again.
In the seconds before it stalled, on both occasions, it seemed to all of a sudden go very rich, like it was very soft on power, just the kind of symptoms you get when an engine is really rich, soft in bottom, very "progressive" sort of throttle response.
My friend suggested that it could be a bearing issue?
I'm stumped for suggestions.
When cold, if I turn over the flywheel, it seems to have decent enough compression.
My 21-4C was running allright in the first qualifying heat, everything was fine.
Then the second qualifying heat, it ran great "on the bench" while tuning, then in the warm up it ran great, and then four laps in it just stalled.
Third qualifying heat, replaced the plug, made sure to get it tuned properly, spent 10 minutes running it warm and all, then sure enough it was running great in the warm up, the first four laps it was awesome, and then it stalled and my mechanic couldn't barely get it running again.
In the seconds before it stalled, on both occasions, it seemed to all of a sudden go very rich, like it was very soft on power, just the kind of symptoms you get when an engine is really rich, soft in bottom, very "progressive" sort of throttle response.
My friend suggested that it could be a bearing issue?
I'm stumped for suggestions.
When cold, if I turn over the flywheel, it seems to have decent enough compression.