Originally Posted by houston (Post 11287823)

i love working with the p5 style engines , they run pretty dam good , need a few upgrades from box stock but still a great engine , they do have a better front bearing in them these days though ;)

Originally Posted by megasaxon (Post 11288596)

Ran a 20 main saturday with my P5 in an MBX6T, pitted at 9:55, ran til the 20min mark and had a half track left to go. Finished my lap and ran 3 more laps and it ran out just after the start finish line. Lap times about 27 seconds...so i got roughly 11.5 minutes on a tank with it and they are stump pullers in a truggy. This was with a 7mm venturi and a 2084/21 combo, Werks lightweight clutch with alum shoes and 2 .9s and 2 1.0 springs, 13T bell

Originally Posted by houston (Post 11288762)

Great setup but change the pipe and you will be mo' happy

Originally Posted by shimano (Post 11291585)

Roma needle settings

Originally Posted by shimano (Post 11289600)

Wat are the needle settings for the Roma guys ( I know there all different). I am only getting about 7.5 - 8 mins, running 2069/21, 6.5 venturi, standard losi clutch. 2 Ali 2 comp. I think I have about 5 or 6 litres through it now. Also running 48 - 15 gearing.

Originally Posted by aznitronut (Post 11292158)

How big is the track you race on? 48-15 is a little odd, why did you go with that gearing?

Originally Posted by aznitronut (Post 11292148)

Stock 3 1/2 top. 5 bottom

Originally Posted by shimano (Post 11292273)

Do u know what latitude your at as these are miles away from my settings. I think I'm about 80 - 100 m above sea level

Originally Posted by shimano (Post 11292273)

Do u know what latitude your at as these are miles away from my settings. I think I'm about 80 - 100 m above sea level


What size Venturi r u using

Originally Posted by Muggydude (Post 11294809)

Yes. However, You might want to try a 2096ss pipe instead. It will be very similar, but with a little more power and run time. I love it on my plus 4c

Originally Posted by mjealey (Post 11271747)

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?

Originally Posted by Maximo (Post 11271920)

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...

Originally Posted by mjealey (Post 11272199)

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.....

Originally Posted by mjealey (Post 11295899)

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?

Originally Posted by Maximo (Post 11295915)

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......

Originally Posted by Aleq (Post 11295917)

Maybe you need to flush out your fuel delivery system, chek it for leaks.. Or even clean your pipe.. Build up can be the problem.

Originally Posted by mjealey (Post 11295899)

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?

Originally Posted by chopper82p (Post 11296111)

Ok, check your fuel tank and lines. If it happens 3 to 4 minutes every time, than it must be your fuel tank or lines.

Originally Posted by Eivind E (Post 11296774)

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.

Originally Posted by beidle99 (Post 11296410)

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?

Originally Posted by bigjayjay1 (Post 11296462)

I had a similar problem it was a pain turns out it was my clunker in my fuel tank at a certain level / certain jump she would run dry 'hung up 'and my motor would die - the five min mark.

Originally Posted by SEF (Post 11297490)

Is the only difference between the BTTA, BTT, and BTTS the bearings? Two steel for the BTTA, front steel and rear ceramic for the BTT, and dual ceramic for the BTTS?

Thanks.

Originally Posted by mjealey (Post 11297385)

Tried 3 pipes = OFNA 086, Nova 9886, Brand new never run OS 2090. Pipes are fine as I clean them and like I said I can throw any of the 3 OS .19, OS .21, CRE P5 and it is fine. I actually have 2 MBX6r's. 1 for practice, 1 for races and it does it in both and the other 3 engines will run for 2 hours straight. Tanks, lines are new.

And I actually completely tore down and cleaned the engine to put in front bearing before this weekend. Completely cleaned with no oily residue, assembled using Nova 1n2 oil.......

I have had engine modders, dealers in the south take a look at it and tune it at the track and some thing....

We have to be missing something simple right in front of my eyes..... I WILL find it. These engines are just pretty simple in the grand scheme of things hard to believe I am missing it, but I am.

Originally Posted by houston (Post 11297602)

Flush out hsn ;)

And be sure to use an external fuel filter , screen type best :D

Originally Posted by houston (Post 11297602)

Flush out hsn ;)

And be sure to use an external fuel filter , screen type best :D

Originally Posted by chopper82p (Post 11297698)

You sure you have good pinch? Like some have suggested, it may be a heat problem. Check for sleeve roundness when you have the piston in it. With just the piston and sleeve, slide it up and down and see how far the piston goes up the sleeve and report back.

If nobody can tune the engine, you have an issue with that engine. Maybe send it back to Novarossi and see if they can replace it? (make sure you have a c6tgc or c5tgc plug in there when you do send it back :lol:)

Check the rear bearing. Does the inner race feel tight or is there some play? Rear bearing should be tight, if not, it needs to be replaced and thats likely your problem, if its loose.

Originally Posted by chopper82p (Post 11297714)

Pretty sure if he has had lots of people trying to tune the engine, it can't be as simple as setting the HSN to flush, JMO.

Can't be a fuel delivery problem because it only is happening with his btt, his other engines are running fine.

Originally Posted by chopper82p (Post 11297714)

Pretty sure if he has had lots of people trying to tune the engine, it can't be as simple as setting the HSN to flush, JMO.

Can't be a fuel delivery problem because it only is happening with his btt, his other engines are running fine.

Originally Posted by houston (Post 11297802)

Flush out hsn not set hsn to flush

done by removing hsn, blow out fuel delivery system then restting hsn to 4 turns out from bottomed out