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.

Excuse me if this has been suggested ... whats the condition of your clutch system?

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.

From my understanding, you nailed it.

Flush out hsn

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

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 )

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.

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.

The HSN is what we were thinking at the track actually. It is the only hting we have not checked and didnt have time to play with it anymore at ht etrack as I threw in another engine and raced. I tried the stock Mugen clutch, and a Werks clutch to no help. This motor is dialed as far as tune goes. It will idol all day and for 4 minutes it is super sharp and a strong top end it just flames after holding it full throttle about 4 minutes into the run.

I have taken it apart and clean as a whistle. It looks phenomenal. You can barely turn it over by hand and when hot it isn't much easier. Has a ton of pinch as the motor a few races ago only began to really wear in and run really well. Do not have time tonight but maybe it is the HSN. Done many tests and while puzzling it for sure is not clutch, fuel lines, fuel tank, or pipes. I will dig into it more tomorrow night.

The front bearing is brand new and passes bearing leak down test with flying colors. The rear bearing is perfectly smooth as butter. I know it is not bearings. Last resort is to take the carb completely apart.....

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

Ohhh

Maybe pull the carb off the P5 and try it on the BTT, see if that solves the problem, if it does, then you know its your carb.

I might so that too as the P5 will run all day. Just something stupid and I will figure it out probably....

Sometimes at the track you get stuck one-minded it is the tune. We did try several things to rule out glow plug, clutch, pipe, fuel delivery but anywho..... I am going to look at the carb next.

Like houston said, flush the HSN, but try that P5 carb first.

trying out a hudy break in bench has anyone got any suggestoins when running in nova engines on this thing??
cheers

so my btt started to idle like crap and was stalling and after blowing two nova 6 plugs, so at the end of the day I took apart and noticed 3 or 4 heavy scratches running down the piston.
could this be the result of the element in the plug dropping out???
either way it needs a new piston and sleeve