I have been lapping engines for many years now...I mainly only lap over tight engines and do tradition breakin for most engines.... And usually when I lap I only bring the engines to a normal fitment then do a traditional breakin from that point......However from time to time special circumstances come up where we do complete lapped engines, where they go from the bench straight to the track..... There are pro's and cons to all the different methods.......Usually for my own personal engines I lap the engines to 75% , then run a couple of short tanks on the breakin bench, then its on the ground and ready to race...

Thanks!

Well live and learn i guess... LOL.

I belive there are moore advantages to lapping pistons than just the runin prosess. Thats why i am interested in this method of doing it. For instance, i have found when lapping the sleeve to the block there can also be benefits :-)

I also started lapping engines because it takes so much less time to break them in. I usually run 2 tanks on the bench after lapping and it's ready to hit the track.

Rex

Loves my two benches

I uses an tacometer from my airplane days

Wrap the head and the top of the cylinder in alu tape.

Set the idlegab to approx. 2 mm

Preheat to 110 C

Start the engine and let it run a little high idle speed for 3 tanks at 10000 RPM.

Adjust the lsn to get an temp between 100 and 110 C

Check if the lsn isn't too lean by pinching the fuel line: the RPM MUST increase after a second or two. If the RPM right after the pinch drops or the engine stops, the mixture is too lean.

Next tank is at 12000 rpm and run one tank of fuel at that speed. Still adjust the temp using the lsn.

5th tank is 14000 rpm and now use the hsn to adjust the temp.

6th tank 16000 and 7th 18000. Some engine will be too hot at that speed with the head wrapped - if so remove some of it

The final and 8th tank is small burst of WOT and any other rpm range. Remember slow thottle movements.

After every tank let the engine cool down and preheat before next start.

Break in the engine between 15 and 25 C. If its colder use a heatblower next to the engine, so the bench and the surrounding air is approx. 20C.

Last week I had to pinch 2 P/S sets and when the guy did send them he emailed me that they were not the original pistons but Picco KSR pistons. When received it became all clear to me, he had 2 Sirio AAC sleeves and dit try to fit old Picco KSR pistons. He just grinded them down with sandpaper.... I know experimenting with old stuff is not bad but this was compleetle wrong. So do not try this at home.

Personally I use a Scotch Brite pad to fix pistons but also only to the engines with a to tight fit. We have seen that a some tight fit is needed to get a perfect runned in P/S set with a long life.

Hey
Im wondering if anyone knows a compatible on road manifold for novarossi keep off engines. Id like to use the break in bench. I got a nova on road manifold that didn't fit. How do you tell if the diameters are the same?

Then you did not get a Nova manifold or you try to put on the wrong end.

Why not bore the sleeve slightly instead of lapping the piston?

The sleeve is chrome plated and that plating is not very thick. You never want to mess with the sleeve, it is much easier to work on the piston.

Rex

The plating is thick enough to work on but the piston is much easier.
After pinching I do use a hone tool to create fresh crossed scratches, that will improve the lubrication and compression.

i just got my break in bench. What on road manifold are you guys using ?

First of all....lapping the piston, y'all are out of your mind.....lapping and snapping rods?! You shouldn't every go to full throttle on the break-in bench. It's to run 1/2 a gallon to 2/3 of a gallon at 1/3 throttle max as you just need to seat the piston into the sleeve. Also, fuel is crucial!!! The goal is to run the motor as rich as possible (lubrication to help piston gradually seat) but to get the temp high enough to burn the oil so it doesn't varnish and seize. This is 180-200*F. For this you should run airplane fuel or add 30-60ml of castor oil to a gallon of car fuel to get the temp higher and run as rich as possible.

Get a .12 or .21 (depending on size of motor you're breaking in) onroad header, and use your the pipe you're going to run.

For the guys complaining about the noise, get an empty gallon fuel jug and put it on the stinger and put a small hole in the top as a huge muffler. The same can be done with a large tupperware container to muffle the sound. Here was my setup for both of my FX motors last week.

I bought my bench used. I think it came with a nova onroad header

Novarossi 41016 :-)

And of course ALWAYS use the propeller cover :-)