Originally Posted by ezveedub

I personally stop tapping in bearings with puller/installer. I'll yank out old bad ones if I have too, but never tap them in only if its a light tap in a hot case to make sure them are seated. It is much better for me to remove the bearings and install them by heating the cases. I personally have not found any gauling. I'll find maybe some grey or dark residue that wipes out with a rag. I tap bearings out on wood block when the case is hot, and I freeze the crank and bearings and install them in a re-heated case. They simply drop in. The heat/freeze shrink method works the best for me.

Originally Posted by mremtr

Well , on the bearing failure issue , This is what I have noticed on EVERY SINGLE ONE ,(premature failure), First thing was that there was gauling in the engine case under the top left portion of the case (looking at the bearing from the rear it would be between 10 and 11 on a clock). Now this was only on the ones that failed early. I saw it on 2 Novarossi's and on EVERY SINGLE O.S. ! And I changed a bunch of OS bearings before they were ever even started and it was the same there too. So I think the trouble is NOT REPEAT NOT the bearing it self but in the installation !! These bearing are being pressed in cold ! This is the only way you get this gauling effect, plus the build-up of excess material under one side of the bearing is stressful on it ,thus failure prematurely.
Any of you guys doing your own bearings LOOK FOR THIS !! If you see it then you need to clean that material out of there so the bearing can sit flat on the seat it was designed to fit on.Be careful not to gouge anything up doing it though, I use a very sharp exacto knife and then polish it up if needed.
Always use the crankshaft to aid in the installation too. After the bearings are installed lube the heck out of it and let it cool before removing the crank.
Make sure the crank spins super free too before letting it set to cool off.
Once in a while you need to give it a light tap to seat the rear bearing completely.

Originally Posted by mremtr

I hope there wasn't a ton of confussion? I heat the case to remove the bearings and to install them ! I NEVER pull a bearing out with out heating first.
It makes it much easier to remove the dang things. Also note: you need to be VERY careful afterthe bearing is unseated as it will get cocked in the case and you take a chance at damaging the sharp edges inside were the rod clears. So PAY ATTENTION. I use the crank as a guide to put them in and take them out (actually I use a modified junk crank as a guide to get them out).
Make sure you completely strip the engine of any carb seals ,even the cinch bolt ,as it has seals too, then heat that sucka up ! 375-400 degrees works best for me.
As for freezing , I have gotten good enough that I don't need that extra time frame to get things just right anymore
But you guys trying it for the first time may get yourself a few extra minutes to get it all correct. JUST REMEMBER !! DON'T FORCE ANYTHING !!!! And make sure the piston is at TDC before you remove the back cover !!!
NOT BDC !!!!! Or you will most certainly break the piston skirt !
And remember cleanlyness is next to godlyness so in other words keep things CLEAN!

Originally Posted by nobike

No offense but i only use Novarossi engines and i always will but your wrong about the bearings issue 5% I dont think so, i race at REV all the time and can let you meet another 3-4 people that bought brand new motors and have the same bearing issues, i have four 21-5k and two 367 and three 21-5 and all the bearings seem to go out around the 2 gallon mark and the three of my motors i put aftermarket bearings in before i ever fired them up have 0 issues with bearings one has 4 gallons on it and the other has 6 gallons, again i will always run these novarossi motors nothing in this world is perfect but if these motors had better bearings they would be a perfect 10 BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS-BEARINGS.......................................

Originally Posted by Rocket42

Be careful freezing ceramics, I tried to freeze some ceramic bearings the first time I tried to replace bearings and the freezing process ruined the bearing. Just something to consider others may have done it without fail

Originally Posted by houston

it appears you know a few senseful things about nitro engines also mremtr ! sounds like you may have screwed up a few before getting it right as most of us have and as far as the pressing in the bearings cold at the factory , i wouldnt say for sure that they do , but i would think that they would be wise enough at the novarossi factory to use a certain temperatured block to install the bearings as i do
cobraracing; i also have noticed the same thing with the 9 ball bearings as opposed to the 11 ball offset plus bearings
bottom line , nova has the bearing issue figured out , i just dont know how long it will take to excise all their dated stock
until next time ,
monty

Originally Posted by mremtr

Well you may be correct, LOL , I had a V-Spec almost get me on the bearing coming out, it was a real pisser, but I did manage
I have seen this damage after a few newbee's brought there engine to me and asked if I could fix them.I started out with marine engines and then planes, before I got into the r/c cars.
Been doing this for WAY TOO LONG I worked for one of the best 2cycle engine modders ever (motocross) when I was 17 , and that was way over 20 years ago LOL Dam I'm too old to being playing with toys......

NAHHH !!
I'm working on getting a 5axis cnc just so I can carve up things , (aerospace hydraulic systems) and I might even make a few sleeves while I'm at it LOL.
Time will tell as will the economy.

Originally Posted by houston

nice ! i would make a progressively larger set of pistons if i was a machinist !! hint hint