Smashrc

Want to know what is the different for the R2102 gold and black? Which one is better? Is it worth for the $50 different?

https://www.amainhobbies.com/o.s.-sp...mg2039/p540545

https://www.amainhobbies.com/o.s.-sp...mg2048/p498360

dan_vector

iTrader: (27)

Just the gold head and carb insert. The internals are identical. It depends if you want the gold colored head or not will justify the extra cost! Performance wise the engines are identical.

YBSLOW

iTrader: (9)

I have a couple of each, I can not find any physical difference other than stated above. However the Gold head absolutely runs better? No idea why both broken in on ebis system and both are fantastic.

Roelof

Maybe a better selection of piston and sleeve

dan_vector

iTrader: (27)

I've bought two identical engines before now and one appears to be better than the other it's not unheard of. I would think that it is coincidence that the Gold head in your case runs better than the 'standard' edition.

BigC2007

iTrader: (9)

Hey Dan it could be the weather, carb setting and glow plug that make it seem its running better.

dan_vector

iTrader: (27)

Maybe but I've run them both on the same day with the same results. It does happen even with the tight manufacturing tolerances available today! I have to say though that both engines ran great but one just seemed to have the legs on the other one. This even happens with 2 identical brushless motors too so it's not unusual.

ralphierace13

iTrader: (5)

I will tell u guys y, and this is true also for your regular street cars also. I used to have a cousin that worked at ford when I was younger. ok so they start a production run of lets says 500 motors. now to cut out a motor the machines that cut the blocks and pistons and so on, like everything else those machines that do the cutting have pieces that ware out as the production goes on and after every x amount of cutting the pieces need to be changed weather its blades or water jet nozzles or so on they dull, so lets say the fist 50 motors cut from the new blades or nozzles and so on will have the sharpest edges or cuts or lines so naturally the motors that are cut from the new blades or nozzles or the first motors that are cut right after they change the pieces will be faster. believe it or not. one time my family bought 2 of the same cars and so happens my car was a beast compared to my sisters car so after finding out the production numbers mine had a lower number. so something to think about..

BigC2007

iTrader: (9)

Thanks like the old saying ...... dont buy a car that was made on a Friday or Monday.

Roelof

With standard production cars that is possible because no matching is done. With racing cars pistons are matched with the cilinders. Ofcourse piston rings will take care of the gaps between piston and sleeve but still a perfect size piston hardly needing a piston ring will work better, that is why F1 engines as an example are heated up first before starting, just to prevent a tiny bit wear on the piston with a cold start to keep the perfect fit.

With our engines all comes to microns which is impossible to get produced out of the machines. Even after grinding the sleeves and pistons still a matching of piston and sleeve is done so after seveal processes it is unclear which parts you have from which timeline of the production.

As mentioned by me, the goldhead could have better mached parts for an optimised performance.

ralphierace13

iTrader: (5)

roelf lets break that down cause that don't make sense first off os is not making f1 custom engines for each client they are a factory that mass produces these motors they cut 100 blocks 100 sleeves and 100 pistons and so on and on the factory line as they some out there is a cute little Mexican guy that most likely don't have according to trump his citizenship and he assembles the motors as they are made. second u want to say the gold head is better matched then the black head so how can that be does the guy who assembles the gold head have better reading glasses then the guy with the black head u see what I'm getting at the motors are just assembled and the heads slapped on so there no way they assemble one unit and say oh this is for the gold head. further more I really hope u don't believe that these mass producing companies are sitting there matching these units !! lol

Roelof

With the assembly there is a kind of guideline of how far the piston needs to go into the sleeve until the pinch comes in. If it is in a certain window then it is ok. If not then another piston or sleeve will be tried.

But there is also a perfect height what makes the break-in easy with just taking away the piston its surface roughness with not too much left over pinch or a too low pinch.
If you have several normal engines new out of the box you will notice differences in the pinch, if you have engines with a selection proces from Ielasi, MAX or the early JP then all will have a same height where the pinch comes in.

During the assembly this perfect fit is easy to put aside for the goldhead engines.

I can not say this is really done at OS but several engine brands do select P/S matching sets so there is a highly chance the more expensive goldhead does have selected P/S sets.

Smashrc

The gold head is actually like $50 cheaper then the black head now. So, cannot be wrong getting the gold head.

ralphierace13

iTrader: (5)

[QUOTE=Roelof;14945916]With the assembly there is a kind of guideline of how far the piston needs to go into the sleeve until the pinch comes in. If it is in a certain window then it is ok. If not then another piston or sleeve will be tried.

But there is also a perfect height what makes the break-in easy with just taking away the piston its surface roughness with not too much left over pinch or a too low pinch.
If you have several normal engines new out of the box you will notice differences in the pinch, if you have engines with a selection proces from Ielasi, MAX or the early JP then all will have a same height where the pinch comes in.

During the assembly this perfect fit is easy to put aside for the goldhead engines.

I can not say this is really done at OS but several engine brands do select P/S matching sets so there is a highly chance the more expensive goldhead does have selected P/S

impossible your either talking that for the piston to go up to a certain height and stop so either the piston diameter is too small or too big or its the sleeve pinch causing the piston roelof there is no way from piston to piston of sleeve to sleeve there can be such a measurable difference just cant happen, then what if u say is true think of all the other things that could be wrong such as where the bearings sit the opening could be bigger and the bearing would fit looser or tighter on different blocks, carb openings would be different motor to motor cause if what u say is true then it don't just apply to piston and sleeves every aspect of the motor would be different that is impossible!! no way....
also there is no way they set aside the better ones for the gold head for what reason the gold head is not sold as a better motor or sold as a modified motor it just don't add up.
bottom line some motors are just cut sharper like I said and certain ones get the luck of having the sharper pieces put toghter...

Roelof

The taper of a novarossi sleeve is about 0.3 degrees with the length of 32mm
Over the 32mm there is a diameter change of 0.15mm, that is 5 micron per mm height.

With Novarossi it is almost ideal to have a pinch starting 6mm from the upper edge of the sleeve. From experience I can tell you that 1 mm more or less will result in a complete different break in process resulting in still a lot of pinch or no pinch. That is just +/- 5 micron.

Finding machines that have a tolerance within a few microns with a reasonable production time is hard and pricy so the litle time spend with fitting pistons in sleeves is pinuts.