You are absolutely right, I corrected my post above showing the correct placement of the O-Rings.

GRP now has their user manual posted on their site. Here is the link in case you haven't seen it.

GRP User Manual

Bearing Size .21 GRP?
 

Picked up a .21 GRP tonight, looks good. I want to pop a Ceramic rear bearing in it but cant find the bearing size anywhere.. Anyone know what the size is?

Also the porting isn't so hot, so I'll probably port, smooth, and taper the sleeve. The back of the crank could use a knife edge job too, its a bit blocky and heavy. Once thats done this baby should sing for about 11 minutes!
:nod:

Rear Bearing Size....?

I've not had mine apart yet, but I'll bet the rear bearing is the same as the Ninja engine. Which is the same size as what goes in the V-Spec. Can't remember the size off the top of my head though...

Just remember once you start taking some weight off the crank, you're going to lose some torque...

smoothing the sleeve will not help the motor...exterior sleeve work adds zero power to these motors........... I would not touch the crank either........ my bet is you would lose HP not gain HP with the mods your propose.........Do not cut the sleeve, its a urban myth that sleeve mods add power !!!!

I always thought GRP where a bit rough on the cuts and machining.

they are somewhat rough the way they are cut... Very similar, if not identical to how my newest Sirio's are cut... The GRP sleeve and the Sirio sleeve look as if they were cut using the same machinery.....

The thing is where they are rough will not really affect performance, the key areas of the motor are machined just fine.... Most poeple look at the bottom of the ports and thing smoothing there will create better power, but the top of the port is much more critical, as when the piston first unshrouds the ports its the top of the port that gets opened first, by the time the piston hits BDC the crankcase has lost all its pressure and gas transfer has mostly stopped, most of the intake charge entered the chamber when the port was first opened and crankcase pressure at its highest......... GRP engines do look sloppy at the bottom of the port, but are well designed where it counts...the ports are nicely cut and well directioned, as well they have very good port timing............. Look into the exhaust port of a GRP mill and look how the ports are shaped and directioned, then you will see the real magic of these engines.......

GRP mod..
 

I'm not going to argue with your advise, as I've only been modifying my own motors for about 3 years. I'm sure you know whats up more than I. However I'd like to run something by you guys on the porting.
Its my understanding that when a sleeve is ported, tapered, smoothed and such.. that this increases flow at higher RMP. Also when the fuel charge is thrown from the crank upwards onto the sleeve, that their is a certain amount deflection off the bottom of an un-tapered sleeve. That being said, doesn't the deflection cause an inefficiency? If that deflection of fuel-air was reduced and the ports had a smooth clear path up into the sleeve, wouldn't that increase efficiency?! If you remove the inefficiency's of the motor however minor, you should be able to slightly lean the motor and keep the same performance, thus increasing fuel mileage. Fuel efficiency is the only reason to port a motor in my opinion, as power really isn't increased much at all. Is that an urban legend? Also I get 9-10 minute runs on my RB's at 230 after my mods. Before the mods its 8-9min I've proven this over and over and over again.

One more thing... how does a lighter crank = less power? In every kind of racing, drag racing through motocross, kart, F1, Nascar...ect etc... a lighter crank increases throttle response and efficiency, as it takes less fuel to turn a lighter crank. I do know from my own experience that too light of a crank can effect how an engine idles. Not enough mass to keep it turning... Timing, I rarely mess with except on the WS73 as it needs a bit of a closing side increase because the duration is a bit off on those motors and graet power increases can be made.

I don't know... could all this be BS... maybe:rolleyes:
Anyways, this GRP will probably be done as do my others, and I guarantee I'll smoke the stock guys out their.

Peace...

If you got it under control props to you, i had no idea you knew anything about modding..............my only to respond is because i see people mistakenly judge a motor by the fancy cuts on the sleeve, or in a Ninja's case lack of fancy cuts...... The Ninja is very advanced, you just got to know what to look for.....

Same thing here. I know from actual engine building, the weight of crank changes how fast it revs or makes power, but almost does nothing on the dyno as far as HP rating. Balancing is another aspect of the engine as it will climb RPM faster since it spends less effort wasted in drag or centrifical force to climb the power band. What you will see on a dyno is the power band smooth out compared to a jagged power band from a not so balanced engine that has certain orders of vibrations aligning at certain RPM's. Plus the throttle response feels more accurate when it balanced better. Add better fuel economy also. Right now, I know driver's who are after fuel economy, smooth power and accuracy. The engines are making enough power now, we just need to make use of it efficiently. Then again, we mostly run blue groove, dusty or loamy.

GRP moddd
 

Cool, thanks guys.

Ok, since we are on this topic.. you guys have to see this crank mod I did on a C6BB. It was code named (Starfish) for the quad turbo cuts. Oh man I laugh so hard when I see this thing. I ran it until the crank pin was worn out, it was done after abut 16 gallons. Fastest motor I ever ran, but I wont be doing this to my GRP!! :lol::):smile::D

http://i155.photobucket.com/albums/s...ndrc/CRANK.jpg

Oh ya anyone know for sure about the rear bearing size on the GRP?

I think its like the older Ninja. 14x25.4x6mm. Very common, unless they've changed it like Novarossi likes to every year or so.

Thanks.

One other quick question... Turbo plugs??? $11.50-$12.00 a pop for GRP's! Anyone know of another brand that will fit properly at a better price? I held a Novarossi plug up to the GRP, and thats a no-go as the conical is different shape and length. I know turbo plugs last long but come on! Help! Where do you guys stock up on plugs for this engine?:tire:

Well if the GRP's are the same as the Ninja, I've always ran OD97T with great results...

.

14x25.4x6 is the correct size. The tko bearings are the best I have used. I usually do not change the stock bearings till they go bad. That way you know the motor is fully broken in and there is no metal pinch left. The tko bearings last a long time when the pinch is gone.

Thats one of my gripes with this brand. The parts prices.

O.S. P3 plug.

nothing will ruin a GRP head button faster then a OS plug........ Do not run OS plugs in these motors.

I always ran p3's in my ninja and falcon with no problems.

Why is that?

Have to agree, why is that? I've been running O.S plugs in my Ninja without any issues what-so-ever. I routinely open my engines to ensure all is well, and I've not seen any issues.

Making a statement like that you need to back it with some facts or at least observations otherwise your statement is meaningless...

Thats because the taper on the OS and GRP plugs are different. They are close, but different. I've seen people use OS, GRP and Sirio plugs as interchangable, but they have some slight variations. I have seen someone screw a OS plug in a Novarossi and it pushed the top of the combustion chamber in, so now a Novarossi plug will never seal correctly in that button anymore.

Hmmmm, I don't buy that....

No offense, but I don't believe that or else GRP would make a point that you can ONLY use GRP plugs and thats not the case. They recommend their plugs but make no mention that its mandatory....

I think if an different brand of plug "deforms" the button head or threads, they would definitely make it clear that was the case. How many engines would be ruined this way...

With my ninja, I usually run the OS plugs, but have used mugen turbo plugs, and O'Donnell turbo plugs after an OS without issue...

I just compared my p3 to the plug that came in my GRP they look identical.

I don't think any company says you had to run their plugs, they expect you to. If you owned a Novarossi engine and screwed in the OS Turbo plug, you would see what I'm talking about.

Ive used OS plugs in a P5 and a Nova 28 no problems ran them in my ninja and falcon I actually ran for falcon and they told me to use them at the time.

Hopefully we'll solve this question pretty quick. I e-mailed GRP directly asking them about plug selection....

If Novarossi's are that temperamental, thank gosh I don't own one. I'll stick to my O.S, Mugen's, RBs, and GRPs!

I guess I don't know anything, then. LOL.

I have seen several Ninja motors with OS plugs pissing fuel...they are not the correct taper.... you can torque a OS plug to seal but it can mess up the button if you ever go to run a Ninja plug again... Every manufacturer has a slightly different taper on their plugs...OS plugs will leak in both Ninja's and Picco's, tho I do know many people who manage to use them anyways....... When you thread an OS turbo in tight into the Ninja button you can see a gap between the plug and the button if you look from the underside, as if the plug is a little to short to fully fill the taper..... But before everyone jumps all over me I still have seen OS plugs used successfully in both Picco's and Ninja's...but I have also seen just as many needing to replace their head buttons because the OS plugs damaged the button when they tried to get it to seal...Fuel bubbling out around the dam plug no matter how tight they tightened it..... Safe bet IMHO is to match the plugs to the motor and be done with it.....

All I can really add from experience about plugs is do NOT put an OS plug in a novarossi. You will for sure screw it up. McCoys are OK though if you cannot get novas...

I also advise using the plug recommended my the manufacturer. After all they designed the motors and the plugs and they for sure will work together.

My guess would be that plugs that work in Novarossi's and RB's should also work in GRP's, since they are all manufactured by novarossi. But dont hold that against me if im wrong.

Can someone tell me the factory needle settings of this motor?

My .21 was 3 1/4 out high, 4 out low.

Having had my .21 come set from 2 turns out from factory I had to get the settings off of another engine in order to get it running, as quite simply it was set way too lean on the top and too rich on the bottom.

Consequently the settings I used where:
4 Turns - HSN
6 1/2 - LSN (Carb Barrel Open)

They are on the rich side, especially the bottom but better that than too lean like mine was...

I no longer have the Ninja .21 and Ninja .28 engines....But when I ran the .21 motor these were my settings:

I run 30% Maxy's fuel, Ninja #6 plug (#5 plug in cooler weather), stock 7mm venturi, MSR1005 pipe & header and added one thin copper shim (0.004") to increase the deck height. LSN = 5.5 turns out, HSN = 4 turns out. When looking at the needles both are at the 1 o'clock position. Motor never ran over 250* once broke in. During breakin the motor ran at 280-290*.

I still have a 5-pack of Ninja #5 plugs. If anyone is interested email me at [email protected]

Best regards,

Blah blah blah I just bought a new engine, I looked at the GRP, held it's pretty orange box, looked at Mario Rossi's smiling mug, dreamed of being as fast as Drake, and realized I was about to be another victim of marketing hype.

Not saying it won't be a good engine, I'm just saying it's not gonna be kryptonite to the all the little supermen we already have.;)

Its been "Horizon Hobby" pumping the marketing hype up! They do that with all there stuff.

TBH guys I'd be very interested if where yo've got the needles set once runin too ??

Mines @

HSN 3 3/4 out
LSN 5 1/2 out (BARREL OPEN)

To be honest I still get the feeling the tops rich too, temps low and isn't topping out as i'd like yet. But she runs strong and I'm still learning the motor. I haven't had time to just test run it yet either, I'm always having to try and tune it in on race day :(

I run on a fairly open track with long straight, using 30% BYRON Gen2

Thanks Guys

I got to break in 2 GRP 21's Friday and race one of them Saturday. (One was in a truggy, the other in a buggy) Good engine for sure. Break in was effortless (no blown plugs, but the needles were too lean from the factory). Not one flame out on either motor and they both ran great all day Saturday. Temping 240-260 after 10 minute qualifiers (I expect these to go up a bit until the pinch is gone..much like my Ninja did). So far, I really like the GRP...very smooth with more top end (at least it seems like it so far) then the Ninja Bo1A. This motor is definately different then the Bo1A as well...the crank is epoxied and the sleeve looks a little different (from memory of my B01A), and the piston has a domed top (like a nova 21-5k). 9 minutes per tank in truggy (on a pretty open track with a lot of WOT pulls) - I know I got 9 minutes as I tried stretching a 10 minute qual and ran out of fuel:flaming:, and has plenty of power, but I think the strongest features of this mill will be the smooth powerband, ease of tuning, and long run times. Should be able to do 10 minute pit stops once she is broken in (depending on track of course). It is definately (less finicky they my 21-5kt). Running 53 pipe, 30% titlted green and OD97T plug (the only plug I ran in my ninja, and my current choice for my 21-5kt as well). OD plugs have never let me down

Plug Compare
 

Since no one seems to really know what plugs are similar/compatible, I'll figure this out for us. First close up look is a Novarossi vs GRP. Next I'll get a hold of an OS, then the ODOnl plug and we will see.

DO NOT use Nova plugs in your GRP! Strike #1.... RB and Nova are exactly the same taper so don't use those in your GRP either.

http://i155.photobucket.com/albums/s...eupcompare.jpg