NC250 Big Bore Kit

ChondaChondaChonda · 12-31-2017, 01:58 AM

I've been posting about the install of my "NC300" kit in my LXR250 thread, but I stated thinking that maybe some interested parties may not want to read through the whole 300+ post mess.

SO I will throw up this video and some pictures, please feel free to discuss further.

GlennR · 12-31-2017, 09:18 PM

Good idea. I'm sure I will have a question or two.

It looks like a fairly quick & simple project. How long did it take? Did you need to break the timing chain?

Does Pitster Pro sell the kit? I remember you ordered from ebay, but I saw that the seller there is from Utah also.

ChondaChondaChonda · 12-31-2017, 11:24 PM

Yeah, these motors are easy to work on. Especially with the radiators off the bike and out of the way. I believe the whole teardown and install took me about 2.5-3 hours, but I was taking lots of pictures as I went.

I also took the rocker box all the way apart; next time I would not remove the 2 10mm bolts with copper washers under them. These hold the rocker arm shafts in and it was unnecessary.

The cam chain slips off after you remove either the end bearing or you can unbolt the sprocket from the cam. I used a dental pick to hold it and fish it up through the cases as needed.

I probably overpaid for my kit; I saw it and jumped on it. I would talk to Pitster about getting a kit. In fact, I did ask them and was told that they "were working on something". I took that as " it might be a maybe someday thing" and was quite surprised when Pitster told me he had brought a few home in his luggage after I had mine ordered.

GlennR · 01-06-2018, 12:29 PM

Pitster doesn't have them yet. The ebay price does seem a bit steep, mainly the hefty shipping price. I'll run mine a while as a 250cc and wait for Pitster to sell them, since they gave me such a good deal on the bike.

I actually enjoy running a small engine hard, so I'm sure I will be plenty happy squeezing whatever the 250 has to offer.

I'm planning to do a lot of street riding in the beginning anyway, so I will probably want to upgrade the seat & get the larger gas tank first anyway. I'm also wishing for a rear rack & footpegs, so might try to find or fab something.

Btw, what saddlebags are you using? That's a nice size for the trails.

ChondaChondaChonda · 01-06-2018, 01:31 PM

How bad is the shipping?

It says $12.50 for me. Of course I am only 30 miles from the seller.

ChondaChondaChonda · 01-06-2018, 01:32 PM

I've actually looked around for a used RX-3 to big bore, just for kicks.

ChondaChondaChonda · 01-06-2018, 01:49 PM

Quote:

Originally Posted by GlennR

Btw, what saddlebags are you using? That's a nice size for the trails.

Giant Loop Mojave. I've put a ton of miles on the sides of these and they have been quite tough.
http://www.giantloopmoto.com/product/mojavi-saddlebag/

GlennR · 01-06-2018, 04:22 PM

Quote:

Originally Posted by ChondaChondaChonda

How bad is the shipping?

It says $12.50 for me. Of course I am only 30 miles from the seller.

It was about $45-50 the other day. I just now looked again and it has a "calculate shipping" tab instead, which makes it $23.50. That's a lot more reasonable. Somebody must have mentioned it to the vendor.

Btw, Pitster says my bike's shipping out on Monday & should arrive on Friday.

ChopperCharles · 02-06-2018, 10:53 AM

Once you big-bore an RX3, what would you do about the fueling? It's EFI, so you can't just re-jet and go.

Charles.

franque · 02-06-2018, 01:26 PM

The lxr can tune itself. There's a theory that the lxr has different cams, and it does have a self tuning ECM... If you did some (admittedly difficult) swapping to (as in from an LXR to an RX3) an lxr ECM/injection components, you might start getting somewhere.

ChopperCharles · 02-06-2018, 02:28 PM

I was thinking about this kit for an RX3, actually. I thought the FI was closed-loop for everything except small throttle positions. It doesn't have a wideband O2 sensor, I don't think. Or am I wrong?

Charles.

ChondaChondaChonda · 02-06-2018, 06:50 PM

On the LXR it is self tuning and has had zero issues with the big bore kit; in fact, it starts better than stock. Possibly because the compression ratio is higher and the valves are slightly unshrouded due to the bigger piston.

I'd really like to see someone try it on an RX3 and give us some feedback.

ChondaChondaChonda · 02-06-2018, 06:51 PM

Quote:

Originally Posted by ChopperCharles

I was thinking about this kit for an RX3, actually. I thought the FI was closed-loop for everything except small throttle positions. It doesn't have a wideband O2 sensor, I don't think. Or am I wrong?

Charles.

Even if it's a narrow band O2 sensor, the adjustments made in the tuning band are generally multiplied across the tables. It just takes a little longer to get it dialed in.

GlennR · 02-10-2018, 11:14 AM

I just noticed that they have the BB kits listed on eBay again.

2LZ · 02-12-2018, 05:18 PM

Quote:

Originally Posted by GlennR

I just noticed that they have the BB kits listed on eBay again.

I'm late to the party but do you have the link to this? I may just have to tear one of my RX3's down and give this a shot. Once the C4 is done, I'll be fishing for another project.

12-31-2017, 01:58 AM	#1
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	NC250 Big Bore Kit I've been posting about the install of my "NC300" kit in my LXR250 thread, but I stated thinking that maybe some interested parties may not want to read through the whole 300+ post mess. SO I will throw up this video and some pictures, please feel free to discuss further. Last edited by ChondaChondaChonda; 02-25-2018 at 02:27 PM.
	4

02-06-2018, 01:26 PM	#10
franque Join Date: Nov 2017 Location: Marseille, France -> Conakry, Guinea Posts: 1,481	The lxr can tune itself. There's a theory that the lxr has different cams, and it does have a self tuning ECM... If you did some (admittedly difficult) swapping to (as in from an LXR to an RX3) an lxr ECM/injection components, you might start getting somewhere. Last edited by franque; 02-11-2018 at 09:53 AM.
	0

12-31-2017, 09:18 PM	#2
GlennR Join Date: Oct 2013 Location: Boone, NC Posts: 187	Good idea. I'm sure I will have a question or two. It looks like a fairly quick & simple project. How long did it take? Did you need to break the timing chain? Does Pitster Pro sell the kit? I remember you ordered from ebay, but I saw that the seller there is from Utah also.
	0

12-31-2017, 11:24 PM	#3
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	Yeah, these motors are easy to work on. Especially with the radiators off the bike and out of the way. I believe the whole teardown and install took me about 2.5-3 hours, but I was taking lots of pictures as I went. I also took the rocker box all the way apart; next time I would not remove the 2 10mm bolts with copper washers under them. These hold the rocker arm shafts in and it was unnecessary. The cam chain slips off after you remove either the end bearing or you can unbolt the sprocket from the cam. I used a dental pick to hold it and fish it up through the cases as needed. I probably overpaid for my kit; I saw it and jumped on it. I would talk to Pitster about getting a kit. In fact, I did ask them and was told that they "were working on something". I took that as " it might be a maybe someday thing" and was quite surprised when Pitster told me he had brought a few home in his luggage after I had mine ordered.
	0

01-06-2018, 12:29 PM	#4
GlennR Join Date: Oct 2013 Location: Boone, NC Posts: 187	Pitster doesn't have them yet. The ebay price does seem a bit steep, mainly the hefty shipping price. I'll run mine a while as a 250cc and wait for Pitster to sell them, since they gave me such a good deal on the bike. I actually enjoy running a small engine hard, so I'm sure I will be plenty happy squeezing whatever the 250 has to offer. I'm planning to do a lot of street riding in the beginning anyway, so I will probably want to upgrade the seat & get the larger gas tank first anyway. I'm also wishing for a rear rack & footpegs, so might try to find or fab something. Btw, what saddlebags are you using? That's a nice size for the trails.
	0

01-06-2018, 01:31 PM	#5
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	How bad is the shipping? It says $12.50 for me. Of course I am only 30 miles from the seller.
	0

01-06-2018, 01:32 PM	#6
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	I've actually looked around for a used RX-3 to big bore, just for kicks.
	0

02-06-2018, 10:53 AM	#9
ChopperCharles Join Date: Feb 2018 Location: RDU, NC Posts: 677	Once you big-bore an RX3, what would you do about the fueling? It's EFI, so you can't just re-jet and go. Charles.
	0

02-06-2018, 02:28 PM	#11
ChopperCharles Join Date: Feb 2018 Location: RDU, NC Posts: 677	I was thinking about this kit for an RX3, actually. I thought the FI was closed-loop for everything except small throttle positions. It doesn't have a wideband O2 sensor, I don't think. Or am I wrong? Charles.
	0

02-06-2018, 06:50 PM	#12
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	On the LXR it is self tuning and has had zero issues with the big bore kit; in fact, it starts better than stock. Possibly because the compression ratio is higher and the valves are slightly unshrouded due to the bigger piston. I'd really like to see someone try it on an RX3 and give us some feedback.
	0

02-10-2018, 11:14 AM	#14
GlennR Join Date: Oct 2013 Location: Boone, NC Posts: 187	I just noticed that they have the BB kits listed on eBay again.
	0