Took a plunge... trying a PP LXR250 EFI - Page 21

ChondaChondaChonda · 12-29-2017, 09:21 AM

So, I noticed a small oil leak coming from the front of my rocker box and decided to reseal it last night. While I was there it occurred to me that I haven't seen any information about the camshafts in these NC250 motors.

My tools aren't calibrated pro quality, so take all this with a grain of salt. I did the best I could with the tools I have. I printed a degree wheel which worked, but is probably not as large as it should be for accuracy.

What I found is that the NC250 rocker arms have about a 1.12:1 ratio.

The cam lobe lift on the intake is 0.267 in (6.85mm). Actual measured lift of valve was 0.303in (7.69mm)

The cam lobe lift on the exhaust is 0.277 in (7.05mm). Actual measured lift 0.311 in (7.89mm)

At 0.050 in the duration of the intake is about 217 degrees.
At 0.050 in the duration of the exhaust is about 222 degrees.

My confidence in these is lower than the lift numbers as the small degree wheel made is difficult to be 100% certain. They are ballpark.

Lobe separation angle using these numbers is about 110 degrees.

The overlap @ 0.050in is from about 4 BTDC to about 2 ATDC. Doesn't seem like much, but I dunno.

I'm not well versed in the intricacies of cams, but maybe some who are can glean something from the above.

Megadan · 12-29-2017, 12:31 PM

Very mild lift numbers and cam durations with a narrow LSA to help give it a bit more overlap for high RPM breathing. That looks about right given the powerband of these motors.

I am sure that bigger piston could benefit from a small regrind. If anything, a bit more valve lift definitely wouldn't hurt. Assuming the head can flow enough at higher lift values to see a gain.

ChondaChondaChonda · 12-29-2017, 03:25 PM

Quote:

Originally Posted by Megadan

Very mild lift numbers and cam durations with a narrow LSA to help give it a bit more overlap for high RPM breathing. That looks about right given the powerband of these motors.

I am sure that bigger piston could benefit from a small regrind. If anything, a bit more valve lift definitely wouldn't hurt. Assuming the head can flow enough at higher lift values to see a gain.

Yes, in comparing these to the 250x offerings on WebCam these are mild. The cams shown there have a bit more lift and durations @0.050 from 250 to 270. Of course they run much higher rpm too.

It would seem that something up to a 240/240 with a bit more lift might help. I really don't *think* we are close to air limited on either side of these heads. It would be interesting to flowbench the head and see.

There has been some discussion of sending a cam to Web to have them work their magic. Would be interesting.

ChondaChondaChonda · 12-31-2017, 02:15 AM

Seeing a nice warm day in the forecast we decided to get out to the high desert and ride some and finally get to see how the big bore worked in the real world.

Ran across a frozen burst irrigation pipe:

Anyways it turned out to be a great day. The snow was so dry it had no slipperiness to it even though it was in the mid-40s all day. Altitude ranged from 6100-7000 feet. Bike started better than it ever has.

Lots of variation in the terrain out here; we ran fire roads and whoops and single-track that was rocky and tons of weaving through the cedar trees. The extra power was noticeable right away as I gassed off the top of the first whoops. The front end was lifting higher and faster than it would before. The power band is ideal for running this terrain; a little blip of throttle or clutch fan would get the bike moving. The torque is so much wider that I could get lazy and not downshift because the motor would pull a gear higher easily.

Much easier to get up those tricky climbs that have a corner or deep g-out at the bottom just by grabbing a handful. EFI ran spot on all day. I only heard the fan come on once.

All in all I am very happy with the results. The bike is much more capable than the rider at this point. When we got back to the truck my riding buddy wanted to try it out, so here is the out-take from that little thrash festival:

pete · 12-31-2017, 03:50 PM

Quote:

Originally Posted by Megadan

Very mild lift numbers and cam durations with a narrow LSA to help give it a bit more overlap for high RPM breathing. That looks about right given the powerband of these motors.

I am sure that bigger piston could benefit from a small regrind. If anything, a bit more valve lift definitely wouldn't hurt. Assuming the head can flow enough at higher lift values to see a gain.

correct.. it has a very mild cam...
I would have thought the duration numbers would have been in the
high 200s to low 300s..
theres alot of room for a cam grind...

GlennR · 12-31-2017, 05:00 PM

I've decided to join the club.

Hopefully it's not too late to get the 2017 special.

I've got a bit of credit on my Paypal account so I'll order the BB kit as soon as I get the confirmation on the bike order.

I'm spending a lot of time away from my home in the mountains lately, so I will most likely mount some dual sport tires on it & break it in on the pavement for a while. I already have a pair od Shinko 244's that I almost put on my 2 stroke, before coming to my senses.

We can't plate dirt bikes in NC, so I will need to learn to go through SD or VT.

Happy New Year!

ChondaChondaChonda · 12-31-2017, 05:44 PM

Welcome to the Pitster Posse!

Keep us updated about the mods you make on yours. I really think that sharing the success and fail stories on these machines will go a long way towards getting more riders (especially younger) out there enjoying the trails. With a reasonable cost of entry, reliability and lower priced parts, these bikes can be the answer for many that want to ride, but can't afford to maintain an F1 race bike team.

I have a few more mods on the horizon and will post up what works and what doesn't. Planning to do a video on tear down and refreshing the front forks here soon. My suspension guru friend promised to guide me through it and tune the mid valve to better handle our lower speed technical climbs.

Congratulations GlennR! (BTW_ Pistster is advertising them locally for less than I paid. Almost want to pick up another, but 'she who must be obeyed' doesn't seem to want to agree.)

ChondaChondaChonda · 01-01-2018, 07:59 PM

My riding buddy sent me a text last week that linked to a classified ad for a "Rekluse for a Honda XR650". Guy had taken it out before he sold the bike and wanted to recoup some of his investment. Way cool part was I told him about what I was trying to fit it in and he offered up a full refund if I couldn't get it to work.

He had a cool collection of bikes in his shop and it's always fun to talk Baja stories!

That night I compared the Rekluse to some spare clutch fibers I keep on hand; the outside sprags were the same but the Outside Diameter (OD) was about 1mm to big.

ChondaChondaChonda · 01-01-2018, 08:04 PM

Today I had some free time on my hands and the wheels started turning.

I tore the clutch apart to see just what I was up against. Glad I did because I had some toast frictions in there.

The Rekluse EXP 3.0:

ChondaChondaChonda · 01-01-2018, 08:11 PM

Once inside I could see how close the XR650R (Not XR650L, which would probably fit)

I decided to forego the kind refund offer and try to modify the Rekluse to fit. They come apart quite easily and I soon found out that they are made of rather soft aluminium.

Once down to size the unit dropped right in:

ChondaChondaChonda · 01-01-2018, 08:21 PM

I had to decide if I was going to grind down the "fly weights" that make the Rekluse work. These are centrifugally driven wedges that push out on ramps that cause the unit to expand and engage the clutch.

After determining that I would leave them alone, I reassembled the unit using the springs that were used by the previous owner in his XR650R.

The Rekluse replaces several of the clutch frictions and plates due to it's thickness. I installed it as Rekluse recommends for and XR650R with one fiber and plate below it, then the Rekluse, then another plate and then the standard stack.

Trial and error were the order of the day. I tried several combinations of the new frictions and plates, finally settling on 5 total disks; 4 outside of the Rekluse. It would work with 4 total disks, but I would have to shorten the clutch rod again and I didn't want to grind anything down in case I just want to go back to stock. (WHich is easily done.)

You can see the sprags sticking out a bit further that the clutch friction sprags do here:

ChondaChondaChonda · 01-01-2018, 08:27 PM

After all the trial error seemed sorted out I put on a helmet and jacket and rode the bike down to O'reillys.

It really does work great. Makes the bike easier/funner to ride. I forgot how much I liked the Rekluse in my old 300. I tried starting out in 2nd and even 3rd from a stop- with no issues. (Just to see).

A top speed run on a flat section of highway and I was just touching 74mph. Hit 78 down a gully... Did 60-65 down to the parts store and it felt so right. Could easily run at those speeds for longer distances.

Can't wait to try this out off-road. Hopefully in early February we will get a chance.

nuggets · 01-07-2018, 10:00 AM

Watching!

ChondaChondaChonda · 01-12-2018, 03:43 PM

ben2go · 01-12-2018, 04:52 PM

Those forks are pretty nicely done up for a cheap bike.

12-29-2017, 09:21 AM	#301
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	Some information about the camshaft So, I noticed a small oil leak coming from the front of my rocker box and decided to reseal it last night. While I was there it occurred to me that I haven't seen any information about the camshafts in these NC250 motors. My tools aren't calibrated pro quality, so take all this with a grain of salt. I did the best I could with the tools I have. I printed a degree wheel which worked, but is probably not as large as it should be for accuracy. What I found is that the NC250 rocker arms have about a 1.12:1 ratio. The cam lobe lift on the intake is 0.267 in (6.85mm). Actual measured lift of valve was 0.303in (7.69mm) The cam lobe lift on the exhaust is 0.277 in (7.05mm). Actual measured lift 0.311 in (7.89mm) At 0.050 in the duration of the intake is about 217 degrees. At 0.050 in the duration of the exhaust is about 222 degrees. My confidence in these is lower than the lift numbers as the small degree wheel made is difficult to be 100% certain. They are ballpark. Lobe separation angle using these numbers is about 110 degrees. The overlap @ 0.050in is from about 4 BTDC to about 2 ATDC. Doesn't seem like much, but I dunno. I'm not well versed in the intricacies of cams, but maybe some who are can glean something from the above.
	1

12-29-2017, 12:31 PM	#302
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 8,110	Very mild lift numbers and cam durations with a narrow LSA to help give it a bit more overlap for high RPM breathing. That looks about right given the powerband of these motors. I am sure that bigger piston could benefit from a small regrind. If anything, a bit more valve lift definitely wouldn't hurt. Assuming the head can flow enough at higher lift values to see a gain. __________________ Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124
	2

12-31-2017, 02:15 AM	#304
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	About 40 miles of single track today. Seeing a nice warm day in the forecast we decided to get out to the high desert and ride some and finally get to see how the big bore worked in the real world. Ran across a frozen burst irrigation pipe: Anyways it turned out to be a great day. The snow was so dry it had no slipperiness to it even though it was in the mid-40s all day. Altitude ranged from 6100-7000 feet. Bike started better than it ever has. Lots of variation in the terrain out here; we ran fire roads and whoops and single-track that was rocky and tons of weaving through the cedar trees. The extra power was noticeable right away as I gassed off the top of the first whoops. The front end was lifting higher and faster than it would before. The power band is ideal for running this terrain; a little blip of throttle or clutch fan would get the bike moving. The torque is so much wider that I could get lazy and not downshift because the motor would pull a gear higher easily. Much easier to get up those tricky climbs that have a corner or deep g-out at the bottom just by grabbing a handful. EFI ran spot on all day. I only heard the fan come on once. All in all I am very happy with the results. The bike is much more capable than the rider at this point. When we got back to the truck my riding buddy wanted to try it out, so here is the out-take from that little thrash festival:
	5

01-01-2018, 07:59 PM	#308
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	Rekluse My riding buddy sent me a text last week that linked to a classified ad for a "Rekluse for a Honda XR650". Guy had taken it out before he sold the bike and wanted to recoup some of his investment. Way cool part was I told him about what I was trying to fit it in and he offered up a full refund if I couldn't get it to work. He had a cool collection of bikes in his shop and it's always fun to talk Baja stories! That night I compared the Rekluse to some spare clutch fibers I keep on hand; the outside sprags were the same but the Outside Diameter (OD) was about 1mm to big.
	0

01-01-2018, 08:04 PM	#309
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	But wait... Today I had some free time on my hands and the wheels started turning. I tore the clutch apart to see just what I was up against. Glad I did because I had some toast frictions in there. The Rekluse EXP 3.0:
	0

12-31-2017, 05:00 PM	#306
GlennR Join Date: Oct 2013 Location: Boone, NC Posts: 188	I've decided to join the club. Hopefully it's not too late to get the 2017 special. I've got a bit of credit on my Paypal account so I'll order the BB kit as soon as I get the confirmation on the bike order. I'm spending a lot of time away from my home in the mountains lately, so I will most likely mount some dual sport tires on it & break it in on the pavement for a while. I already have a pair od Shinko 244's that I almost put on my 2 stroke, before coming to my senses. We can't plate dirt bikes in NC, so I will need to learn to go through SD or VT. Happy New Year!
	1

12-31-2017, 05:44 PM	#307
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	Welcome to the Pitster Posse! Keep us updated about the mods you make on yours. I really think that sharing the success and fail stories on these machines will go a long way towards getting more riders (especially younger) out there enjoying the trails. With a reasonable cost of entry, reliability and lower priced parts, these bikes can be the answer for many that want to ride, but can't afford to maintain an F1 race bike team. I have a few more mods on the horizon and will post up what works and what doesn't. Planning to do a video on tear down and refreshing the front forks here soon. My suspension guru friend promised to guide me through it and tune the mid valve to better handle our lower speed technical climbs. Congratulations GlennR! (BTW_ Pistster is advertising them locally for less than I paid. Almost want to pick up another, but 'she who must be obeyed' doesn't seem to want to agree.)
	0

01-01-2018, 08:11 PM	#310
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	Another plunge. Once inside I could see how close the XR650R (Not XR650L, which would probably fit) I decided to forego the kind refund offer and try to modify the Rekluse to fit. They come apart quite easily and I soon found out that they are made of rather soft aluminium. Once down to size the unit dropped right in:
	0

01-01-2018, 08:21 PM	#311
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	I had to decide if I was going to grind down the "fly weights" that make the Rekluse work. These are centrifugally driven wedges that push out on ramps that cause the unit to expand and engage the clutch. After determining that I would leave them alone, I reassembled the unit using the springs that were used by the previous owner in his XR650R. The Rekluse replaces several of the clutch frictions and plates due to it's thickness. I installed it as Rekluse recommends for and XR650R with one fiber and plate below it, then the Rekluse, then another plate and then the standard stack. Trial and error were the order of the day. I tried several combinations of the new frictions and plates, finally settling on 5 total disks; 4 outside of the Rekluse. It would work with 4 total disks, but I would have to shorten the clutch rod again and I didn't want to grind anything down in case I just want to go back to stock. (WHich is easily done.) You can see the sprags sticking out a bit further that the clutch friction sprags do here:
	2

01-01-2018, 08:27 PM	#312
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	It works!! After all the trial error seemed sorted out I put on a helmet and jacket and rode the bike down to O'reillys. It really does work great. Makes the bike easier/funner to ride. I forgot how much I liked the Rekluse in my old 300. I tried starting out in 2nd and even 3rd from a stop- with no issues. (Just to see). A top speed run on a flat section of highway and I was just touching 74mph. Hit 78 down a gully... Did 60-65 down to the parts store and it felt so right. Could easily run at those speeds for longer distances. Can't wait to try this out off-road. Hopefully in early February we will get a chance.
	6

01-07-2018, 10:00 AM	#313
nuggets Join Date: Jan 2018 Posts: 1	Watching!
	2

01-12-2018, 03:43 PM	#314
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	Fork teardown in progress.
	1

01-12-2018, 04:52 PM	#315
ben2go Join Date: Jun 2011 Posts: 1,335	Those forks are pretty nicely done up for a cheap bike.
	1