2012 XC/Harescramble 250R Build

[mx91a]

I thought I'd like to share what I have been working on lately, converting my old MX 250R to a woods warrior which I will be racing with in some PA harescrambles this year. Basically the only major components I will be carrying over from the MXer are the frame and swingarm. The frame is a PRP 88-89 replacement and the swingarm is a Roll Design MX. For the front end I luckily found a set of Gibson +1 long travel a-arms at East Coast ATV. The steering stem is a +2 aftermarket. Here is a picture with the major components installed:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0166.jpg

I was never happy with the stock 88-89 swingarm, linkage and shock setup, I just felt like it didn't have enough travel, especially down travel. So I stumbled across an Elka 450R dual-pro linkage and long travel rear shock and decided to make them work with my frame and swingarm. The main modifications I had to do to get the geometry just right was relocate the linkage mount on the swingarm back about 3/4" and lower the shock mount on the frame and move it forward slightly. It should be good for about 11" of travel with the short MX swingarm. Here is a picture of the setup:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0168.jpg

A close up of the front suspension, Elka fully adjustable shocks, lengthened and re-worked by DeRisi Racing; 19.5" long with 6" of shaft travel good for ~10" of wheel travel

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0160.jpg

Side shot:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0165.jpg

I'll post some more pictures soon of more work I did over the weekend. Let me know what you guys think I'm open to any suggestions to make this R as good as she can be in the woods!

[dustinshuler]

Looks awesome! Can't wait to see it come together! Glad to see people posting their builds!

[J250r]

I love all these builds lately!

This looks like another good one, I'm tuned in for sure

[FL-R]

Were did you get that rotor guard

[Honda 250r 001]

How does the linkage ratio on the 450r compare to the ratio on the 250r?
If wheel travel was what you were worried about. You can set up a stock 250r rear shock with stock 86 linkage to produce 10.5 inches of wheel travel with a short swingarm. I was just wonderin if the ratios were that much better to make it worth while to modify a frame for the 450 linkage.

[hawaiiysr]

x2 on the disc guard. where, how much, and install pictures please

[mx91a]

I got the disc guard as part of a kit on eBay a while ago that included a dual sprocket guard as well for about $200. Both are made by blingstar and the disc guard is part number Q-TRX250R-DG with the rotor guards being for a 450R. A quick search now shows the kit and disc guard alone are still available but the prices have gone up a bit. I will post some close up pictures tonight of the disc guard and sprocket guards with modified CR250 chain guide!

[mx91a]

Originally posted by Honda 250r 001
How does the linkage ratio on the 450r compare to the ratio on the 250r?
If wheel travel was what you were worried about. You can set up a stock 250r rear shock with stock 86 linkage to produce 10.5 inches of wheel travel with a short swingarm. I was just wonderin if the ratios were that much better to make it worth while to modify a frame for the 450 linkage.

I'm not sure exatly how the linkage ratios compare between the 450R and 250R as I have not seen a chart of the 250R's linkage ratio plotted out versus wheel travel. If you have this data and could provide it to the community I'm sure someone could benefit from it. I have heard that the stock 450R shock and linkage has not so much travel and a real hard progression at the end of the travel resulting in a bucking. This is why I went with the aftermarket dual pro linkage as it is designed for a smooth progression curve and increased wheel travel. I have no doubt you could modify the stock 250R shock for increased wheel travel but how is the stock linkage going to respond outside of its intended design range? Another good thing about the 450R setup is it uses all needles bearings for a nice smooth action and the aftermarket availability of linkages with different travels and leverage ratios is great for tunability. The one thing I don't like is how low the linkage hangs and that is the caveat of a long shock linkage setup but it is solid aluminum and sits higher than the rotor/sprocket guards so hopefully it will hold up. If it doesn't work out like I hope I will probably switch to the old XC standby no-link but it's nice to try to outfit the R with some modern suspension to give her every edge possible on the newer machines!

[norcalduner]

Nice looking bike. Can you post some close up pics of how the rotor and sprocket guard are mounted to the swingarm please?

[mx91a]

Here are some closeup pictures of the sprocket and rotor guards as requested.

The rotor guard replaces the stock rear caliper stay that mounts to the bearing carrier with the large circlip and is pinned to the swingarm:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0222.jpg

Here is the dual sprocket guard setup with modified CR250 chain guide feeding it, lets see the chain jump off this!

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0224.jpg

Top down view:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0225.jpg

I chose to go with the guards instead of a skid plate because the swingarm doesn't have mounts for one, I like the idea of keeping the chain guide instead of the flat plastic on the bottom of the skid plate and I think the guards will have less of a tendency to hang up in the ruts.

[FL-R]

I want that rotor guard, any link to where I can get one. I'm converting my mx bike to a xc bike.

[red88r]

http://www.blingstar.com/default.asp

[mx91a]

Here is an update from a couple days ago, making some progress:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0208-1.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0210-1.jpg

Fourwerx carbon fiber shock guards fitted on the Elka shocks. It was a lot of work to adapt these to the Elka bottom rings but I think it was well worth it!

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0209-1.jpg

Hopefully this is the ultimate steering setup in the woods: Precision shock and vibration clamp and CCP center/sides adjustable steering stabilizer. Can't wait to try them out!

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0230.jpg

[socal]

Lookin good man! I think the steering should be spot on. Would guess woods riding requires lighter steerin being there are so many turns/switchbacks? What do I know, I ride the desert! :eek2: Im also interrested in the sprocket/rotor guards as my Laeger swinger does not take a skid!

[Honda 250r 001]

Why did you have to adapt them for the elka shocks? As far as I know elka and ohlins are the same. and Fourwerx handles them for ohlins? Or am I missing something.
Im just trying to figure out what I need to order to get a set of these guards on my elka shocks.

[mx91a]

Yeah the steering needs to be light enough to make quick turns but still resist feedback from rocks, roots and ruts. This is where the dual adjustable stabilizer is nice I can set it a little stiffer in the center to keep the wheels straight in the high speed sections and lighter on the sides for the tighter, slower turns.

To adapt the guards to the elka shocks I machined 3 flat spots into the bottom ring where the holes in the guards are, drilled and tapped them for 10-32 stainless screws and cut some aluminum spacers to the correct length to center the guard on the spring. I was not aware that ohlins shocks are the same as elka I have never had them both to compare.

[Grande Huevos]

thats a pretty sick setup you have !! Whats the story on that radiator it looks HUGE!! thats bigger then a oversized pwr isnt it??

[mx91a]

Yeah that radiator is in a league of its own on size; bigger than the typical 'oversize' radiator. The only one I've seen that compares in size is the JRD unit. I'm hoping it should work good when it gets all full of mud and the speeds are slow in the tight woods sections.

[FL-R]

Which ccp stabilizer did you buy? They dont list them for a 250r, although your frame is round. I need one for my stock framed R

[mx91a]

I bought the 450R center/sides adjustable version. He provided me with the correct 1.125" mount for the steering stem upon request. I just had to narrow the frame tube notches in the mount slightly with a 1" sanding drum to get it to fit my frame as the rails are slightly closer together than the 450R. I believe he has made them for an 86-87 stock frame, shoot him an email and see if he still will.

[mx91a]

Here's some work on the engine I've been doing lately:

Getting ready for the leak down test:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/photo-1.jpg

Only lost about 0.5 psi over 20 minutes at 8 psi! All buttoned up and ready to go:

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/photo.jpg

[skyeryder]

where did you get that vent tube/gas line, everything around here I find around I just don't like.

[socal]

Lookin sweet man!

[mx91a]

Originally posted by skyeryder
where did you get that vent tube/gas line, everything around here I find around I just don't like.

That's a brand new carb so that is the hose it came from Keihin with. You can get it from Sudco:

http://www.sudco.com/fuel.html#keihinpink

[Burns310r]

I vote you pull a vacum on it.

i always do both. I have seen them leak one way and not the other.

[mx91a]

Originally posted by Burns310r
I vote you pull a vacum on it.

i always do both. I have seen them leak one way and not the other.

Good idea. What usually leaks under vacuum but not under pressure? I would think the seals more likely than a gasket. What is a good vacuum psi to pull on the engine?

[Burns310r]

it should hold 6" mercury for 1 minute

[mx91a]

Here are some pictures as of today. On the home stretch now, just have to finish up wiring the ignition, fuel tank, plastic, and some odds and ends and she will be done. So close to starting her up I can hear the sweet sounds and smell the smoke of that beauty running!

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0250.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0251.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0252.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0254.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_0253-1.jpg

[dustinshuler]

Really awesome build! Can't wait to see it finished. Keep up the good work!

[hartwill]

What are your thoughts on the esr clutch cover? I bought one and had it shipped to the guy building my motor, kinda worried about the mixed reviews.. also, just curious but I thought Gibson's used 19" shocks?

[Burns310r]

My ESR clutch cover fit amazingly. No problems here.

[mx91a]

The ESR clutch cover and water pump cover both fit great for me but the casting is a bit thicker than stock so that is something to watch out for. It interfered with the engine stand slightly, I had to remove the bottom bolts and tip the engine up to get it to seat against the gasket. It also looks like it is ever so slightly touching the bottom frame rail but the engine installed fine and I'm sure this will vary from frame to frame. The only thing that has me worried about it is the water pump bearing was pretty tough to turn by hand but should loosen up with use.

The Gibson arms are supposed to take around a 19.25" shock which for +3 arms is probably ok but on these little +1s it just didn't utilize the full limits of the ball joints and tie rods. The wheel travel was not much more than stock either. So taking lots of measurements I determined the arms could take a 19.5" shock without binding and with 6" of stroke would give about 10" of wheel travel, probably about the max to expect from +1 arms. So I sent the shocks and specs to Santo and he installed longer shafts and shortened the bodies. Hopefully they work out as planned.

[hartwill]

I was curious about that because I've heard a few people mention the water pump bearing being tight and heard of a few failing after a couple hours..
Nice build by the way, not sure If I said that yet or not, lol..

[hawaiiysr]

that is the looooogest rear resi line i have ever seen lol!

[HAYESTRX250R]

Looking great mang. You are giving me inspiration to get back on my XC build that halted recently because I took time out to buy a boat.

[mx91a]

Teaser! More photos to come!

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/485420c8.jpg

[socal]

Clean man, love it! Will turn heads at the races for sure!!!

[mx91a]

Here are some more, enjoy!

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_5683.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_5684.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_5700.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_5713.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_5714.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_5729.jpg

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/IMG_5733.jpg

[dustinshuler]

Looks amazing! Thanks for posting!!

[beobe99]

Dam!! Looks so good man, those A-arms are KILLER!

[beastlywarrior]

Originally posted by mx91a
Teaser! More photos to come!

http://i97.photobucket.com/albums/l209/mx91a/2012%20XC%20250R%20Build/485420c8.jpg
:eek2: im gonna build me a 250r and this is what its gonna look like

[norcalduner]

I'm really diggin' those tires. What are your thoughts on these compared to the standard Maxxis Razr? Are they noticeably heavier? How well do they wear on hard pack? Lookin' to use these in the desert.

[jwags13]

Really nice! You running stock ignition or cr250? Did you get a chance to try out the rear suspension set up? If so, how did it work out?

[mx91a]

Well I got a chance to put some time on her this weekend so I thought I'd give a little ride report and try to answer a few of the questions asked. First thing on order was to get her jetted (38mm PWK AS). I settled on a 48 pilot, #7 slide, CCL-3rd clip (same as CEL-5th clip) and 178 main with 114 octane fuel. Power wise she runs real strong and very smooth, no hit in the power at all. That old high compression 265 cylinder, she runs. I'm really loving this TRX-5R pipe. It does give up just a hair of bottom end compared to the typical mx/midrange pipes but the mid-top end pull is much better which I would prefer over a hard hitting pipe that signs off quickly. If I find I'm in the wrong gear or let the RPM's get too low, just a touch of the clutch get the wheels spinning again. For gearing I started out with 13-36 sprockets and think I will stick with that it seems to work pretty good for me.

Had a few gremlins come out in early testing; found out that the used IMS tank I bought was cracked right where the threads meet the tank body, making a nice mess of race gas all over the tank and myself. That cut the first day short, so I ordered a new tank that night and put the stocker on the next day. Also my zip-tied stock radiator overflow (this frame has no mounts for it) got clipped by the sprocket bolt nuts and almost ripped off. So I ordered a Polaris Predator overflow and am going to bolt it to the radiator shroud. Better to have these come out now than during the hare scramble race on Sunday!

As far as the 450R rear suspension, it seems to be working really good, nice and smooth through the woods and over big bumps and small jumps. I haven't gotten any big air on it yet. She doesn't really want to wheelie I'm not sure if it's because of the suspension, smooth power delivery or that I have been riding the ATC250R for the past 6 months and am not used to the heavy front end!

The RaZr Xc tires are working good too, lots of forward bite and slide well too. They handle more like a MX tire being smaller than the standard RaZr (~19" OD). For desert racing they might be a little small I think where you'd want more ground clearance for the big obstacles out there.

Overall handling is great, ride height set at 7", front overall width at 47" and rear at 46.5" I can take the corners almost as fast as when she was set up for MX but still ride fast through the tight stuff and split the trees.

[jwags13]

That was one great ride report! I realized how much of a newb i am and how much more i got to learn about these great machines. Thanks for sharing!!

[bradenc19]

what year ingintion did u use and can u use a 94 and do the same thing w the stator and how do u modifi it to work thanks.

[SilverLake250R]

Looks great! Love it!

[sameltoe]

Originally posted by mx91a
I bought the 450R center/sides adjustable version. He provided me with the correct 1.125" mount for the steering stem upon request. I just had to narrow the frame tube notches in the mount slightly with a 1" sanding drum to get it to fit my frame as the rails are slightly closer together than the 450R. I believe he has made them for an 86-87 stock frame, shoot him an email and see if he still will. Would you be able to modify another ccp dampner? I have the same problem with my arens frame and my 450 one is just off a 1/16-1/8th. I would cover shipping and some...
Sweet build by the way! All these nice builds has me geeked to finish mine up :ermm:

[Portuga]

Badass bike u got there man!! Every time i see a wood R makes me want to run mine next season.

[mx91a]

Originally posted by sameltoe
Would you be able to modify another ccp dampner? I have the same problem with my arens frame and my 450 one is just off a 1/16-1/8th. I would cover shipping and some...
Sweet build by the way! All these nice builds has me geeked to finish mine up :ermm:

I would but can't guarantee it would fit correctly without having the whole quad to test fit it onto. I must have gone back and forth between the vise and frame over 5 times just taking off a little more material until it fit just right. The best advice I can give is to get a 1" sanding drum mandrel and some rough grit sanding bands for it and go to town opening it up. I used the bolts to hold the two pieces of the clamp together and then spread them apart with washers to the correct distance and removed material from each side with the sanding drum, checking fitment on the frame frequently. Also you want to make sure the arm that comes off the steering stem is perpendicular when looking at it from the side. Take your time just remember is easier to remove more material than put it back!

[protrax]

Wow nice clean build I like it !

[tbone250r]

mx91a.....check your Inbox...PM sent

[jerorski]

beutiful xc build, A+ on that bad boy!!