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Beefing up my rear shock absorber

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I am pretty much a novic when it come to my rear suspension. I am riding a 2004 Honda XR250R which is currently in Panama awaiting my return to ride her through South America. I did Central American with the stock shock and am now going to loader her down even more for this next leg. Id like to beef up the rear shock absorber to take the extra weight but dont have any clue to what is the best route.

I weigh about 150lbs and am expecting add another 70-100 lbs. 

Any help would be greatly appreciated and I apologies for my lack of knowledge ;)

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I think adding 70-100lbs to the rear subframe is a disaster waiting to happen in the middle of nowhere. You should get serious about lightening the load.

For the shock, at the very least, you'll need to adjust the preload on the spring. There are 2 jamnuts above the spring. They are tightened against each other so they won't move. Loosen one from the other, then you'll need to turn the lower nut down against the spring, compressing it and increasing the preload. Probably should do this with the bike loaded as you're going to ride it. 

To do that, jack up the bike at the skidplate area to get the rear tire off the ground. Now, with the rear suspension completely extended, measure from the center of the axle, straight up to some point on the fender edge. Take note of that figure. Then take the bike off the jack and, with you sitting the loaded bike, feet on the pegs, have someone take another measurement for you from those same two points. The difference is your sag measurement. Increase preload until you can sit the bike, with it loaded, and be able to measure a sag difference of 3"- 4".

NOTE: Turning the nut down against the spring while you're setting preload is easier when the bike is jacked up with the rear tire off the ground. So you may be putting it on and off the jack a few times while adjusting and measuring.

If you can adjust that much preload into the shock spring to get 3"- 4" sag, then tighten the top jamnut down against the lower nut to lock everything together.

The best thing to have done is to have outfitted the shock with the proper rate spring for the weight it would be carrying BEFORE the trip. You best not ride any rough terrain if you can help it.

Edited by Trailryder42
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Thanks so much for the info. I agree with you on the weight. Bringing the bare essentials. I was hopping to fly back with a new shock. i am having a hard time figuring what to buy. I am assume buying the whole shock and coil would be the easiest to install. Could you point me in the direction of an appropriate one that would fit the 250? I'm also open to buying the the spring and have a shop install and adjust oil and what not. Let me know. Thanks again.

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Use an online spring rate calc to get an idea what shock to buy if you go that route. Race Tech has one. I don't know how you would fill out their calc form but I did just a quick calc and for a bike load of 225lbs it gave a spring rate of 12.1 kg/mm. http://racetech.com/VehicleSearch

As for where to find/buy a spring once you determine spring rate, the last place I bought a spring for my XR was Moto-Pro. I'm not too familiar on places to buy springs these days. Perhaps the folks here can give you some ideas.

I'm not aware of any alternate shock for the XR250.

Thing is, the stock shock is probably just right for your ride weight alone. If you go putting a heavier rate spring on it for those times you ride with 75-100lbs of cargo, it will be way too stiff when riding without. Then depending on what you can tolerate, you'll be needing to have the stock spring swapped back in.

The spring swap alone is pretty simple, no draining or changing of oil, nitrogen charging or any of that. So any small shop in Panama should be able to do that.

Edited by Trailryder42

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Thanks so much. That was really helpful. I calculated 12.1kg/mm also. 

Once I get back to Pamana my brother and I are going to try and ride to Chile. So she might never be ridden again with out the load. Or at least not be me. I think Ill give the bike away if she even makes it :) 

I'm writing a blog if you want to check back and see if this shit show pulls through.

http://Fornoparticularreason.com

 

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Tightening the spring DOES NOT CHANGE THE SPRINGS STIFFNESS it changes ride height. Yes it feels stiffer because preload takes away from that springs compression weight. But tightening the spring will do the OPPOSITE of letting you carry more weight. You put it closer to the end of its compression. Adding weight youll NEED that compression.

The solution is a stiffer ratio spring. 

I had racetech make me one after I used an Eibach 11.5 and it was too soft for this application which is an xr600r all street bike. I got a 12.4. And had Enzo revalve. THATS the best but most expensive thing. Thats what you should do over thicker weight oil anyday. And I had them put 240psi nitrogen in the bladder. Enzo rebuilt it so I wasnt worried about too much pressure when Ive seen guys in Mexico running 300. 

That is alot of weight, but think about a passenger. Ive seen guys in Baja riding double. Not taking the hairy singletrack but its done. But spread that weight. Front fender bag. Tank bag. Rear fender bags. The guys in Baja riding double were just mexicans traveling. Not guys hitting gnarly trails. So if you want to get aggressive, lose some weight. Other than that its valving. Stiffer springs the easiest to do, and you can do it. 

Depends on what money you have. 

Tightening spring preload to feel like its tight enough to support your weight, your sag is not going to be right.

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Thank you. I just contacted MotoPro about a 12.1 kg/mm spring. I think I was exaggerating with the load probably more like 60lb with my 150lbs. 

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Its best to exaggerate in this game

Have fun

And maybe if youre just going to put a stiffer spring...at the least additionally get a nitrogen recharge.

Whens the last time it was charged? To what pressure? If youre paying $100 for a spring, an additional $20 is nothing but totally worth it for a recharge. And dont try to test it cause you might lose fifty lbs doing it. Its much smaller and much more pressure than your tire. Peace of mind and an applicable pressure will make your trip better. If you know the reservoir is pressurized enpugh then leave it, but I wouldn't with a ten year old charge

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2 hours ago, notoriousE-R-I-C said:

Tightening the spring DOES NOT CHANGE THE SPRINGS STIFFNESS it changes ride height. Yes it feels stiffer because preload takes away from that springs compression weight. But tightening the spring will do the OPPOSITE of letting you carry more weight. You put it closer to the end of its compression. Adding weight youll NEED that compression.

 Depends on what money you have. 

Tightening spring preload to feel like its tight enough to support your weight, your sag is not going to be right.

I agree with what you were trying to say. But increasing preload does allow more weight to be carried, a more consistent ride height, "without bottoming" the shock so easily on even the gentilest of bumps and potholes with such a heavy load. Agreed, it will reduce the distance the rear can compress before getting coil bind but I think riding conservatively, avoiding g-outs and rough terrain is better than slamming a shock to the stop from blowing thru the compression stroke over what could be a several hundred mile trip. 

Neither is a good option. Not knowing what resources Mia has, if she's going to be able to find a different spring and someone in Panama to install it, it's the best option if she has to make due with what she's got.

Plus her indicating that she'll probably give the bike away afterwards kinda precludes dumping a bunch of money into it. Any shade tree mech in Panama should be able to swap a spring if she comes up with one but I wouldn't trust one to have the proper equipment and know-how to properly service the nitrogen bladder. A lot of these 3rd world small communities that a rider passes thru on cross country trips like this can only fabricate stuff on the fly. There's no resources for anything else.

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Thats right...bikes already there. My apologies. 

Well we can help you put it on. If you have internet there... ? 

All you need is a 14 and a 17mm open end which Id hope youd carry. A hammer and a flathead. Good things to have too. Unlock lock nut with a few taps, then tap tap tap, quarter turns ober and over til its off. Then 14,17 dismount. With shock out, lift spring and remove retainers. Put new spring on. Retainers. Tighten first nut as much as you can. Remount 14,17s. Now measure for sag. Mayyyybe need a second set of eyes/hands. Sag set. Now lock nut. Thirty minutes if youve done it before. No more than an hour if not.

Well help. 

When was its last charge? Factory assembly? Dont measure it. You probably dont have a 200psi gauge and youll let out alot. Believe me. Just make do.

Start everything at softest settings, then click up as you feel it. Hopefully on a test ride or two. Id focus on compression. But you also dont want to rebound too fast which is what I see when people just add preload. 

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Awesome. Thank you guy. Not leaving till September. Just trying to get all the parts in order. Ill add a hammer to my tool roll for sure. I feel much better about switching out the spring. Ill get in touch once im with the bike if I need any more help. 

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