Quote

You could put the engine of a YZ250 into a frame of the RM250 quite easy. Not a bolt in job, reweld two mounts and get 2 small hubs to bridge the smaller engine size mounts where they bolt into the frame swingarm. A little filing and there you go.

Great topic. Subscribed.

Rcannon, check your pms or email me, eric@flight-guardian.com. Have a question for u.

-eric

joshua_inigo, on 08 February 2012 - 04:14 AM, said:

Right. That's why I suggest maybe the spacers to be able to get the full adjustability as the 08+.

But as mentioned earlier there are a lot of other variables that are into play to really pin point exactly what combinations work best.

Great info everyone.

I'm surprised it hasn't come up yet that the factory teams have access to special offset ground bearing races for the steering stem.
This allows them to tune in the steering axis angle (rake) per the rider and track.

Does anyone know the actual rake/trail numbers for the YZ250, RM250 CR250R and RM-Z250 ?

I did a little google search for Rake / Trail / Wheelbase:

YZ250 (2010) 26.9° / 115mm / 58.3 in.
RM250 (2006) 27.3° / 115mm / 57.9 in.
RM-Z250 (2005) 26.5° / 110mm / 58.1 in.
KX250F (2012) 28.2° / 119mm / 58.1 in.

I didn't find all the specs for all the bikes in one place, those specs are from various web sites. I'm not sure how reliable this info is.
I didn't find a newer RM-Z spec than 2005.

I always thought the RM250 had a steeper rake angle than a YZ250.I
t must get it's turning through weight distribution, shorter wheel base, and/or suspension settings.

Small changes to the wheelbase make a huge difference. I can always feel the chain adjuster position on my YZ250s. When I put on a fresh chain and move the axle forward, the bike always feels much better in the corners. I've often considered buying a half-link with my chains so when they stretch, I can replace one link with the half link and keep the axle forward.

This has been great info. Thank you. I think I will give the 22.5 mm offset clamps a try. According to some of the responses it looks like RG3 is the only company who makes 22.5 clamps for the YZ250, which sucks because RG3 is more expensive than other brands. I guess I can search around for a used set first.

CW, remember when I found that guy who makes the offset races for many of the factory teams? He talked me out of his own products, really, and they were 750.00 for a set.....but it was possible.

I think my decision not to get them was from the 22.5 clamps. The stock bike might not have turned with easy effort compared to others, but it was always predictable. Then the 22.5 clamps went on and that was over. Low speed turning was great, as was high speed. Soft, sand conditions were tough as the bike would tuck and oversteer. This was damn near scary as it felt lie you would high-side at any moment. Dave J and his fork mods fixed this, btu it showed me how little I really know, and understood, about how this bike turned as well as geometry! I decided to play with less expensive, and dramatic, options from then on.

That radiator lowering kit helped turning as well and had no bad side-effects.

The 07' I bought has the gas tanked stuffed with foam. I was talking to the guy who sold me the bike and he said that it made the bike "stick" better around the turns. He was racing the bike at the pro level.

So are the RG3's 22mm or 22.5mm? RG3 claims 22mm.

RCannon, on 09 February 2012 - 05:51 AM, said:

I forgot about that. By the way, I agree about the less expensive stuff and suspension setup.
Usually, just playing around with the rebound clickers, sag and fork height will make a bike turn really well.

I'm actually more than happy with the way my YZs turn when the sag and fork height is dialed.
Still, this stuff is always interesting to read / learn / duscuss.

Wheelie, I have the RG3 top clamp on my 2002... It's a very high quality part, the rubber mounted clamps are excellent.

But I seem to remember that one of the '10-12 four stroke models comes stock with a 22mm offset. I'm not sure if anyone has tried to swap those yet, but if that works you may be able to find a nice set of used four stroke clamps from someone who wanted more bling. Those have the adjustable bar position too.

Maybe someone knows the exact details on that, and weather or not it will work.

I was just about to ask about using the 2010-2012 stock YZ450F or YZ250F triple clamps instead of getting RG3.... anyone have any input?

hmmm........ would they work with just pressing the yz 250 stem in place possibly?

The 2010 yzf450 did come with 22mm offset clamps and the 250 and 450 both have them for 11. I know someone here bought a set of 450 clamps on ebay, but I dont know if he used them yet.

cwtoyota, on 09 February 2012 - 09:42 AM, said:

Hope this means that after all i'm just on the right path for keeping my YZ pretty-much stock and simple for the trails.

All i did was i had me together with a friend who's an all-around MX tuner for the pros here adjust my rear sag, raised my fork 10-mm up the triple tree, play with my compression and rebound clickers and change my stock KYB 01 oil to an ultralight one after more than 6 months of riding.

A huge part of the reason why i chose to keep it bone-stock is that we riders here don't have quite the facility to acquire brand new aftermarkets without doing importation from another country. Well, my 08 YZ250 came all the way from California. Even my Dunlop MX51's, new graphics kit, 2nd-hand DEP pipe, and OEM piston kit came all the way respectively from San Francisco, Melbourne, Atlanta, and Tokyo

RCannon, on 09 February 2012 - 05:51 AM, said:

Wow, lowering the radiators? ---- Do you have a DIY guide RC? Thanks heaps sir!

Looks like i'd like to try the 22.5 offset and the Dave J mod.... But the question is, the cost of importing an aftermarket goodie and sending the forks to-and-from my place to the US and back, might not be a better idea after all.

Might as well perhaps just buy a second-hand alum frame YZ125.... Sweetness

Quote

Do a forum search. He created a thread with some instructions.... Maybe 2 years ago?
RC used the Dubach Racing Development (DRD) kit for the four stroke bikes. Dubach makes quality stuff.

The negative offset helps tons. Make sure your springrate and compression rates are correct though. Use the rebound adjustment on the fork to tune how long the front end knifes past the apex of the corner (the turn-out basically).

I went about this by way of the Rekluse E-Axle. They have stopped making them, but shoot them an email asking for more and they may deliver if there is enough demand.

Quote

This is so much more important than people seem often realize... Rebound keeps you in a turn.

GHILL28, on 10 February 2012 - 09:28 AM, said:

Good day GHill.

Do you have a generic guide for those factors you just mentioned?

Say for a 148-lb rider (that's me), where my rear sag is set at 100mm and my forks raised up the triple-clamp by 10mm. Mine is a 2008 YZ250 so basically it came with a 4mm shorter forks compared to the 2006 and 2007. When compared to these previous SST-equipped models, i'm actually 14mm lower by now. No forks mods and that consider that i'm going back to the standard KYB 01 fork oil and the outer chamber will have an ATF oil. I have softened my compression (i forgot how many clicks but both the fork and shock are really compressible in bumps), and my rebound are relatively stiffer at 4 to 5 clicks up compared to the compression clicks. No offset, just using the stock 24mm offset. My tires are MX51's. i only ride trails and occasionally i'm into enduro competitions.

At the current, i find the bike better for tight/ or goat trails with hillclimbs, compared before i raised the forks up and before the stock suspension settings were softened with clicker adjustments and use of lightweight fork oils. In most occasions in the trails out here, i'm compelled to choose lines outright at short notice as there are climbs that are fully rutted and some of the tight paths feature tight switchbacks, or you might refer to them as hairpins. At 148 lb, do i still have to change my spring rates or spring weights and will a 22.5mm offset provide me with more gusto? What do you reckon? Also, some of the factors here are or could be rider weight related while some are not at all like the offsets. What else would you recommend handling-wise in tight trails?

Your advice is highly appreciated. Thanks heaps....

Quote

You probably should have lighter springs. Check your 'static sag' (also called 'free sag') to find out for sure:

First, confirm that your 'rider sag' is set correctly. You mentioned it was 100mm, just double check to make sure it's close.


For static sag, take your first measurement with the bike on the stand just like you do when you check 'rider sag'.
Put the bike on the ground and let the suspension settle under the bike's own weight. Take a second measurement without disturbing the bike.

This should be about 1" (25mm) if you have the correct spring rate.
If static sag is more than 1.25" (32mm) your spring is too stiff.
If static sag is less than .75" (19mm) your spring is too soft.

At 148 lbs and stock springs, I can almost promise that you'll have over 1.25" (32mm) of static sag.
You probably need to go down one or two steps on the spring rates front and rear.

I think a lot of fast MX guys are comfortable running up to 1-1/2" (38mm) of static sag.
A stiffer spring can help control on whoops and jump faces.

I'm not sure if the offset will get you more "gusto", but it does help.

Slowing your rebound a click or two can help the wheel stay to the inside of a corner once you're past the apex. It wont want to push to the outside as much so it wont require the extra lean effort towards the end of the turn.

joshua_inigo, on 11 February 2012 - 06:45 AM, said:

DT there is half your problem, the MX51 front will push, try a Michilin MH3 on the front. This is a much better tyre.