New-gen shock on pre-gen

[baxtc1]

G'day all, I have just put a 2012 shock on my '92, this has raised the rear a little. Can this be brought back to spec by using the uni-track system from a 2012 model?
All help appreciated.

[csmith12]

Why not just leave it raised a little? This is a common mod that is done to these bikes and considered a handling improvement.

[kxpower?]

I put on the new-gen shock without any changes, it's a hair's breadth higher and a little firmer out back but not to the point of bothering me, and it leaves a lot more wiggle room for carrying a passenger if need be.

If you want the stock ride height why not just put an EO shock back on?

[Ghostt]

Leave it alone, no worries about it being a little bit taller.

It's a proven fact that raising the rear up helps the bike handle better, I could bore you with technical, and physics on why, but I won't, it just doesn't what it does.

[Ginganinja]

Originally Posted by Ghostt

Leave it alone, no worries about it being a little bit taller.

It's a proven fact that raising the rear up helps the bike handle better, I could bore you with technical, and physics on why, but I won't, it just doesn't what it does.

As a seeker of information, i am interested in the handling aspects of why the higher rear makes it handle better. Could you bore me with some of that great knowledge? or a link so i can investigate? I just upgraded my front suspension, and now the bike is unbalanced with the stock rear shock, so it's time to upgrade the rear, just more excuses to buy parts for the bike i guess

[Sirref]

leave it, the shock is the same length it's just stiffer. Your 92 shock was probably worn out to the point where it was being compressed by the bike's weight itself. When I switched out my '99 shock to a 2010 shock I could compress the '99 by hand, which isn't good. The stiffer springs in the shock are making it seem like the bike is sitting higher, which is a good thing regardless if more predictable and sharper handling was the gain you were looking for with the shock.

[Sirref]

Originally Posted by Ginganinja

As a seeker of information, i am interested in the handling aspects of why the higher rear makes it handle better. Could you bore me with some of that great knowledge? or a link so i can investigate? I just upgraded my front suspension, and now the bike is unbalanced with the stock rear shock, so it's time to upgrade the rear, just more excuses to buy parts for the bike i guess

It doesn't make the bike handle better per se. It does however make the 250s handle more like people want them to. Raising the rear and keeping the front stock creates a more aggressive setup which is better when taking corners at low speed but sacrifices some stability in higher speed corners. Realistically too much in either direction is bad, the 250s however are not capable of taking some corners at their true high speed so the negative high speed traction effects are not felt as much as it would be on a faster bike. The newgen 250 and the 300 already have a more aggressive profile that is close to the ideal but the pregen 250 is lacking slightly in the department.

In summary, raising the tail and lowering the front causes the bike to react more to minor inputs allowing you to toss the bike around significantly moreso than you were able to before. This combined with lowered clip on handlebars to provide better leverage for at speed cornering turns the bike into a completely different machine.

*this is taken from personal experience and some twist of the wrist II reading

[kxpower?]

Originally Posted by Ginganinja

As a seeker of information, i am interested in the handling aspects of why the higher rear makes it handle better. Could you bore me with some of that great knowledge? or a link so i can investigate? I just upgraded my front suspension, and now the bike is unbalanced with the stock rear shock, so it's time to upgrade the rear, just more excuses to buy parts for the bike i guess

Ghostt may be able elaborate further on this, but I'll take a shot. Raising the rear causes the angle of the forks (rake) to become more vertical, and the trail to decrease. Both of these changes reduce the self-centering effect of the steering, giving you a quicker turn-in. And it's less stable in a straight line. I experienced the same when I put a shorter fork on my MTB while my good fork got rebuilt. It made it feel like a whole different bike.

Ginga, based on a quick scan of your other thread, I think you've got the opposite happening, your stiff front end and soft rear is pushing your rake away from vertical under load, causing your problems.

[Ghostt]

And I shall, ok boring technical stuff time,

Raising the rear changes the angle of the Swing Arm to put it more in line with the torque reaction of the chain, this reduces lift under hard drives,also they reduce the fork rake Angle and shorten the trail. these two changes quicken the steering and cause the bike to turn with less counter steering input. Finally braking is much improved by the greater weight shift to the front wheel (which does 90% of the braking). Ground clearance is improved as well allowing increased lean angle.

One must also keep in mind that suspension is a balancing act between front and rear, and matching up, spring rate, sag, height, oil viscosity, riders weight, tire pressure, and most importantly the realistic use of the bike. Sure everyone wants that cool track set-up, but if your not going to the track, then don't waste your time and money, the real world streets are so far removed from any tracks.

I hope this helps clear up some things.

[csmith12]

Scott and Jesse, I like your real world approach to the issue at hand. Not getting lost in the detail is a good communication skill.

[Ghostt]

Originally Posted by csmith12

Scott and Jesse, I like your real world approach to the issue at hand. Not getting lost in the detail is a good communication skill.

I try to keep it simple and realistic, I'm an old time racer, cars, bikes, gocarts, etc.... So I'm fully aware of what works on the track, sometimes doesn't work on the street, and negative consequences, that most noobs don't get it.

They see something or read something, and go that's what I WANT, not fully understanding the original propose.

[baxtc1]

The reason for the replacement was that the original shock was 22 years old and I am possibly a little heavier than the ideal pre gen rider. So looking for preload adjustment, the '12 shock was the obvious choice. No problem with the angle of the bike other than the oil level indication.
No track riding (no track here to ride), the extra stiffness in the spring is exactly what I was after, no more bottoming out on the rougher streets.
I am now used to it as it is, so will just leave it, no dramas. Will just have to work out the oil level and will be golden.
Thank you all for your replies, is much appreciated.

[Ghostt]

Originally Posted by baxtc1

The reason for the replacement was that the original shock was 22 years old and I am possibly a little heavier than the ideal pre gen rider. So looking for preload adjustment, the '12 shock was the obvious choice. No problem with the angle of the bike other than the oil level indication.
No track riding (no track here to ride), the extra stiffness in the spring is exactly what I was after, no more bottoming out on the rougher streets.
I am now used to it as it is, so will just leave it, no dramas. Will just have to work out the oil level and will be golden.
Thank you all for your replies, is much appreciated.

I'm puzzled, what is the issue with the oil level?

[baxtc1]

After fitting the shock (and '07 swingarm, another story there) the oil legel did not show on the sight glass. I did not check the level before doing the job, so I don't know how much the difference was. I drained out the oil, leaving the filter in and got 1 litre out.I put 1.4 litres in and it was a touch over full.
I realise the filter chamber will hold some oil, though I have not measured it to find out (had no cause to until now).

[kxpower?]

Originally Posted by baxtc1

After fitting the shock (and '07 swingarm, another story there) the oil legel did not show on the sight glass. I did not check the level before doing the job, so I don't know how much the difference was. I drained out the oil, leaving the filter in and got 1 litre out.I put 1.4 litres in and it was a touch over full.
I realise the filter chamber will hold some oil, though I have not measured it to find out (had no cause to until now).

Hmm so the change in the ride height in the rear is raising the sight glass so much that the oil level is below it? I'm not sure I'm understanding you. As long as you're on a level surface and the bike's on the centerstand the back wheel doesn't touch the ground, so how does that affect the oil level?

Not knowing any better I'd guess either the bike wasn't level side-to-side or you have something unrelated to the suspension going on.

[Ghostt]

Originally Posted by kxpower?

Hmm so the change in the ride height in the rear is raising the sight glass so much that the oil level is below it? I'm not sure I'm understanding you. As long as you're on a level surface and the bike's on the centerstand the back wheel doesn't touch the ground, so how does that affect the oil level?

Not knowing any better I'd guess either the bike wasn't level side-to-side or you have something unrelated to the suspension going on.

Pictures please to show us what your tallies about, plz?
Thank you

[baxtc1]

Tyres are 90 profile, so when on the main stand both tyres were touching the ground on the stock shock, now with the slightly longer shock the main stand is pretty much a support on either side as she stands on the wheels (4 points of contact ).
the altered ride height at rear only has changed the angle of the engine, now tilted forward slightly more than previously.

[kxpower?]

Originally Posted by baxtc1

Tyres are 90 profile, so when on the main stand both tyres were touching the ground on the stock shock, now with the slightly longer shock the main stand is pretty much a support on either side as she stands on the wheels (4 points of contact ).
the altered ride height at rear only has changed the angle of the engine, now tilted forward slightly more than previously.

On a stock suspension with stock tires the rear is about a half inch off the ground on the centerstand (not 100% sure but it's very close to that). Is your centerstand still touching on both feet, or does it wobble from left to right, like a table whose legs aren't just right? I think you're saying that both sides of the centerstand touch the ground. If that's the case, then the bike is at the same angle relative to horizontal as it is with a stock shock. Following me so far?

The only other piece of the puzzle that could cause a difference in this angle is the front suspension, ei if the rear was so high it shifted enough weight to the front to compress the fork springs shorter than their normal sag height. So say for the sake of brainstorming that the forks were compressed an extra half inch (I think that's a very liberal estimate btw). What's the bike's wheelbase, 5 feet? So the difference in angle is half an inch in 5 feet. From the front of the crankcase to the oil sight glass is, let's just say, a foot. That difference in angle should be one 10th of an inch in the sight glass.

The sight glass is about 11/16" in diameter isn't it? That's about 0.7 inches. So the oil shouldn't go down more than a 7th of the diameter of the sight glass. So if it were in the middle of the sight glass on stock suspension, it would be something like 1/3 of the way up the sight glass with our super-high/stiff rear end.

Where I'm going with all this stuff is that it's going to take a huge difference in suspension height to make the difference in the oil level you're describing.

[Ghostt]

Originally Posted by kxpower?

On a stock suspension with stock tires the rear is about a half inch off the ground on the centerstand (not 100% sure but it's very close to that). Is your centerstand still touching on both feet, or does it wobble from left to right, like a table whose legs aren't just right? I think you're saying that both sides of the centerstand touch the ground. If that's the case, then the bike is at the same angle relative to horizontal as it is with a stock shock. Following me so far?

The only other piece of the puzzle that could cause a difference in this angle is the front suspension, ei if the rear was so high it shifted enough weight to the front to compress the fork springs shorter than their normal sag height. So say for the sake of brainstorming that the forks were compressed an extra half inch (I think that's a very liberal estimate btw). What's the bike's wheelbase, 5 feet? So the difference in angle is half an inch in 5 feet. From the front of the crankcase to the oil sight glass is, let's just say, a foot. That difference in angle should be one 10th of an inch in the sight glass.

The sight glass is about 11/16" in diameter isn't it? That's about 0.7 inches. So the oil shouldn't go down more than a 7th of the diameter of the sight glass. So if it were in the middle of the sight glass on stock suspension, it would be something like 1/3 of the way up the sight glass with our super-high/stiff rear end.

Where I'm going with all this stuff is that it's going to take a huge difference in suspension height to make the difference in the oil level you're describing.

Well put, and explained, I think the OP. Is just being a little OCD about the whole thing, that's why I asked for pictures.

[kxpower?]

Originally Posted by Ghostt

Well put, and explained, I think the OP. Is just being a little OCD about the whole thing, that's why I asked for pictures.

It's totally triggering my OCD!!

[Ghostt]

Originally Posted by kxpower?

It's totally triggering my OCD!!

Try tilting your head when you look at it

[baxtc1]

Ocd, that's a laugh.
Just curious about how much change in oil level due to the angle change.
Oil running to the front of the crankcase, so not showing at sight glass.
As I stated, it was low before hand and out of sight after.

[kxpower?]

Originally Posted by baxtc1

Ocd, that's a laugh.
Just curious about how much change in oil level due to the angle change.
Oil running to the front of the crankcase, so not showing at sight glass.
As I stated, it was low before hand and out of sight after.

It's got nothing to do with the shock dude. As I stated.

[Ghostt]

Baxtc, don't worry about it, if you want to check the oil off the center stand while you sit on it, either look at then(btw I check mine like that) or have a mate, or a bird check it for you.

Problem solved.

[baxtc1]

Not solved, ignored.

[Ghostt]

Originally Posted by baxtc1

Not solved, ignored.

With the bike off the center stand, and you sitting on it, it should lessen the rack forward. On the EX-500.com forum a long time member and retired motorcycle racer, "FOG" he makes a set of links that raise the bike about 1.5" at the grab handle.

With no issues being raised about the rack/increase of the bike in relation to any oil or lubrication problems.

Hope this helps you out.

[ninjamunky85]

I raised the forks in the triples about 1/4 inch, which is about all that they can be raised, but it worked perfectly for me.

[csmith12]

Originally Posted by baxtc1

Not solved, ignored.

I aint trying to be a bonehead about things, but I am not understanding what your issue is exactly with the oil level? You raised the rear a bit, the oil level isn't gunna be that far off. It can still be filled and checked via the sight glass, on the center stand or on both wheels. Confused where the problem is?!?!?!?!?

If it was a problem, then the 50 or so active ninjette track/racers that have raised the rear would have already been posting about possible problems years ago.

3 ninjette members have now NOT ignored this question. Can you get us a pic? If what you are saying about the sight glass and angle is not what we are thinking, you have a HUGE problem.

[baxtc1]

No problem, I wasn't expecting any change in oil level indcation, when I saw the change I was curious if it had been noted before, obviously not.
I will wait until I do the next oil and filter change, put in 1.9 litres and see where the level is.