Increase ride height (jack up kits)

[avimistry]

Hi guys

I'm looking to increase the ride height on my Suzuki SV400S. I find myself "in the bike" and prefer the "on the bike" position. When I'm riding and my feet on the pegs it's somewhat better, but it's when I'm at a stop that I feel lower (if that makes any sense). I flat foot the bike with bent knees and often find myself standing on my feet at a stop just to get a better feeling/view. I sat on a 2014 GSXR600 today and found that a little better but still wanting a little more height. I think the gixxer seat height is 810mm so maybe 815-825mm. I came across a company in the UK who does jack up kits (http://www.lustracing.co.uk/suspension/suzuki-jack-up-kits.html). It looks like longer dogbones, so if I could get them machined locally that would be ideal. Also, I've read that increasing the seat height will affect handling (i.e. sharper turn in) which is a good thing, but at what point does it have a negative effect?

Cheers.

[nzspokes]

I gets bad when you jack the back to much and it gets tank slappers.

[avimistry]

I gets bad when you jack the back to much and it gets tank slappers.

tank slappers??

The standard ride height is 785mm so probably just a 25mm jack up?

[nzspokes]

http://en.wikipedia.org/wiki/Speed_wobble

[haydes55]

Increasing rear height will tip the bike forwards, less rake angle. Lower rake angle means sharper turn in, better response, but less high speed stability. I'd Imaging 25mm wouldn't be too detrimental to stability. Every bike is different, what I'd suggest you do is measure standard rake angle and trail. Then use a 25mm thick block under the rear tire, measure rake angle and trail again.

Once you have the numbers, compare then on motorcyclespecs.co.za against sports bikes of similar length (gsxr600 etc.) you could afford to reduce trail to the same as them, but I'd suggest not much further.

[avimistry]

Increasing rear height will tip the bike forwards, less rake angle. Lower rake angle means sharper turn in, better response, but less high speed stability. I'd Imaging 25mm wouldn't be too detrimental to stability. Every bike is different, what I'd suggest you do is measure standard rake angle and trail. Then use a 25mm thick block under the rear tire, measure rake angle and trail again.

Once you have the numbers, compare then on motorcyclespecs.co.za against sports bikes of similar length (gsxr600 etc.) you could afford to reduce trail to the same as them, but I'd suggest not much further.

Thanks for that great info haydes. Just one question, since LustRacing make a 25mm and a 40mm kit would it be safe to assume that those height adjustments are within the safe/efficient handling limits?

[avimistry]

http://en.wikipedia.org/wiki/Speed_wobble

Thanks nzspokes. Need a PHD to understand the Wiki explanation but 'speed wobble' explains it all..

[haydes55]

Thanks for that great info haydes. Just one question, since LustRacing make a 25mm and a 40mm kit would it be safe to assume that those height adjustments are within the safe/efficient handling limits?


40mm sounds like it wouldn't be too great a change to rake angle. But if the sv400 is already pretty steep, it mightn't pay to go to 40mm unless there is enough room to drop the forks I'm the triple trees as well. Dropping the forks will raise both ends of the bike, less effect on the rake/trail.

Decreasing trail would improve turn in, but probably not enough for you to notice a huge difference in every day riding. The tendency to get speed wobbles could be noticed easier, and that's risky to live with.

Check the numbers though, I have no idea how it's set up standard, try dropping the forks to keep handling as unchanged as possible.

[Mom]

Shorten your legs? Oh to have your problem...

Good luck, I am sure there will be a cost effective solution.

[avimistry]

40mm sounds like it wouldn't be too great a change to rake angle. But if the sv400 is already pretty steep, it mightn't pay to go to 40mm unless there is enough room to drop the forks I'm the triple trees as well. Dropping the forks will raise both ends of the bike, less effect on the rake/trail.

Decreasing trail would improve turn in, but probably not enough for you to notice a huge difference in every day riding. The tendency to get speed wobbles could be noticed easier, and that's risky to live with.

Check the numbers though, I have no idea how it's set up standard, try dropping the forks to keep handling as unchanged as possible.

Thanks haydes. Yeah whatever turn in improvements I get is a bonus to a already sharp handling bike but speed wobble is a concern.

[bogan]

Bear in mind longer dogbones changes the suspension link action too.

[avimistry]

Shorten your legs? Oh to have your problem...

Good luck, I am sure there will be a cost effective solution.

Haha.. I'm actually not that tall, 5'6". It's more a case of how I feel on the bike. Confidence is as important as the correct tires...

Yeah, I'm still a learner so cost effective and sensible are key. Besides, throwing on $5000 ohlins or $1000 batlax don't make a better rider, just a better handling machine..

[avimistry]

Bear in mind longer dogbones changes the suspension link action too.

Yeah I'm coming to understand that's it's not a simple swap out story..

Also, as I'm looking to get into weekend track I think it would better to head out and get some track time before making any drastic changes..