2005 640e Suspension Q's

[jachard]

All,
I recently got a 640e and want to get some folks suspension suggestions. I have waded through the 640 suspension threads in the sticky and have a few more questions.

Stats:

Me: 175 ride 90% off road, single and double track.

Bike: Pirelli MT18 front and rear 10psi rear 12psi front
front clicker settings comp 4 from full soft reb 7 in
rear comp full soft reb middle

Scotts damper

Sag at 90mm

Bike looses the front end a bit on soft corners and understeers(pushes) a bit on slow and fast dirt(hard and softpack).


Also, has anyone had any luck with FC? I used them on my 450 and was very happy but they seemed a bit confused over the phone when I told them about the 640.

Thanks in advance!!

Cheers, James

[Luke]

Bump your tire pressures up a little and get your weight forward.

What's your sag in the front?

Have you experimented with the rear sag? You've got the right number by the manual, but a little change one way or the other can make a big difference.

Zerodog -one of the members here- has given me good advice on how to valve my own suspension, so if you want to send your shocks out he'd be a good choice.

[riverside]

I agree with Luke. Zerodog has just finished with my suspension and I haven't rode it yet. From reading other posts and talking with him he is your guy for either re-valve or being able to point you in a direction. He rides an Adventure as well.

Michael

[Zerodog]

All LC4s are very very undersprung from the factory. To make them handle right offroad, or onroad for that matter the spring rates need to get bumped quite a bit. What happens is they are so soft they blow through the stroke front and back. When you are turning the back is sagging low in the travel even though you might have that 90mm sag setting. Getting 90 out of the stock spring requires a ton of preload. This causes the front to be in a choppered out angle and not put weight on the front wheel. This causes the push. If you were to charge into a corner and try to turn faster after hard braking you would knife and the front would oversteer into the apex of the corner. This also hooks the rut or anything else and makes you also loose the front.

The other effect you will have is on steep downhills the front dives down doing the opposite effect. This makes the front ride low making the head angle very steep and causes the bike to be twitchy and not give you a lot of confidence.

Some .46 springs up front and a 7.6 or 7.8 rear spring will do a world of good for you. Revalving them helps a lot too. But the springs are key to at least getting on the right track. A lot of shops, even ones that specialize in KTM don't work on very many or any LC4 bikes in a year let alone ride one all the time. PM me and I can help you out. And probably save you some $$ over the big dogs for suspension work too.

[jachard]

ZeroDog, PM sent.

[clintnz]

I'm around 165lb & probably due to the fact that the bike is set up from the factory for a 155lb rider, I've got most of the clickers set close to the middle - 2 clicks more than mid comp & rebound front, rear comp 3-5 depending on load, rebound on 8 IIRC. I think if I had the F&R comp damping near full soft like you I'd be bottoming out everywhere offroad, & I'm lighter.

Cranking on a bit more comp damping front & back might compensate a little for the soft springs, suspension gurus will tell you that's not ideal though, & the right springs are really the answer.

Good advice from Luke too - the 640E responds really well to getting right forward & elbows up in an aggressive riding position for cornering.

Cheers
Clint

[Sparrowhawk]

Originally Posted by Zerodog

All LC4s are very very undersprung from the factory.

Does this apply to both the newer USD forks and the older RSU? By the way, what would be the best approach for someone wanting to get a 2000 LC4E with RSU forks dialed in, assuming the LBS was not up to the task? Is it just about rider weight or are there other variables involved? I've gone through and had everyting serviced but didn't make any changes.

To tell the truth, I have not had enough dirt experience with different bikes to know if I've got a problem. I have no idea if it is poorly set up or how good it could be if it were set up properly. I know I could throw lots of money at the suspension but I don't know how big a difference it would make, either in the twisties on-road or in the rough off-road. I don't have a bunch of spare cash laying around to experiment without knowing I'll get significant positive results. What is your advice?

[Luke]

Originally Posted by Sparrowhawk

Does this apply to both the newer USD forks and the older RSU? By the way, what would be the best approach for someone wanting to get a 2000 LC4E with RSU forks dialed in, assuming the LBS was not up to the task? Is it just about rider weight or are there other variables involved? I've gone through and had everyting serviced but didn't make any changes.

To tell the truth, I have not had enough dirt experience with different bikes to know if I've got a problem. I have no idea if it is poorly set up or how good it could be if it were set up properly. I know I could throw lots of money at the suspension but I don't know how big a difference it would make, either in the twisties on-road or in the rough off-road. I don't have a bunch of spare cash laying around to experiment without knowing I'll get significant positive results. What is your advice?

If you don't have any problem with what the bike's doing, and you don't have a compulsive urge to screw with it, then don't worry about it. If you have a particular problem you are trying to fix, then base your tuning off that.

For example, Here are the problems I had and how I fixed them:
Twitchy steering in straights: adjust the front and rear preload
Twitchy steering in corners: new springs
Too much brake dive: more oil in the forks
Harsh front end on rocks: revalved forks
Back end kicking off jumps: more rebound damping
Back end loosing traction on bumps: revalved shock.

If your bike has known common problems, you or a tuner can use a recipe to do a bunch of work at once, otherwise you try one thing at a time until you're happy with it.

Start by setting the damping adjusters and preload (front and rear) to spec.
Then start messing with it. There are a bunch of tuning guides available on-line, they're mostly aimed at off-roaders. Here's one:
http://www.mx-tech.com/?id=articles_news&news_id=81


The suspension on your bike is supposed to be better than the newer ones. A lot of folks really like the 50mm RSU forks, and the longer travel in the rear should also help things.