Suspension Tuning

SV650Steve

SV650Steve

Slow
I need help...

2005 SV650S with a ZX rear shock and Zoran/TWF racing front forks.

I cannot get the ride to feel confident and I'm ready to take it to someone who can get me straightened out. The front end feels too bumpy and when I'm leaned over in a corner it does not feel stable. If I hit a bump mid-corner on the street, it feels like the bike could lose traction and low side.

I've followed Zoran's advice on the fork tuning but there's only so much someone can help over email.

The frustrating thing is that I had the stock forks with thicker oil and springs at my last track day and it was perfect for me. I had the forks fully built and now it feels worse. I didn't change anything on the rear end.

Is there always a suspension guy at track days? I don't want to get there and not have the bike sorted out. I'll be at Summit Point on 5/11.

Is there a shop or person in Northern VA I can pay to get me sorted out?
 
The B Team

The B Team

¯\_(ツ)_/¯
Who fully built it? Do you know the spring rates? Who set it up for you? I see the novice emoji in your signature...are you outside of the norm for standard sus, IE super tall/short/fat/light?

Unsure about that specific day, but you can generally find Zeb and Dave with Pitlane Moto, Emerson with Bobblehead, or Kendall with Triple T at various trackdays. If you want a local shop near Nova to get it done before a TD, I think Kenny @ MRP is probably the go to, he's a little north. Keep in mind you're going to be bottom of the stack of work orders this time of year.
 
SV650Steve

SV650Steve

Slow
Zoran is the guy who did the forks: https://www.twfracing.com/PartsPages/cartridgestockforkmod.html

Spring rate is the same that was in the forks when I had the stock forks with just oil and springs replaced... .90kg sonic springs.

Zoran said he set them up to be good right off the bat, but after installing them and really not liking it, he had me do some rebound adjustments until I got it good enough.

I'm very average, 5'10 175#, so should be fine on normal-ish suspension.
 
The B Team

The B Team

¯\_(ツ)_/¯
Jeez I'm blind. Chalk it up to the bottle of cab.

Worth noting the stock spring rate is .712kg. If I am following, you had previously swapped to 90s and then just recently added carts with fresh oil and new springs.

If you're already working with a reputable sus guy and adjusting settings, I'd stay the course until you find what you like. It sounds like it's generally a bit stiffer than you've been used to after refresh and carts. Not unsurprising if you're going from a street setup to track. Also, if I am understanding what you are saying, you are using this bike for both street AND track? Not uncommon to change settings back and forth if that is the case.

Sus isn't black and white, IE there isn't a perfect textbook set of settings that works for everybody in every situation. He's just looked at your weight and pace and made an educated guess to give you a baseline to work from. Keep a notebook and track everything you're doing, so you can undo it if it feels wrong. What tire and pressures are you running? Log that too. Pass all that info along to your guy, and he'll tell you what to adjust. If you get close to running out of adjustment, then he'll swap parts. This may not be the best place to focus time and effort in Novice group, because rates and settings may very likely change as you put on pace, and trying to go back and forth between street and track is going to be boorish.

If you don't want to do that, then call up one of the guys I mentioned above and hire them to get you set up at the track, and ask for some ideas on adjusting for the street. For Summit I'd start with Emerson based on proximity.

That's where my sus talent (and wine) runs out, hope that's helpful.
 
damiankelly

damiankelly

Member
You may have a difficult process trying to get settings to work for street riding and track riding.
you might want a set of forks for the street and a set for track days. They are so simple to swap on the SV it makes sense.
you need a wide range of capabilities for suspension on the street. And more fine tuned on each track. Just buy a second set with stock and redo like you did with springs and oil for street. Keep Zorans for track use.
‘Even better. make it track only!
 
PatricksDad

PatricksDad

New Member
SV650Steve said:
Zoran is the guy who did the forks: https://www.twfracing.com/PartsPages/cartridgestockforkmod.html

Spring rate is the same that was in the forks when I had the stock forks with just oil and springs replaced... .90kg sonic springs.

Zoran said he set them up to be good right off the bat, but after installing them and really not liking it, he had me do some rebound adjustments until I got it good enough.

I'm very average, 5'10 175#, so should be fine on normal-ish suspension.
Click to expand...
If you're in the DMV, Kenny Martin at MRP can probably get you sorted. I'm getting ready to drop off a Penske rear for my SV for revalving and respringing. They're between Annapolis and Baltimore in Pasadena.
 
bmart

bmart

Control Rider
How was the geometry changed from stock, front and back? How does the back feel when riding and going over bumps?
 
SV650Steve

SV650Steve

Slow
bmart said:
How was the geometry changed from stock, front and back? How does the back feel when riding and going over bumps?
Click to expand...
Geometry should be the same as when I had the suspension where I liked it, but it was never stock from the time I got it. It has a GSXR600 rear wheel so that would put the rear slightly taller. But at the same time, the rear shock is 8mm longer than the stock SV shock. Would bringing the forks up through the triple clamps 5-10mm be worth trying?
 
bmart

bmart

Control Rider
Should? You know when you know. Measure.

I would be very tempted to get some data from other guys who have/have had these. There are a lot of SVs around and they should be rock stable and nimble. Dave Brown comes to mind. i'm not familiar with the mods made so far, but if they came from the Internet and not a suspension guy...they may not be excellent. CB-1 guys had this problem in the past with someone posting that something "fit" but it turned out to be dreadful to ride in the hands of anyone with any experience...or nerve endings!

I like my bikes on the nose a bit, but there's a point where the forks are too close to vertical from changes on one or both ends. And keep in mind that if it is sprung too soft/hard for you, you're going to get very strange geometry changes when under load on each end. Body position. Clip ons. There are a lot of variables, but I'd start with what works on others' bikes and get the geometry close to the middle of "good" and work from there to your liking.

(I'm having a not dissimilar fight with a VFR handling like a drunk monkey when my other VFR is superb and even track excellent...)
 
SV650Steve

SV650Steve

Slow
Thanks for the info and the assurance that I'm not the only one fighting suspension settings.

The springs are the same as they were when I liked it. The rear shock didn't change and I took the springs out of my old forks to use in the forks currently on the bike that Zoran built. I say should because there are so many factors at play and I don't have measurements of where the forks were mounted before I swapped them out.

I'm tempted to reduce some compression to see if it absorbs bumps better mid turn, but doing that isn't easy since it's on the very bottom of the forks and Zoran told me it's correct as-is. I guess I will try taking some measurements to confirm the basic stuff like preload and rebound, and then lowering the front end a bit down onto the forks and see where that gets me.
 
PatricksDad

PatricksDad

New Member
I won't be back on the road until next month (shoulder surgery) but I have a street '07 you can ride for comparison that's pretty well sorted for track and aggressive street riding. I go a little over 200 in gear, so I'm a bit heavier but close enough.

I'm in upper MoCo, so if you're still looking for some help in a few weeks we can meet up.
 
M

motopreserve

Member
SV650Steve said:
assurance that I'm not the only one fighting suspension settings.
Click to expand...

…the never ending quest.

I tried to read the details of what Zoran is doing to the forks - but his forum is down. If I understand correctly, he is installing GSXR internals into the stock SV forks? And this setup uses the stock SV springs? Im not familiar with SV forks specifically, so I was surprised the SV length works with GSXR internals.

Also, maybe I missed it - but was the bike setup while you were with Zoran? If not, probably best to start by setting sag if you haven’t already. Both front and rear. Don’t bother with the front until you’ve made sure the front end is properly aligned (if you did the reinstall yourself). If it’s not, could throw your fork sag measurements off.

You mentioned the compression being at the bottom of the forks. Can you only adjust damping inside the fork (changing shim stacks or heights etc) like racetech valves?

Before messing with raising/lowering forks in the triples, you may want to get a basic measurement of the rake and trail so you know where you started, and what effect the changes have on your feeling with the bike. Also, this would give you a way to compare to other SV riders who are having success with their suspension & geometry setup.

Good luck!

Scott
 
SV650Steve

SV650Steve

Slow
Want to follow up to say thank you all for the advice and especially @motorider who volunteered to let me come to his house and look at my bike. I did not end up going that route because I got the bike feeling really good on my own.

I looked up suspension measurements and found my front end was 15mm higher than the highest range it should be. Measured 530mm from where the steering stem meets the lower triple to the center of the axle. It should be 510-515mm. Zoran last year said I should try lowering the upper triple 10mm, and given the measurements, I went ahead and lowered it 15mm. So, with 15mm of fork sticking out from the upper triple, I took the bike for a ride and it was a huge improvement. Bike does not bottom out under hard braking and there's clearance for everything. I put zip ties on my fork tubes to see how compressed the forks got and there was still a ton of room left for them to move. Bike definitely turns in much easier and the true test, cornering with uneven road surfaces, the bike felt planted.
 
bmart

bmart

Control Rider
Really glad to hear this. Stability is nice!

Possibly unrelated is the difference between lowering the front (raising the forks) and lowering the forks (which raises the front). I've seen this come into play a few times before. :)
 
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