It's not yellow and it's no 21 [image heavy]

[philfingers]

Jeff- yes i suspect someone would say that. Rob Collingridge advised on spring rates, he went up from standard [130r/180f?]and I think settled on 180 rears and 225 front, but would need to check on messages from him. Certainly the front to rear balance of mine [275/150] doesn't fit Rob's

Adi- ah yes! Bilsteins are rated like I said, 205's are 250/120 and this is the damping rate, they're fixed damping rates

[jeffw]

Yes 180f/130r is normal for a CEC...mine is 225/180 and could probable do with being 250 but in a BEC I would think that needs to be much lower.

[philfingers]

Well time at home didn't pan out to good. I got 4 days and away again
I got the pesky Quaife rebuilt, lots of pics to post but internet connection here has similarities with semaphore data rates! Box is back in, I resisted the temptation to rebuild that lower reverse box mount. It took me 2 hours to get the lower bolts back in! Anyway it's all filled with oil and connected back up. Forwards travel should be quieter. The reverse is still going to be noisy with the planetary gears.
I have an issue with the engine. The revs take a little while to drop when releasing the throttle. As you have seen in my previous post I have added springs to the pedal. The actual cable/pedal and the linkage on the throttle bodies snaps shut instantly. Could it be anything to do with the cold start device not being connected Adi? And as your previous on the FI return. I really think the return line should be there. I wonder what effect that has on fuelling. The revs taking a little while to drop makes gear changes poor too. Could be an air leak between the bodies and the inlet I suppose
On a lighter note I can confirm the cam cover is magnesium. I did the old school experiment with the swarf from modding the cover, attacking it with the gas torch

[adithorp]

Not having the return fuel line will increase the fuel pressure.The exact effect of that will depend on the state of tune but it'll be relativly higher at lower throttle openings/higher vac, compared with normal, but it might have been mapped that way. At WOT it shouldn't be that different. Normally I'd expect you'd get worse economy in exchange slightly better pick up. If it was better, you have to ask why Yamaha don't do it.

Throttle hang-up was smething I had trouble with. The springs on the TB's aren't very strong. They don't need to be on the bike as there's a cable that pulls them shut but we don't have that. With drag in the cable you get a bit of flutter as the butterflys close and a spring at the pedal end doesn't help that. I used a very light throttle cable (cycle gear cable) and put a spring on the TB end and it's better. It'snot easy to find an attachment point though; I Keep meaning to make a return spring assy to go where the return cable fits but haven't got around to it yet (I've seen someone elses and got a picture somewhere).
Not having the cold start working shoudn't effect that much. It'll just make idle setting more difficult I think as it only lifts the throttle off the stop.Thats probably been adjusted out.

[philfingers]

Yes agreed on the fuel return. I would expect higher fuel pressure at lower power outputs and hence richer fuelling. Removing (or maybe not allowing for more likely) the fuel return is primative way of increasing fuel pressure, just like sticking a pressure regulator in a vice and squashing it to increase its pressure. So Yamaha have a sophisticated EFI. It's a bit like all these 'tuners' offering 30% more power than a stock engine that the manufacturer has spent 1000's of hours on the dyno refining, optimising power, emissions and fuel economy in the process. And laptop tuner offers 10% better fuel economy too! Off soap box. The R1 engine doesn't have a power commander or anything else. I can only assume it's a stock map. I'll look at a fuel return line at some point, fuelling seems ok. Rickover is fine, starts fine and idles from cold.
I'll look again at the TB end and the return springs. I made the air box brace originally to lift it as it was making the throttle linkage stick/tight. It isn't sticking now but maybe the lack of push-pull stock cabling as some bearing on it.
Thanks for the pointers Adi

[adithorp]

It's only a very light spring I have but it makes a difference. This is the return I saw a few years ago and will one day copy...



The cable continues around the throttle and through the cylinder/piston thing that has a spring inside it and then has a (dodgy looking) fixing. As the throttle opens it pulls the piston down, compressing the spring. The spring then helps the return.

Without a PowerCommander (and standard fuel pressure) there's a big hole in the map around 4-4.5k rpm that gives a flat spot. Apparently it's there to get around the noise requirements. If you get that mapped out it makes a huge difference to the drivability

[philfingers]

Thanks Adi. Not a chance of downloading that image here! Will look at some other point
Are you running a power commander on yours? I know Rob C is and his build blog states how much better the car is, runs cooler too from memory. Will look around for one

[adithorp]

Yes PC is fitted. It made a big difference to the drivability when mapped on my old standaed motor. The flat spot is quite literally that on the power run without.

It's pretty much essential on my current motor. It's a BSB engine without the race gear-set and trick electrics; Ported+polished head, raised compression, lightened balanced crank and rods and full race cams. Up 20 bhp at the wheels compared to the old one and +25% over stock torque.

[philfingers]

Moving onto springs rates I emailed Raw about what they would suggest for my car, given the current 275/150 springs. My thoughts were to keep the 150's on the rear and maybe go 200 or 225 on the front. Below is Raw's response

If your using the car just on the road and some track work then 200 on the front would be fine. The R1 Strikers that we have done usually run 180s all round. Is your independent rear suspension?
We have found in the past that if the front and rear spring rate get too far apart the handling is affected. A lot comes down to how you like the feel of the car, some do like a harder, twitchier front.
The link below is to a Striker R1, this is running 200 front and 180 rears

https://www.youtube.com/watch?v=5mLn1s4_G-c


Interesting what Raw have to say. I suppose when you think about it there is less weight on the front of a BEC compared to CEC then it makes sense to drop spring rates at the front of the BEC to compensate. After all springs are there to provide an equal but opposite reaction force. The static (potential energy) component of this is
Force = Mass x Acceleration (gravity in this case)
The front/rear bias of a BEC is less than CEC so requires less spring rate on the front of a BEC
I suppose you can calculate wheel rates, which aren't the same as spring rates by using the corner weights of the two different configurations

I'm going down the route of 200 on the front in 8". I'll have a run over to Raw when I get home. Excuse to test the car

Adi- I think I see what you mean with the TB springs, they locate on the return cable which would normally run to the bike twistgrip