After killing a few lithium ion batteries I decided to start taking them apart only to realize they are pretty much the same thing in different packages. For many of them, like the Shorai, there's half a plastic box of dead space.
Ton up SR250: 100mph, 100kg, 30hp
- Thread starter JadusMotorcycleParts
- Start date
wozza
Been Around the Block
once again to the OP sorry..but I have to point out whilst you have done your homework and come up with a cheaper option...My concern is some young/old uninformed person see's the link and think yeah thats cheap and throws it in their bike and isnt as lucky as you....also your insurance may not cover any damage .
Finally I have been flying RC for over 40 years and currently have about 30 lipos sitting here in a metal ammo case, Ive seen far to many of the hobby king ones puff and fail even with the best charger and most care.....All the power to you for thinking outside the box but not all of us are that smart
Finally I have been flying RC for over 40 years and currently have about 30 lipos sitting here in a metal ammo case, Ive seen far to many of the hobby king ones puff and fail even with the best charger and most care.....All the power to you for thinking outside the box but not all of us are that smart
Agreed. Seems like you know your stuff in this area and I would be happy if I did too, but I don't. For average Joe home mechanic (me included) I wouldn't be confident installing stuff I don't understand. But knowledge is power and more power to those who can! It's awesome that most builders excel at something on their bike from either their trade or profession.
I think your solution is cool though savor!
I think your solution is cool though savor!
To change the subject a little... I received my custom built YSS shocks yesterday - super cool. I had searched and searched online to find shocks that suited - there are many shocks with the correct eye dimensions and the length I wanted, but not spring rate, that is harder to find. I had been in touch with YSS customer support and Hagons as well. As mentioned in a previous post, Hagons have good customer service and can custom make shocks, but they just look so damn ugly! That's just a personal taste thing but I think their product development and production needs to lift themselves out of the 60's. They have one new promising range of shocks - the Nitro range, but they are super pricey.
Anyway, I settled on YSS because they were also super helpful and could build a custom shock. They also look great and are great quality. Check em!
Anyway, I settled on YSS because they were also super helpful and could build a custom shock. They also look great and are great quality. Check em!
Attachments
And if anyone is interested, here are some specs...
Stock:
295mm Eye to eye
14mm Top eye
14mm Bottom eye
14-20 Spring
YSS Custom:
RE302-T - Aluminium
340mm Eye to eye
14mm Top eye
14mm Bottom eye
13-18 Spring (lighter rate for lighter bike and skinny rider)
Stock:
295mm Eye to eye
14mm Top eye
14mm Bottom eye
14-20 Spring
YSS Custom:
RE302-T - Aluminium
340mm Eye to eye
14mm Top eye
14mm Bottom eye
13-18 Spring (lighter rate for lighter bike and skinny rider)
Manual states:
K1 = 1.4kg/mm (0-50mm)
K2 = 2.0kg/mm (50-70mm)
I guess it is more common to write 14-20kg. Which would be kg/cm?
K1 = 1.4kg/mm (0-50mm)
K2 = 2.0kg/mm (50-70mm)
I guess it is more common to write 14-20kg. Which would be kg/cm?
sav0r
Coast to Coast
The K1 will get you close, but the K2 section is over sprung. You should be able to get away with zero preload, but you might immediately be in the k2 range.
I run 75lbs/inch straight rate on my RD and k1 works out to around 78lbs/inch. Your machine ideally will be significantly lighter.
YSS makes great stuff, but I'm not sure you are quite right with those rates. Assuming they are standard size springs the sky really is the limit though.
I run 75lbs/inch straight rate on my RD and k1 works out to around 78lbs/inch. Your machine ideally will be significantly lighter.
YSS makes great stuff, but I'm not sure you are quite right with those rates. Assuming they are standard size springs the sky really is the limit though.
Sav0r said:
Interesting. So I would be better to have a 14-16? Or a 12-16? This is what YSS suggested and I hope they have the experience to give that advice based on bike and rider weight. This is what customer support from Hagons said: 'We can do an equivalent shock to stock but ours is normally sprung and damped better. More like 16kg-20kg instead of 14-20kg.'
sav0r
Coast to Coast
There is a lot of room for interpretation and preference. I'd say you have a really good starting place.
Basically every build will go stiffer over stock because people are heavier today and they wear more gear. That is true right up until you spend a lot of time and effort building a bike that is significantly lighter than stock. At this point you are at the mercy of those selling stuff or at a minimum your own experience and testing.
My personal preference is to run very little preload, run a spring that is the right stiffness to achieve 30% sag, and then let the damper provide platform stability but be digressive from there. I'm not sure what YSS are up to, I haven't dyno'd their shocks, but based solely on spring rate you aren't far off. So give a ride and see how it works. I know you've spent a lot of time on the front as well.
I'm not trying to derail you here, I love your build and have followed it very closely from the get go as it reminds me a lot of my RD build.
Basically every build will go stiffer over stock because people are heavier today and they wear more gear. That is true right up until you spend a lot of time and effort building a bike that is significantly lighter than stock. At this point you are at the mercy of those selling stuff or at a minimum your own experience and testing.
My personal preference is to run very little preload, run a spring that is the right stiffness to achieve 30% sag, and then let the damper provide platform stability but be digressive from there. I'm not sure what YSS are up to, I haven't dyno'd their shocks, but based solely on spring rate you aren't far off. So give a ride and see how it works. I know you've spent a lot of time on the front as well.
I'm not trying to derail you here, I love your build and have followed it very closely from the get go as it reminds me a lot of my RD build.
Sav0r said:
That's good to hear! I see on your webpage how much you have worked/work with suspension and it's impressive stuff. I think some trial and error will be needed in this case as well. But I am such an incompetent rider, I don't think I would know/feel what is good or not :-[
I have been searching around for a titanium fastener supplier for some time now and have received quotes from 3 different companies. The idea was to be able to offer an engine bolt kit in silver, black and gold - to suit different customers tastes. I knew Ti was expensive but not so expensive as the quotes revealed! I've canned this idea to offer customers, but I did order a sample set to see the weight difference and check the quality. Added bonus is that this set can be used on this bike! 170g lost weight just with some bolts ;D haha
The coolest thing to do would be to draw up the front and rear wheel spindles and have them turned up in Ti - to reduce unsprung mass. But that is not within the scope for this project, both in terms of time and money $$$$$$
The coolest thing to do would be to draw up the front and rear wheel spindles and have them turned up in Ti - to reduce unsprung mass. But that is not within the scope for this project, both in terms of time and money $$$$$$
Attachments
sav0r
Coast to Coast
If you have a lathe you can center drill bolts. You'll gain nearly what you do with ti but do so at a fraction of the cost. The reduction in strength is nearly zero for center drilling, it's just a timely process. I know there are aircraft bolts that you can buy center drilled as well.
Ti hubs would be incredible, but you might end up with brake rotor over heating has ti isn't a good conductor of heat. Magnesium might be a better choice.
Ti hubs would be incredible, but you might end up with brake rotor over heating has ti isn't a good conductor of heat. Magnesium might be a better choice.
Making axles out of Ti has been an effective way to reduce weight for a long time, but always more than my budget would stand. Most axles and other bolts can be drilled down the center to deduce weight and it's not hard to lose 20-30% of the weight that way. You could add Ti retaining nuts to save a few more grams.
BTW, many drag racers use aluminum front axles. Yes you heard that right. I would not recommend those for street use, but it's a thing.
On our RD350 drag bike, I bought a GSXR lower triple clamp quite cheaply and had it machined to replace the stock steel one and that saved a huge amount of weight. A lower triple machined from billet would have been nice or maybe even a TZ250 lower triple in aluminum with Ti bolts would have been nice but not available within our price range.
You could replace every bolt and stud on the motor with Ti but the cost would be off the charts expensive. There are easier and most cost effective ways to lose weight, such as plastic or fiberglass or alloy components for seats, and spacers and wheel bearing spacers - as long as you have access to a machine shop.
BTW, many drag racers use aluminum front axles. Yes you heard that right. I would not recommend those for street use, but it's a thing.
On our RD350 drag bike, I bought a GSXR lower triple clamp quite cheaply and had it machined to replace the stock steel one and that saved a huge amount of weight. A lower triple machined from billet would have been nice or maybe even a TZ250 lower triple in aluminum with Ti bolts would have been nice but not available within our price range.
You could replace every bolt and stud on the motor with Ti but the cost would be off the charts expensive. There are easier and most cost effective ways to lose weight, such as plastic or fiberglass or alloy components for seats, and spacers and wheel bearing spacers - as long as you have access to a machine shop.
There's a story about Nick Richichi having a buddy who machined Ti axles for his TZ750 and after the first practice lap he told his guys to take them out. The flex made turning sluggish, since it added flex to the forks. I imagine aluminum would do similar being it's 1/3 the stiffness of chromoly.teazer said:
Interesting discussion! Ti is just astronomically expensive and is perhaps best reserved for dedicated racing machines. But center drilling the axles would be more feasible.
doc_rot did something interesting here:
http://www.dotheton.com/forum/index.php?topic=66016.380 - scroll to page 39.
doc_rot did something interesting here:
http://www.dotheton.com/forum/index.php?topic=66016.380 - scroll to page 39.
sav0r
Coast to Coast
On my RD I went up to a 17mm axle and center bored it. It's definitely light. I used stainless, I forget which grade.
I'm not sure what size axle the TZ ran, but if steel was fine and Ti wasn't I have a hard time believing axle flex was actually the issue, now if the axles didn't have proper clearances or perhaps tensioning that change in feel could very well be the case. Slop and flex I believe are often conflated, whether it be from a results perspective or overlooked during theoretical discussion. When I was working on the numbers for my front axle it was pretty clear that axle diameter after a certain D would not be a significant effective increase in stiffness given the loads the axle sees, from memory I believe diminishing returns started at like 10mm. Even from 14mm stock to 17mm modified there just isn't enough load for it to make a difference. Where the real gains are made though is in the fit of the various components to the axle. And to be clear, a larger D at the fork fixings and the resulting increase in bearing area did aid stiffness, but the beam strength of the axle wasn't a factor. Ideally the axle would be a light press fit in the wheel bearings and then the axle clamped and tensioned in the forks. A nice tight no slop fit in my simulations created the biggest gains in deflection resistance, and tensioning was the icing on the cake. Getting this all right would create the most taught feel. All of that said, I tend to believe that the damping properties of various materials and alloys to be just as important as Young's modulus, this in large part is why we don't see more carbon fiber frames even at the highest levels. That and when chassis systems as a whole become stiffer generally their tuning window tends to narrow making them less friendly to keep inside peak operating conditions.
Anyways... center drilling is a good affordable solution especially if a lathe is available.
I'm not sure what size axle the TZ ran, but if steel was fine and Ti wasn't I have a hard time believing axle flex was actually the issue, now if the axles didn't have proper clearances or perhaps tensioning that change in feel could very well be the case. Slop and flex I believe are often conflated, whether it be from a results perspective or overlooked during theoretical discussion. When I was working on the numbers for my front axle it was pretty clear that axle diameter after a certain D would not be a significant effective increase in stiffness given the loads the axle sees, from memory I believe diminishing returns started at like 10mm. Even from 14mm stock to 17mm modified there just isn't enough load for it to make a difference. Where the real gains are made though is in the fit of the various components to the axle. And to be clear, a larger D at the fork fixings and the resulting increase in bearing area did aid stiffness, but the beam strength of the axle wasn't a factor. Ideally the axle would be a light press fit in the wheel bearings and then the axle clamped and tensioned in the forks. A nice tight no slop fit in my simulations created the biggest gains in deflection resistance, and tensioning was the icing on the cake. Getting this all right would create the most taught feel. All of that said, I tend to believe that the damping properties of various materials and alloys to be just as important as Young's modulus, this in large part is why we don't see more carbon fiber frames even at the highest levels. That and when chassis systems as a whole become stiffer generally their tuning window tends to narrow making them less friendly to keep inside peak operating conditions.
Anyways... center drilling is a good affordable solution especially if a lathe is available.
When designing the rear set brackets I was hoping I could use some rearsets I had over from an abandoned project years ago. They would have worked if I were not converting to kickstart, but because I am, they would get in the way. So I found these other cool folding ones on ebay for a great price and the quality is actually outstanding. I think I will still need to heat and bend the kickstart lever slightly for clearance, or order the wider RD400 kickstart lever. The old rearsets will get saved for a rainy day project ;D
