Rasing the engine in the Frame

[bob]

The only class I could run with is the Thunderbike series and after watching them I figured it probably wouldn't be competitive and It'd be easier to start again with another frame which I do have.

Rob , I understand Bemsee do a 4 into 1 series which basically says if you've got a 100bhp bike, it must weigh 400lbs [181kgs], after that the rules are pretty relaxed....any size wheels/tyre / brake combination. Perfect series for triple running a modified chassis . Of course Gixxer 750s will fall into this category but I still reckon a bike like yours would be competitive.

 

[Laverdalothar]

Hi Lothar,

Picture where you write 'is that you Rob', that's St?phane from Belgium on his 750 SFC with me chasing him on my Egli Lav. The dice lasted the whole session, magic. Good times.

Marnix

I need stronger glasses...  :-[

 

[sfcpiet]

Paul,

The swingarm pivot and the drive sprocket are more-or-less on the same plane.... theoretically, raising the engine should have some influence on squat behaviour (don't think we have enough power for that!).  In practice, you don't notice it, at least not with suspension set up for track use.  Fitting longer shocks also helps a bit to lessen squat tendency, in fact the rear rises slightly under hard acceleration, a bit like a shafty Beemer!

piet

 

[Jota Rob]

The only class I could run with is the Thunderbike series and after watching them I figured it probably wouldn't be competitive and It'd be easier to start again with another frame which I do have.

Rob , I understand Bemsee do a 4 into 1 series which basically says if you've got a 100bhp bike, it must weigh 400lbs [181kgs], after that the rules are pretty relaxed....any size wheels/tyre / brake combination. Perfect series for triple running a modified chassis . Of course Gixxer 750s will fall into this category but I still reckon a bike like yours would be competitive.

Bob, thanks, I'll look into that, best earn some money first, this website is far more interesting but the pay is not so good  

Paul, thats a good point which I had considered, as Piet noted the rear spindle has moved down and the front sprocket has moved up, so although no longer horizontal they are pretty much still in the same plain. Only one way to test these things..

Rob, you're a brave man lending you bike out on the track but its one way to see and hear it from a a different perspective !

Lothar, I think I was in a different group, along with Piet for the most part, or was that 2009 I dont remember? There are few BC photos of me but nothing I wanted to pay for. no. 549
As said Good times !

 

[motoddrob]

Another shot of the Motodd on the old road nth of Sydney, that extra 2" makes all the difference!!
It's about as fast as I'm comfortable with on a highly policed public racetrack road

 

[jotajoe]

The lengthened steering head and subsequent bracing back to the frame mean a fork brace is unnecessary.
That came straight from Van Dijk when he braced my frame. Rob has done something very similar.
A fork brace is a pretty crude device at best and can lead to other fork issues as we all know.

Forgive my ignorance Grant,  (and it is ignorance I assure you)   
Why is bracing the forks detrimental?  Surely the less they twist the better?  Not?

Julian

+ 100 Julian

 

[bob]

On the current Ducati GP bike the designers have delierately introduced flex into the triple clamps because the front end was too stiff. OK, the mega stiff upside downers on a GP bike are very different to our 35/38mm spindlys but it does demonstrate that there's a lot more to this stuff than initially meets the eye

 

[Grant]

I think Jezza will sort out the interesting handling of the Duke and allow someone other than Stoner to ride the wheels off it.
If that pans out I guess no one will see Rossi for dust.

 

[Jota Rob]

Rob,

I reckon your coming to the end of your rather enviable road/track special. Reckon your going to have to make a decision about whether you want to race the thing, then you can get serious about throwing away the starter, alternator and trim everything back and produce a well sorted race bike.

Red's brace is now on the Spaceframe as we had real issues with the front tyre and mudguard being pushed back into the center header pipe under hard braking, It was quite hard too believe we had that much flex when you consider the spaceframe runs much shorter stanchions than any Jota (720mm from center of axle to top of top triple tree which is about 100mm shorter than my Jota). This problem was something that had to be dealt with for safety reasons, the brace seems to have helped with flex under braking which I didn't necessarily expect and has not had any adverse affects on stiction. The problems we had with suspension at Wakefield test day Vince refers too have been completely ironed out now with some additional work to seal the emulator correctly with a machined Marzocchi internal I used from another set of forks I had.

Fitting the new 17 inch Astralite wheels took me a good couple of days to measure up the correct spacers, machine and fit to the bike. The room I have clear between the sliders and the buttons on the rotors is about 0.5 mm and when I first setup the new wheels with the brace on, I was testing the stiction on the front suspension and it went from being locked without the axle done up to free as a bird with the axle torqued up.

It would be interesting to know how far from the ground the engine is on your machine (with static sag). I'll check the Spaceframe to compare, as we haven't had any grounding problems this year with engine cases (only the fairing), and I reckon geometry could well have a significant bearing as the Spaceframe has a fairly modern rake and trail setup compared to a Jota.
Cheers Crispin

Here's a couple of images of the measurement with engine stock but rear of bike sitting 30 mm higher. There is not much static sag on the bike at best but work on around 20mm, cant give you a more accurate figure until its all back together in a couple of years months.

The motor is now sitting 22mm higher at the front lower mounting and around 15-20 mm higher at the rear so those figures would need to be added.

 

[Paul LeClair]

Hi Rob & Rob - the Saxon/Motodd frame  holds the engine about 2" higher than standard - depends on suspension settings. I think that to ground it out in road use would be quite drastic cornering - racing is another matter. I use "Cerrocchi" forks with Marzo stanchions as they are a bit stronger (as Piet has said)- but I hate the poor quality of the sliders and use Ceriani ones. The fork tubes were std Marzo triple length, but were about an inch (or maybe more) above  the top yoke. With the mechanical anti dive fitted, the mudguard only just kissed the centre exhaust tube on the most drastic of braking. I learnt many years ago to remove the dome nut on the chain adjuster and let the screw thread drag on the floor - doesn't rip out hole in the chaincase then. - Regards - Phil

Hi Phil and all

you experienced old racers are finally spilling some of the inside dirt....!!!! I scared the crap out of myself the first time I whacked the dome nut of the primary chain adjuster on the ground in a left hander, and backed off my lean angle/speed for the rest of that day.... later at home I figured I didn't really need the dome nut at all, and I shortened the adjuster screw and cut another slot in it, both with a hacksaw - not up to forum engineering standards from what I am reading, but even if crude, effective!

someone (Phil, hint, hint) no longer competeing actively should spill the beans on all the Laverda racer prep tips, I'd certainly stand in line to buy that book!!!!!!! I am not an experienced old racer, I am just an old inexperienced racer with lots to learn, would be nuice to speed up the learning curve rather than constantly reinventing the wheel.....

also, laughed out loud at Russ's post about the fat old rider needing to lose weight to effectively raise the motor and increase ground clearance, unfortunately I resemble that remark...

Paul LeClair

 

[GregT]

Paul,

The swingarm pivot and the drive sprocket are more-or-less on the same plane.... theoretically, raising the engine should have some influence on squat behaviour (don't think we have enough power for that!).  In practice, you don't notice it, at least not with suspension set up for track use.  Fitting longer shocks also helps a bit to lessen squat tendency, in fact the rear rises slightly under hard acceleration, a bit like a shafty Beemer!

piet

Raising the engine will have an effect on fore and aft weight transfer which is more noticeable than pro or anti squat suspension.
If fitting longer shocks with motor at std height makes the suspension rise under power then i'd judge the sprocket/pivot/axle relationship as std is pretty close to ideal. By this I mean it has enough anti squat to work but not enough to rise and change the under power steering at embarasssing moments.....
The best of both worlds would probably be to restore the std relationship by fitting longer shocks - or remounting stockers - at the same time as the motor is raised
We've been through this in a small (pun intended) way with the macchis. Motor turns "backwards" and c of g is low so very little fore and aft weight transfer.Solution, raise the pivot and run a lot of swingarm droop which improved the drive off corners dramatically.

 

[XBCoupeJota]

Rob,

It would be interesting to know how far from the ground the engine is on your machine (with static sag). I'll check the Spaceframe to compare, as we haven't had any grounding problems this year with engine cases (only the fairing), and I reckon geometry could well have a significant bearing as the Spaceframe has a fairly modern rake and trail setup compared to a Jota.
Cheers Crispin

Here's a couple of images of the measurement with engine stock but rear of bike sitting 30 mm higher. There is not much static sag on the bike at best but work on around 20mm, cant give you a more accurate figure until its all back together in a couple of years months.

The motor is now sitting 22mm higher at the front lower mounting and around 15-20 mm higher at the rear so those figures would need to be added.

Hey Rob,

Similar measurements from the Spaceframe at the same points is 265mm and 335mm so if your bike is sitting 20mm higher than static sag at the moment at 230mm and 300mm the difference is significant (55mm is a lot of clearance difference), hence why we don't have the same grounding problems with the Spaceframe. It's interesting because the overall stature of the Spaceframe is much smaller than the Jota frame and the whole bike sits much lower overall.

 

[Jota Rob]

Hi Crispin
I'll recheck the figure over the weekend when the motor is resited but its probably going to say something similar.
As long as the triple frame has a top spine, this problem is alway going to be there. The motor could go higher but it would start to look a bit silly and a different or  seriously scalloped tank would be required. a removable top spine (clever but feasible) and raise the lower cradle to keep the aesthetics..hmm I have a seriously crashed frame!

I guess you guys have more than enough clearance and I dont have enough, I expect a big improvement on what was, and that's the fundamental  

Cheers Rob

ps how's your motor are you onto an upgrade yet or still running with the more standard one ?

 

[XBCoupeJota]

ps how's your motor are you onto an upgrade yet or still running with the more standard one ?

Hey Rob,

waiting for the BOSS to get back --REDAX-- from overseas to put the new motor together, he's busy packing a heist of Laverda's heading to OZ, including a new race bike for OZLAVERDA Racing. Our first round is 6th Feb so we will still be running the near standard engine, that said we are running 4 seconds a lap quicker at Wakefield from the beginning of last season to the end and maybe we will crack the 1:10 time at the next outing, reality is there is still time left in the package we have from last season so it's looking good for 2011.

Cheers Crispin

 

[andre g]

Hi Rob,
remember, a bike will not be fast if it is leaning inside you have to drive it as straight as possible.
Se you soon
Andre

 

[Jota Rob]

Hi Andre

I dont understand your comment athough, knowing you, I'm sure it has good value.  Can you explain more fully ? 

Cheers Rob

 

[motoddrob]

Hi Rob, why don't you look out for a suitable frame to house your motor. It looks like you've reached your limit with the modified standard frame. Have you ever ridden a Motodd??

 

[Jota Rob]

Rob,

It would be interesting to know how far from the ground the engine is on your machine (with static sag). I'll check the Spaceframe to compare, as we haven't had any grounding problems this year with engine cases (only the fairing), and I reckon geometry could well have a significant bearing as the Spaceframe has a fairly modern rake and trail setup compared to a Jota.
Cheers Crispin

Here's a couple of images of the measurement with engine stock but rear of bike sitting 30 mm higher. There is not much static sag on the bike at best but work on around 20mm, cant give you a more accurate figure until its all back together in a couple of years months.

The motor is now sitting 22mm higher at the front lower mounting and around 15-20 mm higher at the rear so those figures would need to be added.

Hey Rob,

Similar measurements from the Spaceframe at the same points is 265mm and 335mm so if your bike is sitting 20mm higher than static sag at the moment at 230mm and 300mm the difference is significant (55mm is a lot of clearance difference), hence why we don't have the same grounding problems with the Spaceframe. It's interesting because the overall stature of the Spaceframe is much smaller than the Jota frame and the whole bike sits much lower overall.

I said I'd update this when I had a chance to recheck the figures, sat on the bike and settled the forks today and the rear, which would equate to static sag when the bike is loaded back up with engine internals.
Bike dead upright and figures are 240 and 310 exactly 1 inch down on the space frame which seems almost made up, but it isn't. Im very happy with that and wish I'd measured it all before I started, inc rasing the rear suspension,  Have to finish the welding and can move on then.

Hi Rob (Motodd Rob) Thanks for the suggestion, I hope I can answer your question without sounding defensive. All these answers apply, Im never that simple  ???

1/ Because I keep my bikes
2/ I cant afford to change
3/ It isn't at its limit, if it was I'd be wasting my time right now
4/ I like being the underdog, if I didn't I'd probably be riding a Honda Fireblade or something super efficient and less challenging.
5/ I enjoy beating other riders on what looks (arguably) like an old Jota
6/ I'd have to change my name


I accept I could probably (ultimately) make an even faster bike out of a Motodd but see points 1-6 , I haven't ridden one no but it would be fun, if it was sorted.
Cheers Rob  (Robjota)