Genesis Of A Racebike - IT LIVES !!!!!

[davo231481]

ta. thats helped to make up my mind on a colour scheme.

[Gosling1]

well here we are a couple of years later - the 7/11 hybrid hasn't fired a shot in anger since Rd 1 at Wakefield in 2013......on the worst day of racing you could imagine - 1 completed race but managed 3rd in class overall for the day

Due to the 31mm smoothbores having to go back to the owner for use on his drag-bike - the 7/11 has sat idle in the corner of the 4th......but perhaps not for much longer.....

I had a visit on Saturday morning from old mate Steve Holgate - he of the Macintosh Replica fame. Steve took on the job of fabricating a manifold for me, based on an actual manifold that was kindly loaned from old mate Kwak Addict in Victoria thanks heaps for that loan mate, it was exactly what we needed. Steve started the job this time last year and promised it would take him 12 months to complete.....well he was right on the money.

Here it is in all its unmachined and unwelded glory !!













Steve has tacked the runners to the plates, I will need to get one of the local guns down here to complete the welding. Then it goes back into the Uni Physics laboratory (where Steve works - and where a heap of parts for Shadowfax were made over 30 years ago ) - so it can be surface-ground back to a flat surface on both of the plate faces.

The runners on this manifold are a bit longer than the template runners. That manifold was a casting. This one - we are hoping that the slightly longer runner length will add a lot of bottom-end response and torque. Won't know until its finished and fitted up with the DHLA DellÓrtos.........

This is a pretty significant step for this trackbike. Although this year, racing will be focused on the P6 class - I am aiming at a return to P5 Unlimted next year, with a fresh engine and the 40mm side-draft carbs all sorted........should be exciting

Will keep the updates flooding in with the same regularity as the last few years

[Mitch]

This is the best thread I have read this year!

Nice work Gos

[Gosling1]

cheers Mitch

Did some trial fitting of the manifold to the 7/11....... - not good news. The manifold is far too wide with the longer runners. Steve had only done a couple of spot-welds to keep everything together - so I removed them and pulled the manifold apart.

Some small mods with the dremel have sorted it out - the runners now are about half as long as they were - which means the manifold can now be fitted with the Dell'ortos and clear the frame tubes nicely.

Pics to come....

[Gosling1]

OK time for an update on this bike and its most recent endeavours

Rd 1, 2015 PCRA Champs at Wakefield Park yesterday, pitted with the Team Ghetto Racing crew of MickLC and Supamodel. Mick racing in PM F1 and F2, Chops in P5 250 and 350, and myself in P5 Unlimited.

The plan for yesterday was just to qualify and circulate for points. The motor in the bike at the moment is an old GPz1100 motor that, while OK on the street - has probably never seen new internals in 30 years . It still pulls pretty strong though......I fitted up the 29mm smoothbore Mikuni's that had been fitted to the Shadowfax. The exhaust is the street Kerker pinched from the Black Pearl.

At Rd 1 in 2013 - last time this old girl fired a shot in anger - there were some ignition issues and a bit of an oil leak from the inner points cover. I found the source of the leak - a piece of the oil seal had broken off, and there was a small crack in the bottom mounting lug. Sorted these out and the motor seemed to be OK in the shakedown runs up the street .....

I ended up qualifying on 3 cylinders due to a dud plug - doing 1'25"s !! slow as. But at least its a spot on the grid. Managed to finish 3 legs doing times in the 17's - still slow but did have a good race with a couple of punters for the first couple of laps in each leg. The exhaust system was dragging on both side - worse on the right - as it is a street system designed for access to oil drain plug and oil filter. This needs to go, with a better race system that tucks right in for heaps more clearance.

Laurie Smith had wound back the rear shocks as these were way too hard - the end result was great wear on the 160 SportMax rear and the front Dunlop slick still looks good

Here are some pics from the day - thanks to the various photographers Ray Oxford, Leanne Nelson, Richard Chopping and Alison Lewis

The 7/11 coming in from a hard slog


Chasing some Pre Moderns - including Captain Slow


Resting in the pits (battery being charged) - with Supamodels LC250 (ex-MickLC) and Mick's ZX6R.



The results for the day were almost set from the start - there were only 3 bikes entered in the P5 Unlimited class, so a 3rd place was pretty much guaranteed.........but in the last leg, Mick Neason on his GSX1100 had a DNS - which I didn't see until the time-sheets were collected !!! Much joy, thankyou Steven Bradbury - I picked up 2nd overall in class for the day !!





The 3 ghettoteers.......all with booty



So all up - a really good day in the sun. Was excellent to catch up with Rob and Leanne, Stevie Kairl, Rob (Kwakked Up) and many others. Hot day it was - but the meeting ran really well and I hope the rest of the season works like this....

As far as the old 7/11 goes - well it needs some motor work before Rd 2 in May. I have all the bits here for a dedicated race-motor for this bike - about time as well. Maybe even have that manifold sorted and be running the DHLA dell'ortos by the May round

[Kwakked Up]

Great write up Gos.

I thought the old girl looked pretty good on the track. Nice and stable although that is easy to say from the pit wall

If that zorst is giving you grief I could slip the Yoshi off my Z1000 if you wanted to give that a shot for the next round.

[Gosling1]

thanks Rob much appreciated - will see how I go with a home-built 4-2-1 first.....got plenty of spare header pipes to muck around with. What I would really like though - is one of these exhausts

[Gosling1]

Another important milestone for this bike.......huge thanks to Charlie from CanberraRIDERS who has spent some time on the Dellorto manifold over the weekend, welding up the runners to the flange plates............just wow is all I can say ! Check this out....




that is the manifold completely welded up - inside of the runners/flange plates only. The outer sides of the flange-plates now both need to be machined dead-flat, so that they will seal up properly on both the intake side of the motor, and the carbie side of the manifold. The flange-plates did get a bit of flex in them due to the heat from the welding - but that was expected.

After machining, the overall width of the manifold will only be about 52-53mm. This is perfect - overall width of the carbies is around 120mm, so total length of manifold + carbies should be around 175mm. There is exactly 180mm clearance to the frame-tubes measured from the highest point on the carbs (in the installed position) to the most-forward point of the frame tubes as the come down behind the motor. It will become clearer once I get some photos taken.

This is the single most important advance in getting these 40mm side-draft carbies up and running on the P5 7/11. I can hear those babies sucking now !!!!!

[Gosling1]

Update time - seeing as its the weekend of the Barry Sheene Memorial, seems very timely

The manifold came back from the shop last week, after both flange faces were fly-cut on the mill. This means a perfectly flat sealing surface on both sides as well as the overall manifold being parallel between the flange-faces. Here are some pics of the almost-finished product










Had a shot a fitting up the carbs to the manifold today for the first time.......the flange-plate at the rear where the carbs bolt on, needed some slight modification so that the throttle mechanism had clearance to the manifold. Just a bit of dremel work sorted that out

The bolt holes were perfect spec from top to bottom - but slightly under from left to right. No probs, just had to slot the holes a bit so there was a bit of swing room - and the manifold bolted right up ......

Time for the acid test - will the whole shebang - manifold and carbs - have enough clearance to the frame tubes ??? All the work gone into the specs for the manifold dimensions was just about to be tested...........here are a couple of pics.






Success !!! there is more than enough clearance at the rear of the carbs to clear the frame tubes and also allow me to fit some nice velocity stacks. The next step is to fabricate a throttle-actuating mechanism that uses the stock throttle cable. Should be pretty straightforward I think. Once that is done - time to start educating myself on the vast range of jetting available for these carbs - take some educated guesses and then bung the beast on the dyno for some tuning. Really looking forward to this !!!

Stay tuned for dyno updates......

[ZedOne]

That manifold looks great. I love me some fabricated stuff, and not off the shelf bought gear. So much more satisfaction.

Started from page 1...top read.

[Gosling1]

......That manifold looks great. I love me some fabricated stuff, and not off the shelf bought gear. So much more satisfaction........Started from page 1...top read. .....

cheers buddy. This thread will have a pretty long life-span methinks - but there could be some down-time between drinks every now and then . Fabricating stuff is just the best, I really wish I had a good mill-head for some tricky stuff and also a small lathe - but there are a few home-brewed workshops around the local burbs with good lathes and the boys are pretty happy to knock stuff up as required.

I am also doing a carbie conversion for a 1977 Z1000 in the shed, this uses 36mm CVK semi flat-slide carbies from a GPZ1000RX. The conversion required individual inlet manifolds to be fabricated from 4mm plate and ali tubing - there is a thread in this Classic Kawi area about this job - its been fun as well

[ZX9R Man]

Dude that lime green paint job couldn't have been from a spray can !

It looks too 2 pac ish.

Nice job anyway and that Steven Bradbury effort is exemplary.

[Gosling1]

that was a genuine 100% "Summernats In A Can' paintjob no shit. Its all about the prep........and on the day, the paint was laying on exactly as it would have out of a spray gun. To this day it has not had any clear coat.....

Time for a short update on the carbies........the direction has changed a bit.....

The 40mm carbs I have had sitting in the shed for 20 years - are not going to be used on the track bike. Turns out that after all these years - the 40G carbs I have - really are pollution (emission) style. The difference is internal and is based on how the slow-speed circuits transition to high-speed. I cannot change the internal drillings etc - and some of the adjuster screws are plugged completely..... the problem is the internal drillings and jets used, are designed to make the mixture as lean as possible at all transition points. Not what you want in a race motor.....

These carbs will find their way onto one of my streeter Zeddies eventually. It will mean fabricating another manifold but after the lessons learned in the first round - the next one will be spot-on. Also I will have a much better idea of what jetting works for a 2-valve 1200 motor spinning to 10,000rpm ( most of the Italian cars make max HP at only 5-6k......)

But its not all bad news - I picked up a pair of 'C' model 40mm DHLA's today from a local Euro car mechanic. He had a couple of sets sitting in the boot of an old Alfa - we went through them all - 2 sets of pollution carbs - and one set of old 'C' model DHLA's. These are the real deal - the performance version. A lot more adjustable in the low-speed circuits, where the transition from part-throttle to full-throttle occurs......basically - these are the carbies I should have been playing with all along. No matter - they will bolt up to the manifold just like the other ones. Looking forward to giving them the once-over next week.

There are some other unknowns we will have to deal with - fuel being the biggest issue. Not sure yet about the use of a fuel pump - these carbs are high-volume low-pressure. Maybe gravity feed from the tank will be fine........maybe. Time will tell.....I may have to use a small electric pump running at 1.5bar and a couple of solenoids to start/stop fuel flow to the carbs - yes it sounds complex but I am totally convinced these carbs are going to give me a throttle response that slide carbs can only dream of

The C-model carbs will be coming home next week - they are way dirty and will need a good tub - but they are 100% complete and should give me a much better range of tuning and adjustability......

[ZX9R Man]

Awesome work there Goz.
When applying paint you really need the right conditions. Temperature is critical/proper prep work,

[paulsj]

That manifold has come up a treat. I have seen sidecars with z1000's running webers and they sound great! That induction will be sweet!