OK, so lets build a Top fuel bike - The 2nd Installment

I'm going to try and condense the next 12 months progress into one post!

With the decisions made as to the bikes configuration, it was time to move on to how I was going to actually make it. The engine being the main area of concern as I’ve not build an engine before, chassis - sure that’s a known quantity but crankcases and cylinder heads - from scratch, they are firmly in the realm of the great unknown. 

Options considered were:

1) Pay someone else to do it (total consideration time 0.4seconds)

2) Make it from billet Aluminium - it's all the rage these days with the era of affordable CNC machinery, but I don't have one, don't know how to program one, and I don't have a business to justify buying one or an interest is starting one. That said, it's no problem to machine a billet manually but, as an inexperienced machinist it's risky to work on large billets due to the high cost of buying them and the chances of messing them up (High)

3) Sand cast Aluminium - It turns out casting is very affordable, a set of cases is less than a 1/4 the price of a billet, even after heat treatment.  It's a lot less machining to do afterwards and easier to machine too. Plus - seeing as how a great number of the top fuel bikes in existence use Puma cast cases I figured this was the right way to go.

So off I went on a research trip into pattern making and sand casting, I visited foundries and spoke to anyone with experience for advice. I was really lucky to be given a large disc sander and small bandsaw early on - these proved to be invaluable later. 

The first patterns I made using MDF - I hate the stuff but it's accurate, flat and easy to work with. Building it up in layers of varying thicknesses to get what you want. It does however need a lot of layers of paint afterwards to seal them.  Crankcase patterns took 3 attempts to get to an acceptable state. Looking at them 3 years on I’d bin em!

I had two sets of crankcases cast, and they turned out ok. A little bit of porosity in one but the other was good. Virtually all the machining was done on the mill, using a set of dedicated jig plates. Line boring them took many many attempts before acceptable results were acheived.  The crank design uses large roller bearings on the outside and double plain shell bearings in the centre.     

 

 

Cylinder head and barrels came next, the barrels were pretty straightforward as the pattern fairly basic and the engine is totally symetrical, so the same pattern fits the front and rear cylinder banks. The cylinder head however was a lot of work and a conventional pattern would simply not work. Instead it used a series of around 20 core boxes that were used to make sand models of every part of the head. these were then asembled in another giant core box that held them all together. Each head is assembled out of approx 25 sand cores.

 

And so 12months in thats most of the big engine parts cast, and a lot of the basic machining.

OK, so lets build a Top fuel bike

Over 3 years ago now - around July 2019, i made a start on designing a top fuel bike. I knew roughly what i wanted to do, and so set about gathering information and finding out if it was possible. 

The brief was simple - to build a relatively light and simple fuel bike that makes the most of the latest technology - and to get away from the ever increasing trend of bigger, heavier and more.

I did a lot of research into power and weight ratios, bore and stroke ratios, fuel calculations, parts availability, and sketched page after page of ideas for several weeks, and slowly but surely a plan came together. As with anything bespoke, if you want it to be the way you really want it then it's bound to be the option that requires the most work, and also be the one thats the most challenging to build. Mostly because practically none of the parts are out there to just buy off the shelf (not like i had the budget to do that anyway). 

But i thought hey - i've got the shed of dreams, I've waited my whole life to have a workshop like this, think big!

And so - in order to keep it to the breif - Light - simple - trick i made the following decisions:

• To keep it light - no blower, no jackshaft, no gearbox, no huge rear wheel and tyre, no enormous clutch with weights, arms, and release bearings/cannons.

• To keep it simple - no blower, no jackshaft, no primary drive and belt, no gearbox, and no horrendously complicated mechanical fuel injection.

• To make it trick - It would use the latest and most powerful electronic ignition i could find, it would use electronic fuel injection with huge injectors, and use a 100% pneumatic - CO2 clutch, all controlled by the most suitable and adaptable ECU i could find. 

Without a blower the engine would need to have a large capacity, and to do away with a primary drive it would need to be narrow enough to mount a clutch and drive sprocket directly on the crankshaft. A v- twin was a possibility, but to rev high at 3000cc+ would need a bore so big that pistons aren't commonly available. A v-four however works out nicely at common bore sizes and relatively short stroke, and would still end up narrow enough to fit a cluch on the end. Cylinder head layout and valve components would be based on the V&H 2v suzuki prostock head fitted to my funnybike, but with roughly the same valve sizes it would be possible to fit 4 valves per cylinder.

I went for a 360 degree crank design, as 180 cranks can be prone to a 'rocking couple affect' across the length of the shaft, and with such huge pistons and counterweights i thought i'd steer clear. 90degree vee - 360 crank also has a nice even firing sequence of 90-270-90-270.

 

 

The engine would be a 90 degree V4 with 3023cc displacement and a bore of 111,125mm, and stroke of 78mm.Would use DOHC and 4 valves per cylinder 38mm exhaust and 45mm Intake.  Pistons and sleeves being common big block top fuel and top methanol sizes. 

With those decisions made and drawings done, all that was left was to figure out was how to actually make it - as you can't buy an off the shelf 3000cc V4 top fuel bike! 

A 3 year gap

What could possibly have happenend in 3 years thats worth talking about? more of the same, dragbikes, dragbikes and more dragbikes. You get the idea right? 

Facbook stole the crown when it comes to easy to publish posts, and made it easier for people to comments and exchange ideas. But i often think about my poor old Blog, it's more of a resource, a place you can find info. And i find myself referring people to it when they ask about doing stuff. 

So today lets do a blog post and see if the ball keeps rolling ....

Back to 2019 and a season spent riding Bob Brooks YMR methanol bike in the funnybike class - alongside my own bike ridden by Dave Batcheler. That season was one of the best ever, it was just so interesting having effectively 2 bikes in the class, and riding Bobs bike was a great experience, and one that lead to a lot of things. 

Having the bike there to look at, and working on it throughout the season taught me a lot of things - things that were once a mystery i could now see how they worked and at least partly understand, and i decided in the middle of the season that i wanted to build something like this myself.

And thats where the next chapter really begins. It was obvious that whatever i built it had to run on Nitromethane, i'd posted a few years ago that i wanted to build and ride a top fuel bike, and i can't not do it forever!

To be continued .......

Guilty as charged

It feels like I've abandoned my poor old blog in favor of Facebook, but the 2 things are completely different creatures and Facebook is rubbish unless your already on there yourself.
So ..... I've decided to do an update seeing as how a great deal has been going on and the 2019 race season is just over the horizon.
The big 2v engine turned out to be a pain to get the valve timing right, and i wasted a couple of meetings not having it right and it wasn't until the National finals in September that i finally made it down the track. It ran ok too with a very soft setup it managed a couple of messy 7's, the problem with both runs was tagging the rev limiter hard in each gear. The old engine ran out of steam at 10,500rpm, and i set the limiter at 10,800, but this engine just want to rev so i kept turning it up, but still tagging the limiter which unloads the bike and makes it horrid to ride.
And that's how the season ended really, just scratched the surface ....

Over the winter i did a lot of work on the back half Suzuki Hayabusa Project i started for Kev Osman 2 years ago. Finished all the Bronze wending and fixed tabs and brackets on wherever they were needed, made the sprocket support plate and air shifter mounts and basically got it ready for Kev to take it away and do the finishing touches. The end result looks pretty good, and Kev has got it ready for testing in a couple of weeks time, and it'll be interesting to see how it goes.

Back in January our plans for the 2019 season changed quite radically, when received an offer I couldn't refuse - to ride something rather special in the form of the quickest and fastest blown methanol bike in the world - Bob Brooks', beautifully engineered Yellow metal racing bike. Bob has had his very unique bike for sale for a while now and rather than leave it parked up any longer he very kindly asked me if I'd like to run it this season, and of course I jumped at the chance!

The bike will still be for sale throughout the season and hopefully someone will see it run and fancy the experience themselves.
Bob and the Yellow metal team will be helping us run the bike for part of the season as there will be a lot for our team to take in before we can go it alone. The only similarity between our bike and Bob's is the number of wheels! I really fancy the challenge too, we have run a nitrous GSX for a long time now and this is just something completely different so it'll be fun learning something new.

I didn't want my own bike to sit being unused either, so i decided to ask my friend Dave Batcheler if he would ride it alongside me in Funnybike. Dave jumped at the chance and has now been and collected my bike, as I've no room for 2 bikes in the van, or in my shed either as Bob's bike is massive. It does mean that at some point I'll more than likely end up racing against my own bike - an interesting concept!

Bob is bringing the bike up to me this weekend and going over all the various bits and pieces. I may need to take a lot of notes!

Ready or not Redline rumble

Just one week to go till the next race meeting - the all new 'Redline Rumble' at Santa Pod. This meeting was organized after the announcement that there would be no more racing at Shakespeare County Raceway - presumably to make up the number of meetings required to hold a proper championship. It's actually two events in one weekend - with qualifying and eliminations on both days. So - in terms of the championship it's important not to break your bike on the first day or else loose a lot of points the following day.
Not the ideal meeting to go to with an entirely new setup then, but if it's finished in time that's exactly what we will have.
I've been working till 11pm every night trying to get it finished, and it's been a lot more work than i could imagine. But it's getting there and i'm hoping it will be ready to fire up this weekend.

New Crankcases being bored to leave as much material as possible. 

Machining piston pockets to fit the enormous valves, and taking some material off to help get the deck height/compression ratio required

 

Checking the crank after replacing no1&2 webs

 New and old carbs, 48's from 40's

 1640cc 12:1

 V&H 2 valve head

 And 100's of hours later - the nearly finished product

6 months in 1 minute

I'm sure lots has happened between now and the last post. And I'm sure most people have given up on any blog updates but I'll attempt to fill in the 6 month gap.
The first thing that happened was - i built a new frame. Actually I built 2 because I made a silly, expensive, and time consuming mistake on the first one after setting the jig up wrong. And finally realised I needn't have built a new one at all. The only only positives I can pull from the whole experience are ... I'm now dead good at bronze welding, and the new frame has a couple of refinements making it sit better with the engine now 1.5in further forward.
Oh, and it seems to handle just fine too!
Easter was meant to be the first test but the weather was bad and the faster classes didn't run at all. The next event was the non ACU round - the main event, which we entered as there's a lack of meetings now Shakey has gone. We had a few small issues but went quicker each time, running a best of 7.5, sadly not good enough to qualify.
On to the Summer nationals, a well attended event and half the field now running 6's. We made 3 runs with a best of 7.5 again but on the 3rd qualifying run an ignition pickup came loose causing the bike to cut out violently, and then come back on, possibly with the timing being out which caused a holed piston. Back in the workshop I stripped the engine to find the cases also damaged, cracked on the same cylinder.
It's been a long time since we damaged any cases or pistons, do they had done well considering. With no spare 85mm pistons I've decided it's time to build the bigger capacit engine I've been gathering parts for. It should make a fair bit more power, which is what we need now to complete in a much faster classes than previous years.

Bopchops coming home

Today marked a milestone for this year - i finally moved the dragbike from the cellar at my sisters house, where it was born and raised and brought it home - to the shed of dreams.
This is what it's all been about, buying a house just so i can build a shed and have a larger, more accessible place to work on dragbikes. Oh ......and, i guess it's somewhere to live as well :D
The shed isn't totally finished yet, there's still some insulation to go up in the rood space, a chimney making for the stove and the SWA cable for the electric. But it's ahead of schedule and even under budget!