New 2009 Mods on Doc's FJ Racer

The first thing to do was check the state of the motor after a years, 32 races plus 6 track days. So a quickly did a run on the Dyno at ‘Tim Blakemore Racing’ in Bristol which showed up a reading of only 136bhp.
This was 10hp down from the start of the season.

After chatting to Tim he was shocked to know that I still had the rings from two seasons and suggested I look there for the lost power. But then again Tim is always commenting on how badly we prep the FJ Racer engines as I have never changed a single bearing in a motor even though they have done over 50k road miles, I always say “the road miles have just blue printed the motor for us”
So on stripping engine I found the top ring gaps were 0.50mm and oil rings 0.70mm. Wiseco recommend 0.35 for all, so their was slight wear on top and 2nd ring and excessive wear on the oil ring. So this confirm a new set of Rings were needed.
Whist apart I de-coked the pistons and head plus re-lapped the valves in and fitted some pattern valve stem seals for good measure.
On the last Dyno run the engine was still running rich so I lowered the main jets in the carbs from 150 to 148.

Engine Painting;
I promised myself that on this engine strip down I would paint the engine as it was looking very shabby from the touch up of black engine enamel over the years.
Not wanting to have the engine bead blasted (never can be sure of the abrasive beads not getting into engine and destroying the bearings etc.. ) so it was dipped in acid to chemically remove the paint.
Once done I needed to give it a scrub to remove any chemical residue before applying the grey engine enamel. The idea was to make the casings look like they were sand cast.

Slipper Clutch;
After having a go on a 08 ZX10R I was amazed at the slipper clutch fitted as standard to this machine. You would simply bang it down three gears in one go ready for the next bend, let the clutch out without a moment from the rear tyre or gearbox and on exiting the bend, the engine would drive out hard, excellent bit of kit.
After asking around no one had fitted one to a FJ but finally Neil Spalding (the Euro Sport Technical Guru) of Sigma contacted me saying they have a XJR unit that might work. We are a bit worried about it slipping on the power but we won’t know until its tested on the track, it held on the Dyno run, so watch this space!

Extra oil;
The idea was to increase the sump area so it could hold more oil. The theory is the more oil you have the cooler it will run as it will work less. Having a reduced oil temperature when the engine is only cooled by the Air is a bonus, because when the engine gets to hot it will loose power.
My answer was to manufacture a spacer which fitted between the lower crankcase and the sump. I worked out that it would allow an extra 400ml to be held in the sump, that’s 10% larger, every little helps as they say!

Steering angle:
The FJ has a rake angle from the dark ages of 27.5’ degrees. This is great for stability but not good for an agile race bike, even the XJR1300 has 25.5’. Having raised the back up approx 30mm over standard for ground clearance the off shot of this was a steeper steering angle of just over a degree. If we drop the forks in the yoke which would also have reduced the angle, but we would loose some valuable clearance, so there was only two answers.
One; fit an one off set of yokes with adjustable head angle, the problem is the cost which would be too expensive, in the end we are trying to have cheap-ish racing.
Option Two was to cut and re-weld the stem angle. This suited my Bert Munro way of doing things so after finding a professional frame builder (not many good quality motorcycle engineers around now a days and Dave bless him, was 72). So after two weeks the frame had been rewelded in a Motoliner Jig to try and increase the angle by 2’ degrees. Dave I think had problems due to the sheer strength of the frame so the end result wasn’t quite 2’.
To cut the story short I have finally measured the new rake angle at 25’10. I will test the bike on the track as I’ve still got the ability to lower the front by up to 10mm (over a degree) without any ground clearance lost.
I have given the FJ a nicked name, the ST version. ST stands for ‘Shopping Trolley’ as everyone has said it handle like one.

The fork legs has been slightly leaking over the season but being 20 year old I can’t blame them, so I purchased a new set of nitrate coated fork legs from ABE. Whilst apart I polished and lacquered the lowers to tidy things up.

Penske rear shock;
The unit had now been raced for three seasons so I was recommended to have the unit serviced. I contacted K-Tech (well known for servicing the BSB suspension units) who did the work plus I asked for the compression damping to be increased as I was running it on the max setting 6 and had no adjustment left.

Finally the DYNO run;
The proof in the pudding is always the Dyno run but before this I at to run the ‘rings’ in. After asking around I had comments from “a least 300 miles’ to “no need to run in” I decided to run it in on the Dyno. What a great way to run an engine in. No salt, no wind, no cold air, just a nice warm Dyno room and after an hour it was sorted.
After the power run Tim looked at me and said “what have you done to this engine?”
“just a set of rings”, “no seriously, what have you done?”
Tim was shocked at the 162bhp he was seeing on the Dyno and the perfect fuelling.
I have NO answer to why it has increased from a very good 146bhp last year to a massive 162bhp. The only two slight things that might of effected it was I fitted an OE head gasket which is about 0.10mm thinner than the Wiseco gasket and the fact the ignition might be slightly different to last year as I trouble re-lining up the timing marks, so I just guessed.

Dyno charts:
One showing comparing with standard FJ against 06;07;08 and 09 FJ racer runs
Other show full 09 dyno run

09 engine painted

Engine rebuilt with new piston rings and while motor was apart it was repainted to look like its made out of solid Granit

09 spacer

Manufacture a spacer on the sump to increase sump capacity. This 8mm spacer increases the capacity by 400ml, thats 10% bigger on the standard 4 ltrs.

09 slipper

Neil Spading (Moto GP Guru) said that a slipper clutch can be worth up to 2 seconds a lap.
This is the first time a Sigma slipper clutch has been fitted to an FJ. Will have to be set up to handle 140 bhp and slip on down shifts. Watch this space

09 head stock

The standard FJ head angle is 27.5' which is great for two up touring but not good for Racing. Answer.
Re-adjust the head angle by 2'. by cutting and re-welding steering stem

09 brembo brakes

You can never have to much brakes. Answer:
Fit Brembo's finest 4 pads gold line brake calipers from a Ducati 749, fitted end of 2008 along with new fork brace.
All I need is the balls to sqeeze the lever hard.
Note brushed polished fork legs, yokes and new legs.

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