Mallory Park trackday 878JE feedback

[misterdimwiddy]

Thought I'd give some feedback to others considering tuning their TRX following my first trackday of 2012 having made some mods to my machine last winter.

I have ridden at Brands Indy, Snetterton 300 (twice) and Mallory Park last year and found the bike to be an excellent track tool. Was left wanting more power in the face of modern 600/750's (blitzed on the straights) but found handling, braking and corner speeds to be very good.

1) 878JE piston kit, top end rebuild and Akro headers/Devil can
My motor had done plenty of miles (40k ish) but I left the bottom end alone and had the head/barrels off for 878JE kit. No head skim (1.2mm squish measured) and stock cams/valves. Just a new camchain (genuine Yamaha) which was out by half a tooth because of stretch. Carbs are stock with new emulsion tubes + K&N filter.

After 600 road miles to run it in I am on stock jetting and carburation is clean to the redline with biscuit coloured plug electrodes. May be a tad rich but I will wait for FCR's before I go for a dyno run.

It was damp in the morning so a gentle intro for my new motor and was really surprised by the grip from Supercorsas on resurfaced circuit.

The power difference is staggering for just 28cc increase (11.5:1 though compared to 10.5:1 stock). Gearing is now 17/43 which will help but it pulls to the red in top on the short straight before Gerards with a ]massive increase in midrange. I was able to stay with my brothers 2005 naked Z1000 coming flat out of the Devils Elbow in 3rd (couldn't get my foot under the lever to select 4th until I got towards the corner's exit!) and even down the start finish straight he was only just pulling away from me. I was stunned by the difference over a stock motor. Down one gear and hard on the brakes briefly where the pit lane starts, tip into Gerards and then gently feed in the power (footpeg grazing the tarmac) to exit at 8k rpm in fourth leading onto the back straight. No need to over rev it either. It just pulls like a good'un everywhere.

I will admit we were in the beginners group but there was plenty of reasonably fast riders and I was able to hang onto 2006 GSXR750's embarrassing many litre bikes. Puts a big smile on your face. Will try intermediate group next to up the pace a bit now that I know that the bike flies.

There is so much more power to enable rapid corner exit speed that you can now often pass riders on faster machines without them then getting by before the next turn.

I am sure that it is the combination of the piston kit and free flowing pipe that has released the power as is often commented on the forum. I had to hacksaw the old headers off (siezed in exhaust ports) but found that the collars were brittle and could be cut part way through end then split to get them off. Noise was 101dB's (105 max allowable) but this was with a home made stainless mesh dB killer. Not sure that it would pass 105 straight through but it sounds tremendous. The induction noise is more noticable and the whole motor feels quite brutal but not harsh.

FCR39's are next for that extra 10hp which will make a real beast of a bike I reckon.

So. anyone considering these mods and/or going on the track I would highly recommend both. Total cost for the above was close to £900; 500 for the motor (pistons (TTS), boring (TTS), gaskets, camhain, emulsion tubes) and 400 for second hand can/headers (Thanks again Pete). Could say this is a lot to spend on a 1996 bike but the result adds so much to the bike.

2) YZF750 front end (320mm discs)

Was dubious that this change would be anything more than cosmetic but I could not have been more wrong.

Stock forks felt fine to me as did blue spots with Goodridge hoses. No complaints last year especially when it is on the brakes/corner speed that you have to make up ground on a bike with just 85hp.

Others told me that the USD's would make the bike feel more 'planted' and that the change would be noticable but I still had my doubts.

It's difficult to describe the difference in words but the bike does feel very much improved. The forks I have are relatively simple (no damping adjustment) and were set up for a rider a little heavier than my 12st. I have left them alone however. The whole bike feels more taught and rigid (though not harsh in any way). Braking into the hairpin at Mallory even with the back end skipping around never felt disturbing and under harsh braking from almost flat out into Gerhards, the increased stability was noticable. It never really got tangled up in knots before but it is definitely better even at higher speeds.

Not only does the mod transform the appearance of the bike iit works well too (thanks again to Pete PHUK72 who sold these parts onto me a while back). I have R1 yokes which I believe changes the head angle; whatever it is it feels great. Harris clipons give a good riding position without being that uncomfortable.

The other obvious difference is the YZF 320mm discs (R6 master cylinder) over the stock 300's. First session (damp track) I was not that impressed but I wonder whether the pads (unknown brand) had been run with a different set of discs previously and they just needed bedding in. Rapid improvement followed and by the time the track dried out I could use the full power. Feel at the lever is excellent and stopping power is very much greater. I will pop some (pricey!) Brembo track compound pads in later this year and see how that goes.

No need for 6 pots; blue spots are up to the job. My brother has 6pot Nissins (from a Busa) on his Zed and he could not out break me.

3) Weight loss

Only other thing is to strip off as much road gear as I can. It has become a track only bike so many parts are gone and I would guess I may have shed about 10-15kg's. Every little helps I suppose.

I would like to get some pics on the forum because she does look neat as a naked track bike. If anyone can recommend a thread that guides me through this in simple temrs, I will give it a go.

Anyway, enough rambling text from me. I love the bike so much I could go on all night. Hope some of this is of use to other members. I have certainly found the forum invaluable as a guide to these mods and as a source of quality parts so thanks to all those concerned.

Phil

[AndyAshworth]

Thanks Phil for taking the time to write that report (even though it was a while ago). That's very useful to know from my point of view, as my TRX is standard apart from the Akra system. I'll be embarking on various upgrades through the coming months!

[Dan 850]

Good write up but, why the harsh braking into gerards ? I know your bike is probably a bit quicker then my standard trx, but I was tipping in there around 110, coming onto the back at around 120-125. (gearing 16/39) not quite on the redline before the brakes for edwina's. But Just ease off at the end of the pit wall and chuck her in, there's so much room to run wide if you do but it's getting into your head you can get round alot quicker then you imagine. What a corner tho, I can't wait to go back. You need to quicken your rebound up on the back if it was skipping on entry to the hairpin. Are you on stock rear shock ?

Agree the blue spots are plenty good enough, I have the ferodo sintergrip in them and they was bang on, I couldn't justify the brembos. And the bikes are surprisingly good on track, I didn't think mine would be, so we took the r6 too, but didn't once touch it as I loved the Rex too much. As you say power from the 1 litre bikes is the only downfall.

Also what tyres did you run and what pressures ?

Just realised supercorsa. I ran mine at 30 front and 28 rear. Never skipped a beat and wore extremely well.

[misterdimwiddy]

Dan

Thanks for your comments.

Either I'm riding like an old woman as I turn into Gerhards or my 878 is way quicker than a stock TRX (esp with a 43t rear and 15kg weight loss)? I like to think that it is the latter! I recall fitting an RSC 998 High comp kit to my 80's CB900F proddy racer which was then able to stay with Katana 1100 Suzuki's, GPZ900's etc. Those were the days. A few extra cc's and higher compression can make a surprising difference.

Feels quick enough for me and I'm not generally being passed at that point unless it's by a modern ballistic supersport 1000.

No speedo on my machine and so I have no idea what speed I am doing anywhere.

Next time I'm at mallory I will see what improvements I can make.

Phil

[cobbadiggabuddyblooo]

Phil check the gear commander and that will give you an idea of speed...