NEED MORE TOP END!!!

[markrennie]

HI GUYS
just askin for some help please. i now have my racing bike complete and did my first track day at cadwell on 1st of april (no april fool). and found my bike to be good but lacking in top end. i have fcr's and they seem to give stronger midrange power but not so much in the top end. it struggled to get into 4th gear and i only could get 110 mph down the straight, trx's must have more than that surely??. i now have a set of kayla's big bore headers and then will be having it set up at my local dyno but would really like to know whats the next step. engine is standard and if the last owner is to be believed had a full rebuild.
does disconnecting the tps make more in the top? i have a koso dash so dont need to worry about the dash going mental. any advice will be appreciated.

does anyone know where i could get the heat ported and polished?

[Mincehead]

Where are you in the UK?

[markrennie]

oops i meant 5th gear on my first thread, and i live in Cambridge for mince.

[Mincehead]

Well a very quick search turned up this:

http://www.cambridgemotorcycles.co.uk/

Maybe contact them or drop in for a cuppa and a good chat.

By the way, what gearing are you running Markrennie?
Here`s someone I`ve heard of, he comes from Cambridge:

http://www.jordansimpkin.co.uk/Jordan.html

Your motor needs at LEAST higher compression, some peakier cams and the head flowing, the 878cc overbore would bring a few more ponies too and NEVER overlook ditching as much weight as you can.

[trixynut]

Hey mark,

A standard motor with big bore headers and FCR 41's with a foam filter will put out 90bhp (been there, done that) as opposed to a standard bike at 76bhp.

Doing the TPS mod (disconnection: search on here for how I figured out how to do the wiring) sets the ignition at full advance so will give a little more top end and raise the rev limiter a bit too.

Standard TRX will indicate 130mph flat out which is probably 120 in real life.

Definitely a problem if you're flat out at 110.

Sounds to me like it needs a proper ste-up on a decent dyno first and then some careful thought about matching your gearing to the circuit you're running at.

I've done pleanty of track days at Cadwell on my TRX and the 'straight' is not really a straight! Must admit I didnt look down at the speedo very often (too busy hanging on!) but IIRC it was showing about 120 down the straight if I got good drive out that last right-hander before (Barn?) and that was on a standard TRX.

Dave

[markrennie]

cheers mince,
i will be going to cambridge motorcycles to dyno her in a few weeks time and the gearing was standard 17/39 but i did try 16/39 at cadwell and found it worked much better with standard gearing at cadwell (uses the torque better).

[Mincehead]

A link from Jordan Simpkins homepage :

http://www.gord.biz/index.html

[phuk72]

Definitely a problem if you're flat out at 110.

+1

You have a serious problem if you can't get past 110 on a standard bike let alone one with FCRs.

So first things first. Are you sure your speedo is calibrated correctly? What jetting have you got? (I'd suggest you'ld want something like 158 or 160).

Was it stopping accelerating at 110 or just taking a long time to get there?

[Kayla]

Do you have an import (4NX) bike (or cdi)?

[markrennie]

Definitely a problem if you're flat out at 110.

+1

You have a serious problem if you can't get past 110 on a standard bike let alone one with FCRs.

So first things first. Are you sure your speedo is calibrated correctly? What jetting have you got? (I'd suggest you'ld want something like 158 or 160).

Was it stopping accelerating at 110 or just taking a long time to get there?

Hi phuk, speedo has been calibrated to the wheel circumference but is reading from the back wheel with one magnet, i will test digital speedo alongside my gps speedo next time out to be sure of speed.
I have no idea what jets are in it, using the ones it came with but it is going in next friday to be dyno'd and set up with kaylas big bore headers & the race can, so we will see how she spins up after that.

when i rode it at cadwell it seemed to take ages to get from 7,000-8,500 rpm where i have set up the shift light to come on & struggled to get in to 5th along the back straight.

[markrennie]

Do you have an import (4NX) bike (or cdi)?

not sure kayla the original speedo was in kmh so i assume it it was an import, doesn't say anything on the v5 about being an import. how do i check?

[Killerwhale]

Definitely a problem if you're flat out at 110.

+1

You have a serious problem if you can't get past 110 on a standard bike let alone one with FCRs.

So first things first. Are you sure your speedo is calibrated correctly? What jetting have you got? (I'd suggest you'ld want something like 158 or 160).

Was it stopping accelerating at 110 or just taking a long time to get there?

Hi phuk, speedo has been calibrated to the wheel circumference but is reading from the back wheel with one magnet, i will test digital speedo alongside my gps speedo next time out to be sure of speed.
I have no idea what jets are in it, using the ones it came with but it is going in next friday to be dyno'd and set up with kaylas big bore headers & the race can, so we will see how she spins up after that.

when i rode it at cadwell it seemed to take ages to get from 7,000-8,500 rpm where i have set up the shift light to come on & struggled to get in to 5th along the back straight.

8,5k revs...me thinks all TRX/TDM make best HP at around 7,5-8k revs....and peak tourque at 6-7k rev.
U sure u have learn to use the TRXs best powercurve?
If you need speed...gear it?
I´m talking high gears here....if it hesitates to red line at first-second you for sure have an issue.....

[markrennie]

what i would really like to know is now i have the FCRs and full big bore system and a good engine whats next? what should i be looking at next?.
I was thinking big bore kit (is 878 biggest i can go?), cams and porting am i right and can it be done. i wanna build a kick ass TRX over time.

Come on guys fill me with ideas

[markrennie]

thanks for the info killerwhale, i had no idea where it made peak power, sounds like i was wasting time over revving it. i will change shift light to start at 6,500 rpm. no doubt dyno guy will tell me when peak power is made.

looks like i need to learn how to ride the thing

[Killerwhale]

what i would really like to know is now i have the FCRs and full big bore system and a good engine whats next? what should i be looking at next?.
I was thinking big bore kit (is 878 biggest i can go?), cams and porting am i right and can it be done. i wanna build a kick ass TRX over time.

Come on guys fill me with ideas

We all in here can agree the FCR´s is most bang/buck....exept turbo it!
I would for sure go for a head skim....cheap mod to up the compression....
And while you gone the 41 mm route and big bore headers....see to it that your head is a part of that mod (porting)
I went race port, fellow TRX in Sweden went plastic inlets....i got more mid and he got more top....wich really is the wrong way around thinking of it!

You should find a well renouwned (spell check) head porter and at least weld up the exhaust ports....