What did you do today? Cobba's rebuild

[cobbadiggabuddyblooo]

Just as an extra note...
I feel I shall really focus the bike more for track days as I know my days of riding shall be limited due to ongoing back issues.
Plus I really don't want to be another revenue raiser for the govt.
I'm finding the 86-87 hp I had previously ( fcr's n pipes) I'm achieving around 6,000rpm now and the 62 ft/lb peak torque at 5,000 so it's just too tempting.....

I pulled up in the garage about 1 week ago after a quick 5 minute ride after fixing the rad fluid leak and when I removed my helmet a helicopter was hovering overhead.
I waited in the garage and about 10 minutes later, sure as eggs I was visited by the local constabulary with a warning.
Big brother is watching....

I'll get my ballpark jetting and fine tune it on a trackday this month.

[cobbadiggabuddyblooo]

Today's run came together well.
Still runs a little rich down under 4,000 with 1/8 throttle and little load but roll the throttle on upto half throttle I'm finding 12.8-13 and excellent acceleration but when I get close to 5,000 and roll on past 1/2 throttle the number decreases back to 12/hi 11's and WOT to 8,000 show 12.2.
So when I got home, I removed the 155 mains and went down 1 size to a 152.5.
A bit more popping and banging when rolling off the throttle so I feel I may have gone the wrong way on the slow air.
I'll go back to std 1.5 turns and focus on finding the right mains first.

Travelled out to Mt Mee lookout via Morayfield and there is a nice, windy road up the range with plenty of 2-3rd gear corners anywhere from 40-100kph. (25000-45000rpm)
Acceleration from 2nd gear out of the corners is great and easily lift the front wheel or break traction on the rear
Once ontop of the range there is a number of fast sweeping curves and straight stretches to work top gear and the upper reaches of the rpm scale and 100% throttle.
8,000rpm still comes around fast.

I'll see how tomorrow goes with the 152.5's .
Might be the happy medium I'm searching for.

So what did I learn,
Looks like if I want to lean up the 1/8th throttle,I'll try the fuel screw,if not it may actually be the 48 slow jet ????.
The slow air screw is not the way to go about this.

I turned the air screw back to 1.5 std then screwed in in so a little less air to find out how this effects the 1/8-1/4 throttle.
Ran even richer just dealing with traffic to get fuel from the servo. By the time I got home again the gauge was reading 7 -8 then went into error mode...
So I need to quickly remove the sensor and clean and re calibrate once again.
So I'll just focus getting the fuel screws a little leaner to start and place the air screw back at 1.5 std to keep the sensor clean.
This may be what was giving a slightly rich reading yesterday as there is 30 minutes riding in traffic .

I might as well pull the plugs out and clean those too and start from scratch again..
It would be good to see if I can find a cap head screw for the rubber manifold clamps.

[NWS870R]

158 mains, needle 3 notches from top Try running blue stacks with no filtration at all - you'll be surprised how free it spins up & how much 'drive' you will keep

[cobbadiggabuddyblooo]

Quick shot of electrical contact cleaner on the O2 sensor,cleaned, recalibrated and all good.

I went as far as winding in the fuel screw to 1/4 turn and still no real change on things.
A ride at 3/4, 1/2 turn and then at 1/4 I'm still finding rich readings in the high 11's, low 12's at 1/8 throttle.
Loading the throttle from 2,000rpm in 2nd turning into a street, By the time I'm over 3,000rpm and over 1/4 throttle everything seems to start to work.
(I wonder weather velocity or lack of it has some influence on this slow jet issue????)

So I figured tomorrow I'll wind the fuel screw all the way in and just see if the bike still runs.
My guess will be it will and maybe 45 slow fuel jet instead of the std 48 may help.??????

But first off, tomorrow I'm changing the small M4 phillips head screws on the manifold clamps to cap head to make life easier with all the removal of the carbs while I tinker.
I think I'll remove the O2 sensor, ride up to where I check the WOT and refit it up there with it all clean and recalibrated.

Popping and banging on over run was fixed by setting the air screw back to 1.5 turns

[cobbadiggabuddyblooo]

Well as I expected, fuel screws turned all the way in, idle perfectly rev up easily and drops away straight back to idle.
Quick ride once up to temp and the bike accelerates smoothly from about 1800 rpm in 2nd riding in and around the local neighbourhood.
Back home , I then attached the O2 sensor and idles at 13.0 and sits around at 12.0-12.3on 1/8th throttle which is all I use riding in traffic 40-80kph .

I'm sure if I went down on the slow fuel from 48 to 45 this would just give me some adjustment if I need to trim them.
The sensitivity on adjustment of the fuel screw and air screw are not linear, so if set at default 1 turn out, 1/2 turn inwards has a lot more effect than 1/2 turn out.

Now that is sorted, I can now work on the mains.

I know already I will need to move the clip on the needle back from the centre position and lean it up 1 clip as 1/4- 1/2 is good but you open it up any further and the A/F drops to hi 10's-low 11's until close to WOT.

With the std 150 main before the rebuild, the needle clip was move from centre , up 1 to lean it up.
When I placed it back to centre after the rebuild, this was a band aid to richen the mix till run in.

But first I need to find the correct main.
With the cooler months at present, I can find a good working main and once spring summer comes I can find out how going down 1 size works with the different climate.

[cobbadiggabuddyblooo]

13.7 A/F- 150. main
13.2 A/F- 152.5 main

While the 152.5 was in I then out of interest leaned the needle by 1 just to meter the change.
Gave me a better mid throttle reading in the high 12's.

I think the hi fuel readings I get in that 1/8-1/4 transition throttle area may be from the start of the interaction of the needle and how the fuel is atomised. I'm sure velocity all comes into play here.
Velocity is low with the cc's of the motor and the size of the 41mm FCR with small throttle openings and lower revs.
You need velocity to draw the fuel into the emution tubes to work its magic.
Be interested to try the tdmr40's or 39mm FCR's to see if this tidies this up.
But that ain't gunna happen..

The Allen key cap head screws I replaced the phillips head screws on the manifold clamps make life a breeze taking the carbies on and off ..

[cobbadiggabuddyblooo]

So a little research on the fcr idle circuit, fuel screw and seems that the Ducati boys and lads on their thumpers who fit 41mm FCR's have the same issue not only with the slow fuel jet being too big and fuel screw doing nothing but again the same issues with the throttle just on while cruising giving a rich mix just like I'm finding.
They seem to get around this by changing the root (3rd letter on the needle)
Something to look into once I get my main jet spot on.

They have no issues when they roll the throttle on from low revs all is good.
Again just like I'm finding.
At least I know I'm barking up the right tree.

[cobbadiggabuddyblooo]

155 main fuels give me 12.6-12.8 on acceleration throughout the rev range with a 13.A/F at WOT

So I'm happy with the outcome, and I'll now work on the richer mix on 1/8-1/4 throttle while cruising 60-100kph.
You can actually feel the slight surging in this throttle position.

I'm going to order some new 40 slow fuel jets and look at a needle diameter change.

The needle diameter affects that 1/8-1/4 range and with the coding ( EMP needle std) the P denotes the diameter.
To go leaner, I go up in the alphabet so I might try a EMR needle to just nail the last little niggle and with a smaller slow fuel I can acually use the fuel screw. .

Needle code:


3rd letter indicates starting dimension or root diameter of needle. Letters toward the beginning of the alphabet are richer (thinner diameter), letters toward the end of the alphabet are leaner (thicker diameter).


the links below has charts with the needle calibrations and codings.



http://www.southbayriders.com/forums/at ... ts/296433/
(straight diameter is what we are looking at on this chart and how that influence 1/8-1/4 throttle)
--
http://www.jetsrus.com/a_jets_by_carbur ... -41mm.html
( you can see the straight or root diameter is right on the bottom of the needle)

http://www.factorypro.com/tech/tech_tun ... s,Pat.html
(needle coding chart on here)

[cobbadiggabuddyblooo]

Flex jets are on their way to make life easier trimming things up.
I fitted the size 40 pilot( slow jets ) and found I was a bit at the other end of the scale.
Fuel screw 2 turns out and the air screw 1 turn out got me to a similar feel and reading with 48 with the fuel screw all the way in.
So I'm hoping I'll find a happy medium with a 42 and close to my base settings and shouldn't have to remove the carbies again during tuning with the flex jets in place.

[cobbadiggabuddyblooo]

FLEX JET NOTES

Ream out the hole in the fuel bowl that allows you to access the fuel screw with a 6mm drill bit by hand.
Only a touch needs to be removed to allow it to fit.

Make sure you remove the spring, washer and o ring with the original fuel screw.

For better alignment when screwing into place.
Place the flex jet through the access hole in the bowl then screw into place, then screw the bowl to the carbie.

Lubricate the flex jet cable regularly.

[cobbadiggabuddyblooo]

So a little information on the FCR set up.
( I knew I should have kept those TDMR 40's I sold Rich )

I tried a needle with a larger root diameter to overcome the rich 1/8-1/4 throttle response and for some STUPID reason FCR,s when you change the diameter, you also change the starting point of the taper.
I contacted Factory Pro and they confirmed my suspicions on the FCR needles.
They have exactly the same issues when dealing with FCR's and couldn't understand why they designed the needle table the way they have, as it is against the std of other carb manufacturers.
Mikuni for example , you change the root coding, the taper position and angle stay the same.
Simple..
But with the bike now dedicated to track days, that 1/8-1/4 throttle position used mainly on road and cruising will no longer be an issue..
The only time I use this throttle position will be in pit lane so I'll live with that.
Changing the pilot jets to a 45 gives me pretty close to my std 1 turn on the fuel screw though.

[dicky]

Make your own needles, it's not as if its difficult if you have access to a lathe or know someone who does.

[Mav617]

Mine got a new rear shock (R6 plus adaptor), Metzeler Z6 tyre, new chain & sprockets, new pads and pin clips:

[cobbadiggabuddyblooo]

Why not just rebuild the std Trx shock with a damping set up to the rising rate ratio of the Trx??
R6 has 10mm less travel, longer swing arm and different relay arm. The stroke of the shock is similar to the Trx but that's about all.
Been there done that years ago and the reason why I got rid of mine after a short stint.
But it gave me a good lesson on suspension and damping set ups.
How do you find the metzeler tyres on the Trx ??

[Mav617]

Cheers Cob, not rode it yet with the Z6's, heard good reports though. Shock wise I tried getting mine rebuilt but the guy said it was too far gone, so I bought a second hand one that made strange whooshing noises when sat on the bike so I gave up and got the R6 plus adaptor from Kayla. Hear what you're saying but this has to be better than a non-working standard set up?