What did you do today? Cobba's rebuild

[cobbadiggabuddyblooo]

Lifted the cover on the TRX today and decided to finally fit the flex jets into the FCR's.
Removed the float bowls and just had to run a 6mm drill bit through where you access the fuel screws.
The access hole in the fuel bowl just isn't quite wide enough to allow the flex jet to fit.
It's only a poofteenth too small so I placed the 6mm into the drill chuck and rotated the drill by hand to slowly work its way through to avoid any damage to the cast alloy with the hole close to the edge.
Went to fit the 45 pilot jets I ordered but opened the package and Show n Go supplied the wrong jets.

I'll have them in a couple of days to fit in place so in the meantime I'll take the head off and fit another head gasket to gain another couple of points in compression.
Good chance just to check how things look inside. hasn't used any oil even with the 200km's hard riding last track day so good signs
The maths give me 12.5 : 1 up from 12.25 compression with ample valve clearance up my sleeve.

[SDN]

Much easier than tank off and carbs off to do a simple adjustment - well worth it if you like to have a fiddle

[cobbadiggabuddyblooo]

http://www1.odn.ne.jp/cak92920/fcronotherdate.htm

With the down time I've been doing a little research on why the rich setting on 1/8 throttle.
Here was a good database on FCR jetting setting for twin cylinder motorcycles with the TRX in amongst them.
Gives you needle coding,clip positions, jet sizes , HP and Nm readings with temps and barometric pressure readings when set up.


車種φ ニードル 段数 Ｍ　Ｊ Ｓ　Ｊ Ｐ　Ｓ Ａ　Ｓ 参考etc data temp mbar 感想　備考

ＶＴＲ１０００
110/9000
9.9/7000 ＯＣＥＭＴ 4 172,175 45 1 1 halセット
ＯＣＥＭＴ 4 172,175 50 1 1
OCGFR 4 150,152 48 1 1 1/2 4月

ＴＲＸ８５０
83/7500
8.6/6000

ＯＣＥＭＰ ３ １４５ ４８ １．０ １ 1/4 28.2 1013 カス


９００ｓｓ ＯＣＥＦＴ 4 155 60 1 1 1/2 BIセット39φ
OCEFT 3 145 60 1 1 1/2 9/28
ＯＣＥＦＴ 2 140 60 1 1 3/4 6/4

９００ｓｓ ＯＣＥＭＴ ４ １５５ ６０ １ １ 1/2 MPセット41φ

M900 OCEFS 3 125 52 2 1 1/2 岩
M900 OCEFS 3 135 52 1 1/4 1 1/2 岩

900SL OCFFR 4 155 58 7/8 2 itoda

DB2
single EX
テール50φ OCEFT ４ 155 60 1 1 1/2 デフォルト
OCEMR 3 150 60 1 2 11/27
OCEMR 3 155 60 1 2 12/30
OCEMT 4 145 48 1 1 1/4 12/31
OCEMT 3 145 60 1 5/6 2 1/4
OCEMT 3 140 58 1 1/2 1 1/2 1/4
OCEMR 4 150 55 1 1 1/2 1/7
OCEMR 4 155 55 1 1/2 1 1/11 â—‹
OCEMR 4 150 58 1 1 1/2 2/8 â–³
OCEMR 4 155 55 1 1 1/2 2/11 â—Ž
OCEMR 5 155 52 1 1 1/2 3/28 △×
OCEMR 4 155 55 1 1 1/2 3/28 â—‹


真夏予定 3 150 55

XLR250R
H/Z 39φ OCEMS 4 165 55 1 1
1/2 5/24 â—‹


番外
(スパーダＦＣＲ)
Ducati400ｓｓ用
ＴｗｉｎＤ/D33φ ９０FTX ４ １４０ ６０ １ 1 1/2 入手時
デフォルト
９０FTM ４ 140 48 1 1 1/2
90FTV 4 115 48 1 1 1/2
90FTR 3 120 50 1 1 1/2 2/8 â—‹
90FTR 4 120 48 1 1 1/2 3/21 â—‹
　予定案 45


真夏予定 3 115 45

[Mincehead]

Cobba, MAAAAAATE, you`ve become a complete boffin! Nice to see.

[devlin]

What does it all mean?

[cobbadiggabuddyblooo]

Cobba, MAAAAAATE, you`ve become a complete boffin! Nice to see.

Gidday Mince
Hope alls well there mate???

I found if I made notes on the thread, I always have a reference to go back to.
If what I try doesn't quite work, I'll hopefully iron it out another way.
Got onto a Japanese site this arvo that had listed the needle changes he attempted to iron out the same bug I'm chasing down low on the FCR's and looks like I'm chasing my tail there as he found out.
He tried a few different needles, clip position and jettings eventually stuck with the std OCEMP needle.
Std TRX and ECU with Over system and 41mm fcr's .
Info listed below on the link.

So float level and jet changes may be the way to go next.
I've a selection of pilot and main jets and plenty of time up my sleeve to tinker.

http://gpmono.blog89.fc2.com/blog-date-201105.html

[cobbadiggabuddyblooo]

What does it all mean?

Just a bit of data Sean for those who might choose to use FCR's from say a Ducati (which run the same pitch)
It will show the difference in the jets and what you will need to change to get it running ok to suit the TRX.

EXAMPLE on the trx 41mm FCR

ＯＣＥＭＰ ３ １４５ ４８ １．０ １ 1/4 28.2 1013 カス

ocemp needle
3 on 3rd clip position
145 mains (std is 150)
48 pilot
1 turn out on the fuel screw
1&1/4 turns out on the slow air screw
Dyno run day weather... 28.2*c at 1013 Barometric pressure.

The weather results are pretty close to SE Queensland weather conditions 8mths of the year and I suggested to Alex to run a 145 main in the beginning of the year and he found improvements. So it's nice to find other data to correlate against.

As Conrod worked out too using his O2 sensor set up, the std TRX 38mm Mikuni carbs run better 2 sizes down on the main jet from std.

[alextrx850]

Ah, that's better ..close to my settings which is interesting..., so I might be doing something right.
my needle clip position is leaner tho.
The colder weather lately has been good too.
Watching for the heat seeking wallabys nowadays.

[cobbadiggabuddyblooo]

Took the head off the bike today and here is what I found. (2,000km since rebuild)
After talking to Serco who bored the barrels, it seems in their infinite wisdom, they chose to ignore the spec sheet supplied to them that came with the pistons from Arias.
They went with a 0.0025" piston - bore clearance as they thought the 0.004" spec supplied from Arias seemed too high and it would rattle and clang being too loose.



So I understand why I chewed through about 700mm of oil on my last track day.
But a blessing in disguise, the sacrificial ceramic coat on the piston skirt took most of the brunt of the wear on the piston.



It seems that the clearance for your average std trx cast piston is 0.0025.
But the Arias pistons are forged but the plot thickens.

You have a choice of 2 types of forged pistons from Arias.

2618 is a high strength aerospace aluminum alloy. This specially formulated alloy includes elements of nickel, copper, magnesium, iron and 0.25% or less silicon content. The combination of these elements provide for the ultimate in high temperature strength and fatigue properties. Being a very low silicon alloy that has a high coefficient of thermal expansion, 2618 requires greater piston to cylinder wall clearance. This material is ideally suited for high cylinder pressures and skirt loads, as well as elevated combustion chamber temperatures. Applications range from blown, turbo, and nitrous to engines with high mechanical compression ratios. 2618 is 17% stronger than 4032.

4032 is a high strength aluminum alloy with 12% silicon content as the primary alloying agent. These silicon particles are extremely hard and durable and provide a wear resistant surface for the rings, pins and skirt contact areas. Additionally, with the high percentage of silicon, this alloy has a low coefficient of expansion. With 4032, much tighter piston to cylinder wall clearances can be achieved. The end result is a much quieter running engine on cold start-ups’ as well as a more stable piston with less rock over in the cylinder bore. These properties make 4032 an ideal choice for street and many mild racing applications.

My pistons are 2618 so need the higher 0.004" clearance.
Pain in the arse but Serco admitted their mistake and will rectify the issue at no cost.
Piston skirts will be coated again and if the bores are not within the tolerance, they will re bore the spare barrels I have.

Big thanks to Peter at Competition Coatings who has offered to double check the machining work once completed.
The ceramic coating is 0.0005" (1/2 thou) thick so with the 0.0025 piston / bore clearance and sacrificial ceramic coat, that got me just below the lowest tolerance ( 0.0035" ) that Arias advised me after a quick call.
Saved the pistons at the expense of a shorter ring life due to the damage on the bore.
Compression of the engine was still good but the life of the motor would be short lived if I just left it and would be shagged in another 10.000km's

[cobbadiggabuddyblooo]

MOTOR SPECIFICATIONS


Bore. 91mm. ......... 89.5mm std
Stroke 67.5mm ......... 67.5mm std

Head gasket bore 91.5mm ........ 90.5mm std
H/gasket compressed Thickness. 0.9mm ........ 0.76mm std
Chamber volume. 33.8cc ........ 33.8cc std
Piston dome volume. 4.91cc ........ - 4.6cc dish std
Piston deck. 0.65mm ........ 0.95mm. std

Compression ratio. 12.24 : 1

Squish is 1.55mm (minimum 1mm)
Piston/valve clearances 2.4mm inlet 3.4mm exhaust ( minimum 1mm )
KENT CAM Inlet 8.28mm lift/105* Exhaust 8.28mm lift/109*

[Mincehead]

12.24! Do you run super-unleaded with octane booster mate?

[cobbadiggabuddyblooo]

No pump gas 98octane
900 nuda has a 13:1 compression ratio.
I've got enough quench to easily loose 0.3mm at take me there but not running fuel injection will pro only start causing issues.
The MLS gasket on its way is a 0.8mm so it will get me at 12.5:1 which is the same as the Over Arias pistons and was commonly raced on pump fuel here.
All looked pretty good inside apart from the bottom skirt wear and damage to the bore.
No hot spots on the pistons or signs of detonation.
No pin binding so its the clearance that's an issue.

[Mincehead]

Hmmm, ok I`ll take your word on it. I suppose the flowing of the head is important in keeping detonation issues at bay / aiding cooling plus you`re monitoring fuel to air ratio too so that`ll help as well. This `gasket` is that an Aussie company it`s coming from? I`m looking for a good gasket maker / supplier for a very good friend having problems sourcing them for overbored specials.

[cobbadiggabuddyblooo]

Yes Mince, the gaskets I get are made locally here by gasket solutions.
Another old retired soul who's son now does all the work.

Pistons where dropped of at Competition Coatings to have the skirts re coated before opening up the bores to the correct clearance.
While there John read the piston,ring,bore activity like a gypsy reading a palm and showed me a few different pistons he has in for coating and the interaction and markings to look for.
He could tell straight away that one reason the tolerance wasn't correct because they had not only gone on a lower tolerance
but they had obviously not taken the piston measurement from not where Arias had on it's spec sheet.
The coating would have been sacrificed but still evident to bring me within the tightest spec 0.035.
But there was a line along the bottom of the piston skirt polished back with no coating evident at all.
Surprising he was right as this was where Arias gave as the point to take a clearance measurement.

[Mincehead]

Not many folk in the UK doing bespoke gaskets these days mate.