What did you do today? Cobba's rebuild

[cobbadiggabuddyblooo]

185 main jet fitted. I wonder if he was running E85

[PrfctChaos]

Wow!!

I use the #25 pilot jet as well and clip position and mixture screw is similar. However, I'm on #135 main jets, will be interested to hear how you go on the #145.

[cobbadiggabuddyblooo]

Topham recommended 175 mains but seems too extreme. I contact a friend in Germany who supplied the camshafts I was selling and he recommended 150-160max for stock motor, Over system and bellmouths.
I’ll weld an O2 sensor bung into the Over merge at the rear and see what we find and I have a jet kit from 145 to 160 in 2.5 increments.
I’m hedging on 145-150 similar to FCR’s in Qld temps with bellmouths /Over system on stock motor.
First chance I’ve had to tinker with Mikuni TDMR’s.

[Killerwhale]

Topham recommended 175 mains but seems too extreme. I contact a friend in Germany who supplied the camshafts I was selling and he recommended 150-160max for stock motor, Over system and bellmouths.
I’ll weld an O2 sensor bung into the Over merge at the rear and see what we find and I have a jet kit from 145 to 160 in 2.5 increments.
I’m hedging on 145-150 similar to FCR’s in Qld temps with bellmouths /Over system on stock motor.
First chance I’ve had to tinker with Mikuni TDMR’s.

Didn´t FCR and Mikunis differ in measurement of size? 150 FCR is not equal 150 Miks?

[cobbadiggabuddyblooo]

That’s what I thought too Mathias. But Mikuni make a couple of different main jets to suit different models of carbies. I spoke to Huby and he suggested 150-160 maximum for bellmouths and Over system
.

[PrfctChaos]

Yes, Keihin and Mikuni sizes are not the same. If you believe this chart from http://www.historicmotorcycle.org.au/Ad ... y/jets.txt, then #145 Mikuni is similar flow to #170 Keihin (FCR)

drill Dell'Orto # drill Adler
inches --- Kehein # -- DynoJets # -- Mikuni # -- mm --- Bing #

0.035 ----- 92.5 ------- 92 ---------- 86.3 ----- 0.92
0.036 ----- 95 --------- 94 ---------- 88.1 ----- 0.94
0.037 ----- 97.5-------- 96 ---------- 90.0 ----- 0.96
0.038 ---- 100 --------- 98 ---------- 91.9 ----- 0.98
0.039 ---- 102.5------- 100 ---------- 93.8 ----- 1.00 ---- 110
0.040 ---- 105 -------- 102 ---------- 95.6 ----- 1.02
0.041 ---- 107.5------- 104 ---------- 97.5 ----- 1.04 ---- 115
0.042 ---- 110 -------- 106 ---------- 99.4 ----- 1.06
0.043 ---- 112.5------- 108 --------- 101.3 ----- 1.08
0.044 ---- 115 -------- 110 --------- 103.1 ----- 1.10
0.045 ---- 117.5------- 112 --------- 105.0 ----- 1.12 ---- 120
0.046 ---- 120 -------- 114 --------- 106.9 ----- 1.14
0.047 ---- 122.5------- 116 --------- 108.8 ----- 1.16
0.048 ---- 125 -------- 118 --------- 110.6 ----- 1.18
0.049 ---- 127.5------- 120 --------- 112.5 ----- 1.20
0.050 ---- 130 -------- 122 --------- 114.4 ----- 1.22
0.051 ---- 132.5------- 124 --------- 116.3 ----- 1.24
0.052 ---- 135 -------- 126 --------- 118.1 ----- 1.26
0.053 ---- 137.5------- 128 --------- 120.0 ----- 1.28
0.054 ---- 140 -------- 130 --------- 121.9 ----- 1.30
0.055 ---- 142.5------- 132 --------- 123.8 ----- 1.32
0.056 ---- 145 -------- 134 --------- 125.6 ----- 1.34
0.057 ---- 147.5------- 136 --------- 127.5 ----- 1.36
0.058 ---- 150 -------- 138 --------- 129.4 ----- 1.38
0.059 ---- 152.5------- 140 --------- 131.3 ----- 1.40
0.060 ---- 155 -------- 142 --------- 133.1 ----- 1.42
0.061 ---- 157.5------- 144 --------- 135.0 ----- 1.44
0.062 ---- 160 -------- 146 --------- 136.9 ----- 1.46
0.063 ---- 162.5------- 148 --------- 138.8 ----- 1.48
0.064 ---- 165 -------- 150 --------- 140.6 ----- 1.50
0.065 ---- 167.5------- 152 --------- 142.5 ----- 1.52
0.066 ---- 170 -------- 154 --------- 144.4 ----- 1.54
0.067 ---- 172.5------- 156 --------- 146.3 ----- 1.56
0.068 ---- 175 -------- 158 --------- 148.1 ----- 1.58
0.069 ---- 177.5------- 160 --------- 150.0 ----- 1.60
0.070 ---- 180 -------- 162 --------- 151.9 ----- 1.62
0.071 ---- 182.5------- 164 --------- 153.8 ----- 1.64
0.072 ---- 185 -------- 166 --------- 155.6 ----- 1.66
0.073 ---- 187.5------- 168 --------- 157.5 ----- 1.68
0.074 ---- 190 -------- 170 --------- 159.4 ----- 1.70
0.075 ---- 192.5------- 172 --------- 161.3 ----- 1.72
0.076 ---- 195 -------- 174 --------- 163.1 ----- 1.74
0.077 ---- 197.5------- 176 --------- 165.0 ----- 1.76
0.078 ---- 200 -------- 178 --------- 166.9 ----- 1.78
0.079 ---- 202.5------- 180 --------- 168.8 ----- 1.80
0.080 ---- 205 -------- 182 --------- 170.6 ----- 1.82
0.081 ---- 207.5------- 184 --------- 172.5 ----- 1.84
0.082 ---- 210 -------- 186 --------- 174.4 ----- 1.86
0.083 ---- 212.5------- 188 --------- 176.3 ----- 1.88
0.084 ---- 215 -------- 190 --------- 178.1 ----- 1.90
0.085 ---- 217.5------- 192 --------- 180.0 ----- 1.92
0.086 ---- 220 -------- 194 --------- 181.9 ----- 1.94
0.087 ---- 222.5------- 196 --------- 183.7 ----- 1.96
0.088 ---- 225 -------- 198 --------- 185.6 ----- 1.98
0.089 ---- 227.5------- 200 --------- 187.5 ----- 2.00

[cobbadiggabuddyblooo]

But which Mikuni main jet????
There are several varieties for different carbies.
4/042 Hex (50 to 720)
M10/14 Hex (40-200)
N100.604 round (50-240)
N102.221 round (30-250)
VM11/22 round (50-180)

[cobbadiggabuddyblooo]

Std Mikuni BDST rebuild with photos...

https://litetek.co/Guide_MikuniBDST_Rebuild.html

[cobbadiggabuddyblooo]

http://www.mpesuspension.com.au/about-us.html


I purchased a set of Thundercat YZF600R forks for the white trx with plans on keeping it stockish looking. They are early model 41mm forks and took them up to Paul at MPE today to have them rebuilt and working a little better.
The discussion progressed and he explained about this format of “ cartridge forks “ and how the early model yzf model forks from last century where in a way a glorified style of damper rod system and not a shim stack style.
His first comment when I showed Paul the thundercat forks was “ oooohhh mmmm eeer “ I thought you where going to put emulators / gold valves in your std TRX forks???
A far better and cheaper option in his eyes than fitting the Thundercat forks.
By the time I put gold valves in the compression and rebound circuit there is $400 on top of the price of the forks. Then there’s seals and labour.
He’s always one up for a challenge and knows how I strive to get the most from what I have ( within budget ) and find a balance with a enough headroom to deal with the dynamics at play.
So he’s going to strip the forks down and see if he can retro fit a shim stack style cartridge from the collection of forks cartridges he has that have been removed from forks that he had fitted Ohlins internals in its place.

So bottom line is your early YZF 600, 750, 1000, R1, R6 forks basically work much like the current TRX damper rod forks but with the added compression circuit by incrementally opening or closing the port hole size the fluid is forced through on the compression and rebound action.

He mentioned how Japanese bikes changed to shim style cartridges by mid 2000’s and worked quite well but mentioned how Yamaha has gone back to the primal form of cartridge like in the thundercat forks I gave him and some only have this fitted in 1 fork.
Why... Because of cost was the answer and he mentioned about the amount of complaints he has from the MT09/07/10 guy about the bad front end suspension.

I know if I did this again, I’d choose the 43mm later model( 2010 ) YZF600R front end to keep the retro TRX look.

Lesson learnt on this one but know when I get the forks back I know they will be a shim stack style cartridge and cut above and any other Thundercat forks out there with gold valves fitted for improvement.

[pug]

Hi All
I have just fitted the bellmouth kit to mine and they only came with 180 main jets which are in now. Big difference to performance, but the noise is a bit much even with earplugs.
With the airbox on the TDMR's I run 145 main and needle clip 3 from top (blunt end) but now at 4th clip and the 180 main. Pilot jet size forgotten.

I thought the jump to 180 was huge, but removing an airbox is a huge step too. Mine had K&N with the front cut away to expose the filter completely.
Motor has lightened 878 kit, balanced, Kent Cams, ports touched up, 2 into 1 from "Precision"?

I first run the bellmouths with the 145 and 3rd clip......crap, just died when opened throttle other then slow and gentle.
Not sure where to go from here, but after reading all this and pondering a while am thinking of getting 165 mains and raising the needle anther clip.
Thoughts?

[cobbadiggabuddyblooo]

Contacted Huby, a mate in Germany and he suggested 155 max with std motor , Over exhaust and bellmouths and 165 max for worked motor.
Current main jet is a 180 in mine too and first thought was way too rich.
I have a jet kit from 145’s to 165’s in 2.5 increments.
Currently the FCR’s run a 163 and that’s set at 12.5 A/F for acceleration .
When I get the throttle cables i’ll Hook up my wide band A/F sensor and get a reading for reference.

Most will always give a jet on the rich side for their own protection as a starting point.

[pug]

Thanks for that, confirmed my next step...get some 165 main jets, fit and run, then raise needle and run, then ponder some more.

By the way, for others reading this, of all the things done to my motor, suspension, brakes etc...getting the flat slide carbs is the best thing, what a difference they make.

[Tarwetijger]

I've almost the same setup, Pug, and #165 is running fine.

Carbs: Mikuni TDMR40
Jetting: main #165
Airbox: Bellmouths and foam filter (RAMAIR)

See http://www.trx850.com/phpBB_forum/viewt ... =42&t=4391

[cobbadiggabuddyblooo]

Took a while Robert but finally got my Over 6 speed close ratio box..
Picked up a complete Over spec motor including rods, 6 speed , pistons and 2mm O/S valves with some long duration 8.9mm lift cams and port job.
Was a spare race motor from mid 90’s that’s been tucked away in a garage for 20 yrs.
Couldn’t believe my luck...

[dicky]

Took a while Robert but finally got my Over 6 speed close ratio box..
Picked up a complete Over spec motor including rods, 6 speed , pistons and 2mm O/S valves with some long duration 8.9mm lift cams and port job.
Was a spare race motor from mid 90’s that’s been tucked away in a garage for 20 yrs.
Couldn’t believe my luck...

You did what?
How the fsck did you find that?
btw, Happy New Year.