What did you do today? Cobba's rebuild

[cobbadiggabuddyblooo]

https://thumpertalk.com/forums/topic/10 ... planation/

[cobbadiggabuddyblooo]

Short term memory loss..

Photo Hosting

http://www.trx850.com/phpBB_forum/viewt ... lit=photos

Photobucket

http://www.trx850.com/phpBB_forum/viewt ... os#p119688

[cobbadiggabuddyblooo]

http://www.trx850.com/phpBB_forum/viewt ... mod#p90783

Fuel tap modification to ..... on / off / reserve

[cobbadiggabuddyblooo]

BEARING SIZE CHART LINK

http://www.trx850.com/phpBB_forum/viewt ... ize#p75644

[cobbadiggabuddyblooo]

Cam timing changes today and reduced my overlap by decreasing my exhaust lift at TDC ( overlap ) from 3.2mm to 2.5mm. I made no changes to the inlet cams from the previous setting of 2.3mm at TDC. Happy to loose 3 or 4 hp up top for extra gains in the midrange and a little more torque.
Next job was to makes some changes to the slipper clutch. It didn’t engage much with the 3 - 15% heavier duty springs I had fitted so I replaced them with 3 new OEM Yamaha std weight springs .
So std weight springs fitted all round should engage the slip a little more now on overrev changing down plus with less overlap I now have a little more dynamic compression to deal with too.
Now I just have up remove the spare std motor fitted on the bike and put the balltearer back in one day soon.

[cobbadiggabuddyblooo]

CHAIN PITCH INFO... 520 / 525 / 530 Drive Chains and Sprockets

500 series chains are identical in most components like
Pin diameter
Roller diameter
Side plate size
The 5 represents the pitch in 1/8 inch so it’s 5/8” pitch
The 20 / 25 / 30 represents the roller width in 1/8 inch.

520 is 5/8” pitch - 2/8” wide
525 is 5/8” pitch - 2.5/8” wide
530 is 5/8” pitch - 3/8” wide

So in saying that if need be you can run a wider chain width on the narrower width sprocket to get you out of trouble or get you home. ( 530 chain on 520/525 sprockets )
But there is a little side play and will wear the sprockets a little faster.

You can not run things the other way around ( 520 chain on 525 or 530 sprockets ) as the chain is too narrow for the wider sprockets.

[Rod.s]

CHAIN PITCH INFO... 520 / 525 / 530 Drive Chains and Sprockets
The 5 represents the pitch in 1/8 inch so it’s 5/8” pitch
The 20 / 25 / 30 represents the roller width in 1/8 inch.

520 is 5/8” pitch - 2/8” wide.........1/4"
525 is 5/8” pitch - 2.5/8” wide..........5/16"
530 is 5/8” pitch - 3/8” wide

You new I couldn't let that one slide

[cobbadiggabuddyblooo]

Then it would be a
510
550
530
And no common denominator on all 3...
These chain sizes would be confusing to the masses thinking 550 being a larger numerical value being wider than a 530.
Why not just change to metric you may ask ??? Well that’s even worse with a
15.875/6.35
15.875/7.9375
15.875/9.525
Or just say can I have a big , or bigger or biggerest 5 type chain please

[Trx envy]

Interesting thread this, keep it coming.

Taking motors apart is good fun isn't it?

As an aside, that's an interesting bike Mr Thompson is astride. A Penton, small capacity MXers with Puch engines and KTM parts, built from 68 to 78.

Anyway, as you were.....

And an m16 in .223 cal, in a hunting stock..
Yep, as you were.

And Dunlop canvas sandshoes and hairy legs. Perfect accompaniment for an M16 and an exotic dirt bike while going about your daily ramblings on mescaline. As you were...

Ok, about halfway through this thread now. That is the most bad arse bike ive ever seen. And amazing wealth of info sharing too.

[cobbadiggabuddyblooo]

Got a good crank up for sale plus a carbon can Over Racing exhaust if anyone is chasing either one.

[cobbadiggabuddyblooo]

This link from youtube shows how to change pin polarity on the TPS.
Something you have to do if using TDMR carbies due to the TPS positioned on the opposite side of the throttle action tube. Otherwise your TPS reads 10% at 0 and 0% at 100 which will mess with your ignition mapping on throttle percentages.

https://m.youtube.com/watch?v=QA8g89oXyZY

Cable assignment TPS sensor plug is as follows
to change: cable black / blue and cable blue
exchange with each other as the TPS sensor of the TD
MR carburetor has a different direction of rotation
-

[cobbadiggabuddyblooo]

FCR THROTTLE CABLE ATTACHMENT BRACKETS AND TPS SPRING MOUNT LINKS.

https://rover.ebay.com/rover/0/0/0?mpre ... 3363968039

https://rover.ebay.com/rover/0/0/0?mpre ... 2564475579

[cobbadiggabuddyblooo]

SDP 630 HH+ DP sintered pads to suit Brembo calipers

Pad size. 71.1mm x 55.5mm x 8.7mm

https://rover.ebay.com/rover/0/0/0?mpre ... 2077542698

https://www.motorcyclespareswarehouse.c ... uki-yamaha

http://www.trx850.com/phpBB_forum/viewt ... =6&t=12309

[dicky]

or from Metal Gear, buy local
https://www.metalgear.com.au/view_model ... l_id=10415

[cobbadiggabuddyblooo]

Carb jetting settings link.
I now have a pair of TDMR40's with bellmouths to compliment the Over exhaust to place onto Ash's (ekoja) white 95 model import I purchased from him 2 months ago.
I put 0.85 springs up front and next is to get the Rear shock rebuild over Xmas plus get an O2 sensor bung welded into the Over system.

NEEDLE JET INFO AND SIZES

http://www.pjmotorsports.com/mikuni-needle-jets.html

http://www.trx850.com/phpBB_forum/viewt ... et#p115021

Cable assignment TPS sensor plug is as follows
to change: cable black / blue and cable blue
exchange with each other as the TPS sensor of the TD
MR carburetor has a different direction of rotation

DESIGNATION
SIZE-Eistellung
ORDER NUMBER
MAIN JET
145
(180)
N100604 Size

Slow Jet
25
(27.5)
N224103 Size

DÜSENNADEL
10EI01-50
J8 size

idle air
120
N211100 Size

CLIP POSITION (DN)
2. (3.) from above
-
needle nozzle
P-6
785-40004 Size

MIXTURE SCREW
2.5 turn out
-
SYNCHRONIZATION VALUE
210 mmHg + -15
-
IDLE SPEED
1000 rpm + -100
-
FLOAT HEIGHT
13mm


DESIGNATION
TORQUE
AIR FILTER ADAPTER
8.0
nm
GASSCHIEBER LID
2.0
nm
FLOAT BOWL
2.0
nm
drain plug
8.5
nm
COUNTER SCREW (SYNCHR.)
2.0 Nm
NEEDLE-locking screw
3.0
nm
-