What did you do today? Cobba's rebuild

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cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Sun Mar 24, 2019 6:05 am

Cams chain sprockets have 8.95 x 283 on them and first thing I noticed was the clearances and shim values.
All clearances are with spec and shim values are 180’s-190’s and what looks like no material removed from the base circle.
Made me think maybe someone swapped the cams for a std pair so time to investigate further. :-k

Measured the lobes against a std pair and definately 1mm more lift so confirms my guesses they are a pair of billet cams.
Reground cams they find extra lift by removing material from the base circle and hence the shim values are larger by the amount ground off.

I’ll post photos shortly once I get the suspension back from being rebuilt.
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Tarwetijger
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Re: What did you do today? Cobba's rebuild

Post by Tarwetijger » Mon Mar 25, 2019 11:58 am

cobbadiggabuddyblooo wrote:Now it’s time to try and find as much tech info as I can on the Over 6 speed.
I sent Don Stafford in Melbourne a message as I know he was the Over Racing Authorised dealer here in Australia and had a fully kitted Over racing TRX he raced back in their day.
Sold that tho for $19,000 with all the spares 13 yrs ago but hopefully he’ll still have some info.
Are you familiar with the papers I got with mine?
I can make a proper scan to PDF if you like.

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I've posted them before but image hosts keep @#$%^&* things up.

cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Tue Mar 26, 2019 1:17 pm

Yep all good Robert.
Already have that printed off.
Lars on the German forum came through with the YEC ratios and gears used on the Over 6 speed.
Ist is lower than std 1st
2nd is between 1&2nd
3,4&5th fill the gaps of 2nd & 3rd
With 6th just a touch over std 4th gear.
Should give me the drive I’ve been looking for out of the 2 slowest corners around my local circuit.
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cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Tue Mar 26, 2019 2:06 pm

SP...... std Yzf 750 ..... YEC ...... Std TRX....... TDM900
2.461.........2.571........ 2.923..... 2.571........ 2.750
1.941.........1.941........ 2.188..... 1.850........ 1.947
1.631.........1.555........ 1.778..... 1.429........ 1.545
1.434.........1.368........ 1.500..... 1.174........ 1.240
1.300.........1.217........ 1.273..... 1.039........ 1.040
1.190.........1.083........ 1.125..... N/A.......... 0.923

Your gears are std YZF750 Robert . I originally thought the YEC ratios may be SP gears but the yzf750 SP close ratio differs from the trx YEC 6 speed too.
So gears are specific to the trx.
TDM 900 in a world of its own.
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Sat Mar 30, 2019 7:56 am

YEC motor specs
870cc
Comp to be determined but well above 12:1
Squish band 1mm (0.040”)
Current piston/ valve clearance 4.1mm intake / 4.5mm exhaust
Cam 283* with 8.95mm lift
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Tarwetijger
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Re: What did you do today? Cobba's rebuild

Post by Tarwetijger » Sat Mar 30, 2019 12:59 pm

cobbadiggabuddyblooo wrote: Your gears are std YZF750 Robert.
I guess so. All partnumbers of the gears start with 4FM = YZF750R.
TDM 900 in a world of its own.
Maybe because of a different end ratio (chain and sprockets)?
cobbadiggabuddyblooo wrote:YEC motor specs
870cc
Comp to be determined but well above 12:1
Squish band 1mm (0.040”)
Current piston/ valve clearance 4.1mm intake / 4.5mm exhaust
Cam 283* with 8.95mm lift
That's a lot of lift, am I right?

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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Thu Apr 04, 2019 6:53 am

Ok cam specs on YEC

252* inlet and exhaust
Symmetrical camshafts
Lobe centres 104*
8.95mm lift.
Inlet 22/50
Exhaust 50/22
Lift on inlet and exhaust 2.9mm at TDC
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Tue Apr 09, 2019 1:40 am

Put the YEC motor into the white TRX and it’s quiet, smooth and goes like stink.
I ‘lol give it a healthy run next week with the new front and rear suspension and in the mean time, i’ve Purchased some black R6 5 spoke rims and can tinker with them to fit onto the trx.
220mm caliper set up is easy to replicate as I’ve done that on the black bike.
Digital / analog GPS speedo gauge retrofitted into original dash deals with speedo drive issue.
Last edited by cobbadiggabuddyblooo on Tue Apr 09, 2019 11:42 pm, edited 2 times in total.
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Tue Apr 09, 2019 12:33 pm

TRX AND 03-05 R6 5 spoke front wheel information

TRX & T-cat ......INSIDE FORK TO FORK WIDTH AT AXLE..... 158mm

1/ .... Centre of left disc across the hub to centre of right disc.
2/ .... hub width from bearing to bearing
3/ .... top hat width
4/ .... speedo drive width
5/ .... axle diameter
6/ .... disc diameter
7/ .... bearing dimensions


TRX front rim
1/...Disc centre to centre...... 128mm.
2/...hub width.....................
3/...top hat.........................
4/...speedo drive.................
5/...axle diameter................ 17mm
6/...Disc diameter................ 298mm
7/...bearing .......................

03-05 R6 front rim
1/...Disc centre to centre...... 127.2mm
2/...Hub width..................... 123.5mm ( inc bearings )
3/...right spacer................... 11x22mm ( top hat butts against seal )
4/...left spacer..................... 23.5x22mm ( speedo side )
5/...axle diameter................. 22mm
6/...Disc diameter................. 298mm
7/...bearing......................... 22x44x12
8/...axle sleeve.................... 123.5 (L) x 22 (OD) x 17 (ID)
9/...(123.5+ 23.5+ 11=158mm fork width at axle)
Last edited by cobbadiggabuddyblooo on Mon Apr 29, 2019 2:40 pm, edited 6 times in total.
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cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Tue Apr 16, 2019 1:56 pm

Cunning plan for the R6 front wheel on the trx.
R6 uses a 22mm front axle and I grabbed one of my spare alloy clip on bar.
Yes you guessed it they are 22mm and the length allows me to make 2 axle sleeves from the 1 bar.
They are 16mm I.D. so I’ll run a 17mm drill through it and make up 2 top hats for spacers either side.
If all goes to plan that’s the front wheel sorted.
A GPS 85mm speedometer will fit nicely into the std gauge position in the dash.

As for the rear wheel , the R6 rim has a 28mm axle so I’ll go the other way and machine out the swing arm to accomodate the larger axle.
I can machine 6mm from the sprocket carrier just like I did on the YZF750 5.5” rim for chain alignment. ( R6 & yzf 750 centre of rim to offset hub is the same )
The disc side differs from the YZF750 and TRX rims because the R6 rim has the 220 mm disc mounted 20mm closer to the centre of the rim.
I may not be able to do the same as the 220mm mod I have on the other TRX because with my calculations I will have the Caliper just clipping the spokes when in place.

So I think the easiest will be pick up a small caliper or maybe a small Brembo and just make up a mount and space accordingly. Hopefully the torque arm won’t foul on the edge of the tyre and may have to space it at the caliper by a few mm’s.
I’ve seen a few in Germany that run the std R6 caliper and mount that runs on top of the swing arm but the plan with the white TRX is to keep the original look and caliper mounted lower and in the original position.

Costs so far is $520 for f&r complete wheels, discs, sprocket carrier plus 1 rear axle.
Thanks to Rod offering to machine the spacers for the front wheel to save a couple of $$$$

Hopefully machining the swing arm, finding a rear caliper and making a mount will not exceed $300 so I feel it will be a worth while investment for $800.
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cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Fri Apr 19, 2019 10:16 am

Now we have a new challenge with the R6 rear wheel into the std swing arm.
I double check the offset on the hub and the 6 mm removed from the sprocket carrier will definately give me chain alignment when the rim is central and aligned.
But the sprocket carrier differs from the std trx and yzf 750 one and the bearing and dust seal sit out 8 mm further.
The std rim top hat spacer on the sprocket side gives 5mm clearance to the swing arm so I’ll have to machine off the 9 mm from the centre of the R6 sprocket carrier hub and not run a seal.
I have 3mm to the seal plus the 6mm used to hold the seal in place and that gives me the 9mm required and down in line with the bearing itself.
This will easily give me the 5 mm distance to the swing arm again for a top hat wheel spacer, wheel and sprocket alignment.

The dymags run a bearing with no extra seal so I just have to make sure I have waterproof wheel bearings.
As Rod informed me this is the reason behind different coloured bearing seals to donate if they are waterproof, water resistant or dust seals on the bearing.
Next is working out a calliper and mount but will be an easy task.
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Sat Apr 20, 2019 11:40 am

Top hat spacers are 23.5mm long and 11mm long.
3.6x32 + 19.9x28 = 23.5mm
3.6x32 + 07.4x 28 = 11mm

I used a spare alloy clip on handlebar and it's O.D. is 22mm and perfect as the same size as the R6 axle.
The internal I.D. is 18mm so I'll take it down to 17mm and I can cut 2 x 124mm from the 1 bar so gives me a spare.
298mm R6 discs line up perfectly so no issues there either.

This will work on either std TRX forks or Thundercat forks
298mm R6 discs where used from 03-04 in a 5 bolt pattern used on the 5 spoke wheel.
They kept the same bolt pattern for another 10yrs I'm lead to believe but dont know if there where any hub changes.
They changed axle size in 2016 too.
My wheels are from an 05 but share the same bolt pattern and hub width.
05 was the first model with 310 mm discs and I purchased mine without discs and went and bought earlier 03-04 discs.
Last edited by cobbadiggabuddyblooo on Mon Apr 29, 2019 2:33 pm, edited 3 times in total.
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cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Sat Apr 20, 2019 12:38 pm

I felt it only fitting to keep the name of the bike EKOJA out of respect for Ash, the previous owner since the bike entered the country in 2001 and is one of the original forum members and was 79 when I purchased the bike from him.
The bike was totally std including stock pipes and the plan was to keep it that way but....
So far it now sports the modified Thundercat forks, Modified R6 rear suspension, Over Racing Exhaust and TDMR40's.
It currently has the YEC 6 speed motor in there too and the black R6 wheels will balance things out nicely as I'm still planning in keeping it looking pretty well std from a distance including the analogue dash.
To get around not having a speed drive on the R6 front wheel, I've chosen to fit a GPS speedometer in place of the std analogue gauge.

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Last edited by cobbadiggabuddyblooo on Sat Apr 20, 2019 3:05 pm, edited 1 time in total.
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cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Sat Apr 20, 2019 1:02 pm

YEC motor scrubbed up well
More than enough Piston valve clearance with 4mm+ and 1mm squish is at optimum.
Carrillo rods and billet cams dialed in.

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cobbadiggabuddyblooo
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Re: What did you do today? Cobba's rebuild

Post by cobbadiggabuddyblooo » Sat Apr 20, 2019 1:03 pm

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