jpe's Bumble bee - The collected mods

Please share your secrets! What mods have you made to your TRX?

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jpe70
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jpe's Bumble bee - The collected mods

Post by jpe70 » Wed Jan 16, 2019 9:51 am

I do have my own website that occationally gets a new blog text, a few random threads on this forum and posts on the ever changing FB but I thought I'd collect the specs here since I mostly write in Swedish otherwise. And so not to spam the "What did you do..." thread or loose it among likes on that other place.

The beginnings you can read about in my other threads, so won't go into that just start off with the build.
Last edited by jpe70 on Wed Jan 16, 2019 11:05 am, edited 2 times in total.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Wed Jan 16, 2019 10:03 am

First up, bike was put thru some much needed service just to make it pass MOT. This thread: http://www.trx850.com/phpBB_forum/viewt ... =5&t=12215

The first, actual modification was Cobba's wiring mod for the ignition. A simple matter of getting a cheap relay and some cable. Instructions here: http://www.trx850.com/phpBB_forum/viewt ... =6&t=10897

Image
Last edited by jpe70 on Wed Jan 16, 2019 1:22 pm, edited 1 time in total.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Wed Jan 16, 2019 10:25 am

Rear swing arm and wheel

Stock swinger replaced by a ThunderAce unit.
The fit is a simple matter of removing the old and mounting the new without changing anything. I use stock suspension & linkage and that will affect squat somewhat due to slightly different mounting point on T-Ace swinger. Only did a rough measurement but I lost about the difference between 160/180 rears in height, my bike was 25 mm higher with Kedo dog bones before the change so I still have a positive from stock.

R6 rear wheel.
Late 5-spoke wheel fitted in the ThunderAce swing arm, the wheel is stock and I use a sprocket carrier from my old -07 R1 which is identical to later R6. It needs collars and spacers from 03-04 R6 to fit, the R1 parts I used at first will make the whole setup 2 mm wide. Brake is an overlaying issue, can't remember the bracket just now and I think the caliper is R6. The caliper mounting points have been filed down about 1-1.5 mm to line the whole thing up with the disc. coxylaad used this exact setup before me and I did no changes.

Yamaha parts list:
  • 4XV253760000
  • 5SL253270000
  • 903872801900
  • 5SL253670000
  • 4XV253170000
  • 5SL253830000
  • 5SL253660000
I'm waiting for a 520 drive package, a complete R6 -04 setup should work with the TRX axle and the rear R1 carrier.

Image
Image
Last edited by jpe70 on Wed Jan 16, 2019 1:25 pm, edited 1 time in total.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Wed Jan 16, 2019 10:55 am

Front end

Images in this post: http://www.trx850.com/phpBB_forum/viewt ... 24#p121218

R6 -02 forks.
For reasons unknown I opted for a RSU fork... No, not really. I wanted to leave an ever so small opening for the bike to be entered into Classic Superbike and at the same time make my job as simple as possible. Early R1 USD w/o radial brakes could possibly have qualified but I went for the simpler R6 option.
The better choice would have been 03-04 R6 fork, but I found a cheap -02 so that's what we have. I'm mating those with the stock TRX triples bores out to 43 mm from stock 41.
Measured length difference between stock and R6 is 46 mm. Stock differs slightly between right/left so that's an average. With the bike sitting at 30 mm rise above clamps on stock fork the same attitude will place the shorter legs 4 mm above the recess with clipons removed. Stock handles are 20 mm high. (30+20-46=4 mm)

The R1 calipers of course fit straight off on the R6 fork, but I will need a new front fender.

R6 front wheel
A rear matching 5-spoke so works with the R6 front axle and legs. Stock TRX is however 5 mm narrower than the R6 so collars from R6 will not fit as is. Will need to have them machined (2.5 mm) a corrected 1.75 mm each, or have new shorter ones made. From this we also learn that the R6 wheel is wider than TRX over hub and discs, since calipers still line up with the discs. Yamaha apparently used same disc offset on nearly every road bike from early nineties and on thru radials. Discs are the original R6, 5-spoke first appeared on -04 far as I know?

Oh, right. No more speedo drive... :roll:
Last edited by jpe70 on Tue Feb 12, 2019 7:35 pm, edited 3 times in total.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Wed Jan 16, 2019 1:55 pm

Bits and pieces

- Tore down the carbs at least twice, that is mostly service and renovation due to age. Changed a few parts, worked one stuck air (fuel) screw loose and did some changes to jetting last time around. Should be set up with screw 3,5 turns out, pilot 47,5 and main 150 now. Needle in the highest position. That's the first change in 12 years or so, bike's been running with stock pilot (45?), screws at 2-ish and 145 main until now. I have a dyno time planned for spring when bike's running so will have an idea on the settings then. Should need no more than one more change.
Image

- Wanted to spray the cam cover red, but my better part argued against it. The Polar green not matching red very well,... So used black instead,I decided at the start of my little overhaul to use black as complement on other parts anyways. Only, I should have gone for matte.

- Replaced the very old coolant hoses with CMS silicone counterparts, eBay, and removed the fan while things were apart. Also, plugged the carb bypass figured I don't need heating the fuel beforehand.
Image

- Trying to weigh all things removed or replaced (within limits). Bike is on a diet and I want to know how far I can go without actually cutting things. So far I can still restore to stock.
Image

- I've also removed the resistor from spark plug caps and replaced with a cut piece of M5, replaced ancient wires at the same time. Surprisingly easy job with the caps honestly.
Image
Last edited by jpe70 on Mon Jul 08, 2019 8:45 pm, edited 2 times in total.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Wed Jan 16, 2019 2:37 pm

Alternative front end I was contemplating:

R6 USD triples from 06-07, they have same offset as TRX.
Legs from R1 99-02 because they are closest to TRX in length and stroke so bike would not stand on it's head and I already have the brakes.

Might go there next time. :roll:

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Re: jpe's Bumble bee - The collected mods

Post by cobbadiggabuddyblooo » Thu Jan 17, 2019 12:32 am

Been there done that on the black TRX. (Best choice if keeping bike in period racing.)
Took quite some tuning and gold valves to get the most from the damping system they use.
If I did an upside down fork conversion again I’d go 06-07 R6 with fork extensions.

I’m currently attempting retrofitting another cartridge rod in thundercat forks on the white trx to keep it right side up. Emulators are a better choice in the std trx forks than Thundercat forks.
laughter is the best medicine

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Sat Jan 19, 2019 9:03 pm

Drive

So, chain and sprockets arrived. No surprises everything fits (thank you), however there's the issue of alignment. Haven't checked into that, a common mod is shim front cog out some 6 mm if I remember correctly. That's when going YZF, don't think I need that much it seems to be about 3-4 mm at the most. This is after all not a YZF conversion, but a combination of ThunderAce, R6 and R1 with a 520 drive not stock 525.

I'm replacing an off-centre R1 rear sprocket with a flat 520 for R6 so that gives me maybe 2 mm if my eyes serves me decently.
Image

New front sprocket is asymmetrical so I'm mounting it with the wide center facing in and turning the nut around to use all available thread. Still using the large 17 tooth since it will give me more options in the rear. R6 rears in small sizes around 40 is hard to come by to match a 16 front, with the 17 I can use the more common 42-48 range without gearing the bike waaay to low.

Did not expect the new rear to be black however.... :roll:
Image

Figuring out the alignment is next issue, I'm thinking about getting a laser to get a correct line. Alternatively I can eyeball it, just need to make sure the rear is straight. We'll see... 8)
Image
Last edited by jpe70 on Sat Jan 19, 2019 9:24 pm, edited 6 times in total.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Sat Jan 19, 2019 9:10 pm

Numbers

You get the numbers, but I'll point them out anyway. There's total weight reduction in milligrams, stock wet weight in kilograms and current calculated wet weight.

Image

Cost? Is that even an issue?

In short then, so far around €3500 including the bike. There's maybe €600 more coming before spring and I'm not doing anything at all on the engine this winter.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Wed Jan 23, 2019 6:58 pm

Spacers

Sent some drawings over to my contact in the morning, before going home the same day I got this image on messenger. Sweeeet! They produce parts for Öhlins Racing so should be decent quality. :roll:

Image

New spacers to mate R6 wheel and forklegs with stock triple. 2.5 mm shorter than stock R6 -04 spacers. Measures ID22/OD28(31)/L15.5
Also from scratch a new spacer for engine sprocket, did some measuring but could not get conclusive results so I just decided on slightly narrower than the usual 6 mm, it's a 5 mm spacer to go behind the R6 front sprocket (ID25/OD35/TH5)
This fit will depend on how the sprocket look, mine is an asymmetrical one rather similar to the stock part. Hopefully it won't put too much angle strain on the chain, I only have (2 mm) corrected 5 mm freeplay between chain and rubber so don't want to move the rear further in. Also running out of thread on the axle so moving front further out... nah. [-o<

Gonna pick them up this weekend and see if things fit.
Last edited by jpe70 on Tue Feb 12, 2019 7:38 pm, edited 1 time in total.

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Re: jpe's Bumble bee - The collected mods

Post by cobbadiggabuddyblooo » Thu Jan 24, 2019 10:51 am

What I did was removed the studs from the clutch hub ( sprocket carrier ) and machined down the 5mm to get sprocket alignment .
You can use std sprocket with no need for offset front sprocket and easy if your changing gearing to suit different tracks.
You will see the rear sprocket sits on an 5mm raised section so very simple easy job.

The wheel offset to hub on the Right hand side ( brake side ) is the same as the std trx wheel , yzf 750 and R6 , just the sprocket side is 5mm wider on the hub with 5.5” rim. There is no need to change spacing on the brake side to keep the wheels centred just alter the sprocket side.
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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Mon Jan 28, 2019 7:27 pm

Well... that didn't go as planned. #-o

Image

Someone needs to do a better work measuring. 8-[

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Re: jpe's Bumble bee - The collected mods

Post by coxylaad » Wed Jan 30, 2019 9:46 pm

=D> =D> =D>

this looks great! keep up the good work.

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Re: jpe's Bumble bee - The collected mods

Post by jpe70 » Mon Feb 04, 2019 6:00 pm

coxylaad wrote:=D> =D> =D>

this looks great! keep up the good work.
Thanks! The old "inheritance" are being used for a good cause. 8)

Somethings' been nagging me for a while and figured it out the other day. Front fender! R6 legs and narrow stock triples. R6 mudguard won't fit between the legs, so to speak. :roll:
Stock fender has the wrong fittings but is narrow enough without using violence. So, some more fitting is in order then. Just need to finish what I'm doing at the moment since I want the bike on wheels asap.

R6 wheel spacers, part 2

My new front wheel 15.5 mm spacers turned out too narrow (previous post). So did some additional measuring with them in place with feelers and turns out I was 1.5 millimeter off. So, back to "ye olde" drawingboard and get new one's, this time 16.25 mm in length. That's 1.75 mm shorter than R6 stock btw. Fits like a glove!
Front axle is another possible issue, it is very close to bottoming in the threaded left leg, but with the new correct spacers it looks like it will just about work. This time I've tried it a few times just to make sure.

In hindsight, it's possible I didn't think this conversion through... #-o

As for rear wheel. I used this 5 mm spacer to align front and rear sprocket. Cobba (and orthers) has instead modified the rear sprocket hub to have the rear sprocket sit 6 mm closer to the wheel and keep the stock placement on engine sprocket. Wise, it will not increase pressure on outgoing bearing as my solution surely will. However, checking my chain freeplay agains the tire I don't have 6 mm to go for some reason. May 3-4 mm before the chain starts rubbing. And I did convert to narrower 520. And I'm using a previously used configuration from another bike.

Any ideas? Other than re-measure centering?

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Re: jpe's Bumble bee - The collected mods

Post by Racer-unk » Thu Feb 07, 2019 8:00 am

van't wait for you ride it and give some feedback....
I am keen t do the Thunderace swingarm.....will look good

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