jpe's Bumble bee - The collected mods

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

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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Tue Dec 22, 2020 7:36 pm

dicky wrote:Please do make drawings.
I wish that all the home engineers over the years had made drawings as we seem to be reinventing the wheel.

Yeah, I miss that too. There's a bunch of mods done and everyone but a few just writes "I changed this for that with a some modifications". If not drawings, so at least some measurements...

But there things are, and getting worse with FB replacing forums. Now you have me feeling old too... :lol:

Expanding on this change then. I'm going back from my ThunderAce swingarm/R6 wheel to stock swingarm/R6 wheel, and I've read up a bit more since the other day. Might be I'll go for option 2 and machine out the axle holes to accomodate the T'Ace/R6 axle instead of making adapters. Seems like the YZF750 adjustment blocks will fit straight on then. Also, the brakes will probably have to be my current overlaying R6 setup since apparently the GSXR caliper interferes with the R6 wheel? That implies moving the torque arm tab from under to over.

Basically, I could just forgo all this and get an YZF750 swing arm. Much easier but I will not gain any weight on the bike. But since it's already heavy it's option 3 if I can find one for no money. They seem to increase in price currently.... :roll:
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Re: jpe's Bumble bee - The collected mods

Postby Rod.s » Thu Dec 24, 2020 1:14 am

I've found over the years that many home builders are not sure of their work, so tend to just gloss over what they are doing. I've also seen some home built "engineering" that is so dangerous and poorly built it's astounding :shock:.

With the rear axle bearing, there are quality bearing suppliers that will supply modified bearing to suit your situation. Easy done and can be cheaper than making up stepped adaptors. So if the bearing you need is not standard ask for custom bearings.
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Sun Dec 27, 2020 9:00 pm

Who would have thought.... Just bought an YZF swing arm. :roll:
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Sun Dec 27, 2020 9:01 pm

Rod.s wrote:I've found over the years that many home builders are not sure of their work, so tend to just gloss over what they are doing. I've also seen some home built "engineering" that is so dangerous and poorly built it's astounding :shock:.

With the rear axle bearing, there are quality bearing suppliers that will supply modified bearing to suit your situation. Easy done and can be cheaper than making up stepped adaptors. So if the bearing you need is not standard ask for custom bearings.

True and true. But it's not just the bearings to consider, also spacers and brake caliper hanger are made to fit one or the other axle dimension.
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Sun Feb 14, 2021 8:17 pm

YZF750 swing arm in place in the frame. I figured (incorrect) that my wheel setup from the ThunderAce swing arm would transfer directly since they have the same inner width 272 mm. Not so. Or I've been riding last 2 seasons with rear wheel off centre without noticing.

I have my 04 R6 wheel, and the R1 07 sprocket hub (same part as the R6) to fit in the newish YZF swing arm, and I also have an older R6 02 rear brake caliper and hanger. Was about to give up on this due to amount of work and just reinstate the working setup, but after a talk with my garage pal I'm giving it a second chance.

So what's the issues? Brake caliper and hanger need disc sitting further out, wheel does not center so need new spacers and sprockets does not align even though I have spaced out the front earlier. After some discussion we came up with the following:

- Space out the brake disc to fit the carrier better
- Possibly take some off the brake hanger to get it closer to the rim and center caliper on the disc.
- Put the smaller of my two spacers in between rim and sprocket hub to align sprockets (R6 and R1 use different internal spacers)
- Measure distance on each side with wheel centred in the symmetrical swing arm and have new spacers made
- Get a holder made for the swingarm to place the carrier against taking up the brake torque. (I had an idiot moment thinking early R6 swingarm was similar enough to the YZF750 for it to work....)
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Wed Mar 17, 2021 8:49 pm

Rear end updated

Progress! Got the modified spacers and brake holder in place today. A quick check says wheel are centered but need to confirm that better another day. Looks better than the previous setup with ThunderAce and newer R6 brake if I may say so. A few grams lighter too. Just need to get a stopper for the caliper made that fits the swing arm.

Brake caliper and holder from R6 2002, the holder shimmed off 3 mm on the inside to align with the disc on the newer wheel. One newly made 20 mm custom spacer and one modified R1 spacer taken down 1 mm. The only question now is, place it more forward or more straight up/backwards?

Also managed to get a positive out of the ruined porting of my bike's cylinder head. Managed to find killerwhale's old top end, should be just to drop in already slightly ported. Many thanks goes out to Rune who saved the season and sold it to me. :)

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Last edited by jpe70 on Wed Apr 07, 2021 8:47 pm, edited 1 time in total.
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Re: jpe's Bumble bee - The collected mods

Postby Tarwetijger » Thu Mar 18, 2021 4:01 pm

Oh I'm jealous at the rear caliper!
I would take the most forward tilted option, in that way it is easier to get your rear wheel in and out.
Or under the swingarm for the lowest centre of gravity. :D
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Thu Mar 18, 2021 4:29 pm

Tarwetijger wrote:Oh I'm jealous at the rear caliper!
I would take the most forward tilted option, in that way it is easier to get your rear wheel in and out.
Or under the swingarm for the lowest centre of gravity. :D

Somehow it looks lighter/smaller than the single piston caliper I used before... It isn't, but it looks like it.

Yeah, I'm voting for the forward too. Could have used under like on the YZF, easy solution with all brackets already in place. But I feel wheel changes are easier with caliper over.
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Sun Apr 04, 2021 8:38 pm

Updates have been made, there is a time limit this time:

Rear end finished with the chain glide from stock swing arm and a shark fin chain guard. Slightly shorter brake line for R6 still too long but better than the Thunderace one. Ported head with one bad cam shaft bearing, mounted nevertheless since my original cylinder head was destroyed by someone that should just "smooth it out". New intake from an old TDM 3VD since they fared the same destiny. Thinner head gasket for higher comp, and a set of V2 cams with very little play on intake valves. Need to fix that.
Changed sensor for the Koso instrument to an active one reading bolts instead of magnets, home made link arms CC 176 mm for the swingarm. Removed all brake fluid canisters using only the hose, cleaned and rebuilt front calipers. Honed cylinders and new piston rings. Oil pressure sensor connected to the Koso instrument.

Need to get it track ready before 24 april, pictures and specs to come. No furter weight saving of carb rejetting done, guesstimating 95 hp if it holds up?
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Re: jpe's Bumble bee - The collected mods

Postby cobbadiggabuddyblooo » Tue Apr 06, 2021 3:31 pm

40* of overlap on the V2’s so don’t be surprised if you have a steep advance curve under 4000rpm.
Change gear by 8500 will put you right back in the thick of your torque curve too...
The cams really start to work from 6000rpm ..
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Tue Apr 06, 2021 7:21 pm

cobbadiggabuddyblooo wrote:40* of overlap on the V2’s so don’t be surprised if you have a steep advance curve under 4000rpm.
Change gear by 8500 will put you right back in the thick of your torque curve too...
The cams really start to work from 6000rpm ..
You’ll love these mods

I'll adjust the curve with a little less advance in midrange and steeper increase between 3-4000 rpm. Think I have some example to give me hints.
Shift light is set already for 8500 so I'm good there. :D

More push from 6 is not a bad thing on a track bike, but...

I won't have any chance of dyno'ing the bike before coming track days so I'll have to wing it for the first run, with the ported top and the cams will I need to rejet the carbs richer? Running dynoed TDMR40's but setup for stock cylinder head.
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Wed Apr 07, 2021 8:28 pm

jpe70 wrote: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.


Would you look at that. A bit more than 2 years ago and just about half the cost... :roll: :lol:
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Re: jpe's Bumble bee - The collected mods

Postby cobbadiggabuddyblooo » Thu Apr 08, 2021 12:39 pm

The gains you find from the rise in compression will offset the losses in dynamic compression due to the overlap but your still gaining nearly 20* more inlet duration plus the extra 0.3mm lift. They are an asymmetric cam too so faster opening ramps so again a little more gain.
To decrease your overlap take the lift at TDC down by 1mm on the exhaust cam. Good chance the loss of less overlap will be offset by pumping loss with the earlier opening exhaust valve.
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Sat Apr 10, 2021 9:00 pm

Here's where we ended up: viewtopic.php?f=42&t=493&p=123404#p123404

Thanks for watching, I'll be back if I stumble over a free big bore kit or something. :lol:
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Re: jpe's Bumble bee - The collected mods

Postby jpe70 » Wed Apr 21, 2021 7:11 am

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