XBR rebuild

[tommy]

hi joolz  i tryed those chrome paints and they dont really work ,my mate sprayed my xbr crankcases ,head and barrel in 2 pac  about 3 years ago and its still on  them the other covers are polished i will do the same on my new xbr project . make sure any surface to be painted is spotless but 2 pac works well and you can get a good range of colours

[JOOLZ]

I have assembled the crankcases now, I had to wait a long time to get my crankshaft from Eastwood racing not their fault, they stripped my crank 3 weeks ago and when reassembling the new conrod discovered there was a roller missing from the kit, so I had to contact the company I got the rod from to send a replacement, the first one they sent was the wrong size but they got it right in the end. The only major problem I had during reassembly was as I torqued the cases down the shaft got tight, It took some head scratching, and I thought the only variable was the new bearings, but I looked, and they looked fine. Suzanne disagreed and said there was a very slight gap (I installed the bearings by putting the crank in the freezer for 6 hours and heating the bearings to 125'c they slide straight on) not quite far enough as it turned out. The remedy was simple. I cut some pipe that fit the inner race of the bearing to 60mm length, cut a square plate to fit over the top of the pipe with a hole drilled in the center and used the flywheel bolt to gently pull the crank into the bearing, it only moved a fraction but it did the trick. Crank now spins freely and all the gears are selectable, thats as much of the engine as im going to do for now as the rest will be built up when the bottom end is back in the newly rebuilt frame

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[JOOLZ]

Bottom end finished, ): Next stage strip the frame and sort that out.

[JOOLZ]

The final piece in the mechanical jigsaw, my special grind cam

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[guest564]

What timing and lift does that give you?

[JOOLZ]

Hi the timing is left inlet 26 54 with the right hand inlet advanced by another 6' and exhaust 53 23 and the lift is 8.6mm on intake and exhaust. The engine has been tuned for max torque and a wide spread of power rather than all out peak power

[guest564]

Hi the timing is left inlet 26 54 with the right hand inlet advanced by another 6' and exhaust 53 23 and the lift is 8.6mm on intake and exhaust. The engine has been tuned for max torque and a wide spread of power rather than all out peak power

You do need a good spread of power with the stock gearbox.

[Propellor]

Hi the timing is left inlet 26 54 with the right hand inlet advanced by another 6' and exhaust 53 23 and the lift is 8.6mm on intake and exhaust. The engine has been tuned for max torque and a wide spread of power rather than all out peak power

Hi.

Just belatedly been reading through your rebuild with interest.

I wondered why the "staggered" timings for the inlet valves? Also, is the difference 6 mins or 6 degs?

Cheers.

[JOOLZ]

The staggered inlet cam timings are a result of some ideas that Phil Joy and myself were researching individually.
When I went to get the cam reground we were chatting about various things and "split phased" cam timing was mentioned as a way to get a very high swirl into the mixture and keep a high velocity in the inlet tract despite a more aggressive cam timing.
6 degrees by the way.

[Propellor]

The staggered inlet cam timings are a result of some ideas that Phil Joy and myself were researching individually.
When I went to get the cam reground we were chatting about various things and "split phased" cam timing was mentioned as a way to get a very high swirl into the mixture and keep a high velocity in the inlet tract despite a more aggressive cam timing.
6 degrees by the way.

Thanks for reply. Fascinating stuff. Your forecasted power/torque figures suggest you've not had to go chasing rpm rpm to achieve a decent power figure. No point in trying to cram more of the stuff in there if it won't all burn, I suppose! Did it yield the results your expected?

Any videos (+audio 

Cheers

[Propellor]

Ps:  I assume the 6 degrees is crankshaft "phasing"?

Also, I may have missed this, in reading through your posts, but did you have the forecasted hp figure confirmed in practice? If so, how close were you? I find it incredible that such a thing could be calculated with the accuracy you mention. Presumably all this data, for the computer to crunch, is all gathered empirically? Or mostly?

Again, fascinating stuff.

[guest564]

Those timing figures are the same as the Megacycle X34 cam.

148-x34
.384" 260° 104° Use modified springs, guides and pistons. 26 btc/54 abc .007"
.351"   256° 105° good all-around off-road. 53 bbc/23 atc .009"

[JOOLZ]

Ps:  I assume the 6 degrees is crankshaft "phasing"?

Also, I may have missed this, in reading through your posts, but did you have the forecasted hp figure confirmed in practice? If so, how close were you? I find it incredible that such a thing could be calculated with the accuracy you mention. Presumably all this data, for the computer to crunch, is all gathered empirically? Or mostly?

Again, fascinating stuff.

No camshaft inlet time phasing.  I use an engine building computer software, you can build any motor on it virtually, just programme in all the engine specs and it will give you the hp and torque curves, you can then play around with the ignition and cam advance retard, valve shape,etc and move your power curve around and see what it does. The only thing it wont do is calculate 2 inlet valves timed out of phase. They recon to about + or - 5% accuracy I paid enough for it so I would like to get it on a real dyno to confirm all the figures
Real life performance seems to reflect a good improvement in power it will pull at tickover in 3rd and it certainly wheelies almost too easily, I have to be careful when I accelerate away from stopped as it lifts the wheel even from quite low revs.
It is a good fun bike to ride, its super light at 278 lbs so it accelerates like a scolded cat, and its flexible enough to ride about town but its designed for twisty A roads and thats where it comes into its own

[JOOLZ]

Those timing figures are the same as the Megacycle X34 cam.

148-x34
.384" 260° 104° Use modified springs, guides and pistons. 26 btc/54 abc .007"
.351"   256° 105° good all-around off-road. 53 bbc/23 atc .009"

Thats right, that cam was on my list of cam timing figures when I was talking with Phil Joy and deciding what would be best for the type of use the bike was being built for, we just modified that by putting in the 6' difference between the inlet opening times

[Propellor]

Ps:  I assume the 6 degrees is crankshaft "phasing"?

Also, I may have missed this, in reading through your posts, but did you have the forecasted hp figure confirmed in practice? If so, how close were you? I find it incredible that such a thing could be calculated with the accuracy you mention. Presumably all this data, for the computer to crunch, is all gathered empirically? Or mostly?

Again, fascinating stuff.

No camshaft inlet time phasing.  I use an engine building computer software, you can build any motor on it virtually, just programme in all the engine specs and it will give you the hp and torque curves, you can then play around with the ignition and cam advance retard, valve shape,etc and move your power curve around and see what it does. The only thing it wont do is calculate 2 inlet valves timed out of phase. They recon to about + or - 5% accuracy I paid enough for it so I would like to get it on a real dyno to confirm all the figures
Real life performance seems to reflect a good improvement in power it will pull at tickover in 3rd and it certainly wheelies almost too easily, I have to be careful when I accelerate away from stopped as it lifts the wheel even from quite low revs.
It is a good fun bike to ride, its super light at 278 lbs so it accelerates like a scolded cat, and its flexible enough to ride about town but its designed for twisty A roads and thats where it comes into its own

So that's 12 degrees of crankshaft rotation, between phasing of inlet cams? Quite a bit.

Re weight. Wow! That is some achievement. That's as light as a 250 RS. Give or take the odd kg. And by default you have raised the combined c of g, I guess. I can see why it might be more eager to wheelie. How do you go on with fork dive?