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Author Topic: CB500/4 racer resurrection  (Read 5692 times)

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Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #50 on: December 30, 2017, 01:55:10 am »
Hmm,  thanks for te info, wonder why the piston mods for 750 into 500 are so far away from the actual shape?
Anyway, I welded a short section of CB750 fork tube across width of my 550 swing arm in 1978 then heated it up and beat tyre clearance into it.  ::)
 It was noticeably stiffer (and heavier) but still really needed another 2" length to improve stability at 115~119mph, for some reason it straightened out real well at 120 or more?
Mine is still in Britain, they were popular there because of 600cc insurance bracket.  You got a 250, 400 Yam RD or 400F (depending on how much of a hooligan you were) Suzuki GS550 or CB550, Kawasaki meant going to Z650 and big jump in insurance, had 4 or 5 at one time, plus a few wrecked/written off and 500f bits. I remember selling one to my brother (78 FourK) touring style just wasn't me, to soft and too little ground clearance  ;)
The Lesters would be worth a bunch now though  :( (he traded it for a GS1000)
maybe they were not so concerned about making good squish at the time, but i do recall they said to machine the first few mm flat to match the over bore and then do a 12 taper too, no?

I remember (circa 1982) my stock 500/4 waving/tank slapping at the most unexpected times but i think it was more due to the 19" front, #$%*ty tires/shocks of the time. my race 500/4 is on 18" front, stock swingarm, proper rubber and shocks, super steady at 120. some people here even race with the 750 arm which is shorter for quicker steering, no issues either.

Offline MessnerMoto

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Re: CB500/4 racer resurrection
« Reply #51 on: December 30, 2017, 03:54:58 am »
nice flow bench. I like the use of duck tape the most :D and thx for the article I am exploring it

Offline crazypj

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Re: CB500/4 racer resurrection
« Reply #52 on: January 01, 2018, 06:18:15 pm »
The various dimensions I can find are saying 15 degrees. I ave more but with multiple ard drives from various computers over the years searching multiple terrabytes is taking a long time. If I could remember what I named stuff it would help. I used to just write things in service manuals, much simpler to find things before computer storage got too big I'm just going to match stuff then re-machine if I  really have to.  8)
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Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #53 on: January 02, 2018, 07:40:46 am »
Btw, checked 550 parts lists and couldnt find the clutch side bolt you mentioned between the tranny bearings...

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #54 on: January 08, 2018, 03:15:09 pm »
not exactly related to the bike, but getting acces to the lathe i used in the past was becoming more and more of a problem; you can thank the bureaucrats and liability laws...

finding something that could fit my small space without turning to the myriad of chinese made stuff was a challenge.

After the guy published this twice in ebay at a crazy high price, then he made a u-turn and sold it almost dirt cheap for what is a Swiss made precision/hobby lathe. It's a Lesto / Scintilla GD1123 (Scintilla in italian means spark, these guys used to make magnetos in the early days for BMW, Motosacoche, etc....). Allegedly they also inveted the electric jigsaw, but that's another story.

required quite a bit of work to sort out some little problems, but now i cna get work done!

90% of my lathe needs is for spacers in aluminum or nylon, and it can handle those soft materials pretty well. 

Offline NickO

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Re: CB500/4 racer resurrection
« Reply #55 on: January 09, 2018, 05:43:11 am »
Scintilla AG (Swiss) was founded as a subsidiary of Brown Boveri in 1917 to produce magnetos as you say TG, (Brown Boveri latter became ABB). It is now part of the Bosch group.

I have a Bosch electric jigsaw from about 1985 and it has "Scintilla AG" on the name plate.

Offline crazypj

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Re: CB500/4 racer resurrection
« Reply #56 on: January 13, 2018, 12:19:57 pm »
not exactly related to the bike, but getting acces to the lathe i used in the past was becoming more and more of a problem; you can thank the bureaucrats and liability laws...

finding something that could fit my small space without turning to the myriad of chinese made stuff was a challenge.

After the guy published this twice in ebay at a crazy high price, then he made a u-turn and sold it almost dirt cheap for what is a Swiss made precision/hobby lathe. It's a Lesto / Scintilla GD1123 (Scintilla in italian means spark, these guys used to make magnetos in the early days for BMW, Motosacoche, etc....). Allegedly they also inveted the electric jigsaw, but that's another story.

required quite a bit of work to sort out some little problems, but now i cna get work done!

90% of my lathe needs is for spacers in aluminum or nylon, and it can handle those soft materials pretty well. 
Precision lathe is always worth it. I had exact same problem with 'liabilities' preventing me using equipment (even though I was the ONLY trained machinist there)
It will last 'forever when your using mainly alloy and plastics, with correct tool grinds you can easily do most steels as well, just take a bit longer on a small machine where your using 0.010" cut depth instead of 0.100" (although even the 7" mini lathes will do 0.200" on Nylon, Teflon, etc.

Btw, checked 550 parts lists and couldnt find the clutch side bolt you mentioned between the tranny bearings...

 I'll dig out a crankcase and check, been a while since I've had 550 apart.
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Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #57 on: February 12, 2018, 12:50:52 pm »
Been quiet for a while simply because the lathe let me tackle a ton of suspension related stuff that was just waiting to be done.
1. bought a set of bitubos and they feel just great. removed the springs and their claim that there is a separator piston between oil and gas seems true. all emulsion shocks will have these "bubbly" noises when stroking them, the bitubos really felt like it's only oil passing through the orifices. and same weight as the agricultural konis i raced with till now.
2. Bitubo stock shock bushings just wouldnt work with my CB500 top mount/KZ650 bottom mounts, so to redo them all new in nylon.
3. Turned a swingarm chain protector for the left side, and a nylon spacer for the right.
4. the kawasaki swingarm pivot has a 2mm bigger ID, so turned some 1mm thin walled sleeves, a good test of precision for any lathe...
5. this year we are allowed 38mm forks, so upgraded from the heavy stock 35mm to a 38 set off a kawasaki. each complete fork leg is lighter by 3 pounds and the bonus of teflon lined slide bearings instead of steel on ally...
6. used the occasion for a major hydraulics update fitting CBR damping cartridges, required quite bit of spacers to be designed and turned so the hydraulics can work properly.
7. had an all alloy kawaski triple clamp set from another projects sitting around (-1.5 pounds), it was meant for a 41mm, so X4 41/38 sleeves turned
8. kawasaki and honda steering stem bearings differ in ID, so another set of turned adapters, the top one having 0.5mm wall thickness :)
Things are getting ready to put the cycle part back together, so it'll start looking like a bike again soon
« Last Edit: February 12, 2018, 12:59:54 pm by turboguzzi »

Offline bwaller

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Re: CB500/4 racer resurrection
« Reply #58 on: February 12, 2018, 01:02:52 pm »
Very Nice.

What would you say if I landed at your place with a suitcase full of parts needing machining? Old pal, LOL
« Last Edit: February 12, 2018, 06:00:57 pm by bwaller »

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #59 on: February 13, 2018, 01:25:48 am »
you are welcome to visit brent! actually, about time... while i'll be doing the work we'll send you to visit the guzzi, mv agusta and lambretta museums around town ;)
more suspension work:

1. turned some driver to press in the needle bearings in the kz650 swingarm
2. the thing is ready for mounting with new race stand bobbins and chain protector

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #60 on: February 13, 2018, 01:38:12 am »
ready to mount then...

i really dislike having to squash on the frame with the swingarm bolt to take up the gap of a loose  fit, so i machined the new bearing sleeve to +0.1-0.2 mm more than the internal dimension inside the frame.
In order to make it slide in easily, i use a car jack between the frame sides applying really light pressure, that's all is needed to make the swingarm drop in.

the new bitubos complete the rear end. cant wait to feel how theyll do on track

Offline Bill/BentON Racing

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Re: CB500/4 racer resurrection
« Reply #61 on: February 13, 2018, 05:20:44 am »
under ball cleaning went fine, glad i did it, quite a bit of muck there...
less exciting news are all sort of issues coming up under deeper inspection.

center crank bearing area has a tiny step form wear, micrometer says it 0.01mm lower, waiting for a new plastigauge kit to make sure.
what's a bit worrying is that two of the four sizes of bearing shells are now "no longer in production", hope i wont need the size thats not available.... any alternative sources?

next, and this is a bit unexpected, quite a bit of fretting on the seats of the two larger bearing of the tranny. unlike the two needle ones, these are not pegged and looks like under racing abuse they did rotate... anyone ever seen this type of wear?
the clutch side one looks worse and its only now that i realize that unlike the drive side, this one doesnt have a bolt in the middle to clamp the bearing better...  your thoughts on the subject are welcome!
I found some NOS bearings,  what part number or color is no longer available? Glad to see you back on the 550
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Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #62 on: February 13, 2018, 08:34:52 am »
tnxs for the offer bill, but bottom end is buttoned up already with second smallest shells and all is within wear limit like that.  going from memory here but i think the A & D (smallest and the biggest) sized shell bearing are the ones no longer available.

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #63 on: February 14, 2018, 02:41:34 am »
just need to add wheels and a motor and it's a done job :)

Offline bwaller

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Re: CB500/4 racer resurrection
« Reply #64 on: February 14, 2018, 04:24:32 am »
Are those shocks longer? Seems like a crazy arm angle but I realize with no weight on .

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #65 on: February 14, 2018, 11:41:38 am »
Still need to adjust pre load and length but bike has to be complete before

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #66 on: January 10, 2019, 08:52:17 am »
well, as you can see from the year long gap, my accident and tibia/fibula fracture took a toll.... two three months after the accident i started doing some work again, so chassis mods finished, pics later on.
Time to tackle again porting upgrades. when i did it back in 2009, I went with mostly with gut feeling, time for a reality check.
Mike kindly gave me some flow numbers (green line) from a slightly polished stock 550 head with stock manifold (same as the 500), as they were for 10" H2O, I got them converted to 28" as that's the calibration reference of my bench.
So assuming my CNC'd flowbench calibration plate is good, my work netted a 22% improvement mainly above 5mm lift without spoiling low lift (red line), so cant really complain.
I have now a good baseline, so curious as to what gains will opening the seat to 0.9 valve diameter will give.
As we all know, air has it's own thinking, so it was mildly miffing to discover that the whole 10 degs downdraft angle project i built into the manifold yields only a 2-3 CMF improvement compared to a pure horizontal manifold.
if you want to translate the numbers to other H2O heights, you can use this calc.
http://www.wallaceracing.com/calcdchg.php
« Last Edit: January 10, 2019, 08:54:43 am by turboguzzi »

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #67 on: January 10, 2019, 02:13:35 pm »
frame mods pretty much ready, gpz600 38mm fork and aluminum triples with cbr600 cartridges, new plates for the brembos, GF replica tank, kz750 swingarm, adjustable floating piston bitubo shocks, rear disc instead of the heavy cb350 drum. battery is now a flat 3.2 ah under the seat.
« Last Edit: January 10, 2019, 02:15:43 pm by turboguzzi »

Offline bwaller

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Re: CB500/4 racer resurrection
« Reply #68 on: January 11, 2019, 06:39:38 pm »
Nice. Will get to my rear disc conversion this winter. Curious what weight savings there is, any idea yet?

Offline RAF122S

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Re: CB500/4 racer resurrection
« Reply #69 on: January 12, 2019, 05:28:04 am »
Looks good TG.
David
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Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #70 on: January 12, 2019, 05:54:24 am »
Nice. Will get to my rear disc conversion this winter. Curious what weight savings there is, any idea yet?
not as much as you'd think.... cb350 wheel all included (brake plate, sprocket, avon 130/65) was 14.4 kg. new wheel (with disc, sprocket, heidenau 130) 12kg
thing is that after adding caliper, hanger and MC, there might be 1-1.5 kg savings only. difference in tire weigh might take this towards 2kg, but i think that's optimistic
weight wise, nice, but not a must have i'd say.

Offline bwaller

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Re: CB500/4 racer resurrection
« Reply #71 on: January 12, 2019, 02:20:35 pm »
Yeah well, figured as much. Still, weight removed from a good area.

Offline 754

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Re: CB500/4 racer resurrection
« Reply #72 on: January 12, 2019, 11:05:34 pm »
 You can carve at least 25 percent of the rear caliper hanger bracket off weight wise, and hourglass both wheel spacers, and use aluminum axle adjusters. 
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Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #73 on: January 16, 2019, 08:44:26 am »
time for some fun and put the flow bench to good use. as i dont have countelss 500 heads to work on, am taking a bit more experimental approach here without causing irreversible damage.
using these silicon port and head negative castings, plan is to do now a few cavity sets in paris plaster, easily modify them and see what works best before even touching the real head. there are a few porting strategies i want to try, so this will enable me to see where each one takes me.
 

Offline turboguzzi

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Re: CB500/4 racer resurrection
« Reply #74 on: January 22, 2019, 02:26:08 pm »
well, tomorrow the Frankenstein type experimentation begins.
I've cast negatives from the silicon port mold in paris plaster, when back together they essentially recreate the port and head combo of the head.
just to make sure i have a good base of comparison, did a first flow check and the plaster "head" flowed to within +/- 2CFM @ 28" H2O compared to the real head when tested back to back, so we're good, ready to start mods.
Changes to the plaster head are super quick, soft material and of course the port is open in the middle to work on, so no pain involved and if i get stuff wrong, no damage to costly parts.
first step will be taking the valve throat to 0.9 of the valve diameter and see what happens.
going to try also what an oversize valve does as well as D-porting it.

« Last Edit: January 22, 2019, 02:28:51 pm by turboguzzi »

 

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