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Enduro / Dirt / Scramblers / CB100 Scrambler Beginner Bike Build
« Last post by cyclone64 on Today at 03:19:41 »
About 3 years ago my brother bought a 1972 CB100 at a swap meet thinking he'd use it to learn to ride on. It was a runner but had been used as an OHV and had most of the lights removed, missing side covers, bent handlebars.

Fast forward to today, and my girlfriend wants to learn to ride. Had him drop the 100 off so I could fix it up for her (and hopefully him) to learn on. Found a bit a rust and fell into the rabbit hole.

Ongoing album can be found here:

So far it's been stripped to the frame, degreased, sanded, painted with rust reformer and engine enamel. Wheels cleaned up, new brake shoes, new tires and put back together.

Along the way I've made a few modifications:

SL125 exhaust - had to fab up a mount for it from some 1/8" 6061. Does anyone have a black header paint that's not super matte?

$30 Amazon seat. Not comfortable, but I don't see a CB100 as a long distance tourer. Quality seems... Good enough.

Classic dirt bike handlebars.

Chopped the front fender. May still cut down to a reinforcement bracket only and possibly add an SL front fender.

Various other bits and pieces.

Current plans going forward include:

1. SL125 rear fender (on the way)
2. Maybe plasti-dip the wheels a semi-gloss gold to match my Ducati...
3. XL100 skid plate (on the way) hoping it fits!
4. 12V conversion (seems to be differing opinions on this, hoping I can just add a regulator/rectifier, 12v battery, flasher relay, lights and be good to go).
5. Full LED light set.
6. I have all new cables and controls ready to go on.
7. Thinking about 3D printing an intake runner - I don't like the stock airbox toolkit battery conglomeration but I hear these 100s don't take kindly to a pod filter.

Let me know what you think!

Specials / Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Last post by goodoltup on Today at 01:59:14 »
^^ Hi Pete,
You are right, it would be easier and more efficient to make plates that fit on the inside, or the outside, of the original mounts. But I would be concerned about any movement allowed by the bolt-plate interfaces, I think a weld would be more secure. I guess you could weld the plate to the original mounts, but all in all, I think it would be more attractive to make new mounts and have them welded in.
Hey, Throttlefest is going to be killer.  Sebastian Bach is playing.

Thought I'd play around with this plastic mount on the back of the frame.  I made up an alloy bracket to fit a bottle, tube or tool roll ...

BUYING / 1977 CB550 tank
« Last post by carnivorous chicken on Feb 19, 2018, 23:43:08 »
Asking for a friend... She's looking for a 1977 CB550K tank. If you've got one lemme know. Thanks!
Race Ready / Re: Farm boy’s Rattle-can Racer
« Last post by teazer on Feb 19, 2018, 23:42:11 »
TZ runs close to 15.5:1 geometric and runs happily on anything above 100 octane.  My personal preference in VP range is U4.4 which seems to provide great throttle response.

Back to your calculations. If the head volume to mating surface including squish annulus is 12cc, we can calculate compressed volume.   14mm deep chamber with 51mm diameter (inside squish band) less piston crown volume = 15.6cc.  At 12cc, yours must be closer to 25:1.  Well that's not right.

Please re-measure to the volume to the surface that the head and barrel meet which is presumably to that machined ring just outside the squish band.  Please also confirm diameter of the chamber just inside the squish band and overall depth of the chamber.  Piston crown height is probably around 4.6mm from edge to top of the crown - please measure and confirm before you do anything to the chamber.

If I am right about those heads, they were machined by RK Tek - see P5 of to see what they look like after machining.  RK Tek heads run higher compression than stock and I am sure he pushed my reprofiled TZ350 head up to 17:1

In fact he has your heads on his web site - or some similar ones..

Engine and wheels sold
And at only 20% more than a brand new klr! Or about 2k less than a demo thruxton R at the local dealer. What a steal!

Sent from my iPhone using Tapatalk
Hey,  featherbed frames are pricey.  😂
Cafe Racers / Re: Project Shinjimei- 73 TX500
« Last post by two-smoker on Feb 19, 2018, 23:10:27 »
Good stuff. The only thing I would do with carbies is put genuine Keihin jets in, particularly the mains, as the Chinese jet sizing sometimes leaves a little to be desired. I've seen a larger jet number with a smaller hole which obviously causes all sorts of problems.
Indeed. I know I'm gonna have to change the jets anyway. Might as well get the good stuff.
Race Ready / Farm boy’s Rattle-can Racer
« Last post by farmer92 on Feb 19, 2018, 22:33:05 »
Running VP m3 fuel (turns out a vendor is 15k from my place) will probably require somewhere in the 15.5:1 or 16:1 compression ratio range.
15.7:1 (a. bell p.24) will require adding 2.25cc to the Combustion  area. So i need to deepen the center by 3.5mm... still better than 10.

This thing may just have picked up a lot more boom.
Hey! Thanks, Chris.  Trying to get it ready for some Thaw pre-running.  I figure you, E and me could hit some routes early and map.  I know E at least plans as much, but he's not allowed to have all the fun by himself.

I'm not? Well I'm out then. See y'all, I'm going to throttlefest
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