CB900 Scrambler - Rally Approved!!

Re: CB900 Scrambler - Stage One Complete

Here's a cool blurry cell phone pic.



I've ridden the bike to work every day this week without any hiccups.

Yesterday evening I felt like doing a non-commute ride so I went to some local back roads near my house. On my way back home I heard a distinct metallic twang and ringing from behind me followed by the an intermittent vibration under the seat. I was cruising about 30mph at the time so I eased off the throttle and used front brake to get her to the side of the road. I put it on the kickstand and assess the back end only to find the above situation.

The jam nut on the damper rod wasn't tight enough on re-assembly so it backed out of the upper shock mount and let loose on a bump which let the spring fly off while I was going down the road. The ringing sound I heard was the spring rolling down the road behind me before ending up in the grass on the shoulder. The vibration under the seat was the rear tire kissing the seat pan since it only had one shock to support my ass.

This is why I wear ATGATT. And this is why I carry a basic metric tool kit.

I walked back up the road and retrieved the spring. Re-assembled and finished my ride a few miles to the house. Consider me luck yet again that the spring didn't end up in the spokes or bounce into an oncoming car or come loose doing 70 on the highway.

Note: I noticed a good amount of whatever damping fluid is supposed to be in these old shocks making its way to the outside. They didn't look servicable when I had them apart so my quest for new suspension needs to happen sooner than later I suppose.

8.3 weeks to Rally WV.:evil

Re: CB900 Scrambler - Stage One Complete

A lucky escape there, Glad your OK and no serious damage to the bike.
If you want to raise the back end with your replacement shocks and don't want to use riser blocks, have a look for some mx shocks usually they are longer. The CB shocks are the longest road shocks so you wont get any joy with road specific shocks. An idea I had after getting the swingarm powder coated so it was to late to implement, was cutting of the lower shock mount below the eye and welding a plate underneath to raise it up. If you use the same thickness plate as the original it should be OK structurally.

Re: CB900 Scrambler - Stage One Complete

notlob said:

An idea I had after getting the swingarm powder coated so it was to late to implement, was cutting of the lower shock mount below the eye and welding a plate underneath to raise it up. If you use the same thickness plate as the original it should be OK structurally.

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I think I might machine a piece of plate steel for each side to extent the axle carriers at the end of the swingarm. It's 8mm thick steel I think...can't remember. I'll be making a bracket to accept modern eye-to-eye shocks as well so I can do that at the same time. I'm hoping that opens up some options.

Something like this but without the shocks layed down so far.

Re: CB900 Scrambler - Stage One Complete

Going for an eye to eye shock would give you loads more option on shocks, that's the way to go methinks.

Re: CB900 Scrambler - Stage One Complete

notlob said:

Going for an eye to eye shock would give you loads more option on shocks, that's the way to go methinks.

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That's what I thougth after a first cut at searching for a 15"ish shock with some comp/reb adjustment.

Dime City makes weld-on clevises for this type of conversion. I'm going to go over to the local metal yard to search for some steel channel I can cut sections of to do the same. It's probably worth my time and gas money to buy them pre-made but fabricating is half the fun.

Re: CB900 Scrambler - Stage One Complete

I fixed the rear shock and motor mount bolts. I went over the whole bike making sure no other external fastners are loose. Probably not the last time that will be required.

Also finished wiring up my dash lights last night. The female pins from the stock harness were the same as the ones in the connectors supplied by Trail Tech (I haven't looked up the official name for these connectors) so I unclipped them from the 9-pin (it is only populated with 8 pins) stock gauge cluster plug and inserted them in the new 6-pin harness. (after an hour or so of drinking beer and looking at the wiring diagram and confirming with a multimeter)

I ran two lights for the turn signals, a neutral/clutch in light, and the oil pressure light. I may combine the turn indicators and run the high beam indicator...not sure which I prefer.

The turn indicators share a common ground and seperate positive.

The neutral and oil light share a positive and two seperate grounds. This is important to note since the indicator bulbs are LED and have to have the correct polarity.

I left the pins that were the positive for the high beam indicator and the tach/speedo backlights in the stock plug for now. I may use the backlight pin for a USB accesory plug that will only on be when the key is on. I'll have to see what fuse they go through to confirm if that is a good or bad idea. Should be fine for a USB plug for GPS or phones.

The stock flasher relay didn't work with the new LED signals so I borrowed the LED flasher relay from my KTM to test it out. BINGO! I'll throw the one I ordered back on the KTM when it comes in the mail.

I wet sanded the where the gas fumes melted my masking paper into the paint. I sanded the whole tank enough to cut down on the maroon nature of that last coat of paint. After the 400 grit wet sanding I dried it and rubbed it down with scratch removing/polishing compound. It left it with a really nice satin finish that looks sort of like vintage paint that's been waxed.

This post is almost worthless without pics.....

I'll get some tonight.

Re: CB900 Scrambler - Stage One Complete

Love this build. Really cool bike.

Re: CB900 Scrambler - Stage One Complete

LBC said:

This post is almost worthless without pics.....

I'll get some tonight.

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Still worthless ;D

Re: CB900 Scrambler - Stage One Complete

Bless me Father for I have modified a motorcycle. It has been 7 days since my last build update. These are my build pictures....

I've been riding more than wrenching the last week or so...where were we...

I finished wiring the new dash and signals.
Looks good and it works!





Also messed with the paint on the tank. I need a better camera and the right lighting to do it justice.

Last Thursday I had to stay late at work and got caught riding home in a downpour. Once everything was good and soaked I lost spark intermittently. Not sure if it was a bad ground to the coils or spark getting out of the plug wires. I was able to keep teh rev up and nurse it home.

All my plug wires, connectors, and the inside of my controls got a good coat of wire dryer(dielectric spray stuff..smells mostly like silicone spray). I was back in business once things dried out and my ride to work last Friday was uneventful. Hope I don't test that again but I may get teh garden hose out and give it a shower to be sure it's "fixed".

I went to Queen City Mods and Rockers Rally last Saturday with the bike. Had tons of fun! There were probably 200 motorcycles and scooters and 175 differnent makes and models. Japanese, American, Britich, Euro, etc. etc with some stock and pristine, some rat bikes, some cafe bikes, some in between and hardly any two alike!
Plus great live music and pinup girsl and roller girls and more bikes!

https://www.facebook.com/#!/QueenCityModsRockers?fref=ts
https://www.facebook.com/#!/media/set/?set=a.332749220189112.1073741832.242553049208730&type=1
https://www.facebook.com/#!/media/set/?set=a.10151480481893099.1073741824.54690963098&type=1

The ride for the day went all around the Ohio river valley near Cinci. I made it through about 3/4 of the 100 mile ride and my bike wouldn't pull at one of the stoplights. Sweep crew had a volt meter. Batter was about 9 volts...damn.
Luckily the guys I went to the rally with had trailered to town so I had a ride home and didn't have to cut the party short!!!! On a good note the bike handles great on the current rubber and until the electrical gremlin it ran really strong.

I think it was just a loose fuse or connection on the relay but I'll confirm that this weekend. This past week I was working long days every day and I didn't make time to thouroughly trouble shoot.

I have a spare stator in one of the parts boxes that looks good and has the proper resistance. I'll also probably order a new reg/rec just to be on the safe side come race day.

7.1 weeks to Rally WV. The adventure continues!!!

Re: CB900 Scrambler - Stage One Complete

That looked like a good day out.

At least your getting the gremlins ironed out early. May well be worth considering a newer mosfet type reg/rect, probably have to do some jiggery pokery with the wiring. Rich Ard posted a list up recently of bikes that run them.

Re: CB900 Scrambler - Stage One Complete

notlob said:

That looked like a good day out.

At least your getting the gremlins ironed out early. May well be worth considering a newer mosfet type reg/rect, probably have to do some jiggery pokery with the wiring. Rich Ard posted a list up recently of bikes that run them.

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Definitely a good day out!

Nice tip on the MOSFET R/R. I like that idea!

When I find the definite root cause of my non-charging I'll let ya'll know for future build posterity.

Re: CB900 Scrambler - Stage One Complete

In case anyone doubts the potential of these DOHC bikes....I think CRD has it down.

I guess this is the owner's personal ride.

via bikeexif

Re: CB900 Scrambler - Stage One Complete

Your right there it was the very 1st bike they did and has been going through an 2nd update for past 3 months or so.

Guess where I got the inpiration for my cb750 build below

Re: CB900 Scrambler - Stage One Complete

I tracked my charging issue down to a faulty charging rotor. This seems to be a common failure as the epoxy on these has aged and is in a hot dry location. The rotor rotates inside the coil which is mouted to the case cover. The rotor should be at ~4.3ohms across the two copper slip rings but it reads 0.8ohms which I'm told indicates a short in the windings. The coil is good and my parts box had a good spare. The interwebs also tell me that when the rotor goes it usually takes the reg/rect as well so...$250 later I have parts on the way. I'm hoping to do another local ride if the parts get here Friday and they are all I need to fix the glitch.

Re: CB900 Scrambler - Stage One Complete

If you mean that you just spent $250 on an r/r, I'm tremendously sorry that I didn't get back in here soon enough to let you know that the list of MOSFET r/rs is on the last couple pages of my XV920 build thread. I picked one up from a 2007 ZX6R for $30, and it'll still be working after another stock r/r would have gone toes-up.

Re: CB900 Scrambler - Stage One Complete

Yamaha has the same problem with the XS650, very similar design.
I much preferred the earlier ones,(CB500/550/750 SOHC) rotor was all steel and both coils stationary
Probably not as efficient but 'almost' indistructable (until you crash )

Re: CB900 Scrambler - Stage One Complete

Rich Ard said:

If you mean that you just spent $250 on an r/r, I'm tremendously sorry that I didn't get back in here soon enough to let you know that the list of MOSFET r/rs is on the last couple pages of my XV920 build thread. I picked one up from a 2007 ZX6R for $30, and it'll still be working after another stock r/r would have gone toes-up.

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No. Notlob sent me toward your link and I liked the idea. I bought a new Rotor, rotor puller bolt thing because I'm lazy and didn't want to make one, a $30 CBR MOSFET R/R, and a new starter relay. I paid a bit extra for shipping to get it all here before the weekend.

For those interested...but not enough to dig for it... the regulator/rectifier link is here

Re: CB900 Scrambler - Stage One Complete

Those rotors are expensive to replace. they do work OK if between 3 and 5 ohms, to get a good reading you need to clean up the face and really push the tips of the probes in to the copper rings. I had one that read 1.5 ohms just putting the probes on as you would normally do, when cleaned up and pressing the probes into the copper I got a reading of 3 ohms.

Thanks to Rich Ards list I'm trawling ebay for cheap reg/rec for future projects

For a rotor puller you have a back axle in your wheel, you can use that its the same thread

Re: CB900 Scrambler - Stage One Complete

Ha! I'll tell you, man, it's weird to put a multimeter on my battery and have it stick at about 13.6 no matter what I'm doing on the throttle.

Re: CB900 Scrambler - Stage One Complete

Rich Ard said:

Ha! I'll tell you, man, it's weird to put a multimeter on my battery and have it stick at about 13.6 no matter what I'm doing on the throttle.

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That sounds like a winner! I'll let you know how it all comes together.