CBX Racing

CBXs, new bikes, old bikes, cars, trucks, general chat, off topic, this is the place to post it.
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Syscrush
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Re: CBX Racing

Post by Syscrush »

Well, how am I gonna get my CBX Racing fix for the next 3 weeks, then???

Seriously, good luck with the next steps.
Phil in Toronto
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Pics of Perry, my '79.

Warwick Biggs
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Re: CBX Racing

Post by Warwick Biggs »

Ah, Phil, I will think of something. Like starting up the lump and jacking up the shorter dog bone to the max in readiness for track testing?

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Re: CBX Racing

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So I did try to start it. It started first pop without any choke but was smoking badly and was very lumpy. Then the CR Specials started spewing fuel everywhere which sometimes happens if they have been dry for a while. So I left it overnight and sure enuf' when I turned the fuel on this morning it was not leaking so I started it up again but then it started dripping oil from both Colin Marley's lovely billet crank end caps and from the countershaft. So I closed it down. Then after 10 minutes while I was investigating the oil leaks it started dripping fuel again, but from a different carby!

It is still running way too rich and it looks like I need smaller pilot jets as well as new O-rings for the float bowls and probably a new set of needles and seats tho' I'm damned if I can see any visible wear on the needles. At least the new ignition appears to be working. But I don't think it has solved my problem.

Who was it that said it sounds like carby's to me? Sometimes, going second hand is not as economical as it might appear because re-building CR Specials is an expensive process. The float bowl O-rings alone come in at over $120 and I haven't costed the needles and seats yet.

In the vain hope that it may be running well enuf' for our test and tune day I had jacked the rear ride height up by about 15 mm (pretty much the max with the shorter of my 2 custom dog bones) and nothing is fouling so I was hoping it would be good if I could experiment with dropping the forks to lift the front up a bit and compensate for the reduction in trail. In theory it should give me nearly 3/4" in extra ground clearance and improve the swing arm angle for better drive out of the corners.

But clearly there is still a lot to fix before then.

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Re: CBX Racing

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This morning I finished the CBX ready for track testing. I fixed the oil leaks with good old fashioned half mill gasket paper and no silicone. For ages I have been plagued with intermittent oil leaks from the crank end caps. I discovered why with my vernier gauge. The stainless Allen screws holding the billet caps on were fractionally too long for the threads. 15 minutes with an angle grinder, bench grinder and wire brush fixed that. Started her up and no more leaks.

While it was running I reset the idle so that it is good enuf' for a track test. Its still running too rich but its running. The main concern is that it not bog down under load. If that is fixed I will try to get it back on the dyno for some carb tuning. Fingers crossed. I've also jacked up the rear suspension quite a bit so I will have to be careful and I should double check the static trail before I take it out just to make sure it doesn't fold on me in the first corner.

Here are some pics of the current crop of racers in my stable. The CBX naturally towers over the others even if it is the slowest. The GSXR 750 is very much the dark horse, the NC30 is the dainty filly and the CBX is 'the lump'. I have re-fitted the fuel line quick release because I don't trust Pingel valves and with the diaphragm removed there is a risk of a rod thru' the cases if fuel were to leak into the combustion chambers. It happened to early CBX's that lacked a diaphragm. I've also shown the improved Prolink swing arm angle.
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Re: CBX Racing

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Here is the quick release....
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Re: CBX Racing

Post by Warwick Biggs »

Check out the angle...
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Re: CBX Racing

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My, what a big motor you have.... 'the lump' in wolf's clothing.
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Re: CBX Racing

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The dark horse had to be converted to race shift but otherwise is a stock motor but with race glass, engine protectors and less than 5,000 klms on the clock.
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Syscrush
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Re: CBX Racing

Post by Syscrush »

Warwick Biggs wrote:This morning I finished the CBX ready for track testing. I fixed the oil leaks with good old fashioned half mill gasket paper and no silicone. For ages I have been plagued with intermittent oil leaks from the crank end caps. I discovered why with my vernier gauge. The stainless Allen screws holding the billet caps on were fractionally too long for the threads. 15 minutes with an angle grinder, bench grinder and wire brush fixed that. Started her up and no more leaks.
Gotta love an update like that. Good work.

Here's hoping that the track testing goes well and bears fruit.
Phil in Toronto
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Pics of Perry, my '79.

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Re: CBX Racing

Post by Warwick Biggs »

Did anybody notice from the pics anything particularly unusual about my most recent chassis modification?

Some people go to extreme lengths to lighten every component. I've gone a step further.

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Re: CBX Racing

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For the technically minded and as it is currently set up I have extended the Wilbers rear shock from its previous 295 mm fully extended length to 302 mm and dropped the standard length Prolink front forks to within 7.4 mm from the top marker ring on the tubes to the top of the triple clamp. This gives 115-120 mm trail with a 15 mm increase in ride height at the front At the rear it is more complicated because the 7 mm increase has to be multiplied by the linkage ratio (OK, I forget what it is but it should roughly equate with the change at the front lifting the entire bike around 15 mm. I have measured the swing arm angle as around 13 degrees from horizontal which in theory is ideal.

Of course, all of this is experimental and the final settings will have to be determined at the track.

But nobody has spotted my most radical chassis innovation.

Recall also that the head stock has been cut and shut to bring the rake back from over 278 degrees to 25 and of course I'm running much stiffer progressive springs.

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Re: CBX Racing

Post by Warwick Biggs »

Sorry, typo. The rake has been pulled back from over 28 degrees to 25.

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Re: CBX Racing

Post by Rick Pope »

Warwick Biggs wrote:Did anybody notice from the pics anything particularly unusual about my most recent chassis modification?

Some people go to extreme lengths to lighten every component. I've gone a step further.
It appears you left out the top motor mounts... :o
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Syscrush
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Re: CBX Racing

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That sounds like a lot of trail, still. I hope it feels good out there.
Phil in Toronto
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Pics of Perry, my '79.

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Re: CBX Racing

Post by 80 cbx dude #6216 »

Warwick, I also had a problem getting my crank caps sealed after some engine work last year. I tore one of the original gaskets and made one from gasket material. It worked initially, but after some highway, higher rpm riding, it started leaking. Made another, same issue after running the motor hard. Finally purchased some gaskets made for the engine and never had a problem since. Just some food for thought. I hope shortening the bolts will take care of your leak.-Mike

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