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Just to be clear...
the people that know are not me. They are the people that manufactured the cams and sold them to you. Use them!
You learn much faster and more effectively if you build on the information and recommendations from others rather than insist there is another way.
Do it the proven way then make changes once you have a baseline of knowledge and a modicum of experience.

Wow, nice to see you all are just as salty as ever. Always great reading your replies. However, "people that know" were once as ignorant as i seem to be...but hey, don't really care if i've insulted anyone. Like I said, just trying to learn.

I'll include pictures for ya next time...

View attachment 103797
Or do it your way and keeps us informed and entertained...
Who knows, you might end up there eventually.
 

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Alternatively you could possibly use a borescope or fibre optic endoscope to visually inspect inside the assembled engine, but that would prove very expensive if you don't have somebody in the optics related industry.
I have a 15 quid borescope from ebay.
Does the job perfectly.

To the op, get some soft wax in there and make sure you have clearance (or get on ebay and buy a 15 quid bore scope so you can watch the valve to piston clearance)
Once confirmed get building that engine
 

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You have to admire anyone building a CB900 overweight turd into a race bike, even the factory had loads of problems with them in the late 80's :cool: (the big bore 750 with shorter stroke was better as a 998cc motor)
 

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Discussion Starter · #164 ·
Just to be clear...
the people that know are not me. They are the people that manufactured the cams and sold them to you. Use them!
You learn much faster and more effectively if you build on the information and recommendations from others rather than insist there is another way.
Do it the proven way then make changes once you have a baseline of knowledge and a modicum of experience.



Or do it your way and keeps us informed and entertained...
Who knows, you might end up there eventually.
well, i tried until i failed. went to the "wax" approach to verify enough clearance. here's my attempt at using the dial, but there was no good angle.
103863

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However, i still believe there's a mathematical way to determine P-V clearance without the camshaft installed. Hypothesis at this point.
 

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Discussion Starter · #165 ·
You have to admire anyone building a CB900 overweight turd into a race bike, even the factory had loads of problems with them in the late 80's :cool: (the big bore 750 with shorter stroke was better as a 998cc motor)
that was 2 years ago. still running strong. at 490 lbs, not as overweight as the original.
 

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Discussion Starter · #166 ·
someone asked to see the underseat battery box i designed for this 750 project. here it is.

103864
 

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Discussion Starter · #167 ·
hello all, been quite awhile. recovering from COVID and waiting on late parts due to late shipping, et. al. took me away from this post for an extended period. Pictures of where project #2 is at today.
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Question for the group. this is the top of my Rickman 1/2 fairing and i can't find any good pictures of speedo, tach and gauges and lights. What i'm asking of the group are pictures and/or ideas for how to set this up. Any recommendations on manufacturers, styles, etc. i'm planning to stick with traditional cable driven speedo/tach, unless someone has a recommendation for an upgrade that would work. i did update the rotor, so i now have electronic timing/RPM.

Thanks.
 

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Glad you recovered! WTF was covid like 😷

Curious about the position of your bars, are you planning to move those down to clear the fairing or move the fairing up to clear the bars and levers? I'd be getting all those clearances sorted before worrying about the instrumentation cluster, that can go wherever you have some space left.
 

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Discussion Starter · #169 ·
Glad you recovered! WTF was covid like 😷

Curious about the position of your bars, are you planning to move those down to clear the fairing or move the fairing up to clear the bars and levers? I'd be getting all those clearances sorted before worrying about the instrumentation cluster, that can go wherever you have some space left.

have not made all my adjustments. but yes, i plan to move things down to make sure they work.

any recommendations on the console equipment/design?
 

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Discussion Starter · #170 ·
have not made all my adjustments. but yes, i plan to move things down to make sure they work.

any recommendations on the console equipment/design?
PS, COVID wiped me out, but my wife is still recovering from the Pneumonia SHE got. it sucked and we're, btw, very healthy.
 

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This will be of no help other than maybe a visual aid.
I saw a Moto Guzzi build, at least I think it was, and the guy had a dash that had the speedo at the top, in a digital 1.5" tall number. Below that was an analogue tach, that could be rotated to your preferred position. Then the idiot lights were lined between the two. It was a one piece unit and he had cut a piece of aluminum shaped to the fairing curve to mount it. Sharp looking unit.

I think he was a Brit but could be European and there was nothing cheap on the bike so I doubt you'll fined it on the average cafe crap site. It is the basic idea of the one below, different configuration and the bezel was metal or at least looked like it.
 

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Discussion Starter · #173 ·
thanks for the ideas. will check them out. new problem for you. i want to upgrade my braking system. i have Nissin 4 pot calipers for the front and as you can imagine, on the current 276mm OD rotors, the inside pots hit the spokes. So, i'm trying to find 320mm OD 58mm ID rotors with no luck. also striking out trying to find a hub ("hat") that fits 58mm and mount floating discs. no luck finding hubs that will work for this bike (flat rotor will not work, i don't think). So, any thoughts on where to find floating discs that meet my requirements?
 

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You will have to machine adapters to mount rotors. 2006-2016 R6 rotors are 320mm.
 

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Couple of ways to mount instruments.
Easiest is a clamp on bar/tube around steering head with flat plate to mount everything.
Better is a welded on bar.
I've seen spacers made to raise original clocks so they don't interfere with fairing and look 'almost stock' but that is rarely the best way to mount them.
For piston to valve clearance, fit light spring, fit head with DTI as your picture and just push down until valve contacts piston. That will tell you max lift available. The problem is, valve to valve clearance.
For that you need to look at things. I seem to recall valve to valve was more critical than valve to piston and also more difficult to measure. Use tubular spacers on cylinder studs and connect cam chain with the cams your using so you can turn motor over and physically measure clearances at overlap. I think someone posted pictures of it 10 years or so ago?
 
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Discussion Starter · #177 · (Edited)
Related, but separate build question. here's where the build is at for the 900.

104865


i'm struggling with the carburetor tuning. i've been patiently swapping out jets to get a good idle to WOT transition. in all cases, regardless of jetting, when the engine is warm, it will rev up to high mid-range RPMs without moving the throttle. this happens even at Honda's recommended settings. So my question is this;

Does this happen because too much gas is allowed in thru the needle jet, causing the engine to keep the vacuum piston "up?" Can't set the needle as it's not adjustable. replaced the return springs on the vacuum piston and that calmed it down a little. any other suggestions?

SettingsFactoryRun 1 (from another mechanic)Run 2Run 3Run 4Run 5Run 6
Pilot Jet35353838383838
Main Jet68981081081026868
Secondary Jet105105115110108108105
Needle Jet Pos.N/AN/AN/AN/AN/AN/AN/A
Final Air/Fuel (Turns)23.51.51.7522TBD
 

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Sounds like a vacuum leak. Spray som carb cleaner around the intake boots to see if the engine speed reacts. Could be bad intake boots or a leaking hose/fitting.
 

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Discussion Starter · #179 ·
thanks. also, went plane stock on the jets all around. also, replaced my 900C vacuum pistons with a set of 900F. C's have 2 holes to release pressure on the piston while the F has 3. that has me very close to where i want to be. But, i'll verify vacuum is good.
 
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