Project CB350F cafe brat

Several issues. 14.7:1 is not what you actually aim for under normal driving conditions. Accelerating needs much more fuel and at cruise, you can go much leaner.

You have options. Best is to take the bike to a dyno shop and have them run it and jet it accordingly.

Or go the DIY route and get idle nice and clean and then jet for the mains by doing a plug chop and then fine tune the midrange on the needle clip position.
 
teazer said:
Several issues. 14.7:1 is not what you actually aim for under normal driving conditions. Accelerating needs much more fuel and at cruise, you can go much leaner.

You have options. Best is to take the bike to a dyno shop and have them run it and jet it accordingly.

Or go the DIY route and get idle nice and clean and then jet for the mains by doing a plug chop and then fine tune the midrange on the needle clip position.
Click to expand...

Cheers for the help. I’m keen to try the DIY route first and if it doesn’t work then I’ll get someone to tune it for me. So with the mixture, do you have a better point to aim for? All I’m trying to do is have a more accurate way of tuning the bike above how you would normally balance and tune a carb setup.


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For sure having data is useful as long as we know what to do with that data. I have an Innovate A"F meter and wide band O2 sensor i used with a data logger and to honest it would have been cheaper to slap it on the dyno - which is what I ended up doing to get it into the ballpark. Dynobikes in Moorabin can give you a quick run and gas analysis and there are others in other states.

Ideal-stoichiometry.jpg


That curve gives you a better idea of what you want 12.6 for max power and 15.4 for economy on light throttle cruising and richer for idle, but what does your motor want?

The way I set up carbs is to start with stock settings and go up say 2 sizes on pilot jet and two or more on teh main jets to start with. I check FUEL levels (not float levels) to make sure that I have a solid starting point. Fire up teh bike and adjust the airscrews until the idle is nice and clean AND when you roll on teh throttle it doesn't die. I often end up with slightly larger than perfect pilot jets if the carbs are larger than stock so that the bike picks up cleanly as throttle is opened.

If it's any sort of rideable, the next jet to fix is the main jets and that requires a box of jets and a few sets of cheap spark plugs of the right heat range. Do a plug chop at WOT under load and inspect the plugs. You want cleasn insulator and no signs of overheating on the side or center electrodes. After that's set, then I move needles up or down to get mid throttle right.

Another trick is to ride it up a slight hill and open the throttle wide at a fixed point going up the hill and time it from there to the top . Change jets and repeat until you have the fastest time up that hill. Consistency of starting speed is obviously important as is avoiding the state revenue raising employees (police).

How modified is the bike?
 
teazer said:
For sure having data is useful as long as we know what to do with that data. I have an Innovate A"F meter and wide band O2 sensor i used with a data logger and to honest it would have been cheaper to slap it on the dyno - which is what I ended up doing to get it into the ballpark. Dynobikes in Moorabin can give you a quick run and gas analysis and there are others in other states.

Ideal-stoichiometry.jpg


That curve gives you a better idea of what you want 12.6 for max power and 15.4 for economy on light throttle cruising and richer for idle, but what does your motor want?

The way I set up carbs is to start with stock settings and go up say 2 sizes on pilot jet and two or more on teh main jets to start with. I check FUEL levels (not float levels) to make sure that I have a solid starting point. Fire up teh bike and adjust the airscrews until the idle is nice and clean AND when you roll on teh throttle it doesn't die. I often end up with slightly larger than perfect pilot jets if the carbs are larger than stock so that the bike picks up cleanly as throttle is opened.

If it's any sort of rideable, the next jet to fix is the main jets and that requires a box of jets and a few sets of cheap spark plugs of the right heat range. Do a plug chop at WOT under load and inspect the plugs. You want cleasn insulator and no signs of overheating on the side or center electrodes. After that's set, then I move needles up or down to get mid throttle right.

Another trick is to ride it up a slight hill and open the throttle wide at a fixed point going up the hill and time it from there to the top . Change jets and repeat until you have the fastest time up that hill. Consistency of starting speed is obviously important as is avoiding the state revenue raising employees (police).

How modified is the bike?
Click to expand...

Cool. So if I set the idle jet and then go for 12.6 with the appropriate main jetting while being balanced then I should be ok. Maybe go a touch higher so I’m not getting the plugs dirty all the time.
It’s a stock engine and carbs with new rings and a 4 into 1 exhaust which came with the bike. Maybe just maybe it won’t need jetting at all but I’m not holding my breath. Also changing the jets is really easy but changing the needle height is a bit more involved. At least that can be done at the end to adjust that mid range as you say.

It seems to me that using the wideband sensors is a much better way than checking the plugs. The timed run up a hill seems like a good idea. I’ll do that when the tome comes.


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IMG_1247.JPG

Playing around with the battery layout. These cells are shit. The ebay tricked me but that’s my fault really, I had a feeling they would be dodgy low mAh cells. The pink and green ones are out of old laptops and even they are better than the blue ones at 1 Ah each. I’ll get some 3ah ones from Samsung or something which will give me a 9 Ah battery


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IMG_1250.JPG

I have a question! What the hell should I do about this mess on the forks. Paint? I figure that if I paint the forks out of the bike they will scratch going back in. I’ve toyed with the idea of wrapping brown leather around to hide it but I’m not fully sold on that idea either. Any input will be appreciated. Cheers legends


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Just spotted your thread.
Re the batteries....9ah is OK, but what is the CCA rating (cold cranking amps), that's the ommph required to turn the starter.
This link might give you some info, if you don't already know.

The rusty stancions could be covered in leather 'chaps' fixed with poppers. Or you could fit a shrouded headlamp mount that sits between the yokes, covers the stancions and holds the headlight. Or, you could use gaitors on the lower parts and a metal (or plastic) tube to slide down the upper stancion.
 
NoRiders said:
Just spotted your thread.
Re the batteries....9ah is OK, but what is the CCA rating (cold cranking amps), that's the ommph required to turn the starter.
This link might give you some info, if you don't already know.

The rusty stancions could be covered in leather 'chaps' fixed with poppers. Or you could fit a shrouded headlamp mount that sits between the yokes, covers the stancions and holds the headlight. Or, you could use gaitors on the lower parts and a metal (or plastic) tube to slide down the upper stancion.
Click to expand...

Hi mate. Yeah the cells are 8c which is 9ah x 8. So 71 CCA. I actually don’t know if that’s enough or not

Cheers, maybe the gaitors but I don’t want the bike too black. I mean black is the best but it needs something to break it up. Guess I could make something else chrome up front otherwise the stitched leather might be the best option. Mmmm need to think it over some more but cheers for ya suggestions mate


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stubsryan said:
Hi mate. Yeah the cells are 8c which is 9ah x 8. So 71 CCA. I actually don’t know if that’s enough or not

Cheers, maybe the gaitors but I don’t want the bike too black. I mean black is the best but it needs something to break it up. Guess I could make something else chrome up front otherwise the stitched leather might be the best option. Mmmm need to think it over some more but cheers for ya suggestions mate


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Click to expand...
I can't pretend to know details of CCA, but maybe match the 77 to the 360 specs?

Yu might find some stainless pipe/tube with an internal diameter (i/d) to match the stanchions, if cut to the correct length it would sit snug and still allow a headlamp mount bracket.
 
IMG_1295.JPG


So I’m my infinite wisdom I threw this part out when I did a clean up. Farrrrrkkkkk. There is no way I’m paying that much but I’m sure I’ll find a used part somewhere. At that rate a bike would cost $30,000 to build in parts. Crazy expensive.

As for your suggestions, cheers legends, I’ll investigate and choose soon enough


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So my last tank had too many holes in it. Decided to go and clean the red tank up but that thing has seen more filler than katylen Jenner. Ordered a cb550 tank and it’s close but still needs a tank bashing go work. Closer than the other 3 tanks. Hopefully some photos soon people.

Still no luck with the timing advance bit might have to order online as the wreckers has nothing that would fit the diameter of the spindle housing. Fuck! Probably going to cost me $150. What a mistake. Fucking hell! Also a new drama, the new tank from a 550 is shorter than the 750¿ tanks I had. That means my seat is short but I’ve already devised a plan to fix that.
Rearsets are on the way, making the linkages myself with stainless tube. Picked up the front brake line and a tachometer. Maybe have it running and doing roosters down my lane way in 4 weeks depending on mail


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What about a used advance unit for say a CB175/250/350K/360/500 or so on. Springs and weights might be slightly different but I suspect that there are alternatives that could save you a ton of cash and would be close enough in terms of advance curve and total advance. What is the diameter of the shaft it fits on?
 
teazer said:
What about a used advance unit for say a CB175/250/350K/360/500 or so on. Springs and weights might be slightly different but I suspect that there are alternatives that could save you a ton of cash and would be close enough in terms of advance curve and total advance. What is the diameter of the shaft it fits on?
Click to expand...

Decent idea. I ended up finding the right one for $60 USD delivered. Not ideal but it had to be done. I tried at a motorcycle scrap yard but nothing fit


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Put oil in the front forks today. Also had a look at the front guard but that’s not going to work I don’t think. Not till I sort out the front wheel alignment issue at least. Standing at the front of the bike the tyre is too close to the right fork. Maybe needs to go 7mm to the left which is weird. I’m not sure what the issue is. Maybe I laced the wheel too far to one side? I might remove the wheel and flip it around to see if it changes or stays the same. That will narrow the fault down to forks or wheel.


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It appears the wheel isn’t laced exactly in the centre. It’s not far off, 7mm was a bad guess. I’ll loosen the spokes a 1/4 turn on the narrow side and see if that makes a difference. It may end up needing 3/4 of a turn but I’m not sure till I do it
IMG_1505.JPG
IMG_1506.JPG



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Also thinking about making a custom front fender from fibreglass. I would like to try with aluminium but I don’t have the tools for that kind of thing yet.


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