JETTING SOLVED! Could this be real?....and WORK?

Well, cant argue that a Dyno isn't a nice tool. I just think they are not readily available for your average cb350 builder.

Besides, this was about whether or not the ebay kit was a smart investment or not.

I still believe that it's a waste. And would deprive the purchaser of the pride of figuring it out them selves, and heaven forbid learn something. Instant gratification is usually short lived. But, it kinda goes hand in hand with the way people think these days. Which is, why do it my self if somebody is willing to do it for me...?
 
Louie, No argument that learning by doing is the way to go. Those of us that were lucky enough to either have a great mentor or to have lots of books and magazines to refer to did learn to do somethings eventually.

My point was that for a newbie a spell on the dyno is a great investment and for those of us doing it long enough a dyno is still a great tool. But it's just a tool and does not replace that vital human touch. Experienced racers have all sorts of tools including weather stations to help them to get the last ounce of performance out of their bikes.

But there are not many of those guys here. The question that Brandon asked was is a good place to start with jetting. The answer IMHO is yes for anyone that doesn't have a lot of experience jetting a bike They will still need to fine tune it in all probability but they will get into the ball park right from the get go.

If a bike is modified much from stock, who knows where the jetting will end up. Should they go up on the needle and main jet or up on the main and slow jet but leaner on the needle and how do they tell what's right and what isn't?

All the advise I have read here and on most forums about reading plugs is flat out wrong and has led, in a couple of extreme cases, to burned pistons and wrecked motors. That's not very likely on a CB350 that's fresh out of the barn.

The other way to look at this is to say, screw the theory and the fine tuning because the bikes is hardly state of the art and isn't in perfect condition, so how can we make it rideable. In that case, it's probably not worth a dyno or a jet kit. Just ride the bike and see how it feels. Try a couple of sizes up on the main jet and see how it runs, tweak the low speed with the air screw and if that feels OK then leave it at that.

I don't race karts with pumper carbs, I build street and race motorcycles and I like them to run as well as possible at a reasonable cost. There is no point in trying to get the carburation 110% accurate when the rest of the motor is worn. There is also no point in trying to get to perfection when good enough is adequate. It all comes down to how good is good enough and what is the most effective way to get there.

If they have a jet kit for a CB350 with pods and stock carbs, I'd try it. Same for a CB360 or CB750/900 DOHC. For a SOHC motor with regular old piston carb, I'd go up on the mains and tweak the air screws.

On a two stroke, all bets are off unless the jet kit came from the late great Leon Moss at LEDAR. This stuff ain't rocket science guys. Al it takes is a logical approach and an open mind (and a large box of jets needles and emulsion tubes)
 
teazer said:
I don't race karts with pumper carbs, I build street and race motorcycles and I like them to run as well as possible at a reasonable cost.
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Hahahaha! I take it that was a shot at me Brother Teazer!? I have been building and racing motorcycles for over 20 years!

I only brought karts...which are one of my other personal passions...into the equasion when we were having the forward facing carb debate a couple weeks back...and yes again when we were discussing side valve/flathead engines...and you already know that I run both pumper and Keihin slide/bowl carbs.

I was not aware that I had become your arch enemy for having a different opinion as you. I am here to share information and ideas and learn from those that I can and although you and I have greatly differing opinions on most subjects I have never called you wrong but if you feel the need to take shots at me because you have been building bikes for 4 years well then I guess now I know how you really feel.

Lighten up a little bit Brother Teazer, opinions are just that, and are nothing personal at all.
 
I think there's a failure to communicate here joey. I'm not having a dig at you. You are not my "arch enemy".

I admit that find some of your posts and ideas a little off the wall and try to explain politely why that's how I see it. I try to be polite and respectful and sometimes the way I write is taken out of context. That happens.

What I did say, was that I don't have your experience with Karts so that isn't my perspective or "come from place", so I told you where I'm coming from. No more no less.

I don't recall making a personal comment about you or attacking you. Lighten up dude.

There's a lot to learn and I'm still learning after 40 years and having built top quality show and race winning bikes 2 and 4 stroke (OK so the shows were small) on 3 continents, and I continue to learn something new every day.

As to "facts" and "opinions" that's a really good point. That is usually overlooked. Opinions are often interpreted as if they were facts and facts are often treated as opinions.
 
No sweat man, I know there are many people here all with largly varying skills and opinions but when it comes down to it we all share one thing...the love affair with the motorcycle. I admire that there are so many people here building such a diverse field of machines and that most are home builders turning wrenches out in the garage. I have always thought of guys like us as motorcycle enthusiasts, not bikers...and as craftsman, not mechanics. I know that sometimes there will be debates over opinions, facts, designs and theory, however I also feel that sometimes we forget why we are here...as people who have such a strong common bond and all share in the love affair with the motorcycle, and the craftsmanship of building our own machines that goes along with it, we should all act a little more like what we are...BROTHERS.
 
Brother Swagger I have never used that before...I did not read the whole article as it was rather long but it looks as if they are still using the original jet with this system as an additional jet for adjustments...is this correct? I have used externally adjustable needle main jet setups on butterfly carburetors and they are very easy to adjust and work very well also.
 
Dial a Jet or a latter version have been used for years in the Sled set. It's a valid enough approach to a situation where you need say a #400 jet at sea level and a much smaller one, say 280 at 10,000 ft.

Not much application on a bike though.
 
I wonder why something this this couldn't be used to fine tune externally.....
 
As do I. You could set a baseline and adjust to suit as you do further mods...
 
Brother Swagger I think it would be a great setup to use like that and I actually think the external hoses look trick too!
 
Has anyone looked at Dial a jet kits and stopped to ask themselves what it does and how it works?

I's basically an extra jet that works like a powerjet in that it adds extra fuel at the top end. At low to mid speed the air at the top of a carb is basically stopped or moving slowly. It's relatively stagnant and at high revs the air at the top is at a different pressure to teh rest of the carb throat.

That's why on say a T500 carb, the vent from the float bowl doesn't go to atmosphere - it goes to that area of the carb, to fine tune flow by adjusting teh pressure differential across the fuel in teh bowl. Very clever stuff.

With a power jet, the point at which it starts to work is proportional to the length of the jet .

So in simple terms a Dial a jet will add more fuel at the top end that lower down the rev range which is fine it that's what you need. If it isn't what your motor needs then it won't help.

It's just another tool that you could use to fine tune the A:F ratio across the revs. Why not just jet it right in the first place.......
 
Right, did I ever tell you I really like cheese? I like cheese. I'm also fascinated by small, shiny objects. just sayin'
 
Love the sense of humour. Cheese is amazing in its variety. If you like blue cheese, try St Agur. It's the smoothest blue around IMHO. Awesome cheese - and way better than jets.
 
Thanks for the suggestion Joey. I'm not familiar with that particular cheese ( or many of the others out there).

If you like subtle flavors, try a hard goat cheese. Not at all the taste or texture you might expect.

We had an evening recently where we each had to create a dish and I was given cheese as the subject. It's only a once a year thing so no biggie.

I knew I wanted a blue cheese so i tried a couple at teh local cheese store and then had to work out what to put it on. I tired three or four crackers and none of them worked. So then i started to bake pita bread chips and tried a range of different spices/herbs on them until i found one that really worked with the texture and flavor of the cheese.

Then i matches it to a Spanish stuffed olive that added the right offset to the flavors.

The point of the story is that I know nothing of teh science of food and have to rely on experience (limited) and the empirical approach try and test and repeat until you get the right answer.

There are many ways to get to an answer and life is all about the journey as much as it is about the destination.
 
Success! I derailed this thread into a cheese discussion. I'm ready to moderate!!
 
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