A camel through my main jet?

James A. Corbally /

Stripped down my carb so I could note the numbers on the jets for future reference. The pilot was #48, the biggest one listed in the repair manual for any of the models.

However, when it came to the main jet, it was rated #70. The closest main jet value in the manual is #60!

What's going on here? The moped article here said jets are often rich on European machines, but by that much? What could I expect by fitting a lower one? Better fuel consumption I hope. I'm told I shoud be getting high 80mpg to 90mpg. I'm getting more like 60-70.

James...

Re: A camel through my main jet?

Don't know the info about your problem but loved the title of your post.

Brian S

Re: A camel through my main jet?

Ron Brown /

James,

Mentioning the model and year of your ped is allways a good idea if you want to know what size carb jets others use.

You can determine if your main jet is too big by doing a high speed plug chop but make sure your air cleaner is in good condition or remover first.

Ron

Re: A camel through my main jet?

Japan is in Europe now ?

I gotta read the newspaper more!

By "Euro" I meant peds manufactured in Europe... not just sold in Europe.

But in fact being from the US I know nothing about your Japanese Katana 50 or anything else sold in Europe.

It would seem that you have too big a jet if that size is not listed in your parts book.

But proceed with caution.... you need to a plug chop with a new plug (per that article)... then go down one jet size at a time (if indicated by plug color) and test it each time.

Re: A camel through my main jet?

James A. Corbally /

Glad you liked the title Brian, that's about as Biblical as I get! :)

Thanks for clearing up the "Europed" thing also, Fred.

I changed the plug over the weekend along with cleaning the air filters and changing the tranny oil (it was black and watery.-Eeuuww!). I had leaned the jet needle one notch, and sure enough the plug was a lighter tan than the one I'd removed a while back. It still looks healthy though, less carbon depositing also. The ceramic did have a small circular defect though, like a piece had broken away. The plug has the ceramic slightly further out, unlike the first one or the one I'm using now, so perhaps it's a matter of exposure.

The only problem I can see for a plug chop is that full throttle and top speed aren't the same thing on my machine. I can get it to its' top speed of around 75Kph(47mph) by using half throttle. I generally increase to just over half, the RPMs building up, then drop it a tad and it accelerates to its max speed. It will sometimes "stutter" at around half, but less so now that the needle is leaned. Opening the throttle full gains nothing in speed, unless it's on an incline or I've got a pillion. Then I can sometimes get a "surge" to top speed. With two people, this surge usually "stutters", pulling forward and back.

I know at what throttle position the main jet should be effecting it at, but I'm not certain if my higher speed is done on the needle or the main. It seems to be more in the needles' range, which coincides with the "leaner" plug.

All of which makes it bloody difficult to be certain of what's going on in there. Anyone got a VERY small camera? (Or should that be camel?)

:)

Regards,

James...

One hump or two ?

Your description of "my top speed and full throttle are not the same thing" is an almost perfect description of a 'too big' main jet.

The main jet is supposed to be the controller of fuel at full throttle/top speed.

.. the needle is supposd to control 1/4 to 3/4 throttle

...the pilot is supposed to control idle to 1/4 throttle

First try a short test with NO air filter... speed go up?... plug not white?..

Then go to the Suzuki dealer and buy the next 2 or 3 sizes smaller main than what you already have.

Put the air filter back on...

Then set the needle clip back to its original position.

Then test the first size smaller main.. ('test' meaning both performance and plug color)

If the plug is not too white... try the next one smaller again.

Just watch the plug color!

Going white can mean a piston seizure!

(at least $100 US to fix... 70 pounds?.. and a week or two to wait for parts)

Note : Too much oil on a foam filter is a common mistake causing 'richness'... put the filter between absorbant paper and set a heavy book on it and let the excess oil get absorbed out over time.

Re: One hump or two ?

James Corbally /

"One hump or two", I like that :)

Fred wrote:

>

>

> Your description of "my top speed and full throttle are not

> the same thing" is an almost perfect description of a 'too

> big' main jet.

>

Excellent, we're probably on the right track so.

> The main jet is supposed to be the controller of fuel at full

> throttle/top speed.

> .. the needle is supposd to control 1/4 to 3/4 throttle

> ...the pilot is supposed to control idle to 1/4 throttle

>

Which is why I thought my throttle setup was so weird. More twist should equal more power AFAIK.

> First try a short test with NO air filter... speed go up?...

> plug not white?..

Actually, I did that last year. When my air filter box lid was stolen, I replaced it and first began noticing a flat spot. The shop suggested that test, and when tried, the machine took off down the street. Was only a short test however, no more than 150-200 metres. I've still got "fiddly" throttling to this day. Then again, it had only been derestricted a short while before the theft, so it may have had the same "spot" before as after.

It's my plan to replace the entire air box before I do too much fiddling, remove the filter "variable", so to speak Even so, the fact that Suzukis' own manual has no other model of this machine with such a big main jet is telling. Perhaps the dealer fiddled with it when he installed the carb heater....

> Then go to the Suzuki dealer and buy the next 2 or 3 sizes

> smaller main than what you already have.

>

I'll start looking into that.

> Put the air filter back on...

> Then set the needle clip back to its original position.

>

> Then test the first size smaller main.. ('test' meaning both

> performance and plug color)

>

> If the plug is not too white... try the next one smaller again.

>

> Just watch the plug color!

> Going white can mean a piston seizure!

> (at least $100 US to fix... 70 pounds?.. and a week or two to

> wait for parts)

>

Need to avoid that! This thing is my ticket to work. Otherwise it's out of bed at 5:30am to arrive in work at 7:45amshudder, as opposed to getting up at 7:00!! Did that for 3 years, don't wanna do it again....

> Note : Too much oil on a foam filter is a common mistake

> causing 'richness'... put the filter between absorbant paper

> and set a heavy book on it and let the excess oil get

> absorbed out over time.

Nice idea, a "filter press" of sorts :) I've just cleaned/reoiled, so I'll be sure to check I didn't overdo it.

Thanks to everyone for their ongoing help BTW, I usually don't get replies on Usenet, or the enjoyable conversation!

James...

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