I'll leave carburetor-related musings to Srinath and others, especially since you have multi-position clips.  The carbs on my '99 are still absolutely stock.

I'm curious to know how many miles/kms the bike has, and when the valves were last checked/adjusted.  My friend richard (re)gained both power and mileage when he brought his much-too-tight exhaust valves back into spec.

I agree with Kerry, if the carbs are fine and they're stock, I would suspect the valves. This is assuming the carbs are stock and O.k.

120 mains are on the lean side, maybe starving the bike for gas and making run too lean which makes it run hot and then you get bad mileage, er, fuel economy.

Leave the clip where it is (if it's not broke, don't fix it).

And, with the 120 mains that may be why you're not experiencing fuel starvation. The mains are too small to empty the floatbowls at higher speeds.

The previous owner dyno-tuned it, so I would hope that he removed the brass plugs over the mixture screws. So, hopefully those are set at 3 turns out. And, your bike shouldn't be equiped with the 37.5 pilot jets, which also makes it very lean down low in the powerband. That leaves floatbowl height, which you have stated in another thread, that it is correct.

If you change to 125 mains, you may have to change the clip on the needle.

My non-expert question I'd pose is whether you checked the plugs to read the air/fuel balance from that end.  Anyone checked on Srinath lately?  --Mike D.

Your floats are too high ... Biggest single factor for low gas mileage ... Floats should be right about at the level of the float gasket and no more ...
You can run to 90 wihtout running low and gasping for fuel ... yes but not with 120 mains ...
Cool.
Srinath.

OK you got the floats set right ...
Ironically I make right about 35 with my 47K mile 89 ... but its got pipe and K&N and 150 mains and 40 pilots ... You are definitely low for gas mileage ...
OK The other disturbing thing ... My 89 made 120+ Psi compression cold ... 100 is low ... very low, its 14 psi lower than the minimum specified by suzuki ... by all accounts Yours should be in the morgue ... Check valves ... It its too tight its going to cause poor running especially when cold or as its warming up ... and going to make startup's and warmup's a nightmare. Else I'll say count yourself fortunate that its still running and forget the gas mileage ... BTW what is the oil consumption ... mine is up to a quart in 250 ... Old and worn = motor uses more everyhitng ...
Cool.
Srinath.

I think the compression was much more cause when I was testing it, it blue the guage right out of my hand. Not use to these high compression engines.(First bike, worked on cars in the passed).I'll go and test it again tonight or tomorrow. Fortunately I've finaly received my  Clymar manual.

I'm not the kind of person that likes to drive something till it breaksdown so, I'd like to find any problems and trry and fix them.
If it is the valves, how can I test and what can I do about it ?
Also, do you think it would help if I dropped the main needles a bit to bring down fuelconsumtion ?

Conserning the running of the bike starts firsttime in the morning without choke and idles fine at 1200rpm, although I usualty use the choke when it's cold cause it's better for the engine. It runs a bit unevenly when I pull away but as soon as yo pass 4000-5000RPM the power starts kickin in and then drives quite nicely. As I was mentioning it has a bit of a knock in the engine when it's hot and it idles but not very load.
Another thing I noticed. My friend as a GS500. She has the 96 model and I the 99 (both with stock pipes) and it seems that mind is a lot loader then hers.(I can't see any holes drilled in it and the buffel is still intact)

Any help or suggestions would be very welcome.

Well check compression then ... and adjust the valves or atleast check them. Dropping needle might bring down fues consumption but the side effect will be that it will run leaner ... making it hotter and effectively reducing its overall life. And beyond a certain point you cant lean it out wihtout it running like shaZam!.
Cool.
Srinath.

I was checking and the compression is 125psi on both cylinders which must be good news.I also saw that my left plug was burning very dark other one is nice brown.Something must have gone wrong on the one carb.Hell, if I wasn't from South Africa I would have send my carbs to you aswell for rejetting and servicing, since everyone else is doing it. Looks like I'll have to do it myself. What is the implications of rejetting ? Without changing the pipe

Another thing,. TShould I be conserned about the knock in the engine. Only when engine is hot and I stop. It comes and goes when it's idling.

Could anyone tell me how to post pictures ?

OK is that 125 cold or hot. Hot is what really counts, but 125 cold is good.
Cool.
Srinath.

I spoke a week back about this problem. Concerning the compression. Somebody reminded me the other day that your actually supposed to turn the engine at full throtle when testing compression. So I tried it today while the engine was hot and it gave me a massive 135 almost 140 psi on both cylinders so I think valves are out of the question.

I'd still like to get these carbs sorted out. Everywhere you guys talk about disassembling but nobody really goes into detail on how to set them up. My one carb is definitely too rich 'cause the one plug is much darker.

My main concern is the fuel consumption (35mpg or 15K per l) and I also seem to have that power problem below 4000rpm (that is if it's not normal)

You know by now all the specs everything pretty much stock (120 jets, stock exhaust etc)

What am I to do, what could be blocked, with what setting should I experiment ?

Sorting the carbs for a stock bike with stock airbox, airfilter and exhaust pipe:

Jetting: Remove the brass plugs over the mixture screws and adjust to 3 turns out.
Make sure you have size 40 pilot jets.
Order a set of size 125 main jets (small round Mikuni).
Set or shim the needle .5mm up from stock setting.

Static synchronize the butterflys.

Set the float level: Preferably using the u-tube method (most dynamic), set it such that the fluid is level with the top of the floatbowl.

If you can, vacuum synchronize the carbs.

Still check the valve clearances every 4000 miles.

And, there is no power below 4000rpm, or, you could pretend there isn't any.

I though the mains Mikuni refers to are large round mikuni slotted ... small round is more like the keihein ones. I dunno usually I am picking it from a tackle box type box at the store ...
Cool.
Srinath.

Large rounds are what I used, worked like a charm..

trey

Thanks for the info.
Do I have to change the main needles as well ?
Can I buy the jets from Suzuki ? If any one knows whats the partno it would be nice since my dealer couldn't find the 125s on the microfiche

PS Large round, small round ?

Quote from: seshadri_srinathI though the mains Mikuni refers to are large round mikuni slotted ... small round is more like the keihein ones. I dunno usually I am picking it from a tackle box type box at the store ...
Cool.
Srinath.

Oops, yep, right, large round.

Don't change the needles, just the position.

Jets would be available as aftermarket items; Sudco makes them, Tucker-Rocky or another large motorcycle distributer would stock and ship them.

I need a distributor list.
Ron Ayers
Parts Unlimited (?)
Tucker-Rocky

Of course, these are U.S. distributers.