The non-running GS450ET is now RUNNING!

[surviverguy]

Carb 2 is almost perfect at 30/130 with needles raised and idle mix 3/4....just needs a little more midrange fuel with thinner needles. Gearing could be higher. I'd sacrifice some acceleration for some higher speed. A larger front sprocket and smaller rear will do the trick. Not sure how many teeth to change yet....I'll do some searching...

[surviverguy]

I believe my front sprocket is 16t. Bought an 18t front sprocket. It wasn't just top end speed I was after. I wanted to slow down the shifting a bit- stretch the range between gears. If I change the rear sprocket, it won't be before it's worn out.
Bought a slipstreamer clear windshield and a new brake lever tonight. Lots of shiny new parts will be here soon! It'll be another transformation for this old machine!

[pete]

The L's I think have 16/43 but I'm not sure how much difference that makes as they also have a 16 or 17" rear wheel...

What size rear tyre are you running? I find with my 4.10 x 18 and stock gearing that it's fine, but I'm after acceleration rather than top speed.

I do the traffic light drags every day and want to get away from the cagers but I still find I can hit the speed limit very easily when out and about for fun, so I definitely don't need more top speed.

Did your K&N's not come pre-oiled? Mine were sealed up in plastic bags from the factory and were pre-oiled. I did buy a recharge kit though which I'll probably do at the third service (11K km's).

Edit: Forgot to say if they're not oiled, then you're going to need to re-visit your jetting once they're oiled too...

[surviverguy]

I'm running 18's front and rear. I'm driving mostly small state highways without many stops. I'm trying to stretch 4 and 5 gears a little to avoid 6th gear unless using the interstate. I am more accustomed to 5 speed bikes. A change of 2 teeth isn't going to be dramatic- it'll just turn about 1Krpm lower at cruising speeds ( I think). It'll still be fast off the line, just allowing a little more time between shifts.
I thought the K and N's were preoiled...it's just yesterday when I say it on the filters- "oil before using"...it made me second guess myself.
I've been a mechanic for over 25 years, just don't have a lot of experience working on mc's... The tuning is a real challenge!
The bike is running well in all throttle positions accelerating until it hits about 6Krpm. At around 6K from 1/2 to 3/4 throttle it starts surging power and then loosing power..up and down up and down..if I go to full throttle it gives full power and stops the surging/ bucking or if I reduce throttle at 6k it'll smooth out. Do you think it might be too rich? i thought it was too lean until I recently read an article about carb tuning which said that the symptom was from too much fuel...

[pete]

That sounds a lot like my issue which is surging at probably 1/8 - 1/4 throttle, and I know for a fact my jetting is too rich still...

Only way to tell for sure is to ride it at that throttle opening constant for a few minutes and plug chop...

My surging is a PITA because that's exactly where the throttle needs to be held to do the 60kph speed limit here...

[surviverguy]

I put a mark on my throttle grip and a piece of tape with indicator lines of idle, 1/4, 1/2, 3/4, WOT beside the throttle to get a better idea (visual) of what was happening. It makes it a little hard for me to guess because I changed three things at one time...That's a good idea to do plug chops when and where it's messing up! Good idea there mate! I'll try that soon.

[surviverguy]

http://bikeadvice.in/

read this about tuning Mikuni carbs for K and N's

OOOps...bad link!

[surviverguy]

How to: Fit a K&N Filter and Rejet a Carburetor

by Deepak on February 4, 2010


This post is for all my fellow bike riders who wish to extract the last possible juice out of your ride. This post is regarding to the fitting of free flow air filters, its effects and how to rectify it using the method of re-jetting.
You need to consider re-jetting your bike whenever there’s been a major change to the air intakes (like installing K&N filters which allow more air to pass to the carburetor), or adding drag pipes. Both modifications will lean out the air-fuel mix. The stock jet can only allow a certain amount of fuel to pass through and is designed according to the specification of the vehicle. Installing larger jets increases fuel to the carburetor to restore the 14 parts air to 1 part fuel optimum mix. This mixture is called stoichiometric ratio. Whenever the amount of air intake is increased, the fuel part is also to be increased. In all other cases, the stock jets will take you through 95% of your riding requirements.

Since the main jet effects all speed ranges after idle, you need to get the main jets right first, and then tune the mid-range and low end. All tuning should be done on a fully warmed up engine because that’s the way you usually ride; the spark plugs should have been previously checked and cleaned; the gas tank should be at least half full; a new or recently installed fuel filter if present; the air intake filters checked for holes, and cleaned; and all air intake and manifold connections tight and secure; the battery fully charged; and the carburetors synchronized, if it’s a multiple cylinder engine (more than one cylinder, eg: kinetic comet ) for optimum results.
We are now going to tune the carburetor without the help of a tachometer (engine speed). High speed or top end main jet sizes are determined by full open throttle performance. Low and mid-range tuning is determined mainly by how the bike feels to you as you roll the throttle. Mikuni CV carburetor is different from the Keihin CV. So is the difference with other carburetors. So tuning will be different in different vehicles.

Note: If you do sense a loss of power, or rough running on a stock vehicle, it may due to some other reason. In this case re-jetting is not the solution to the current problem. Please take the bike to an authorized mechanic and rectify the problem.
HIGH SPEED JETTING
High speed performance (80 KPH and up) is controlled by the main jets. To make sure you have the right main jets, take your bike out to an open highway where you can safely (and legally) open the throttle all the way in top gear. Ride the bike full open and let the bike get to top speed. Again, do this only if you are experienced and comfortable running at top speed and you are not in danger of injuring yourself or someone else.
A. If at top speed or before, the bike runs rough, heavy throttle feel or begins to hesitant and buck, your main jet is TOO BIG. The mix is too rich (more fuel than the optimum 1 part fuel to 14 parts air) and you are getting an uneven burn and poor performance. Install smaller main jets and take the bike for another test run. Another way to determine rich mixture is, when u cold start the vehicle and if the bike starts in the very first crank the mixture is rich (no need to use the choke in this instance). Low fuel efficiency and more smoke in the exhaust than usual are some of the characteristics of a rich mixture.
B. If before top speed the engine is running smooth, but has no power, seems to be running hot or knocking from the engine and you can’t push the bike to top speed, then your main jets are too SMALL. You are running too LEAN a mix (less fuel than the optimum 1 part fuel to 14 parts air) for maximum engine performance. Put in LARGER main jets and take the bike out for another test run. Another way to determine lean mixture is the difficulty u feel when cold starting. Even after repeated cranking, if the engine does not start, the mixture is lean. When u closes the throttle in a downhill, if u hears popping or cracking sound from the exhaust, it is again due to the lean mixture.
MID-RANGE OR MID-SPEED TUNING
The carburetor needle controls mid-range performance. The needle tapers down to a point that fits into the main jet. The needle is lifted upward (along with the slide) by the carburetor diaphragm as the air flow increases through the carburetor. As the needle moves upward it is withdrawn from the main jet, allowing more fuel to mix with the increased air volume. All that is needed to modify mid-range performance is to place (or remove) one or more small, thin washers between the diaphragm and the head of the carburetor needle where it’s held in the diaphragm. Adding washers effectively raises the tapered needle further out of the main jet at all engine rpm’s and allows more fuel to mix with air to create a richer mix. Removing a washer effectively leans out the air-fuel mix.
There’s usually no need to replace the stock needles since they have proven over time to provide good performance and good gas mileage. If you do use a third party needle for increased performance, then anticipate lower fuel efficiency.
Mid-range tuning is accomplished mainly by how the bike performance feels to you. If there’s a smooth increase in power as you roll the throttle, then you’re there. If there’s a slow response or there’s no power, then the mix may be too LEAN and you may need to add one or more washers to richen the mix. If the bike accelerate with power, but feels rough, you may be too RICH and need to remove one or more washers to lean out the mix. Now take the bike out for a test spin.
LOW OR SLOW SPEED JETTING
Now you can tune for low end performance. If you are getting a poor pickup or hesitation off the line, or a lot of backfiring on deceleration, then you need more fuel through the pilot jet. You increase fuel flow through the pilot jet by turning the pilot jet screw OUT a half turn. It’s best to start at 2 1/2 turns OUT on the pilot screws and then increase the turns OUT 1/2 turn at a time, and go for a test run. Do these until you get the performance you want and/or there are no back fires on deceleration. If you go more than 5 or 6 FULL turns out, you will probably have to install a LARGER pilot jets. Larger pilot jets are usually needed if you have removed the stock air intakes, air box and installed K & N filters which dramatically INCREASE air intake volume.
I am not posting how to successfully repair the carburetor because of its complexity for a normal person. And friends, please make sure that a professional mechanic is always nearby if anything goes wrong.
GENERAL PROBLEM SOLVING TIPS:
If you get inconsistent running, fluctuations in power, you are probably running rich. Lean running is more likely to cut power completely. If you have poor power at small throttle openings and a surge at wider throttle then you may be running lean. Quick ways to see if you are running rich or lean.
* APPLY CHOKE AFTER WARM – UP TO ARTIFICIALLY RICHEN THE MIXTURE.
If you bike runs better with the choke on even after a few minutes of warm – up, your original mixture might be lean in the lower rev range. This test does strange things to the upper rev range, so don’t use it at highway speeds.
* REMOVE THE AIR FILTER COVER AND ARTIFICIALLY LEAN OUT THE MIXTURE
Temporarily remove the air liter cover (to INCREASE air to the mixture), and go for a test ride. A well tuned bike (where the air and fuel mix is right on) will run pretty badly (i.e. mixture too lean) when you do this. But if the mixture was originally too rich, the bike will run better. Then u can fix the air filter cover and lean the mixture.
If your bike’s performance has a hitch or hesitation at certain speeds or you can’t tell if it’s rich or lean, experiment by leaning out the mixture which is the easiest way to find out – if the mixture was originally too rich, the bike will run better immediately. If the mixture was originally too lean, your bike will run worse immediately
(Use the tuning techniques listed above to adjust the low, mid- and high speed ranges).
Now u might also understood why manufacturers stick to a particular setting and not going for extreme tuning. Extreme tuning will call the need for extreme keeping up of it. Friends, it’s all about experimenting with different settings. Also if found a good setting, don’t forget to check the fuel economy too. And always ride safe!
- Abiram Menon

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[pete]

Wow ok, that makes the simple plug chop process look a little complicated...

There's a plug chop write up somewhere on BassCliff's site that makes it much simpler.

Essentially what you've done marking the throttle positions is the right way to go about it with plug chops.

I have nowhere I could possibly do top speed runs with WOT and just getting time to do plug chops, re-jet, try again is pretty much impossible for me, which is why I'm waiting for budget for the wideband.

If you have time to do them, then go for it, you'll definitely have a much better running bike!

[surviverguy]

I confirmed the surging was from too rich a mix by running the bike cold and noticing that the performance was better cold than when warmed up. I'm going to lean it out some. Guess I didn't need thinner needles after all!
Pete, you can do the same thing without a tuner. Just pay attention to how it runs in the first four minutes of riding compared to after ten minutes. If performance goes down when warm- it's too rich!

[pete]

I confirmed the surging was from too rich a mix by running the bike cold and noticing that the performance was better cold than when warmed up. I'm going to lean it out some. Guess I didn't need thinner needles after all!
Pete, you can do the same thing without a tuner. Just pay attention to how it runs in the first four minutes of riding compared to after ten minutes. If performance goes down when warm- it's too rich!

Mine doesn't seem to matter... but it really doesn't stay cold enough for long enough either for my slow brain to work it out.

I have 0 confidence in my ability to look at plugs and go by feel which is why I want the fancy way I guess... for the moment I'll put up with the richness because at least I know I'm not going to hole any pistons...

[surviverguy]

Going with the idea that my current set up (30/130/ needles raised 1mm) was too rich I leaned it out. I took the 30 pilots out and put the stock pilots in and lowered my mains from 130 to 120 and lowered the needles about .75mm from stock position (or 1.75mm lower than testerday's position) ...and took the bike out for a test drive. I got 200 meters down the road and came right back home!
It was so lean that there was no pulling power...it ran like crap. The only thing that worked better was the choke.
I pulled the carbs back off the bike and raised the mains back to 130 leaving the needles lowered .75mm below stock position and left the stock pilots in place.
I Took off again for another test ride and found and it was much better. The difference between night and day. It's the best running setup so far. I still get a tiny bit of surging at around 3/4 throttle at about 6krpm but it's much better running and faster than ever and also using less fuel.

[pete]

Glad to hear you're getting her dialled in

I think my ignition issue was contributing to my poor economy around town.

Last tank when I felt that surging I figured it was out of fuel as I'd hit the 170km I've been getting around town. However, I only put 8 litres in and figured maybe I hadn't filled it properly last time?

Anyway, so far I'm over 180km on this tank after I definitely filled it properly and I'm still not on reserve yet.

The tank between this and the last one included a bit of an out and about weekend ride and the first tank after sorting the issue was the GSR run, and when out and about like that I get something like I'm used to getting 230km's out of a tank.

I'm keen to see how I much I get on this one before needing reserve... might have had ignition issues for longer than I thought!

[surviverguy]

Mine doesn't seem to matter... but it really doesn't stay cold enough for long enough either for my slow brain to work it out.

I have 0 confidence in my ability to look at plugs and go by feel which is why I want the fancy way I guess... for the moment I'll put up with the richness because at least I know I'm not going to hole any pistons...

I can help you tune your bike from the other side of the world. I am your cheap tuner. The first question to ask is how does it perform at full throttle? Does it fly like a bat out of he'll? Y/n
If yes then the main is close enough. The midrange issue you have is from being too rich. That's the surging. There's no mistaking surging. Surging pushes your body forward and back and forward and back. To cure midrange surging it's all in the needle. To lean the midrange you have two choices- either lower the needles you have 1mm for starters or get a different needle.

[pete]

I can help you tune your bike from the other side of the world. I am your cheap tuner. The first question to ask is how does it perform at full throttle? Does it fly like a bat out of he'll? Y/n
If yes then the main is close enough. The midrange issue you have is from being too rich. That's the surging. There's no mistaking surging. Surging pushes your body forward and back and forward and back. To cure midrange surging it's all in the needle. To lean the midrange you have two choices- either lower the needles you have 1mm for starters or get a different needle.

See here's the thing... I *think* it pulls ok up top but I can't remember properly how it used to pull in stock form, so I'm not sure if it's right or not...

As for the needle, well, until I get those mains sorted I don't want to touch it... my greatest fear is too lean and too hot and a hole in a piston... yes I'm a touch paranoid...

And it does bog just off idle too...

Don't stress, I shall get it tuned... eventually