[martinlt]

hi all,

i've just put my bike into my local dealer to gave a K&N air filter plus dynojet stage 1 fitted. they've called me this evening to let me know they're having problems setting it up. when set up as per the instructions, bike runs fine up to 3,500rpm then like a dog afters.

anyone done this setup before or have any ideas on what the settings should be? (btw. the bike has a stock exhaust).

as per subject, it's a 2003 gsx600f.

cheers for any help.

 

[87gsxrnut]

1. Never take your stuff to the dealer.
2. You should really be leaving the carbs alone unless you are going to get a slip on or full system. OR, you are going to put it on the dyno, and have it tweaked with the stock setup.

Although I have seen lean conditions do this, It sounds to me as if it is running rich. I have had this problem on several bikes in the past running Mikuni RS-Series carbs.

Long story short, carb tuning w/o a dyno is a very time consuming process. Most dealers won't take the time to do it right. Sounds to me like they don't want to pull the carbs off again. I also wonder if they buttoned up the airbox correctly, and have correct fuel flow into the bike w/no air leaks. I have pulled carbs sometimes 4 or 5 times on a bike to get the tuning sorted out good enough to ride. That is the way of carbs. A dyno will get you in the ballpark much quicker though.

If everything is connected correctly, and it is running OK up to 3,500, then bogging, sounds like you need to drop the needles a clip or two.

If you get into the upper range and it stumbles, or doesn't pull right, then the main jets might need to be swapped. Bigger does not always mean better. Once you get it to rev OK through the rev range, synch the carburetors, then run it on the top-end under load for a bit.

Look at the exhaust, or pull a plug. You should be able to eyeball it if it is a bit lean (gray or whitish exhaust) or rich (black w/more carbon). If you come up w/a light tan, you have it in the ballpark. Of course, that is just what I have observed. Race fuel, among other things changes combustion color characteristics.

Too rich is better than too lean.

Then take it to a dyno and have it tweaked.

Of course, what the heck do I know? :lol: These are some of the things I have used over the years to help me sort carbs out.

Hope this helps somewhat.

- Ross

 

[martinlt]

well, they supposedly do have a dyno at my dealer - at least that's what they told me when i booked it in.

thanks loads for your tips. i'll take these along with me tommorrow morning as i've also found that dynojet have packaged some kits with setup instructions for us models only to european locations. i've managed to print out the intstructions for the european models, so thought i'd cross check that with them too.

once again, thanks for your help & time.

 

[87gsxrnut]

If they have a Dyno, there is absolutely NO reason why that bike shouldn't run perfect when you get it back. That is regardless of the instructions.

This is a very common bike w/a motor that has been in existence in one form or another since 1985. Carbs are very common too. There should be no mystery in the setup here.

I wouldn't imagine the Euro setup is much different from the US, but I guess there could be some pollution stuff on there that might affect it. I wouldn't imagine the pollution stuff is much different than the US California model.

- Ross

 

[martinlt]

so i've got my bike back but...

i seem to have 3 or four decent flat spots, revving out above 8000rpm sounds and feels as if i'm on full choke. all in all, not happy.

i feel like i should get the standard kit /setup put straight back on, and kick my ideas of using the dynojet/K&N setup.

 

[87gsxrnut]

Save your Dynojet until you get a slip-on or a full system. You can still use the K&N filter. You might want to have the stock setup re installed, then tuned on the dyno for now.

To give you an idea of what you need to properly tune carburetors, I have something like 15-sets of main jets, pilot jets and needle shims for my bikes running the RS carbs. The dynojet kits will give you up to three jetting choices in most cases, depending on what type of setup you are running. There are no spares really for tuning.

I personally have never had any problems in setting up the carbs w/Dynojet kits and instructions. I have had them run well too. But, there are other bikes that I had to fix, in situations like yours, that took an extremely long time and a LOT of work to get right.

Like I said, the dealer doesn't want to mess with it, or they are not skilled enough to do it right.

Either way, get a shop manual and a Haynes/Clymer manual for your bike and start learning. You will save yourself a LOT of headaches in the future. You will also find out that the "mechanics" at a lot of bike shops, especially dealers, aren't as good as you once thought.

- Ross

 

[martinlt]

sound advice. thanks. i'll invest in a Haynes too.

btw, i've since found out that whilst my dealer has a dyno, they can't use it as it is lacking a cooling fan!! so after telling me, before i booked in my bike, that they had a dyno it turns out they've set it up by hand.

that's exactly what i was trying to avoid doing myself by putting in to them in the first place. grrr.

 

[87gsxrnut]

Ah ha! I knew something was up. That is total BS. They are a dealer, they can afford a fan. I'd raise total hell, and tell them since they lied about the dyno, they should set your bike back to original specs for FREE.

They should have been up front with you in the first place. Man, I have seen that crap for so many years. I started working on my own bikes back in 1988 for that same reason.

Now, off to ride for a bit!

- Nut