Jet kit?

[Chewtoy]

Am noticing that the bike is down on power in mid-rpm steady throttle - around 5,500 RPM in 6th. Seems like if the wind blows or I hit a cigarette butt, the bike is really sensitive to it - it seems like there is not much torque there. Opening the throttle solves that, but since I want to typically stay below 100 on my way to work, am wondering if one of the jet kits would help here.

I also read somewhere that these bikes like to eat exhaust valves, which could be related to a lean condition. that and not adjusting the valves.

The bike is due to go into the shop for a valve adjust and tune, so I was thinking of a jet kit at the same time. Any suggestions?

Thanks.

[ptxyz]

some bike particulars will be helpful here but, let's assume an early (97-98) with stock pipes and not unreasonably high miles (under 30k?).

i'd think you'd only get the full benefit of a jet kit with aftermarket pipes. while a properly installed & tuned kit will help with throttle response, there's not much new power to be had with a jet kit alone.

if you're bike's otherwise stock and you don't want to break the bank, have the carbs synced (as a mater of course, this is done when installing a jet kit as well). with a couple of adjustments each (fuel / air, butterfly stop) on each of the 4 carbs, there's plenty to optimize here.

my old '97 was happiest right after a carb sync. if i recal, i traded her at around somewhere over 40k and the valve clearances were still within spec.

[BearXX]

I put a kit in my old 97. Fixed the problem

And it got a bit more power too

[Chewtoy]

some bike particulars will be helpful here but, let's assume an early (97-98) with stock pipes and not unreasonably high miles (under 30k?).

i'd think you'd only get the full benefit of a jet kit with aftermarket pipes. while a properly installed & tuned kit will help with throttle response, there's not much new power to be had with a jet kit alone.

if you're bike's otherwise stock and you don't want to break the bank, have the carbs synced (as a mater of course, this is done when installing a jet kit as well). with a couple of adjustments each (fuel / air, butterfly stop) on each of the 4 carbs, there's plenty to optimize here.

my old '97 was happiest right after a carb sync. if i recal, i traded her at around somewhere over 40k and the valve clearances were still within spec.

You are correct, it's a '97 just under 30k w/stock everything. not looking for more power, just better drivability. From what I see, a dynojet phase 1 kit will do.

Pipes are probably not in the bike's future. Being quiet has kept me ticket free (knock on wood) for the last 3 years of lurid and illegal speeds daily.

But I'm not married to dynojet. If anyone has a better idea, sing out.

Thanks!

And Thanks Bear!

[brianmacza]

My '97 is on ~190,000km now and at the last valve check (at 160,000km) everything was still within tolerances.

Sounds a bit like the infamous 5500RPM flat spot to me... I cured it by installing a K&N air filter and a set of slipons but kept the stock jetting. The 16 tooth front sprocket also makes a huge impact, and my '97 romps away from my son's '02 XX quite happily - he has stock airfilter and a Yoshi 4into1 but no power commander yet.

Have you tried running a fuel system cleaner thru the tank yet? I do that pretty much monthly, and it makes a noticeable difference if I skip it for a couple months. Clean jets seem to work better for some crazy reason....

[Chewtoy]

My '97 is on ~190,000km now and at the last valve check (at 160,000km) everything was still within tolerances.

Sounds a bit like the infamous 5500RPM flat spot to me... I cured it by installing a K&N air filter and a set of slipons but kept the stock jetting. The 16 tooth front sprocket also makes a huge impact, and my '97 romps away from my son's '02 XX quite happily - he has stock airfilter and a Yoshi 4into1 but no power commander yet.

Have you tried running a fuel system cleaner thru the tank yet? I do that pretty much monthly, and it makes a noticeable difference if I skip it for a couple months. Clean jets seem to work better for some crazy reason....

Cool. I'll grab some fuel cleaner and give it a go.

[blackhawkxx]

Am noticing that the bike is down on power in mid-rpm steady throttle - around 5,500 RPM in 6th.

If your bike was OK before and down on power now, you shouldn't be looking at a jet kit but finding the problem. I have a Dyno Jet kit in my 97 and it works perfect but without finding your troubles first, you will be chasing your tail.

[Chewtoy]

Am noticing that the bike is down on power in mid-rpm steady throttle - around 5,500 RPM in 6th.

If your bike was OK before and down on power now, you shouldn't be looking at a jet kit but finding the problem. I have a Dyno Jet kit in my 97 and it works perfect but without finding your troubles first, you will be chasing your tail.

I think it was always this way, just decided to do something about it. Had the bike tuned by my local shop when I first assembled it 3 yrs ago, and had the carbs disassembled and ultrasonically cleaned @ that time as well.

[blackhawkxx]

There is a slight flat spot from the factory on the 97. Even remember reading about it in Motorcyclist magazine when it came out. A jet kit will help the flat spot if tuned well.

[Chewtoy]

Okay, got the Factory Pro jet kit b/c it did not require drilling of the slides.

Doing one thing at a time, replaced the needles with the ones from the jet kit, if the bike runs the same or better, will move to the mains. Don't expect to go much higher on the mains since I have stock pipes.

I figured out that the new K&N filter is flowing more air, and is making the flat spot more pronounced. Most expensive free part I ever got.

[tomek]

Am noticing that the bike is down on power in mid-rpm steady throttle - around 5,500 RPM in 6th. Seems like if the wind blows or I hit a cigarette butt, the bike is really sensitive to it - it seems like there is not much torque there. Opening the throttle solves that

It seems your problems are not related to mains and /or the needle height . Mixture at steady , cruising rpm is controlled mainly by the pilot circle . If the jet kit does not have new idle fuel jets open the "idle" screw by 1/4 and go from there .

[Chewtoy]

Am noticing that the bike is down on power in mid-rpm steady throttle - around 5,500 RPM in 6th. Seems like if the wind blows or I hit a cigarette butt, the bike is really sensitive to it - it seems like there is not much torque there. Opening the throttle solves that

It seems your problems are not related to mains and /or the needle height . Mixture at steady , cruising rpm is controlled mainly by the pilot circle . If the jet kit does not have new idle fuel jets open the "idle" screw by 1/4 and go from there .

I hear you, but before I read your reply, had placed the factory Pro needles in the slides in the 2nd position. Had a run on Sunday, and the flat spot is reduced, but not eliminated.

Will have at it again next Saturday. The bike honestly feels a bit tentative from 5-7k, thinking that K&N just flows more air than the stock air filter. May go up 1 size on the mains.

One other thing, got a set of JIS screwdrivers from Amazon. What a difference from US Phillips bits! Made the job much, much easier.

[Desert Goat Herder]

Did you adj the mixture screws? You might want to move the needle clips to the third groove (raise needle). Did you replace the slide springs? I found with the dynojet or k&N jet kit (not sure which one is installed as it was in the bike when I bought it) I needed to use the stock springs instead of the kit springs. Check to make sure the tank vent isn't plugged. I had that problem on my 98 and it left me walking with a 1/4 of a tank though it acted like it was out of gas.