What is typical on freeway

Hi Guys, I have a 1980 kz650 f1 all stock. I finally got new tires on it so I took it out on the freeway. I noticed it doesn't have much get up when I open the throttle in 5th gear. So if I want to get going and pass someone I have to shift down to 4th. I'm talking 70 to 80 mph. 4th gear is about 10mph per 1000k rpm so running 80mph in 4th puts me at 8000rpm and I don't like to have the engine rapped up that much. Will it hurt it to run it there? On the highways, 50 to 60mph I have to shift down too but I figured that was because I am lower on the RPMs and out of the power band. I'm running 16/40 for sprockets. Is this typical for the 650? Is that why everyone likes to mod the bike? Is this where the pods and rejetting would help? Thanks to all!

My 77 KZ650C1 is currently running a K&N filter in stock airbox and essentially a straight pipe. Pretty much stock otherwise (I've played with the sprockets and finally just decided stock was a good place for my daily riding.

That brings me at exactly 5k at 70mph in 5th. I really feel the powerband kick in around 3k and I can still feel it at 5k. Going from 70 to 100 feels like it would happen without my even realizing it. If I give her a nudge her on the freeway, she wakes up and I hold on.

How is your bike otherwise? Have you checked that you're where you need to be on your carbs and plugs? Maybe you're missing under load...? although I expect you'd probably notice that so *shrug*

I have done it all by the "sounds about right there" technique. I cleaned the carbs,, new gaskets, new carb boots to the air box. After cleaning I read another post where WG talked about even though they look clean they may not be. I replaced the fuel lines. Rebuilt the petcock. New chain and sprockets, New tires, new fork seals. Had the seat recovered. New spark plugs. I checked the MPG cause a few years ago it was in the low 20's but now depending on the ride is 35 to 50 range. Sounds like I have a bit more work to do so the power will be there like yours. More dollars and more time. I haven't tried to read the plugs. not sure what I would do if I did. Since it is stock that all should be right shouldn't it? I think the mains were like 97.5, bad memory. I don't have a timing light so I'm not sure on the timing. I don't have a repair manual either so not sure where the timing should be. I don't have a manometer so I'm not sure about the carbs being synched, probably aren't. Though my bike is running much better now I know it has more room for improvement. Thanks for the reply. More money, more time= more power. Less money, less time = happier wife. What to do?

Post edited by: aarons80kz650, at: 2007/07/27 00:32

I'm feeling kinda lazy. Where are you in relation to I-90?

I did my undergraduate in electromechanical engineering so gear-head, I'm certainly not...but I'm heading that way in a couple of weeks and what limited knowledge I have, I'd be happy to toss your way.

My mileage is ranging about upper 40's, lower 50's so I'd expect you're probably about right but I've got a timing light, home made manometer, compression gauge, etc that you're welcome to use while I'm in the area to check things out. Girlfriend has a sister in the area she wants to stop by to see.

I'm in Seattle and heading to Boston...oh damn, am I ready for this.....I don't know, don't ask.....

Regarding the plugs, if you look up "plug" and "chop" on most sites you'll find reference to running relatively clean plugs under load for a good distance (mile or two) and killing the engine. When I've done it, I've run Tess at around 6k, hard, on a nice straight for a couple of miles..hit the kill switch and pulled the plugs to see where they were. Then later, run it at idle for about 5 minutes and killed it again. Checked the plugs. See where they were. (I have a colourtune I used on my old XS650 which I love but most people don't have/know/trust/etc) which I think is a good judge of idle but the plugs will tell the tale...


I guess what my verbose rambling is getting at is...when did you change your plugs and what do they look like?

I'm 8 miles north of I-90 from Post Falls, 12 from Coeur d'Alene

Why pull the plugs hot? I have read this before, just wondering. I'm too tired to go out for a run now, its about 2:40am so I just pulled the plugs cold. I was suprised at what I saw. They were changed a few months ago when I started trying to get the bike running after sitting for aobut 3 years. Before cleaning the carbs. They have about 300 miles on them of varied riding, stop and go, highway, putting around the lake. left to right 1234

UhuUUUoo this is where it all begins you pull the plugs cause someone here tells you to. On top of that one of your plugs is darker then the other.
My friend by the time we get done with you you will have a bike that runs like a raped date and a wife that hates you...........r motorcycle.:evil: :whistle:

Well I can tell you from experience these things are a process to tune. I have a 77 650B. Before me going this site my plugs looked EXACTLY like yours, and yes you need to clean your carbs, set the floats, and rejet.
WG is probobly the best person to get info on carbs.
Do you experience any poping noise out the carbs? Can you idle for a long time without giving it throttle?

OHH yeh I would get rid of those resistor plugs if you have the caps on your wires. B7ES is a good non resistor plug.

from the looks of the plugs you have one of them that is fouled out, it could be ignition, or fuel related, I would put a new set of plugs in and see what they look like after a ride.
Check the plug wires to make sure they are good, as stated you need to run the compression check and timing, also check the valves, just a full tune up then see what it runs like

Aaron, Since my name has been brought up a couple times in this thread, I guess I need to say something...

Your plugs don't look horrible but you need to spend a couple bucks on tools and get over it... if you want to ride a 30 year old bike, you just have to do some maintenance. Buy the manometer and buy the compression gauge. A compression gauge is fairly inexpensive. Then buy the manual you need. A manometer, a compression gauge and a Clymer manual will go about $100 total. You need them to do basic tune up and maintenance.

Then tune the bike up. Stop using resistor spark plugs. Use regular gas. Clean your air filter. See the coil repowering article under wg's Tech Stuff Index on our website. I suspect there is nothing wrong with your bike or carbs a little attention wouldn't fix. As for the original question... the power break up at higher rpms. this is very likely an ignition problem issue; wires? caps? coils? You didn't mention if you had points/condensor or an electronic ignition but if you have points/condensors, get rid of them and get an electronic ignition or at least tune them. Oh yeah, buy a timing light and check the timing... ooops, tell the missus that it is my fault you spent over $100 on tools hehe

aarons80kz650 wrote:

Less money, less time = happier wife. What to do?

I wouldn't know

but if I WERE to come up with something, it would be to get a couple bucks cash back at the store each time...maybe take a couple of twenties here and there from your paychecks before anybody notices and stow it away somewhere. Then put it into a prepaid credit card and make your purchases from there.

You have a good hiding place, right? for your purchases? Get out of bed when she's asleep (you've perfected the cuddle-rollover to get your arm out from under her, right?) and do your work. She'll probably not notice new parts or tools if you give them some grease and weather. You've had them for a while, right?

You know, just some thoughts....

That one spark plug shouldn't be 100$. The visual i'm getting here is a spark plug with a compression gauge screwed onto one end and a manometer onto the other end.

Take the dark plug and put it into another cylinder and see if the clean plug gets dark. As posted above, check your spark plug leads for loose,split ends where they screw into the coils/plug caps......a can of Chemtool B12 might help with gunk in your carbs....chris3

Ok, new plugs, non resistor type b7es. Ran 1 mile for warm up then ran 3.5miles at about 6k rpm in 3rd gear about 52mph. Turned around and ran back another 3.5 miles killed the engine and coasted to a stop. left to right 1234.

4 still looks a little wet.
As for how long it will idle without gassing it? I let it idle after this test and it idled 3 minutes before I got board and killed it.