Hello from Maryland!

Hey all, I just picked up a 79 KZ650SR from eBay.

My dad had a red 78, and this one is a midnight blue 79, but close enough, right? Gonna relive my childhood!

While I'm here, I've got a quick question. I backed it off the trailer and fired 'er up - started right up. I let her warm up for a couple of minutes, and then when I went to take off, it didn't really want to... how long do you all let your bikes warm up before riding? It was 55 degrees, rainy, and I'm used to the low-end torque of my Vaquero and Vulcan 800, so I may be missing something here. Also, she started without the choke (about 1.5 hours prior the previous owner had started her up on the trailer, so I thought that was OK), and will stay running so long as I didn't let the RPMs fall too low.

I guess a better question is how many RPMs do you all tach your bikes up to before starting to let the clutch out? Like I said, I'm used to riding V-twins, and even had issues with a new Ducati X Diavel I rode on a demo day recently, since you had to give that one the nuts (3-4k RPMs) before letting out the clutch. Bike has just shy of 15,000 miles on 'er.

The bike starts and runs well, and once I got moving, I got all the way to 2nd gear before slowing and pulling a U-turn. I hope to go riding tomorrow (supposed to hit the 60s here on the East Coast). Just want to make sure that (A) there's nothing too wrong with the bike and ( I'm not doing something to break it.

Here's my new-to-me bike!


Thanks!

-John

You may have to clean the carbs. The pilot jets are very small and prone to blocking. A guitar string or a strand from a wire brush is a good cleaning tool. If you have seen my clips you can tell how much is needed to take off. These bikes are docile at low RPM but wake up after 5000 RPM. :woohoo:
Steve

Interesting... the PO said he rode the bike this morning, so I assumed the carbs were plenty clean. He got the bike a few years ago in non-running condition (said it hadn't run in 30+ years), and did a lot of work to it (which you can tell - it's in great shape for a bike this old IMHO). My first thought was that I didn't let it get fully warmed up. If I can't get it to run well tomorrow, I'll start by having the carbs cleaned - I've got a trustworthy mechanic local to me who is fair-priced.

I'm not all that mechanically inclined, but once he gets a bike running well, I can keep it that way.

-John

Check the valves too.
Steve

Have you shined a bright flashlight into the tank. What do you see in the way of rust? How does the bike behave when you are parked with the bike running in neutral and then roll on the throttle? Off idle bogging is often a dirty carbs issue as SWest mentioned. Rusty metal on the inside of the tank would support his (and my) theory. As for people selling old bikes...they say lots of things to get them sold. Often those things aren't true like "Runs perfectly" or "Just had the carbs cleaned and gave it a tune up". Take sellers words with a grain of salt.

OK, I just got back from my maiden voyage - 10 whole miles, including a stop for fuel.

Here's what I know now:

1. The bike takes a while to warm up
2. Once warmed up, it revs freely and runs like a scalded dog
3. Shifts fine, brakes fine, steers fine, all the cables and stuff work great
4. Tank is clean. There are a couple of spots in the center that look like a gas pump filler tapped it, but that's it
5. What a fun ride!
6. Carbs seem just fine, bike pulls strong and has plenty of pep
7. Idle varies between 2k and 3.5k RPMs
8. Clutch is great. Got her into 5th gear, snapped the throttle a little bit, go no slipping

Is #7 above normal, once warmed up, and after riding? I noticed it at stop lights and once I pulled into my driveway. What should I check for on that one?

Also, I plan to have my regular motorcycle mechanic look her over (hopefully this coming weekend) and let me know if anything I haven't noticed is amiss.

Thanks for the quick replies, but this one looks solid, folks

It dang near brought a tear to my eye to be back on a 650SR, after over 20 years without one (like I said, my dad had one when I was growing up, and I have fond memories of sitting on it, pretending to ride, as well as riding as a passenger).

Now, to just keep her running smoothly.

-John

Take the cover of the ignition side and lube the spark advance. It could be sticking.
Steve

Thanks! Will do

-John

Typical idle is between 900 and 1100 rpms. I like mine just a bit high at the 1100 rpm mark. 2K to 3.5K is extremely high. There is a large 'thumb screw' between the upper rear of the 2nd and 3rd carb. That is the idle adjusting screw. You say it takes a long time to warm up. How much time is a long time in minutes? When you say the idle varies, do you mean it wanders around after being at full operating temperature?
EDIT - I just looked at the service manual. The manual calls for 950 to 1050 rpms. Very simple adjustments, no tools required.

ajsfirehawk wrote: Typical idle is between 900 and 1100 rpms. I like mine just a bit high at the 1100 rpm mark. 2K to 3.5K is extremely high. There is a large 'thumb screw' between the upper rear of the 2nd and 3rd carb. That is the idle adjusting screw. You say it takes a long time to warm up. How much time is a long time in minutes? When you say the idle varies, do you mean it wanders around after being at full operating temperature?
EDIT - I just looked at the service manual. The manual calls for 950 to 1050 rpms. Very simple adjustments, no tools required.

Agree! 2k - 3.5k is not idling. If the bike won't idle smoothly at or below 1,100 rpm there's a problem and it needs to be addressed. Ed

Welcome John.
Nice 650SR!


Try the idle adjust as mentioned above, as your idle is a bit high.
Sounds like she is in fairly good running order.

Thanks all ... I believe SWest is right. I didn't have time to look further into it last night, but to better answer y'alls questions, here goes:

1. At 55 degrees, it took about 3 minutes, by my estimation, to warm up to "ride-able" status.
2. The idle before riding is right on the money - around 1k RPMs. It's only after riding that it gets higher, and easing the clutch out at a stoplight reigns it back in, to a point. This is why I think SWest is right about the spark advance sticking.

Further, it looks like someone in the past 38 years put a regular KZ650 tank and seat on this bike, as they do not match my dad's 78 (my mom found a picture).

It does have painted fenders, upgrades brakes, and the VIN has a "D" in it, so I do believe it's an actual SR. Are there any other ways to tell, or differences between the regular 650 and the SR?

-John