A few questions 2003 750

[Fastymz]

I have my 2003 750 for about 3 weeks now. I just back into ride too. I can work on cars no problem, but had a few questions about the bike.
Do all Katana's idle a little erratic I mean from 900-1000 or so. Also at idle there is like a rattling noise I can't find where it's coming from.
The seems a little weak below 5000 rpm normal?

Thanks I new here so I hope you guys understand all the questions.

[wicked1z]

My 99 has a good steady idle. I am sure that these good people here can help you with your problems. They are some of the friendliest people on the net. I also have a little rattle coming from mine but mine is coming from a faring that has a busted peice where a bolt is supposed to go. Try putting your had on all the plastics to make sure it is not coming from something loose

[scottynoface]

1.) Your idle is a little low. Bump it up and it should smooth out.

2.) The rattling can be a number of things, fairing bolts windscreen dash mirrors keys etc...the key is to start grabbing things when you hear the rattle and note when it stops.

3.) Weak below 5000rpms is relative, but yes, most I-4 motorycle engines suffer from low power in low revs. As long as it's not bogging, that's not normal.

[Kapp555]

I just sold my 03 750. The idle is definitely not normal. Mine idled perfectly even. I had mine set right about 1150 rpms. It was solid like a rock. Check your air filter and clean it, make sure the boots around the carbs are not cracked or loose ( a likely cause). Finally, check for a vacuum leak.

If you just got the bike take the time to pull off the plastics (its a pain) and remove the tank and go around and check and torque all your bolts. I do this with everything I buy. It is amazing what all you will find and you will likely find whats giving you the vibes.

[gobigorange189]

1.) Your idle is a little low. Bump it up and it should smooth out.

2.) The rattling can be a number of things, fairing bolts windscreen dash mirrors keys etc...the key is to start grabbing things when you hear the rattle and note when it stops.

3.) Weak below 5000rpms is relative, but yes, most I-4 motorycle engines suffer from low power in low revs. As long as it's not bogging, that's not normal.

ditto everything he said

[The CyberPoet]

Do all Katana's idle a little erratic I mean from 900-1000 or so.

(A) If it moves from 900 cold to 1000 warm, it's set too low. Your idle should be set to 1250 on 98+ Kats (1350 on the California models). Turn the idle adjuster, which is by where your left knee sits when you're on the bike.

(B) If you're saying it bumps up and down at warm idle (doesn't find a steady idle, needle fluctuates across a specific range), that's indicative of a need for a valve adjustment and/or a carb sync procedure.

Also at idle there is like a rattling noise I can't find where it's coming from.

Could be the valve adjustment, the cam chain, or just regular noise (since there are no water jackets to help absorb the sound, the kats tend to be louder than water-cooled-engine-based bikes).
How do you tell the difference?
You do the valve adjustment, the carb sync procedure, and now that you know those are good, you leave it at idle and listen -- if it sounds just like a singer sewing machine, the cam tensioner spring needs to be replaced. If it doesn't sound literally just like a sewing machine, it's normal, or something else on the bike vibrating in harmony with the engine...

The seems a little weak below 5000 rpm normal

Yes, esp. below 4k. The primary power-band of the bike is 7200 - 9450 RPM, and it's actually "lugging" below about 3500 RPM, because it's an engine designed to take very small displacement cylinders & pistons and spin them very fast.

Cheers
=-= The CyberPoet

[Fastymz]

Thanks for the help!
I'll bump the idle to 1200 and see what happens. Yeah the motor seems noisy to me but I still get used a bike again.
As for the low rpm power issue, I just got ride of my 65 mustang had 400 pounds of torque and a 200hp shot of nitrous it made all it's power down low. So I think I just need to get over it and rev the bike like it was made to do.