Help buying CBR600F3

guvna · 03-19-2007, 10:42 AM

I'm really hoping someone can help me here with this one. I'm about to buy a CBR600F3 1995 model for a really great price, and everything checks out fine as far as both me and a Fireblade riding friend can see.

This is except for the power delivery. I have never ridden a bike like this before, but it seems a bit strangled at low revs, and doesn't respond very well under hard acceleration from low rpm. It seems fine once into the CBR joy zone RPM range.

Its got a nice after market pipe on it, so I'm wondering would this be because its running too rich, or the carbs are not balanced, or something else? Its done 103,000km too. Can anyone help at all?

SoCal94F2 · 03-19-2007, 2:32 PM

It is not uncommon for a bike that sits for a while to have this happen (should this be the case). The fuel evaporates from the carb bowls and leaves a resin like residue on the jets. The mains have a big enough hole in them that they usually remain clear (allowing full power) but the pilot jets and idle jets have very small holes which easily get plugged (idle to midrange). Because the idle adjustement is so readily accessable, it usually gets cranked up to compensate for the lack of those circuits working as well as lets the bike still idle (usually a little fast or eratic, can be hard to start when cold) While its a bit of a PITA to pull the carbs off and remove the bowls, you can pretty easily fix this by running the small wire of a twisty tie (without the paper covering) through the pilot jet hole as well as the idle tubes, verify they are clear then reassemble. While off, check and clear the air vents in front of the carbs too. Be carefull using compressed air as some of those vents go the the rubber diaphrams on the slides and they can burst.

You might also check for rust in the gas tank as that too can plug up those jets.

Triax · 03-19-2007, 2:51 PM

+1, could possibly need a new airfilter or better yet a fuel filter. Most people neglect those two items.

guvna · 03-19-2007, 4:30 PM

That is exactly the situation SoCal, it hasnt been ridden a huge amount and your description of the problem is spot on. I agree that it could quite possibly be a fuel/air filter too.

That helps immensely, as I was a little worried it was a bigger problem. My last bike blew a crankshaft after 3mths and I now have to sell it as i really cant afford the repair bill, and the last thing I needed was to buy another time bomb.

*sinfuldragon* · 03-19-2007, 4:36 PM

while you have the other bike... might be worth it to take it apart and learn a few things. I know if I had a spare bike I would have that baby in pieces learning how to do different things. Just a thought

guvna · 03-20-2007, 9:49 PM

Yes, that is what I am going to do, pull the Eliminator apart and learn something while I save myself two grand

With cleaning the carb jets, is that something that can be achieved by running a jet cleaner like Wynn's or whatever, or not? I am trying to get hold of a service manual that tells me the best way to get to the jets you referred to SoCal.

What do you think?

ohi stopthat · 03-21-2007, 5:45 AM

What did you blow up ? Would it not be cheaper to source a 'used motor' instead of trying to fix it !

guvna · 03-21-2007, 6:37 AM

The guy at Race Replica Kawasaki reckons its the crankshaft. I think thats BS because I would assume that if that was true the bike wouldn't turn over at all, and both cylinders would be affected. BTW its a Kawasaki VN250 Eliminator. The front cylinder is knocking under throttle and the bike will only go about 50Km/h. He quoted me $2600 to repair it, and now the DH is trying to charge me 300 bucks to get it back for 5hrs of alleged work. The only other Kawa dealer here is also completely crap unfortunately (Cosways Melbourne). Moral of story - I'm never buying a Kawasaki again

You know, I think the VN250 has the same engine as the GPX, it may be cheaper it looks like its only about $700 for one...

SoCal94F2 · 03-21-2007, 3:01 PM

Unfortunately, the carbs have to be removed from the bike to do this right - additive just doesnt seem to do it.

You'll need to:
- remove the plastics, (pop rears off + 10 bolts)
- remove the seat (2 bolts)
- remove the tank (2 bolts + fuel, vent and vacuum lines)
- remove the airbox lid and filter (4+ bolts )
- remove the airbox (12 bolts + make a note of all vacuum lines and mark locations - very important)
--- (You will see all the front air bleed jets now on each carb - 3 of them)
- loosen the intake boots at the head (4 screws and small hands)
- pull carbs from head carefully so as not to stretch boots too much (leave throttle cable on)
- drain each bowl of fuel using the small flathead on the bottom of each bowl
- Flip carbs over and remove one bowl at a time (3 phillips screws)
- Remove the two flathead jets and clean, also clear last remaining jetless tube of any resin - then reinstall
- Carefully replace the bowl and repeat for each carb
- Reverse instrcutions to reinstall and your done.

Good luck, I'll keep chacking back on this thread if you have questions.

sheepofblue · 03-21-2007, 3:24 PM

Before I would do a large amount of work I would try cleaner (yes sometimes it does not work) If it does not help you are out about $2 if it does you have saved a lot of labor. Remember that a bottle does a auto tank so don't use a ton of it. Also get the good stuff (OK maybe more than $2) Good luck.

bikerpipes · 03-21-2007, 6:04 PM

I have real good luck with Sea Foam

guvna · 03-21-2007, 7:09 PM

Quote:

Originally Posted by bikerpipes

I have real good luck with Sea Foam

I'm going to check that out, thanks. I agree that it is very possible that it wont work but its worth a try like you say. I saw some STP stuff, so I'll get that if Sea Foam is not available.

Thanks again SoCal, I can follow those directions if the petrol additive does squat which is the likely outcome.

I really appreciate the help, you all have been really helpful

guvna · 06-26-2007, 11:50 PM

UPDATE: I thought I'd update you just incase someone else has this issue.

I ran some Wynn's carb cleaner twice on a full tank, being careful to not over do it. The first dose didnt do a huge amount, but the second seemed to make a difference.

What seemed to make the most difference was when I went for a ride day with some mates, and for about 4hrs I didnt let the bike go below 7 grand, most of the time I was around 8-13,000. I really caned it. It blew what ever crap was in the system clean out the exhaust. Its still not the most powerful in the lower RPM range, but I sort of expect that from a 600 which produces max torque around 12-13,000 RPM or whatever it is.

This bike also had a stutter/skip when around 8000 and above, and I fixed that with a oil change to Motul 5100 10W/50. That was AFTER the above was done. I encorage anyone who does this to change their oil after a couple of treatments, as the crap that it cleans probably ends up in the oil. I assume that some residue from the product may be there too.

I recon that it was the COMBINATION of carb cleaner and a totally pinned right hand.

Hope that helps someone.

Rock on.