Topic: Hmm my Dad's CB1000 Custom

[uptworedline]

I'd really like to help out my dad with his bike, but there's a problem I can't find.

Well the bike is an '83 CB1000 Custom. The bike is in primo condition, but at about 10% throttle (while in gear), the bike will hesitate. Once you give it more throttle, or when the RPM's go up, the bike smooths out and rides fine. It is only hesitating with a little bit of throttle. Any pointers on where to start? coils? jets? Does the bike have points? I'm alright with old hondas, tinkered around with a few before.

TIA!

[TwoTired]

Start with a tuneup and air filter replacement.

If it has an accelerator pump, look there.


I never worked on that bike though....

[TomC]

Hi Uptworedline
     There is an accelerator pump. Which is plumbed to four very little outlets. A set up designed in heaven for old gas to clog up.
     <WWW.CB750C.COM> is a web site for these bikes. You can down load a manual for your fathers bike there. If you have a fast internet connection.
     I am helping a friend get one running.
          TomC in Ohio

[uptworedline]

thanks guys. i remember my old 78 cb750 had an accelerator on like the 2nd or 3rd carb, just left it on when i rebuilt them. i'll have to check to see if his bike has one, i thought i took a peek, but might not have looked hard enought. if it is that, then i'm sure i'll have a good 'ol time gettin those carbs out.

[uptworedline]

anybody else have any ideas?

[Aaron J Williams]

From your description I would say it is hesitating right when the carbs are making the transition from the idle system to the main metering system. Cleaning the idle jets should solve the problem.

[uptworedline]

From your description I would say it is hesitating right when the carbs are making the transition from the idle system to the main metering system. Cleaning the idle jets should solve the problem.

thanks, I'll have to take a look at those with him.

[ofreen]

Has it been sitting until recently?  If so, maybe all you need to do is run a couple of tankfuls of gas through it. 

[Green550F]

don't forget to check the emulsifier tubes above the jets! They like to build up crap too which will make for odd running.

[dusterdude]

you can run some seafoam through it and see if that helps

[uptworedline]

it has been sitting till recently, and we've run a few tanks of gas. i'll check those other things too, and perhaps run some sea foam through it. ty

[uptworedline]

Hi guys,

Where can I find a set of forks for a 1983 CB1000 Custom? My dad's has a leaky fork seal and while replacing them is an option, replacing the forks would be much easier. Thanks in advance!

[Alan F.]

yup, definitely try seafoam or some type of fuel system cleaner. check the Tarozzi fork tubes document located in the link in my signature line for forks that used the same tubes as this bike. Perhaps CB900-CB1000-CB1100 as well as some CBX models may have forks that are directly compatible.

The web site www.motogrid.com has a feature where you can search the parts fiche for a specific part number....then enter that number into a search box to find out "what other machines use this part" (or some similar wording) if you find a match for fork tubes and a few brake components, front axle and maybe even a lower triple tree....you've found your donor bike. Then its off to search eBay, craigslist, swapmeets, friends' garages......

Cheers and good luck.
Alan

[kirkn]

Eh.  I've never once had good luck with the Seafoam / fuel additive route to clean up a set of gimpy carbs.

Get the manual, pull the carbs  (and it isn't rocket science, nor difficult unless you start to skip steps, as in "aww, I don't REALLY need to remove the battery to allow the airbox to slide back..."), rebuild 'em one by one.  By rebuild, I mean disassemble them one-at-a-time down to parade rest, dunk the bodies in Simple Green for ~30 minutes, dunk the parts same way.  Use compressed air to blow through EVERY passage cast in the carb body.  Confirm that air blows out EVERY opening from EVERY passage.  Reassemble.  Sync them on the bench as best you can by eye.

Reinstall.

Simple if you take it step by step, and stay organized!  And, other than the compressor, no real specialty tools are required.


Ditto the fork seals.  It's just a lot of unbolting and then re-bolting stuff back on.  If you REALLY don't want to do 'em, at the very least, take the fork legs off and drop 'em off at a shop to replace the seals.  It'll be cheaper and less hassle than shopping around for a new set of forks...

Just my two cents.

Good luck with it, whichever route you choose! 

Kirk

[uptworedline]

sorry to bump a post from 2 years ago ^^for you that didn't notice.

I'm now looking for a set of forks? read 3 posts back

[kirkn]

Gotcha.

ebay or any on-line salvage yards.  Also, craigslist national search engines can turn up folks that are parting 'em out.

Google "CB1000 forks" and see what ya get...

Good luck,

Kirk

[uptworedline]

thanks kirk I appreciate the help. have you ever had any experience in replacing fork seals? I could probably do it, but chances are I wouldn't do it right, even with reading a tutorial or something. plus you need a special tool that you can actually make with PVC or something.

[kirkn]

Yep, I've done it a few times on different bikes.

You need some kind of impact tool (hammer impact driver, electric impact wrench or pneumatic impact wrench with an allen wrench bit) to loosen the damper rod bolt, because if you just use an allen wrench, it'll just spin and spin, and it's difficult/impossible to hold the damper rod still.

The seal driver is the part made from PVC.  That's how I've done it - just find a piece of heavy-wall PVC pipe at Home Depot or Lowes that's close to the ID/OD of the seal.  Put the seal in the freezer for a few hours prior to install to shrink it a bit, and the seal taps in just fine.  Actually, if the PVC ID is too small but the OD is right, you can just cut a slit down the length of the PVC and 'open it up' over the fork tube.  Works great.

In fact, I'm just getting ready to do the job on my ancient Honda SL125 forks that have been leaking for a while now.  The new seals (ebay) just showed up a day or two ago.

Good luck,

Kirk