The lack of uniformity would indicate the dampeners being bad. The pull up on the handlebars extends the front forks and can show you how much "sink" there is when it's weight is on it and how much more when you are added. The grease line will be at the highest point on the fork tube (or, conversely, the lowest) Good working forks should remain extended (bike on side stand) and not sink when you let go of the bars. Standing the bike upright will cause some sink, adding you on the seat will cause more. Getting off should cause them to extend a small amount. What we're doing is diagnosing condition of the fork assembly. What is has to do with the back is that the bike is supported at both ends. duh Rear suspension fails before the front. If the front is tired, can we expect less from the back? Suspension is the only two week course at a Honda training center. Understanding how it works and how to tweak it is a great education. 30K is a good long life for a stock suspension. The rewards from a rebuild would be well worth the time / money. Most evaluations of Hondas over the years have faulted the rear suspension as being poor from the start. As I am a light rider that has not been the case for me. Here in PA, our roads are a challenge and fork performance is vital. Because I quipped about the bike being supported at both ends, the course I'm suggesting is do both ends at the same time. If you repair the rear, you'll be quite aware of any shortcoming in front. The rear dampener portion is not rebuildable and must be replaced. OEM ? I wouldn't. Call progressive or visit on-line and check what they can do. As I have said, there have been wonderful advancements in many fields. You can easily wind up with a bike in a condition superior to as-new. I love to enhance a Nighthawk, never to compromise one. The 650sc was pretty good when new, I wish I could say as much for some others. The CX500 needed all the help it could get. That bike was just plain soggy. The front end would pogo in corners and dive when stopping. A fully dressed, loaded Wing presents it's own problems. A ton of aftermarket accesories, two overweight riders, couple of cases of beer in the bags... add a trailer too. Can you say "mushy" ? There is a fine line in suspension between soaking up the bumps and great handling. When you get it right, the suspension absorbs the impact and retains control. A bicycle is precise in control but everything is transmitted to the rider. Springs alone can absorb an impact but without dampening, no control. We are fortunate to be able to tune a motorcycle suspension in many ways. It's a great subject and one I enjoy discussing and doing. My suggestion is to replace those rear units. They were toast around 10~20K.
--- On Thu, 11/13/08, Gene Henry <[EMAIL PROTECTED]> wrote: From: Gene Henry <[EMAIL PROTECTED]> Subject: [Nighthawk Lovers] Re: '84 CB650SC - rear shocks To: [email protected] Date: Thursday, November 13, 2008, 3:43 AM 225 lbs. The disconcerting thing is the lack of uniformity. Sometimes it doesn't do it (or it does it smoothly and I don't notice it). Other times I can have all my weight off the bike and leg over the seat when it suddenly rises. How will pulling up on the handlebars affect the rear shock pistons??? Thanks! Gene ----- Original Message ----- From: Dennis Hammerl To: [email protected] Sent: Wednesday, November 12, 2008 8:58 PM Subject: [Nighthawk Lovers] Re: '84 CB650SC - rear shocks Can I ask a delicate question ? Are you a large person ? The springs are just relaxing back to the size the shock will let them go to. 30K is not a lot for the bike but Honda rear suspension is not exemplary. I am a rather light person and for the most part my rear suspension is actually a bit hard. As I don't make it work very hard, I expect it will last a long time. Your rear suspension may be sacked as the Brits say. Progressive makes great replacements, but a bit pricey. As long as you aren't causing the rear end to bottom out, I wouldn't replace them. In case you haven't noticed, the forks do the same thing when you get off. Bike suspension has not changed in it's basic concept for many moons. The spring wrapped around the shock absorber is a nice compact unit. ( on a race car they call it a "coil over") The adjuster on the bottom preloads the spring by changing its captive length. The shock controls the spring's action. Most of the shock's control happens to dampen rebound (how the unit returns to normal after being compressed) This is usually expressed as a percentage; 50-50 being the same dampening in either direction, 60-40 would be 40% compression / 60% rebound. ( I had a drag car that used 90-10 front shocks. The front would rise quickly and almost stay there causing weight transfer to the rear.) Your shocks may be bad after 30K and have poor control over the springs, hence the pop-up when you get off the bike. A cool thing to do is to stand next to your bike and grab the handlebars and pull up as hard as you can. Then smear some heavy grease on the exposed fork tubes. Go for a ride. The grease will be wiped off, up to how much of it's travel you used. At rest, the line should be somewhat above the seal that wiped it. If it sets right on it, consider that some work is in order. Sacked springs. --- On Wed, 11/12/08, Gene Henry <[EMAIL PROTECTED]> wrote: From: Gene Henry <[EMAIL PROTECTED]> Subject: [Nighthawk Lovers] '84 CB650SC - rear shocks To: [email protected] Date: Wednesday, November 12, 2008, 2:03 AM My '84 CB650SC with 30K miles, (I got it at 22 K - $650!) and having been laid down perhaps several times by previous owner(s), has the disconcerting habit of "raising up" on the rear shocks as I dismount. That of course causes it to lean more as it raises, and it feels like it will tip over. Of course it won't, really, but it feels strange. I am assuming the rear shock(s) need attention, but because of the coil springs, nothing can be observed. Has anyone else had this problem, and if so, what was the cure? Thoughts, Dennis? anyone? Also, there is a "whine" somewhere - transmission? final drive? - most pronounced when decelerating. Any ideas here? Running Amzoil 90 in final drive, Mobil 1 synthetic in engine. I have done the carbs (plugged low speed fuel passages) new battery, new front tire, front fork leaking on one side (winter repair job). It is a "late in life (I'm 72) addition, and I love to ride it. I am constantly amazed at the good condition of 25 year old parts - especially rubber and plastic - that are still good! Honda, you did one hell of a job in designing and building! It'll outrun a $18,000 Hardly 1200+cc and a BMW ($10,000) 1300+cc. Until I chicken out (make that old injuries triumph over testosterone). Gene --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en -~----------~----~----~----~------~----~------~--~---
