1999 Winter Rebuild

I like kill-free.

 

It is a cold wet spring day here so a good day to finish the rebuild on the front forks
I was surprised at the condition of the internal components considering the totally blown forks seals and trashed front wheel bearings
While I had them apart I replaced parts that really did not need to be replaced but I want to do this once, attached is an image of the old bushings after I believe is 30,000 miles, I could find a couple of scratches but that was it


I guess I will pack rat them away in case I need a quick fix in the future
At this point I have finally decided that since everything is new inside I should install a set of fork springs and be done with it
It has been many years since I have tried to setup a set of forks for the track let alone for the street, my choices up here are not that great and have decided to go with a set of Race Tech springs, I had progressive springs in the race bike 25 years ago and thought I would try the straight rate spring on a street bike since I found the progressive spring just ok for feed back. I went to the Race Tech site and if I set the spring calculator for Intermediate /B Class it gives me a 0.94 kg /mm spring, and with a Novice /C Class setting it gives me a 0.91 kg/mm spring, not sure what the differences are between the two levels of rider but I figure I am safe with the intermediate
I have got some feedback from some of you guys and was informed that the race Tech spring calculator readings are a little on the stiff side, so based on that if it sounds right I will go for a set of 0.90 kg/mm fork springs
As far as fork oil weight I guess I will go with Race Tech's recommendation of 5W, surprised at this as I always used 10W, but that was a long time ago.
Have you guys found the recommended fork oil level of 120mm right?
As well as the factory spacer length correct?
So guys does this all sound right or should I change the spring rate? or fork oil weight?, spacer length?
I should add that the days of me dragging a knee through the grass at the edge of the track are long over and I wanted a setup for cruising or day trips around my province

 

Nice work!

It might be helpful to know your weight w/ or w/out gear.

I'm 160# w/out and 185# with, and I run .9 in the vfrs, and .925 in the track bikes. Straight rate is definitely the way to go. I think that the spacers and fluid level sound okay, but if you're in there...you're going to want to address the terrible damping. 5W is fine. I run 7W, but had to request that over the 5W normally used.

While you may not be dragging your knees in the grass, proper suspension is much safer at any speed.

 

Good eye, I should have included my weight, 190 lbs without any riding gear and I know for sure I will never see the 170lbs I was when racing

 

I'd suggest the .95 instead.

 

bmart always has some good insight on suspension and sees/ experiences what proper suspension can do for you. If you're coming from years of progressive springs and are not expert / aggressive, I think you're gonna be happy with some .090. But everyone is different, and these are just opinions. I'm 185-ish without gear, expert, and depending on the bike/usage, run in the range of .090 to 1.00 on most of my bikes.

I've been pretty happy with the oil height recommendations as a starting point. But I started beginning 5 - 10mm lower. I started calculating how many cc's resulted in 10mm oil height increase. Then after some suspension break in miles, I could add some known cc's of oil to dial in what I wanted. Adding is way easier than removing oil, and I didn't need to remove the springs to measure what oil height I was going to.

Be sure to verify you're pre-load spacer length with your adjustment all the way out.

In any case, it's going to be such a nice improvement.

 

Thanks guys for the input into fork springs it was a great help to hear others thoughts
Last night I finished the refresh on the thermostat housing and hoses, I am still impressed at how Honda puts little dabs of paint on the hoses to help with alignment
It gave me the idea to do the same with the wife's nail polish if I found a hose without a paint mark

 

Had time last night to install the new refurbished set of junk yard front rotors, they took a lot of work but did not turn out too bad
I will say that if you have to replace one or both front rotors at some point that you take the time to remove the factory lock tight material on the rotor bolts, and replace with new lock tight.
I could tell when I went to test fit the rotor on the after market side the rotor bolts would pass over a few rough threads in the hub, I am sure for the original lock tight not being removed and replaced with new lock tight before install. looked like a fast install as the rotor bolt hex heads were distorted a little, probably from not using a good hex head .

 

Looking good. Did you do some light resurfacing on the rotors?

 

The junk yard rotors were rough to look at, I would guess a fork seal leaked on them at some point plus the normal wear living on a CBR600
I started with a 3M pad in the die grinder, lots of brake cleaning fluid and finished with a hand sanding with emery paper 120 grit if I remember right
In the end they measure out at 4.3mm thick and factory is 4.5mm so not much wear really

 

Nice. I recently cleaned up some CBR600F3 rotors that led a dirty life under leaking fork seals too. They were stained BAD. Came out pretty good, but they will likely go on the 92 VFR with a 94 VFR wheel. That bike has some weathering issues anyway, so they will look right at home.

 

I just went through the valve check process and by the looks of it they are all within the factory spec range,
NOT PERFECT, but I am not too keen on pulling the cams for what I will gain. Wish the hell I had a full range set of metric feeler gauges to play with.
Anyway I have a question
In the manuals I have they both refer to having the engine warmed up, pull things apart and than do your compression test.
I am wondering what you guys have found for compression test results if your engine has been sitting for say a couple of months, and is cold when the compression testing was done?
Do you find the cylinders are still in the 165-175 psi range or find the cylinders have a wider psi range?

 

I don't do a lot of compression testing these days, but I'd do it like Honda says to do it:

Warm up the engine.
Stop the engine, then disconnect the spark plug caps and remove the spark plugs.
Insert the compression gauge.
Open the throttle all the way and crank the engine with the starter motor.
Crank the engine until the gauge reading stops rising. The maximum reading is usually reached in 4-7 seconds.

Maybe let the engine cool completely and repeat to see how much of a difference? But warming everything up makes sense as that is where it is designed to operate and take maximum loads.

 

I don't do a lot of compression testing these days, but I'd do it like Honda says to do it:

I should maybe explain why I was trying to get a compression reading when the engine is cold
Before I did the valve clearance check I did a compression test just to see how close the cylinders were to each other
Round# 1
Cyl #1 = 170 psi
Cyl #3 = 140 psi
Cyl #2 = 120 psi
Cyl #4 = 165 psi

Round# 2
Cyl #1 = 174 psi
Cyl #3 = 160 psi
Cyl #2 = 145 psi
Cyl #4 = 170 psi

So after doing the compression test on the cold and not running motor for a good two months I was hoping that when I did the valve check I was going to find Cyl # 2 had a tight valve and there was leak by.
That was not to be the case, the valves were all within the factory spec range, even tho Cyl # 2 was a little snug on the exhaust side ( 0.0115 " +-)
so to say this is pissing me off a little bit is an under statement, and as you can see the bike is not in any state to be warmed up to do the compression test the correct way





Long story but this is why I was wondering if anyone had some baseline compression numbers on a cold motor etc.
Not sure why Cyl # 2 has given me these two low compression numbers compared to the others so I will give it another go but this time I will rotate the motor over a number of times to get things loosen up and try it again, hope I do not have a bad valve.
Truth be known it will not matter much at this point as I plan to put it back together and drive it this summer, shit like this drive me nuts looking for the issue and solution
Any thoughts out there?

 

Stop thinking like you think and enjoy the bike. Life is short.

 

Pretty much agree with bmart. Watcha gonna do about it? Is there any thing that needs to be done? Doubt it. You haven't really done the compression test yet. And just look at the difference just from RD 1 to 2?

Bench synch the bodies and get it wrapped up.
Ride the piss out of it and get some heat cycles on your new oil.
Vacuum synch the bodies.
Ride the piss out of it some more, and
Enjoy your sweet, gone thru, VFR.

 

Message received
You guys are right on the money, I guess 40 years of analyzing and trouble shooting engineering designs has given me some bad habits to over think
And you are right about life being too short, last week I had to say good by to a 30 year friend,racing buddy and master engine builder and perfectionist,
Thanks for all the advice and help with this rebuild, the old brain cells were rusty
Look forward to reading about your guys builds and VFR's

 

Just thought I would take a minute to show you guys how the winter rebuild turn out after 8 months in the shop
The matching Corbin bags will get installed once I receive a new replacement left passenger foot peg, but for the most part she is finally mechanically sound once again .

 

Sweet! Great job. Enjoy your effort and work.