1985 Nighthawk cb700sc mild resto.

wahvtec

Member
Thanks, I'll give it a try. A few spots catch my fingernail, and fail the penny test (leaves copper behind when streaked). Ill give it a whirl and retest. I need to make sure it is still round as well once I get the caliper. Two sides are worse, likely the points where the knocking occured.
 

wahvtec

Member
So I went to work and got a caliper. I decided to measure the journal for roundness. Upon setting the caliper and carefully rotating I watched the needle move, then took measurements at the two extremes. I'm getting a 0.035" difference in roundness. This seems like quite a bit. Having trouble finding a service limit for this particular measurement
 

DohcBikes

Fuck You.
wahvtec said:
So I went to work and got a caliper. I decided to measure the journal for roundness. Upon setting the caliper and carefully rotating I watched the needle move, then took measurements at the two extremes. I'm getting a 0.035" difference in roundness. This seems like quite a bit. Having trouble finding a service limit for this particular measurement
go on ebay and buy a crank. You don't understand theprocess

fckn drunk so don't mind me

what's the measurement of the journal dude

bearingmaterial
 

wahvtec

Member
I get what you mean. Im sure the material left from the bearings makes the measurements useless. I have the emery paper and wd-40 ready for some wet sanding in the morning. Yeah im already browsing ebay for a crank haha
 

cxman

Active Member
you will need one rod at least as well as the crank

the cap you showed in the picture with the rod bearings has been damaged by the bearing moving around

i would not reuse it without resizing it as a new bearing could spin from not being held properly

make sure you chec the oil pump over and the pressure relief valve as well

also check the oil filter bypass valve for being stuck open
 

wahvtec

Member
Thanks cxman good tips. I already cleaned the oil screens etc and it wasnt pretty. One major concern I have is how the heck to clean the oil cooler and frame tubes to get any contamination of metal out. This is one of the weird ones where the oil flows through the frame, and an oil cooler bolted to it. Getting a rod is no problem if I have to get a crank I'll likely buy one with the rods still attached just to have extras.
 

DohcBikes

Fuck You.
I might catch flak for even asking but are there any radiator shops in your area? They can clean that cooler. I like what I'm hearing, sounds like you might be in It to win it. Cxman is probably right about the rod. I think the crank will be fine. Should be using a mic not a caliper but there is bearing clearance for slight irregularities. I suggest polishing that journal then measuring again. If you don't like what you see find another but be sure to measure it too ;)

Since that engine might have died from oil starvation you should measure everything.
 

DohcBikes

Fuck You.
Also does your engine have hydraulic lifters? if so you will want to see if they are damaged or collapsed and stuck.
 

teazer

Active Member
DTT BOTM WINNER
Be careful with the wet and dry. You might try some Muriatic acid and see if that will remove the bearing material from the journal. You can buy it at a Pool supplies store and get eye protection and rubber gloves and try not to spill it. Pour a small amount into the cap off the acid bottle or other small container and use a cotton bud to wipe the acid on the journal.

Muriatic acid will dissolve any aluminum and if left too long will also damage the iron. We use it to remove piston material from the bores of a seized motor. Often that's enough to get a race bike back into service if it was caught early enough as it tightened up. Works on Nicasil bores and iron bores with careful application.

It's cheap enough to try and won't hurt the crank as long as you don't leave it soaking in the stuff.

I suspect that the rod will be out of round and the crank may be scratched and possibly out of round. If that's the case an ebay crank and rods might be a cost effective solution. If not you need to find a crank specialist.
 

wahvtec

Member
Thanks for all the info guys. I know I'm surpassing my budget, but after some reading and thought I'm going to learn as much as I can from this project even if it adds a lot to the timeline. I believe there is an old radiator repair shop in the area, I'll give them a call. A newer nighthawk 750 oil cooler also fits and bypasses the frame tubes. They are cheap with hoses so that's a backup. I think for now I'm going to work on getting a decent mic since a lot of measurement is in my future. I work with scientist with little to no mechanical understanding and they ruined the caliper it appears :mad:. I do plan to polish, and remove the material and remeasure with a better tool. Good tip on the muratic acid, I read that a few times elsewhere but it just made me a little nervous of rusting surrounding steel. It is hydraulic tappets and I purchased the bleeder tool early on thinking that was the problem. The manual says to inspect and bleed whenever the cams are removed, so that'll be done once the head gets pulled. Today I'm going to take a breather and go do some target shooting :D
 

cxman

Active Member
a caliper is to crude you need a micrometer and a inside mic

or just take them to a local machine shop they will measure them and tell you
 

wahvtec

Member
cxman said:
a caliper is to crude you need a micrometer and a inside mic

or just take them to a local machine shop they will measure them and tell you
Yeah they are tools i would like to have, im ditching the caliper and looking for mics that fits the bill at a reasonable price. This isnt the first time i've needed them. Thayll be my next purchase this week hopefully

Machine shops are pretty sparse lol im in a remote town in georgia that originated the song statesboro blues haha
 

wahvtec

Member
Well just an update. I've been putting a lot of time toward working/applying for my next job, and interviewing. Finally found some time to tinker. Main reason for the update is to state that the project isn't dead. Since the crank has to come out I'm pulling the cams tonight. Hoping the results of oil starvation didn't hurt the top end. What do you guys think of the wear on the cam/bearing? Thanks in advance.
 

Attachments

wahvtec

Member
Updated to more soberly taken pictures. Just showing the worst of the bearing surfaces which is the end bearings. All of the end bearings were similar, other surfaces untouched.
 
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