1982 CB750F...Better Devil

pidjones

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Jimbonaut said:
O’rielly? Who what where?


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My local O'Reilly auto parts (chain store). Many auto parts dealers have a brake rotor lathe.
 

doc_rot

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There is also True Disk, they grind rotors instead of cutting them which they claim is better. They can also drill holes in your disk. Ive had them do several disks for me and they always turn out super nice.

https://truedisk.net/
 

Jimbonaut

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I’ve already been pointed in Tom’s direction at True Disk and I’m waiting for a quote, thing is I’m in Canada and the shipping will be a total drag. Think I may have found someone local though but the more options the better.

I was planning on pulling the rubber off the comstars are repainting them but underneath all the crud they’re actually in pretty decent knick. The aluminium could use a bit of a spruce up - is there any kind of clear coat on comstar aluminium rims or can I just sand out any scuffs?


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pidjones

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Don't know about the reverse Comstars. The ones on my '78 GL1000 cleaned up nicely with scotchbrite and other assorted light abrasives. I painted them with Duplicolor black wheel paint followed by clear gloss. Still lookjng good a couple years (but only ~500 miles and a tire change) later. Took about eight hours each to clean up.

You might try Canada Tire for rotor turning.
 

Jimbonaut

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True Disk comes highly recommended but unfortunately the shipping is going to be that plan's undoing. Hopefully I've found someone local that can resurface them.

Yeah, I was looking at scotchbrite or some steel wool, just not sure if there's any clear coat on the ally. I guess the way to find out is rub some Autosol on there - if it doesn't go black then there's clear coat ?
 

pidjones

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Avoid the steel wool (unless it is SS wool) on aluminum. It will leave particles that later rust. Honda is bad about not coating aluminum wheels. GL1800s are a bear to keep looking good. I had mine powder coated.
 

Jimbonaut

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Gotcha - no steel wool on the aluminium. Very good to know. I may end up pulling the tires off after all and bead blast the aluminium parts to remove the clear (which apparently these comstars have) but I'd rather not strip the paint - I think it's anodized on there so if I can keep it so much the better. The black is in pretty decent shape.

This showed up when I got home from the pub last night -



It's a shift detent star made by Vince and Hyde Racing in NZ, who design a bunch of mods and performance parts for the F series of CB 750's, 900's and 1100's. The star's custom profile allows for smoother shifting and is a pretty straightforward job to install, especially with the clutch basket already removed.

Apparently.
 

Jimbonaut

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I'm also looking into this mod to replace the clutch dampers inside the hub -

https://www.vintagecb750.com/parts/instructions/73-1131.pdf

I had no idea these dampers were even in there, they don't show up on any parts fiche or in the manuals because they were never designed to be removed or replaced by Honda. Like most rubber in 35+ year old engines though they get pretty hard and un-dampy, and replacing them can remove the chatter from your clutch at idle. Anyone done it?
 

doc_rot

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Done it on kz650. it was pretty straight forward. takes an afternoon. made launching the bike much smoother. I drilled the tip of the M6 so when i punched the end it slightly flared out.
 

Jimbonaut

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Detent star installed no drama -



Thought the KLR had been handling a bit sluggish, sure enough had a flat. Season's on countdown now so every day counts. Wheel's off, patch up tomorrow hopefully and then white- and frozen-knuckle it through the last few weeks

 

Jimbonaut

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Borrowed a big ol' bag of shims and got to work on the valve clearances, now that I have switched out the 750 cams for 900 cams. Got pretty close too. Between 0.004 and 0.005" on the intake (with one at 0.003") and 0.004 and 0.005" on the exhaust (with 2 at 0.003)

Need to machine a couple of exhaust shims down 3/1000" and then I'm in pretty decent shape.

 

doc_rot

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Jimbonaut said:
Borrowed a big ol' bag of shims and got to work on the valve clearances, now that I have switched out the 750 cams for 900 cams. Got pretty close too. Between 0.004 and 0.005" on the intake (with one at 0.003") and 0.004 and 0.005" on the exhaust (with 2 at 0.003)

Need to machine a couple of exhaust shims down 3/1000" and then I'm in pretty decent shape.

i would buy the correct shims instead. They are precision ground and hardened and any shop that can accurately grind them will probably charge the same amount as a new shim.
 

cb250nproject

If you can make it better do so
You don't want to be any less than .005 " its better to have too much, than bend a valve. Trust me I'm talking from experience, I think i still have the bent valve out on the work bench.
 

Jimbonaut

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I hear you guys. 0.003” is certainly tight but it’s within spec, on the tight side though for sure. 0.004” is fine, especially on the intake. But yeah, 0.005 on the exhaust would be great.

I know a machine shop here that can accurately machine shims for $10 - I’ll look into buying some too.

Edited to add - nope, you're right. I'll pull the two at 0.003" as well.


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doc_rot

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Are they hardening the shims post machining? case hardened parts have a very thin outer shell. any machining can weaken them and potentially produce catastrophic results. I would buy new shims for peace of mind
 

Jimbonaut

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Checked again with the machine shop and it's a Texas-sized ten four on the hardening. Which is a good thing, as OEM shims are rare as pope shit in these parts.
 

Jimbonaut

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There are, and there's also a supplier here in Canada (vintagecb750.com) that sells them. Not OEM though. Anyone used the non OEM (K&L??) shims? All good? Not all good?
 

pidjones

Well-Known Member
Jimbonaut said:
There are, and there's also a supplier here in Canada (vintagecb750.com) that sells them. Not OEM though. Anyone used the non OEM (K&L??) shims? All good? Not all good?
I think I used two. Didn't have the bike for long after, but they seemed fine.
 

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