Author Topic: Ill-Advised Super Sport (CB750-F0) (Read 21677 times)

SOHC4 Cafe Racer Fan · « **Reply #25 on:** July 13, 2018, 12:00:54 PM »

I would refresh your cam chain tensioner parts, while you have the motor apart. These rubber bits are 40 years old.

Jessamine · « **Reply #26 on:** July 13, 2018, 04:58:23 PM »

Quote from: SOHC4 Cafe Racer Fan on July 13, 2018, 12:00:54 PM

I would refresh your cam chain tensioner parts, while you have the motor apart. These rubber bits are 40 years old.

Not a bad plan, but I'm gonna try to avoid pulling the head if I can help it. Rubber is on the hard side, but looks like it's otherwise in good condition still.

If the valves are messed up or there's other damage lower down, I'll definitely get the tensioner parts swapped out.

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Jessamine · « **Reply #27 on:** July 13, 2018, 09:00:20 PM »

Pulled open the carbs tonight to inspect; float #1 is obviously set incorrectly, and there was a lot of crusted old fuel collected under the float valve seat. Float valve #2 is a different style than the others, clearly a makeshift replacement. Main jets are all 110, slow jets are all 40.

Seems a little lean compared to jetting I've been reading about here.

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Don R · « **Reply #28 on:** July 13, 2018, 09:51:15 PM »

The loose valves could be bent ones. If the valve head is leaned over (bent) it can't close all the way and that will leave more lash. I'd get some bolts in the cam gear and check compression. If the bolt fell straight in you might be able to roll the engine forward and it could fall out. Not likely but it might. Did the bolts do any damage while backing out?
They only made 75's until may or june and went to 76 production so the 75's are more rare. Honda got sued for re-titling old bikes and lost, going to the 76 model early was a poke in the eye to the US attorneys. They paid me $37 for retitling my "1973" cb500 K2.

Jessamine · « **Reply #29 on:** July 14, 2018, 01:57:31 PM »

Got myself a new tool for cleaning out carbs: a heated ultrasonic cleaner!

I figure beyond my new CB750 I can justify it because I just took on two more bikes for freelance clients that need thorough carb cleaning too-- a CX500D brat and a Batavus HS-50 moped.

Will post before/after shots once I've had a chance to disassemble and run everything through it.

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Jerry Rxman Griffin aka MuthaF'er · « **Reply #30 on:** July 14, 2018, 03:40:11 PM »

Now thats a nice tool!

Stock jets are 105 and 40.

Jessamine · « **Reply #31 on:** July 14, 2018, 03:44:02 PM »

The carbs are coming out great. Sooo much cleaner than just carb cleaner alone gets them.

But I found out one of the slow jets (#3 carb) had a crack in it, so it felt off as I was threading it back in after cleaning. With only a little experimental pressure, it snapped clean in half!! Glad I backed it out right away and it didn't go in the carb body. Add a replacement to the list, I guess!

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calj737 · « **Reply #32 on:** July 14, 2018, 04:38:05 PM »

Make sure you buy Keihin brand jets, not Keysters.

Jessamine · « **Reply #33 on:** July 15, 2018, 01:58:33 PM »

Quote from: calj737 on July 14, 2018, 04:38:05 PM

Make sure you buy Keihin brand jets, not Keysters.

Got an authentic Keihin slow 40 in a cart at DCC. Was considering picking up some other main jets at the same time; 110 seems lean to me (esp with pods) from what I've been reading.

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Jerry Rxman Griffin aka MuthaF'er · « **Reply #34 on:** July 15, 2018, 02:41:43 PM »

Well that's fine IF the other 3 are KeiHin too. Do they have the KeiHin symbol on them?

calj737 · « **Reply #35 on:** July 15, 2018, 03:53:24 PM »

Quote from: Jessamine on July 15, 2018, 01:58:33 PM

Quote from: calj737 on July 14, 2018, 04:38:05 PM
Make sure you buy Keihin brand jets, not Keysters.
Got an authentic Keihin slow 40 in a cart at DCC.

To my knowledge, and through experience, DCC does not sell true Keihin brand jets. They list “Honda Keihin” jets, but Honda isn’t the manufacturer, Keihin is. Also, none of the pictures of the jets in their site show the Keihin trademark on the jet, nor the jet number. Maybe the jets for your F are different, but I would encourage you to look elsewhere for known resellers of Keihin jets. Like here: https://jetsrus.com/a_jet_kit_street/honda_750_CB750F_1978.html

Jessamine · « **Reply #36 on:** July 15, 2018, 07:30:30 PM »

They're listed as "Brand: Keihin" and have a Keihin part number... are you sure? The jets on Jets R Us are about twice the price ($10 for one slow jet). I know there are serious quality issues with Keysters, but are there similar problems that have been reported with jets bought thru DCC?

Quote from: calj737 on July 15, 2018, 03:53:24 PM

Quote from: Jessamine on July 15, 2018, 01:58:33 PM
Quote from: calj737 on July 14, 2018, 04:38:05 PM
Make sure you buy Keihin brand jets, not Keysters.
Got an authentic Keihin slow 40 in a cart at DCC.
To my knowledge, and through experience, DCC does not sell true Keihin brand jets. They list “Honda Keihin” jets, but Honda isn’t the manufacturer, Keihin is. Also, none of the pictures of the jets in their site show the Keihin trademark on the jet, nor the jet number. Maybe the jets for your F are different, but I would encourage you to look elsewhere for known resellers of Keihin jets. Like here: https://jetsrus.com/a_jet_kit_street/honda_750_CB750F_1978.html

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Stev-o · « **Reply #37 on:** July 17, 2018, 03:58:12 PM »

Congrats on getting the bike, looks like you are off and running. Subscribed...

Jessamine · « **Reply #38 on:** July 17, 2018, 04:47:58 PM »

Quote from: calj737 on July 15, 2018, 03:53:24 PM

Quote from: Jessamine on July 15, 2018, 01:58:33 PM
Quote from: calj737 on July 14, 2018, 04:38:05 PM
Make sure you buy Keihin brand jets, not Keysters.
Got an authentic Keihin slow 40 in a cart at DCC.
To my knowledge, and through experience, DCC does not sell true Keihin brand jets. They list “Honda Keihin” jets, but Honda isn’t the manufacturer, Keihin is. Also, none of the pictures of the jets in their site show the Keihin trademark on the jet, nor the jet number. Maybe the jets for your F are different, but I would encourage you to look elsewhere for known resellers of Keihin jets. Like here: https://jetsrus.com/a_jet_kit_street/honda_750_CB750F_1978.html

Just to be safe, I went ahead and ordered a set of genuine Keihin replacements for all 4 slow jets-- I didn't see any branding on the jets in the carbs now, so I want to make sure I get a matched set. I'll keep the mains for now, but anticipate having to rejet larger when I get into tuning the bike.

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Jessamine · « **Reply #39 on:** July 17, 2018, 04:53:52 PM »

Today I started replacing JIS bolts with the new allen head bolt kit I got, and polishing the covers with scotchbrite pads on a rotary air tool. Not sure if I want to bother going the full distance with a buffing wheel (which I don't presently have access to), or if I'll just refine the current brushed look (which I am quite fond of). Still lots of cleaning to do on the cylinder and cases, but I feel good about my progress so far.

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754 · « **Reply #40 on:** July 17, 2018, 05:01:02 PM »

Ummm , don't ever do that on the chrome parts.. again .. unless you are powdercoating..

Jessamine · « **Reply #41 on:** July 17, 2018, 05:08:09 PM »

Don't worry, I barely touched the chrome side covers, and I'm going to be very gentle with the chrome on the exhaust if it's as intact as I suspect under the wrap.

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754 · « **Reply #42 on:** July 17, 2018, 06:26:47 PM »

Whatever you did to the starter, clutch and point cover, don't get near the exhaust with what you used.

slikwilli420 · « **Reply #43 on:** July 17, 2018, 07:11:59 PM »

Quote from: 754 on July 17, 2018, 06:26:47 PM

Whatever you did to the starter, clutch and point cover, don't get near the exhaust with what you used.

Agreed. Chrome ruined at this point.

seanbarney41 · « **Reply #44 on:** July 17, 2018, 07:57:57 PM »

Quote from: slikwilli420 on July 17, 2018, 07:11:59 PM

Quote from: 754 on July 17, 2018, 06:26:47 PM
Whatever you did to the starter, clutch and point cover, don't get near the exhaust with what you used.

Agreed. Chrome ruined at this point.

It's gonna take hours of hand rubbing to get those swirls out of the aluminum too.

Guys, power tools are fast

at wrecking stuff.

Jessamine · « **Reply #45 on:** July 17, 2018, 08:01:58 PM »

Hey, this is chrome we're talking about-- it's not like it looks good even when it's new.

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Cougars750F0 · « **Reply #46 on:** July 17, 2018, 10:05:57 PM »

Please take a look at the front tire it looks like its mounted backwards. There should be a arrow indicating direction.

calj737 · « **Reply #47 on:** July 18, 2018, 03:02:18 AM »

Don’t fret about the swirls. Aluminum oxidizes immediately and without any paint on the surfaces to protect it, those swirls will vanish due to oxides very shortly.

Something that works well is stainless brushes. You can also get them in loose knot cups and wheels to clean and remove the oxidation. Then use a Red then Green scotchbrite pad by hand to polish in a single direction. Leaves a nice lustre behind without so much swirling. You can then touch up the ally with a fresh Green pad occasionally.

Jessamine · « **Reply #48 on:** July 18, 2018, 05:50:29 AM »

Quote from: calj737 on July 18, 2018, 03:02:18 AM

Don’t fret about the swirls. Aluminum oxidizes immediately and without any paint on the surfaces to protect it, those swirls will vanish due to oxides very shortly.

Something that works well is stainless brushes. You can also get them in loose knot cups and wheels to clean and remove the oxidation. Then use a Red then Green scotchbrite pad by hand to polish in a single direction. Leaves a nice lustre behind without so much swirling. You can then touch up the ally with a fresh Green pad occasionally.

Thanks for the tips! It was definitely my first day of many working it. The finished product should look much more impressive.

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Jessamine · « **Reply #49 on:** July 18, 2018, 05:51:30 AM »

Quote from: Cougars750F0 on July 17, 2018, 10:05:57 PM

Please take a look at the front tire it looks like its mounted backwards. There should be a arrow indicating direction.

I thought so too, when I first saw it! Turns out it has two directional arrows on either tire, and that backwards-looking orientation in the front is actually correct.

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Author Topic: Ill-Advised Super Sport (CB750-F0) (Read 21677 times)