New 1982 cb750f

[tangylee]

Yall havnt heard from me but i have been getting a lot of info from this site for about a week now. I thank you all so much for sharing your cb750 knowledge!, I cant believe how much fun it is to work on a motorcycle. I have always wanted one and I finally got a 82 cb750f. Im stoked about it, 32,ooo miles on it... Not too bad? I have been cleanin it up real good and doin other various things but here are my couple of questions.

As you can see in the pic below (maybe) i built a manometer at home the easy way and was curious how much harder/less accurate it is to balance the carbs two at a time (1 and 2) (3 and 4) (the 2 and 3, right?) as opposed to all four at a time (little bit harder manometer to build)?

Also, before i balance carbs i made a little mistake earlier.... when checking out the carbs and cleaning them out a bit I was messin with the three adjustment screws for the throttle valves and i took them all the way out so the valves were basically shut! Is there a factory preset or something so i can set them to that (how?) and then try to balance them?

And my last question... painting the bike. I plan to paint the gas tank first, then the rear shocks, then the exhaust (if thats possible). Can anyone give any pointers on the best way to paint those things. I have zero experience with this so all help is greaty appreciated!

Thanks a lot for all your help, I already got tons of help from yall!

[TOOLS1]

Welcome to the forum. Looks like, you have been getting grease under your nails. The screws, you took out: Screw them in all the way, but not real hard. Just until they bottom. Then back them out 1 1/2 turns. Then start the bike, and adjust each one at a time until it is at it's fastest idle. Then back down the main adjuster untill the idle speed is right again. Then go to the next one, and do the same thing. As, for syncing the carbs. You can do it two at a time. However you must sync all to the same carb No#2. Do 1-2, 2-3, 2-4. I am sure Piute, or one of the other guys will give better painting advice. I just say Rattle can flat black.
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[shinyribs]

Ah,no longer a lurkernow a memberGood to have you here,welcome.I would say that a manometer is probably more accurate than most gauges are.Good luck and have fun!

[Piute]

O.K. TOOL MAN
  My-self I use Engine paint rattle can(bomb)on everything,they have my colors and can by same all over the place.be sure to use high heat primer were ever you sand down to bair metal reg primer will work were heat is not a prob,you can paint your pipes many do and look good for VERY short time,but can keep touching up,
 you will / should use the highest temp you can get in that case, I use 500deg.on 90% of bike ,on berral(center of engine were pistons are I used 1000 deg. but if had 2K in color would have used,have them ceramic coated if possible helps with heat also
    Piute N Judose

   clear coats make last longer don't forget to sand before clear also

[tangylee]

Thanks you a lot for the tips! Ill be getting to that stuff real soon i hope.

Also, does anyone know where to find a new tachometer oil seal for my model bike? (without having to buy a whole set of oil seals?)

[TOOLS1]

Should be able to pick that up at the local Honda dealer.
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[tangylee]

thanks, i didnt even know they sold parts. anyways, one more question for you...  is there anything wrong with using regular SAE 10w-40 motor oil in my bike? thats what the manual says to use but now there is SAE 10w-40 motorcycle specific oils and so on... and suggestions?

[TOOLS1]

I use Texaco Havolin 10W-40, and Fram CH 6009 oil filters (you can get them at most any auto parts store). Some of the guy's run Rotella- T 10W-40 diesel engine oil, But I do not feel that these engines run anywhere near dirty enough to need that kind of detergent. Also I have seen these high detergent oils eat up aluminum Briggs and Stratton engines.
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[sgtslag]

Oil is a testy topic, but I'll give you some basic information, without making a brand recommendation.

Modern automotive oils generally contain "energy star" conservation symbols, which means they contain friction reducers, to save energy.  It really adds up across the whole USA, but it doesn't save the individual enough gas money to really matter.  There has been one specific bike, and only one, that I know of, which had clutch slippage from these friction modifiers.  Our bikes, and many produced today, share the engine oil, with the transmission, and clutch.  The recommendation is to avoid automotive oils with the energy star conservation symbol to prevent clutch problems...  I ran regular, conventional, auto oil in my '79 for 4+ years, without any issues.

I added an oil cooler, and an oil temperature gauge to my bike, a couple of years ago.  I discovered that my engine oil, under heavy load, running down the highway, in 80 F temperatures, was running at 250 F -- without the oil cooler!  Any temperature above 250 F, and conventional oil breaks down into carbon sludge, which leads to engine damage.  It demonstrates that Honda designed my '79's DOHC engine to run at the thermal limit of the oil.

Synthetic oils break down at temperatures of 450 F+.  They're more expensive, but they are more stable.  Synthetic oils can run longer, as they are less prone to shearing of their long molecules in our transmissions, which means they break down in viscosity much slower than conventional oils, which means you can run them longer, for more miles, than conventional oils.

It's a personal choice as to what type (conventional, or synthetic), and what brand.  Some basics, though:

Motorcycle specific products, especially oils, are much higher priced than non-MC products.  They claim they're better quality, but there is no scientific evidence to back up these claims.

Tools mentioned Shell Rotella T (15W-40, diesel, conventional), and T6 (5W-40, diesel, synthetic) oils.  One, or both, have recently been JASO certified, which means Japan has approved them for use in MC's.  They do contain a higher level of detergents than automotive oils, but this does not seem to be an issue.  They are rated SM, or higher, for use in automobiles, which have largely aluminum engines in them, just like our bikes.  They do contain some amount of friction modifiers, but they don't have enough to meet the government's standard, so they do not sport the "energy star" symbol -- still safe for use in wet clutch systems, as per JASO.

Any oil will work.  Synthetics will provide a much bigger cushion on temperature tolerances.  I changed all of my vehicles to Shell Rotella T6 since it is inexpensive, and it performs in January, the same as it does in July (my car spins over at the same speed in January,  in sub-0 F temperatures, sitting outside all day, the same as it spins over in July,...).  Now I only have one type of oil in my garage (for all vehicles, and small engines), except for the air compressor's non-detergent oil (I could use the Shell, but it's 46 years old, and still working, so... why mess with success).  YMMV.  Cheers!

[seestheday]

Great post, thanks for this info.  I was planning on switching to full synthetic and now I know which oil to get.  Shell Rotella is $40 for 4.4L at Canadian Tire and the comments in the reviews even mention guys using it in motorcycles.

They do mention that some people may have had troubles with it on track bikes, but those are a different breed than my 81' CB 750.

[tangylee]

Great info! thanks so much. I think im gonna drain the oil and add some regular sae 10w-40 motor oil with some sea foam and let that run and then sit for a couple days, then drain that and add some shell rotella.  Sounds good to me. thanks a lot guys.

also, im about to grease up a few things (mainly the main wheel bearings)

any tips for this? all I know is i need a grease gun... but does it need a special fitting i need to make?

thanks a lot!

[sgtslag]

I added SeaFoam to my crankcase on my Honda, ran it on the center stand for five minutes (oil got to 180 F, on the gauge, at which detergent oils suspend particles to be caught by the filter media -- minimum recommended temperature before changing it out), shifting through all five gears, to flush out the transmission.  Then I drained it.  My oil was caramel colored when I started; after just five minutes idling on the center stand, it turned coal black.  I put fresh oil and filter in.  Fast forward 5,000 miles...


I added SeaFoam again, to the crankcase, ran it for five minutes, on the center stand, shifting through all five gears, while idling:  oil never changed color, remained a nice, new-looking, caramel color.  I ran it in the crank case for 300 miles, then I got concerned, and changed the oil, and filter, just in case.

After just five minutes, with the oil at 180 F , my engine and transmission were flushed clean.  When I repeated the process, 5,000 miles, and more than a year later, it was still clean inside the engine, and the transmission.  I am now waiting a minimum of 10,000 miles between flushes of the crankcase with SeaFoam.  With high-detergent diesel oils, this may not be necessary until 20,000 mile cycles, but experimentation will tell me how fast it is getting carbon deposits, and varnish, built up inside the engine and transmission.

Bottom line is that the maker of SeaFoam recommends waiting until your oil darkens -- then change it, and the oil filter.  It is best to go by the oil's color change (to black), rather than mileage, or hours of use.  Note that SeaFoam will thin your oil somewhat, so it is a good idea to leave it in for a shorter period of time, to be safe.


With regards to greasing, the only thing I know is that the swing arm requires a needle of some sort, as the zerk is not your typical type.  I found a hypodermic needle attachment for my grease gun, but that didn't work very well -- have to be careful:  it is around a 16 GA SHARP, medical type needle...  Full of un-sterile grease.  Been very tempted to replace that zerk with a standard type.  Other bearings requiring grease are detailed in the FSM, or the Clymer book.  Cheers!

[TOOLS1]

The zerk on the swing are should be a standard zerk. The one on Sarg's bike might have been changed? The wheel bearings are sealed, and must be removed to be repacked. Requires special tools. There is one on the rear inside the cush drive that, you can reach, and shove some grease into though.
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[tangylee]

Again, thank yall so much for the info.   A side story, to make me look like the dumbass i am, the first night i got my bike (first motorcycle for me, im 19), about a week ago, i put the keys on the hood of our truck for some reason as i was taking a look at the bike. A couple hours go by and i realize my sister took the car out.... aka took my keys that were on the hood out!... and now they are somewhere around where i live. no idea... i looked for probably 10 hours though and followed the route she took! never found a thing...

tomorrow im suppose to be getting a call from the locksmith, they had to order a key and they gonna make it fit into my ignition... extra 30 bucks or so plus a week of waiting time.

sucked but soon enough ill get the keys back then ill get to do everything i have been asking about. thanks a lot for the info so far. have fun riding before the winter hits!

[TOOLS1]

And after that, you will find them under the hood of the car, or someplace like it.
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[tangylee]

Alright I got the keys back earlier than expected (not because i found them  i had them made) and put everything back on carefully. Im tryin to start it back up and it has gotten real close a couple times but then i realized one dam carb doesnt have fuel in it? that mean my fuel line is dirty or something? The three carbs closest to the fuel have fuel in them, but that last one (nu 4) has no fuel! Can i manually fill it up or something? or is that particular carb clogged and i should disassemble and clean? thats all i can think of. any help is great thanks

[tangylee]

it took care of itself so nevermind and thanks

[TOOLS1]

Self healing. Very Cool
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[tangylee]

Smoking engine!?! uhhh i think thats bad... any ideas why this would be happening/ how to fix? is it normal for steam-like smoke to rise from an old engine like this?

[tangylee]

A little more info on the subject would be that the bike runs real high rpms even with the throttle valve adjuster all the way out. Im a total noob and basically curious why my engine runs so fast/ smokes. I know it needs a lot of fine tuning i just dont know where to start... and i dont wanna start it if it keeps smoking! I feel like im ruining my beautiful new bike!