Topic: 76 CB 750F horsepower upgrades?

[Nayl]

So I finally managed to find the intersection of price and condition that suited me and pulled the trigger on this: http://www.ebay.com/itm/1976-Honda-CB750-Super-Sport-/151350963980?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2047675.l2557&nma=true&si=cL7a8MAs%252F9nDhXOR618jFH15ST0%253D&orig_cvip=true&rt=nc
which actually appears to be a 75 F, given the color.  My general plan is to massage it lightly to get more HP out of it, possibly going as far as an 836 kit.  My question is, what sort of HP boost will installing such a kit result in, generally?  Apologies if this is something searchable, I've tried and not been able to find it.

[Nayl]

And of course, as soon as I posted this and went back to wandering through the forums I stumbled across what I was looking for, namely a thread specifically discussing what sort of horsepower various mods produce.  But now I'm wondering what applies to this specific engine, since it seems to fall outside the pantheon of K's that get the most attention here.  I had formed the overall impression that the early F's were basically K engines with slightly higher compression, but there seems to be more to it than that.

[ekpent]

Yellow was a 76 color though not as many around as Antares Red. Rumor has it Honda pulled the color because Yamaha went yellow on their MX bikes.
   Give it a ride as is when you get if for awhile, you may like the amount of power it makes now without all the expense and tuning fuss. Only has a little over 13K miles on it.

[Jerry Rxman Griffin aka MuthaF'er]

Wow! Great score. Congrats.

Please don't plan on upping the HP until you realize what you already have. I'd hate to see you get into a high revving tight low mile engine with no real need. You will probably be pleased with what you have. You will find that it will blow away most other 750s already. Bought my 75 new and it ran like a scalded ass dog until I missed a 1-2 shift and blew it.

By the color, Sulfur Yellow, and the serial number that is indeed a 76. It is indeed an updates early K engine and it transcended into the 77/78 K also. The 75/76 added a little compression to the K engine. Went from 9 to 9.2. It has a better cam hence the higher redline 8500 vs 8000. The head was improved also in the combustion chamber which may be the real reason for the slight compression bump. The tranny is geared a little different as well as the front sprocket for better acceleration. The carbs have the mid-range jetting (needle and needle jet) changed also. The 4 into 1 also helps. Watch the rear brake as it will lock the tire in a heartbeat.

If you do decide to do the engine it will have to be pulled first. The cam would be the easiest and cheapest. Also install stronger springs. A 836 with or without the cam would be next in price but I would also do the cam while you're at it. As mentioned the head is the biggest restriction with the engine whether or not you kit it. Open it up and open up the HP potential. This could be the biggest expense but the best change. Do that and keep everything else stock perhaps or hell, do the cam, 836 and head. If you do you'd better be holding on the grips really tight the first time you crack it open. Going over 836 gets REAL expensive due to rods and bigger valves. That job could add $4000 or more WITHOUT all the easy cheap stuff.



 

[Nayl]

Please don't plan on upping the HP until you realize what you already have. I'd hate to see you get into a high revving tight low mile engine with no real need. You will probably be pleased with what you have. You will find that it will blow away most other 750s already.

Indeed.  The longer I think about it, the more I'm thinking that the engine is probably the most solid part of this package, and I should concentrate on the suspension and cosmetics (at the risk of angering the purists, that original yellow color is not my favorite, I'm thinking something along the lines of a CBX red and black scheme).  Rollers in the head race and bushings in the swingarm, and maybe upgrading the brakes/front end, as long as its bolt on or damn close to it.  My initial goal is something that rides and goes as well as my long departed '81 DOHC CB750F, but has the classic look of the earlier generation.

[Jerry Rxman Griffin aka MuthaF'er]

Guess we'll be expecting a comparison then!

[Retro Rocket]

You've seen this then..?  CBX color scheme is gorgoeus....



http://forums.sohc4.net/index.php?topic=103801.75

[Nayl]

Yes, that's the exact bike I was inspired by, I've always loved that color combo and it looks better on a sohc F than anything else I've seen so far.

[BeSeeingYou]

I am surprised you got it that cheap on Ebay....maybe no overseas buyers looking in on that one.    I think you got it for a good price.

If the paint is in very nice shape on the tank and tail maybe it would have more value to sell it providing you find another tank and tail that needs a repaint.  Tanks with nice original paint are rare and do command $$$...maybe enough to pay for another tank AND a new paint job.  Somebody out there HAS to like that yellow color and need it for their restoration.

Like a few others have said ride it for a bit and you may feel it has enough HP for your needs.  Tearing apart a perfectly fine low mile engine would not be money well spent IMO.

[Retro Rocket]

I am surprised you got it for that cheap on Ebay....maybe no overseas buyers looking in on that one.    I think you got it for a good price.

If the paint is in very nice shape on the tank and tail maybe it would have more value to sell it providing you find another tank and tail that needs a repaint.  Tanks with nice original paint are rare and do command $$$...maybe enough to pay for another tank AND a new paint job.  Somebody out there has to like that yellow color and need it for their restoration.

+1, after looking at the link thats a very nice original F, spare tank and covers is the way to go...

[Hon3ybadger]

I agree with these other gentleman. That identical tank sold for over $1000 on ebay last week. Not to put crazy numbers in your head but your sitting on F'er gold.

Do as I did and get a second tank and seat and side covers. Make them some cool color and confuse your friends by changing colors every other day.

[Nayl]

If I can find a solid tank and tail piece I might consider preserving the existing ones, but one of the attractions of this bike was the overall quality of the tank/bodywork, and I doubt Im going to find anything nearly as good for less than big $.  And yes, I know I got a good deal by EBay standards, I had just about decided the only way I was getting a bike for less than crazy money was Craigslist, so I was pleasantly surprised when this went through at the price it did.  All that said, its still not sitting in my barn, so we shall see...

[jdubb1977]

congrats on the F!  I have that exact same bike, although I think yours is definitely in better shape than mine was when i picked it up.  and just to confirm, that yellow was a '76 color.  i'm with you...i couldn't stand the yellow so i stripped it (it was faded and the tank was dented) and repainted it a medium metallic red.  love it now! 

i agree w/ what others have said about the power.  it's gonna take a lot to squeeze a lot of hp out of the engine.  i've given up on trying to keep up w/ my buddies, all of whom have modern bikes.  this past year i've concentrated more on suspension and braking.  rebuild/replace your suspension, add a 2nd disc up front, get a bigger master cylinder, and add a fork brace.  all of those combine to make it a much more responsive beast!  and maybe shed the extra highway bar weight. 

[Nayl]

this past year i've concentrated more on suspension and braking.  rebuild/replace your suspension, add a 2nd disc up front, get a bigger master cylinder, and add a fork brace.

That all sounds great, mind if I ask for some details on what you did?  I was vaguely considering a GL1000 front end which seems pretty close to a bolt-on mod, which would accomplish the dual disc part while keeping the wire wheel.  Otoh, if there is a simple way to add a second disc and just stiffen up the existing fork with a brace, that also sounds good (I hate throwing away anything that still works).  Assuming the bike in your sig is your F1, what wheels are those?

[Don R]

 I think that bike is an F2. I added the second stock disc to my 76F. I love it.  Fast from the past has a nice fork brace too. It fits with a stock or modified fender. I want one. I'd like an F2 front end swap too but the wing swap is a fork upgrade I think.

[jdubb1977]

this past year i've concentrated more on suspension and braking.  rebuild/replace your suspension, add a 2nd disc up front, get a bigger master cylinder, and add a fork brace.

That all sounds great, mind if I ask for some details on what you did?  I was vaguely considering a GL1000 front end which seems pretty close to a bolt-on mod, which would accomplish the dual disc part while keeping the wire wheel.  Otoh, if there is a simple way to add a second disc and just stiffen up the existing fork with a brace, that also sounds good (I hate throwing away anything that still works).  Assuming the bike in your sig is your F1, what wheels are those?

i've always been on the fence about swapping the front end to a GL, or even a newer GSXR.  to be honest, it just sounds like a lot of work and expense.   figured i'd work w/ what i've got and see if i can get it feeling solid.  there's a full dual disc tutorial at http://www.salocal.com/sohc/tech/dual_disks/dual_disks.htm   It's basically what I followed, and at the time (4yrs ago) didn't really know what I was doing.  Turned out great, though.  The stock MC worked but was always spongey.  I bought a 5/8" bore MC off of ebay and it helped a ton.  Braking is nice and tight now.  I rebuild the front end w/ Progressive springs and new 15w fork oil.  Feels good, but there's still more bounce than on a modern bike.  i've heard that the emulators do a great job, but haven't looked into them much.  As Don R said, the Tarozzi fork brace from fastfromthepast is a great fit.  it definitely stiffened up the front end, and it bolts on right above your stock fender.  no mods needed. 

oh, and the wheels are lesters! they came with the bike.  i didn't care for them at first, but after people told me how valuable they are, i started to like 'em.