Topic: high performance street/strip/track motor... advice???

[J.Webster Designs]

hey guys, I have come into a little extra money and want to start gathering parts for the second build of my CB750F. I currently have it on the road. It was not rebuilt but it is running and ride able. I will be doing lots of frame and suspension upgrades and i know what i want to do for those... but the one thing that has me stumped on what to do is the motor..... I am hoping that you guys can help me plan my motor build.

I want to have a dead reliable modded motor that is increased in performance as much as possible without sacrificing reliability from the stocker and can handle some spirited riding in the back roads, a trip here and there to the local road course, and maybe a trip down the drag strip every now and then. but i need the motor to be as dead nuts reliable as possible. I will also probably use things in this motor that may not get used to their full potential but can be great conversation pieces. (possibly Mreicks billet heads, maybe the dry clutch that has turned up etc...)

so far these are the things that i have come up with for the build. I hope that you guys can fill in the spaces for me and confirm my thoughts on these things....

Motor is a 1978 CB750F motor. It is in a 1976 CB750F frame.

Gaskets - all honda genuine where applicable

cylinder head - not sure what is good for these motors so i am hoping that Mreick can chime in on this for me as i will most likely have him build the head. I want to get it to rev nice so lightening the valve train would be great. titanium retainers will most likely get used. don't know if they benefit from increasing valve sizes. and I'm sure that he has the porting and polishing down to a science. I am hoping the valve guide problem with this motor can be addressed as well.

Camshaft - don't really know what is available and reliable power makers in this section

rocker arms - i have heard M3 lightened rocker arms being mentioned.

cylinders - big bore kit... I am not sure what size is reliable in these motors. I am guessing that a 836 us rather reliable due to the amount of people using them. which brand is best? i see kits ranging from weisco to cycleX who makes the better pistons etc...?

cam chain - have heard good things about the tsubaki heavy duty cam chains.

cam chain tensioner - heard good things about the M3 cam chain tensioner.

rods - have heard Carrillo rods being thrown around as being good rods.

Crank - will probably have APE do their magic on it. how extensive should i go before you start getting into reliability and running problems?

cylinder head studs - APE heavy duty studs.

transmission - have heard back cutting gears being thrown around. are there any other modification that can be done to increase performance without hindering street ability?

primary chains - heavy duty primary chains. I think i have heard the M3 chains being thrown around the most.

Clutch - APE extra plate kit and heavy duty clutch springs

Oil cooler - i think terry (from OZ) has a good adapter plate?


I have built car and truck motors things ranging from ford 289, 400 (now a 408), modular motors, chevy 350s,454s. etc... but motorcycle motors are a new thing to me. I really am at a loss in which direction to go for these things as some things are made by multiple people but may not be the best in terms of reliability. so what do you guys say? help a brother out???

Thanks in advance
Justin

[Jerry Rxman Griffin aka MuthaF'er]

Justin,

You have some very good ideas. For starters I hope you have $5,000. If you're using the F2/F3 engine your choices will be more limited especially in the big bore kit. Dynoman.net has the only 836 I know of for the F2/F3. Dynoman also has the only crank stud kit. Turn Mike loose on the head. Don't worry about the crank as Big Jay knows how to apply his magic. He'll even install those Carrillos for you. The other stuff is secondary to this.

[wannabridin]

ya know justin, if you sell one, maybe two more of those gauge faces that i have yet to put on, i'd reckon you could make some extra cash for the motor    but ya, i wish i could have some extra cash like you!!  but seriously, i've promised i'd brag for you about those faces, guess i need to do that...

[J.Webster Designs]

Jerry, I realize that the price to build up these motors can get rather out of hand.... the carillo rods are a grand by themselves.... head work... another grand plus. Mreicks billet cylinders... 1500 plus machining so closer to 2 grand. the list goes on..... I am fine with the way the bike is right now that's why i want to start picking up pieces here and there so that the upfront cost doesn't seem soo bad.

As for the cylinders and the cylinder head, if there is more availability in parts, i would not mind switching to K cylinders and head if that is the smart choice. I already have a problem with this motor as i cant get factory sized rings for the stupid thing so i HAVE to go to a big bore kit.... so if you guys think that the K cylinders and head are a good idea for ease of parts availability then that is the route i want to go.... I don't want to get into a situation where i only have 1 option for parts for this motor. It would kinda be like when i rebuilt my ford 400 motor. only one guy made flat top high compression pistons, and there were no aftermarket heads available.... sure edelbrock came out with some aluminum heads for them now... but its the what if factor.. what if i need to replace rings on this motor if anything does happen to it and the maker of the only set of bigbore kits for it is no longer around.... now i have to look into redoing work that could have been avoided by going with the K cylinders and head.

Jerry, how has your motor been going??? i have seen a couple posts hinting at a hot rod motor of your own...

Garrett... it would be nice to make some additional money by selling gauge faces, but the truth is that i make very little off of getting them out to people. but it still doesn't hurt to have a few extra dollars lying around when you are a college student trying to build custom cars,trucks and motorcycles....

[andy750]

Check out Spartys Hot Rod build for all your info. If you build a motor like his you will be able to do all you want and more. His bike (like Mike Rs) is incredibly fast. Bu then you`ll need the suspension to handle it as well as the frame mods, etc etc....so check out MCRiders build thread for info on those components...and the engine build.

Good luck
Andy

[J.Webster Designs]

andy... Thanks for the lead... it looks like a great motor.... What kind of power does that thing make?

[andy750]

andy... Thanks for the lead... it looks like a great motor.... What kind of power does that thing make?

You will need to ask Sparty....but Mikes makes 98 as tested on the Dyno....its an amazing bike!

[lordmoonpie]

Not that I want to blow my own trumpet but it might give you some more ideas Justin if you check out my motor in the "ultimate engine" thread. Mike's Million Dollar CB is definitely better proven than mine right now but I hope to have some news on the Million Pound CB soon....

[voxonda]

All comes down to what you want to do with it. As a daily drive, my advice would be to give it a good tune up, new primary's, new camchain, ported head and maybe, just maybe a hotter cam, but look out it is a F2! Do not get wild!
For a all out drag/sprint/roadrace....just let yourself go, and spend that well earn't money!

rob

[J.Webster Designs]

once this build is done, it will no longer be a daily. but it will still need to be streetable. trips out into the country roads, weekly bike meets and rides for people to oooo and awwww at it. but far from a daily. i am hoping that by the time i have all the parts for this motor and the frame is ready to accept it, i will have a XB12Scg as a daily. but if i dont, i still have my truck as dependable transportation. so no matter what it will not be a daily. i just want to get a nice motor high horsepower CB750 motor together for this bike as a stock motor in an updated suspensioned bike will just be strange.....

[Jerry Rxman Griffin aka MuthaF'er]

Your F already has big valves but the head has design problems that you may be able to overcome. It can have guides replaced and be ported and hope for the best. Lighter stainless valves, heavier duty springs, and Ti retainers would be good. Basically the more extreme valve angle used to accomodate the larger sizes and related stress creates wear on the guides. I just don't know how practical it is to put serious cash into that engine with that head and hope for the best. I'll defer that question to Mike Rieck. Might be better off longevity wise to use a K top end and spend a little more on the head.

As far as my engines go, I've been collecting and paying for probably 2+ years now. My 750F has been 810F since late 70's. I did it basic then. Bored and cammed with springs and Manley stainless stock size intakes for weight and strength(broken valve due to over rev on missed shift). I wanted to do more but didn't have the cash or expertise back in the day. I picked up a spare 78 K engine along the way for parts. My 810F will become a 900F and the 78 K will become a 1000 chop eventually. The 900 is planned as a more streetable high rpm high HP rider. The 1000 will be more of a brute torque toy machine. 

For the 900 I found a NOS Henry Abe kit, had Jay do a lightened crank with Carrillos, had Mike do a stage IV head with 5mm stem KPM conversion kit with all the goodies that uses 34mm intakes, Ti retainers, springs and serious porting, Megacycle 125-75 cam is on order, may get a RC315 also to try, Tsubaki cam chain, HD cylinder studs, just got HD crank studs, M3 tensioner.

The 1000 is at APE now getting kitted with Big Jay's new 1000 kit. This won't be the techie engine the 900 will. I have his Crower rods to go on that. They are about 50gm heavier than the Carrillos but much stronger than stock. Along the way I picked up a head from a 3/4 (TQ) midget guy in Indiana for cheap with 33.5mm KPM Black Diamond intakes, KPM springs and mild porting and had Mike spiff it up some but it's not as nice or expensive as the full job he did on my other head. It now has 33.5 KPM Black Diamond intakes, KPM stainless exhausts, KPM springs and Ti retainers, decked .010. I will still need both stud kits, the spare cam I'll eventually have will go in this engine. Crank will need to be done. The expensive stuff on this one is out of the way. It will be a "potential" spare sitting on the floor next to my bike until it gets it's own bike 

I hope to get started on the tear down soon as I have most of the parts needed for a complete restore with the 900 rebuild. All engine parts accounted for! Taking my time for 3 reasons: using the cash installment pay over time method, somewhat lazy and my garage is already full. You really have to be careful with this stuff! Mine actually got started due to those damned cam tower pucks leaking and I need to take the engine out and tear it down. Might as well (fill in the blanks)........ too!  And look at what a cash pit it has turned into. The extra time I've taken has also seen the evolution of parts availability. Jay/APE has progressed/regressed into a high perforamnce parts suppier again, as has Dynoman, by bringing out new tech high performance parts. Support the arts, huh?!!

Other advantages about the 5mm conversion kit for the K and early F head are less disruption of intake/exhaust flows due to a 1.5mm reduction in valve stem diameters, lighter valves, the springs are lighter as well as the titanium retainers because they also have smaller diameters. 

Just do your research and spend your $$ wisely and with the right people! One mistake can ruin the whole money pit, er investment, er engine. Many more K engines have been developed than F2/F3's. Oh, and the reference to Sparty's engine is good info! Top notch 836 should you go that size!








 

[J.Webster Designs]

Thank you for the information...

Your F already has big valves but the head has design problems that you may be able to overcome. It can have guides replaced and be ported and hope for the best. Lighter stainless valves, heavier duty springs, and Ti retainers would be good. Basically the more extreme valve angle used to accomodate the larger sizes and related stress creates wear on the guides. I just don't know how practical it is to put serious cash into that engine with that head and hope for the best. I'll defer that question to Mike Rieck. Might be better off longevity wise to use a K top end and spend a little more on the head.

This was my thoughts exactly and the reason why i think that its best for me to just go the K route.... now that i have decided that i want to go the K route... Is the F bottom end better than the K bottom end? i think i heard of this somewhere....

[voxonda]

Bottom end of F2 is stronger, but the K are strong enough.

[Jerry Rxman Griffin aka MuthaF'er]

77/78 F rod bolts are better if you were to use those rods, tranny has a different ratio that is better suited for quick take offs, output shaft has double row bearings vs earlier K's (I think this is correct??) and 630 sprocket setup vs early K. You just need to remember to use cylinders AND head in this swap. My 75 F has the lower ratios too but it's a 530 output shaft. Subtile changes throughout the years but we have charts that explain all that.

Someone else chime in if I missed anything.

Downside to the K swap is you have to replace the valves too if you do this so more expense, provided you want larger valves. However if you were planning on replacing the valves anyway it doesn't matter, huh! I'd sleep better doing this though.

[J.Webster Designs]

yeah... I have made up my mind that this will be the route that I end up going.... what year model K top end should i pick up? Mreick... you will be the guy working on the top end... any recommendations on what year i should pick up?

[andy750]

yeah... I have made up my mind that this will be the route that I end up going.... what year model K top end should i pick up? Mreick... you will be the guy working on the top end... any recommendations on what year i should pick up?

Get the 78 or pre-72.

cheers
Andy

[J.Webster Designs]

reasoning behind those years andy?

[MRieck]

I finally have a chance to chime in. The K head and cylinder with the F2 bottom is an excellent idea. The 76F/K or 77/78K head is nice as the chamber is better. The early K chambers can be reworked but it takes time to deshroud them and get them even. Some of the stuff in your list is good and some not necessary. I'll PM you and give you my phone #.

[honda3303]

"33.5mm KPM Black Diamond intakes, KPM springs and mild porting"

what/who is KPM?

[MCRider]

"33.5mm KPM Black Diamond intakes, KPM springs and mild porting"

what/who is KPM?

http://www.blackdiamondvalves.com/

Turn down your volume before clicking the link.  

[Sam Green Racing]

"33.5mm KPM Black Diamond intakes, KPM springs and mild porting"

what/who is KPM?

http://www.blackdiamondvalves.com/

Turn down your volume before clicking the link.  

Hey MCR, don't give to much away to this guy, he knows enough already
Click on the APE add at the top of this page and scroll up to the top, take note of the pics then look at his avatar

Welcome to the Hipo and race forum Chad.

Sam.

[MCRider]

"33.5mm KPM Black Diamond intakes, KPM springs and mild porting"

what/who is KPM?

http://www.blackdiamondvalves.com/

Turn down your volume before clicking the link.  

Hey MCR, don't give to much away to this guy, he knows enough already
Click on the APE add at the top of this page and scroll up to the top, take note of the pics then look at his avatar

Welcome to the Hipo and race forum Chad.

Sam.

I see, I was tricked. Now we have a couple of "A" officionados?

In my defense, I have APE Ti retainers and springs in current project. I am recycling some old SS Manley valves or I'd have sourced from APE.  APE did my crank also.

[Sam Green Racing]

MCR, Nippon is looking for a set of Manly valves, where can he get them ?

http://forums.sohc4.net/index.php?topic=61648.0

Sam.

[MCRider]

MCR, Nippon is looking for a set of Manly valves, where can he get them ?

http://forums.sohc4.net/index.php?topic=61648.0

Sam.

I bot mine in 1980. AFter 50,000+ miles in a hot street motor, they were still in usable condition and I had no reason to replace them. I did replace the guides.

I don't remember where I got them. Either some place in CA like APE or Action 4, or Yoshimura East where I had my head done.  Act 4 and YE are no more. Don't know where APE sources their valves now.

Sorry.

PS: Maybe these guys would know: http://www.manleyperformance.com/  

[Flying J]

i have a 78 bottom end that i would let go for cheap. You would just have to pay shipping.