Topic: 836cc Power is Way Too Much Due to Some Very Bad Advice

[RRRToolSolutions]

The CB rips the clutch loose at 7,000 rpm since I installed a $200 NOS Honda stock clutch - Darn it! I just got it back together last night and my 1st ride greets me with a quick sweep of the tach needle past the 10 mark....

I made use of some bad advice while I had my 836 down for the frame mods. I had installed a new Barnett clutch fiber plate and spring kit back in August when I was putting the engine back together. It worked extremely well in terms of "grab". In fact, it worked too well and caused jumping when put into 1st and I'd had a few false neutrals show-up when going through the gears. A local friend and long-time CB750 owner told me he'd drag raced his previous 750's and used only "stock Honda clutches" without ever having one slip or problems. He insisted that he hated Barnett fibers because they would swell more than the stockers and cause the "sticky" transmission problems I was having. He also insisted the stock clutches on the CB750 worked so well that a new set of stock Honda springs would be all it needed.

Well, the engagement to first is clock-work perfect, the shifting is as smooth as any bike I own. This morning I'm really happy about taking advantage of his advice and the expense of replacing a new Barnett system with less than 200 miles with the outrageously expensive Honda fibers (those 7 fibers are $18 each! and the steels are $8). I'm happy for a good 20 miles or so. I come to a stop sign, look down and the oil gauge shows a drop in pressure, so I know she's warmed-up and the oil has thinned a little - all good. I click into 1st and hammer it once rolling fully expecting it to hoist the front tire like it's done so easily for the previous 200 miles. Nope, not this time.

A bad clutch usually shows it's ugly head in the higher gears. This damn thing is so weak that it's won't handle the 836 in 1st. I loosened up on the adjuster making sure to give the cable 1/2 of slack and brought the rpm up while in 2nd so I could watch it. At 7,000 shes starts and before I can get out -she tachs over 10,000. While I am just tickled at the output, I'm not happy at all about having to replace more clutch components.

Question - I like the shifting quality and love the way my transmission behaves with the Honda fibers/steels. Will a simple swap to heavier springs solve this? I don't want to go back to the Barnetts, but 10 grand on the old tach will soon open a few windows on the frontal case areas...

Input really appreciated.

Thanks,
Gordon
 

[eldar]

Well if you can, put the barnett springs back in and see what happens. Just a question though, what weight oil you using?

[mrbreeze]

Eldar jumped in there as I was starting to type but he said the same thing as i was thinking.If all is adjusted properly,I would try heavier springs. The oil is very important.Most people here don't recommend synthetic oils.

[scondon]

 I use the stock Honda plates and springs on my 836 and after 10,000 hard miles everything still grabs great. It is a '78 F3 bottom end and there may be an extra friction disk and plate(stock) compared to earlier CB750's. I forget

[RRRToolSolutions]

I use Kawasaki (Motul) 10-40 motorcycle specific synthetic oil exclusively. I buy it by the case from my very good friend and local Kawaski dealership (I have 11 Kawasakis so he loves me!). I use this in every 4 stroke bike I own and have never had a problem. The previous clutch did well with it.

I just thought of something - the new Honda steels came with a smooth surface on both sides, there were no perferations - not one. The old steels had them. I know their purpose is to catch and hold oil. I assume that a smooth surface would give more "grab", but did I lose something with the new steels?

[joeb]

Well I tossd teh Honda clutch package and went with the A.P.E. set up,  not a problem here I also use 10-50 wt. oil.  Give the heavy duty springs a try.  I also run a 78 F3 bottom end.

[Geeto67]

I use Kawasaki (Motul) 10-40 motorcycle specific synthetic oil exclusively. I buy it by the case from my very good friend and local Kawaski dealership (I have 11 Kawasakis so he loves me!). I use this in every 4 stroke bike I own and have never had a problem. The previous clutch did well with it.

I just thought of something - the new Honda steels came with a smooth surface on both sides, there were no perferations - not one. The old steels had them. I know their purpose is to catch and hold oil. I assume that a smooth surface would give more "grab", but did I lose something with the new steels?

I have used the barnet springs with stock honda fibers for years without incident on my 750s. I don't have an 836 but I am pretty abusive to the bike and I tour close to or over the weight limit of this bike a lot. I prefer the honda fibers to the barnett fibers but the springs (and sometimes the steels) I go barnett all the way.

[sparty]

I use Kawasaki (Motul) 10-40 motorcycle specific synthetic oil exclusively. I buy it by the case from my very good friend and local Kawaski dealership (I have 11 Kawasakis so he loves me!). I use this in every 4 stroke bike I own and have never had a problem. The previous clutch did well with it.

I just thought of something - the new Honda steels came with a smooth surface on both sides, there were no perferations - not one. The old steels had them. I know their purpose is to catch and hold oil. I assume that a smooth surface would give more "grab", but did I lose something with the new steels?

I have used the barnet springs with stock honda fibers for years without incident on my 750s. I don't have an 836 but I am pretty abusive to the bike and I tour close to or over the weight limit of this bike a lot. I prefer the honda fibers to the barnett fibers but the springs (and sometimes the steels) I go barnett all the way.

Ditto.  Barnett springs with stock fibers and plates.  This is what some of the higher H.P. fours are running and waht was recommed to me for my 836cc.

Sparty

[HondaMan]

It seems to me...the Honda "K" setup uses one more plate and fiber than the Barnett setup. When you installed the Honda parts, did you get the extra plates?

Some late-market Honda kits included one extra-thick plate in place of the extra parts, and some Barnett sets did the same to reduce the pack height when Barnett's 1-less kit was used. This makes it all pretty confusing... 

I often replaced Barnett kits with Honda kits to get the power onto the ground, especially in racing situations. I also "repaired" several Honda setups where 1 steel and 1 fiber were missing, causing hi-RPM slip. I can only presume someone ahead of me in those situations had replaced a Barnett set with Honda parts, not knowing they were ending up one plate set short.

Make sure the corks all line up, so the oil outflow passages are lined up when the clutch is released. It is conceivable that the corks might not be perfectly aligned on both sides of the plates, making them essentially have a "front" and "back" side. The Barnetts were famous for this problem, in particular. I haven't seen Honda's parts lately, but you never know... 

The result of misaligned plate oil passages is a loose grip on the shaft, so to speak. Stock Honda plates can handle nearly 100 HP under normal conditions, I've seen it. Don't use STP or MGC or other oil additives: these stick to the cork relentlessly, causing slip. And, it's really hard to remove, once soaked in.

[eldar]

I would certainly have to go with hondaman. I thought about it but did not remember enough to be able to say anything intelligible!

[Jerry Rxman Griffin aka MuthaF'er]

You guys got me curious. This is from the "for what its worth" department. I have the Barnett clutch kit in my kitted 75 750F. I am using the stock springs and it is doing fine. I was given the wrong replacement springs (longer apparently) which caused an "ear" on the clutch lifter plate to snap off when tightening (much like the first water pump on my car I replaced) so I put the stock springs back in. I counted my stock plates I removed. I have 7. I also have 1 additional Barnett plate leftover.

I found an information sheet that came with the Barnett HPK-14 kit with a manufacture date of 6/23/99. It states:
"Note: Honda produced some CB750F Super Sport models that has a clutch that consists of six friction plates and one double, spring-loaded, riveted anti-chatter steel plate. To use our 7 plate kit in these models you will have to replace the double steel plate and run the normal 7 friction and 6 steel set-up. If you wish to retain the double plate, you will need just 6 friction plates. If in doubt, CHECK YOUR SHOP MANUAL AND/OR YOUR LOCAL DEALER."

It's been a while since I've done mine so I don't really remember. All I know is my clutch doesn't slip, it is noisy when not engaged, and I have 1 new Barnett disc still unused. I was assume from this that I retained my one double, spring loaded, riveted anti-chatter steel plate and it still chatters. At least it doesn't slip. Perhaps this unearthed info might help.

Jerry

[Big Jay]

Well I tossd teh Honda clutch package and went with the A.P.E. set up,  not a problem here I also use 10-50 wt. oil.  Give the heavy duty springs a try.  I also run a 78 F3 bottom end.

That is the answer to any 750  clutch issue. This kit has two more friction plates than stock. Your 7 disc clutch becomes a 9 disc and will hold all the power you can put to it.

http://cbrzone.com/clutches.html

[RRRToolSolutions]

Guys, thanks for the inputs. This is why I posted, I needed to know what would prevent the notchy shifting and keep the 1st gear "clunk" from happening. The Honda plates were purchased and installed to the factory parts fiche and shop manual. There are 7 fibers/6 steels/4 springs/4 new 6mm shoulder bolts in this clutch - straight from Honda. I soaked the fibers in oil for a couple of days before I installed them. During installation, I made certain that the fiber grooves all had the same back slash direction (sling the oil outward in normal rotation).

I'm going to re-install those springs since most here agree.

Thanks!!

[MRieck]

I'm late to the game but I've alsways used OEM steels and fibers with Barnett springs. Bead blast the steel plates too.

[RRRToolSolutions]

Mike, should I go back to the original dimpled steels that had 9,000 miles or stay with these new smooth ones?

At this rate, I'm going to have to quit using 1104 Bond and put the gaskets on dry. That stuff is a pain to get off the cases.

Thanks,
Gordon

[eurban]

Just to clarify here.  . . . .All stock K and Fs use 7 friction discs and 6 steel ones. The late bikes (I believe it is all the 77 and 78 models F and K ) use a "upgraded"  clutch that includes among other things a double thick riveted steel plate in the clutch sandwhich and an outermost  friction plate which has wider tangs.  The Fs may use stiffer springs.   The clutch center is actually about 1/8" deeper on these late stock  setups and the basket has a wider notch at the ends of the "fingers" which the wide tanged friction plate fits into.  As to the APE setup . . . .

Well I tossd teh Honda clutch package and went with the A.P.E. set up,  not a problem here I also use 10-50 wt. oil.  Give the heavy duty springs a try.  I also run a 78 F3 bottom end.

That is the answer to any 750  clutch issue. This kit has two more friction plates than stock. Your 7 disc clutch becomes a 9 disc and will hold all the power you can put to it.

http://cbrzone.com/clutches.html

The APE setup does not fit these late clutch packages with the stock double thick plate installed.  However if you ditch the double thick steel plate and replace it with a regular thickness plate (this would be in addition the extra steel plates that APE provides) then it will fit, but since the clutch center is actually deeper (but not deep enough to keep the double plate)the fit is less than ideal and probably contributes to the ruckus at neutral idle that I experienced.  Also the outermost clutch friction disc in the APE setup does not have the wide tang to properly fit the late style basket.  Basically in my opinion to make the APE setup work properly in the late bikes you would need to replace all the clutch parts (clutch pressure plate is probably OK) including the basket with earlier parts.  I know this is not exactly related to the orignal question but I don't think recommending this Kit to all 750 owners is proper; I for one spent a good chunk of $ to find this out!

[MRieck]

Mike, should I go back to the original dimpled steels that had 9,000 miles or stay with these new smooth ones?

At this rate, I'm going to have to quit using 1104 Bond and put the gaskets on dry. That stuff is a pain to get off the cases.

Thanks,
Gordon

I don't think  it makes a difference wether you use the new or old steels Gordon....just bead blast them and use the Barnett springs. I have new steels in mine though I'm running the F2 clutch assembly (with the riveted plate).

[angeldeville]

I'm going through some hassle with my new Barnett as well. my problem is chatter/slippage while taking off in first gear. I finally got fed up and put the stock stack back in with the barnett springs.

I wish this thread had shown up before I went through all this hassle!

[Sam Green Racing]

I went with Mikes sugestion of useing stock Honda plates with the stronger (Barrnet ?) springs.

Although we have only run the bike once, gear engagement is clean, slipping the clutch of the line is smooth and when it goes fully home it bites perfectly.

I think the 836, stock honda clutch and stronger spring set up is superb, thanks again to Mike.

Sam.

[scondon]

Same here,Sam   when I put the first bike together it was suggested that I just clean the steel plates, replace fibre disks with stock Honda, and add heavy duty springs. Well the heavy duty springs I ended up with were just way too heavy (could barely make it cross town before my clutch hand cramped up) so I put the stock F3 springs back in and have had a very decent clutch for 15,000 miles now despite the heavy demand the motor, and my throttle hand put on it.

    The '78 shop manual states very different wear limits between K8 and F3 clutch springs despite the fact that the clutch package is identical. this has led me to believe that the F3, and possibly F2, clutch springs are longer and "heavier' than other CB750's.

 Geez, Sam. You've been waiting an awful long time to reply to this thread, haven't ya

[Sam Green Racing]

There was a related thread and while searching for 836 related stuff came across this one, thought it was worth a bump Sean.

Sam.

[scondon]

There was a related thread and while searching for 836 related stuff came across this one, thought it was worth a bump Sean.

Sam.

   You bet,Sam. A lot of really good info has been buried over the years, glad ya dusted this thread off for another look

[RRRToolSolutions]

Hmm, I'd forgotten I had that trouble with the clutch. I guess it's a perfect time to report that even with lots more motor than before - the stock, Honda fibers and steels work perfectly using the heavy Barnett springs. I've not had one hint of it breaking loose and the clutch pull is still very nice. It's a firm pull, but the Honda design handles it perfectly.

Honda steels +Honda fibers + Barnett springs = happiness under a lot of pull.

Thanks to those steering me into the light on this one.. Gordon

 

[coyotecowboy]

I've got some high-RPM, high gear (4th and 5th) clutch slippage problems on a basically stock K2 (pod air filters and thats it).  I had the clutch apart about a month ago and checked everything with a micrometer, all parts mic'ed like they were new, the fiber discs still had the marks from the surfacing machine on them (probably don't now though ) The real problem is that I'm not sure if the clutch components are Honda, Barnett, APE or what.  The oil passages in the fiber plates are straight-cut, not slashed and the steels are peened or dimpled, whatever you want to call it.  It clunks into first (roll it ahead while snicking into first makes it alot better though) its hard to shift, like its sticky, occasionally find neutral while shifting, never when you WANT to find neutral (its hard to believe how fast those little fours hit 10,000  ) BUT it only takes light pressure to get the clutch to release.  Everything is adjusted by the book, if the books are right.  I'm running dinosaur oil (Valvoline 20/50 4 stroke motorcycle)  It seems like the clutch is releasing waaaaay early in the stroke, 1/2 inch free play and pull it another 1/2 inch and its fully released.

I'm out of ideas (short of putting stiffer springs in it or spring spacers) so I thought I better ask the experts

[nteek754]

Hey all well Ive had good luck will all setups barrnett (two differant ones) years ago  just the  fiber discs no springs but also  had good luck with  some stockers  and now running a  setup from ebay (it was cheap) and brand new in the package circycle  came with extra plates and heavier springs  running it in my 836  70 engine  the only thing it does once in a while is chatter a bit on take off its like its  in between bite or no bite it just wants to bite and no in between but I can live with that  now  to install them longer springs I used two longer bolts across corner to corner  sucked it in enough  too get two of the stock bolts started then got all four  STARTED key is to  bring them all in sloooowly  not to break an ear off the pressure plate seen that many times  think I did it 20 years ago  but one thing you got to keep in mind if you have one slip and ride it that way you are gonna  kinds glaze it and  it will never be right  unless you sometimes can take them out and sand them to roughen them back up a bit resoak and reinstall  like someone said theirs was slipping took it out and it  met all specs but was  probably glazed over  now here is a new twist brother  years ago put some washers in behind the springs useing stock plates and his clutch is working great been in two differant engines  but I think he had to modify the washers to fit in and not fetch anything up good luck have fun seven fifty four ever Craig in Maine