Topic: Re: 650 overbore/550 engine hybrid underway...final stages

[paulages]

i started tearing down the 650 last night, and now i have a better understanding of what would be neccesary to do either option working around the oil passages. there is only about 2.5 mm clearance from the existing sleeves to the passages to the head, and that's roughly equal to the radius increase with the 750 liners. seems to me like you'd have the same problem no matter what pistons you are using if you use the 750 liners. i really like the idea of running external lines, so i'll probably just leave the spigot centers where they are and figure out the best way to plug the oil passages from the block. still can't tell where he's got his lines running from, but i'm assuming an adaptor at the oil filter would work, as with the oil coolers.

[paulages]

i spent the evening tearing both engines down, comparing each component as i stripped it. still haven't split the cases (i will tonight), but it appears as if i will be able to do this:

-550 bottom case, to keep the kickstart (the 650 case wasn't machined at all at this point)
-650 top case, to allow clearance for the hy-vo cam chain. no milling neccesary, as with the instructions provided by mr. hayes
-550 gearbox and clutch
-650 crank
-750 sleeves
-65mm pistons (maybe from an 836 kit)

i will provide an update with photos (for those who have been interested in the comparison of 550/650 engine internals) when i get the cases apart. one clear difference so far: the 650 cylinder studs are considerably thicker than the 550 studs, and are actually bolts, rather than studs with double-ended threads with have the nuts on the top. dynoman say that they have never heard of heavy duty studs for the 650, but they look pretty good to begin with. much thicker than the stock 550 or 750 studs.

[Tommy Neimeyer]

Did I understand you to say you will be using the bottom case from a 550 and the top case from a 650?

If so, this would be the first time I have ever heard of this.  Do they have the same O.D. on the crank journals?  How will you decide which bearings to run if each case half requires a different bearing?

Also isn't there a difference in the primary chain tensioner between the 550 and 650? 
Can they be mixed and matched?

More questions to follow.....

Cheers, Tom

[Pinhead]

I understand wanting a kickstart, but I'd personally keep the 650 lower half simply due to the vastly improved clutch... Especially since you're going for higher horsepower.

[Tommy Neimeyer]

Paul,
  A couple of other things come to mind.  If you run oil lines to the head, you will need to put some type of oil restricter in the line so you don't rob the oil from the main bearings.  I would also block the old oil passage at the head as well as at the case, no sense in letting oil work it's way down and find a way to seep out.

I appreciate you sharing the 550/650 comparison, keep it going.

Cheers, Tom

[paulages]

tom, you may be correct about the crank journals. i split the 650 case tonight, but didn't have a proper puller to remove the alternator from the end of the crank. as i understand it, the 550 and 650 cases were the same before machining, this being the entire reason why the 650 top end fits on the 550 cases. i imagined the journals to be part of the casting process, but hadn't considered that they could have been machined differently with the 650. if Honda was trying to save in production costs by reusing the 550 cases, it seems (and also going by their history of reusing existing parts when engineering new bikes) that they would have simply left the journals alone and designed the 650 crank around them. this is of course speculation about something which has a definite answer...hopefully tomorrow i will have it open, and then move on to opening up the 550 for comparison.

by the way, do you know where the oil lines were fed from on that 550? from the gallery openings just beneath the crank on the bottom case? seems like if you were going to thread in a hole for the lines at the ends of the cam, you could also thread in a hole just where the oil passages turn up to go through the cylinders, thereby feeding the exact same amount of oil it would have had anyway.

[scunny]

to remove your alternator, just use a bolt of the same threads, the crankshaft end is a taper, the alternator has an internal thread, the rear axle from the 650 is the same pitch, but any coresponding diameter and thread bolt will do

[bryanj]

Mix n match on casings is NOT a good idea as they are machined as pairs to get the mains in line and sized right, for an example try swapping just a bearing cap on a 750 cam tower---usually takes about 6 to get one thats close enough to run and they aint as highly stressed as cranks!
500/550 dont have primary chain tensioners, which is why the chain can eat into the oil galleries--never pulled a 650 that far down so dont know but the chain is the same part number so i doubt it.

Wish i had the time and parts to do one of these, i think it will be a hoot when you eventualy get the carburation right----have fun finding main jets, i had some tiny adaptors made so i can use screw in type that are way cheaper and easier to get!

[MRieck]

Mix n match on casings is NOT a good idea as they are machined as pairs to get the mains in line and sized right, for an example try swapping just a bearing cap on a 750 cam tower---usually takes about 6 to get one thats close enough to run and they aint as highly stressed as cranks!

I totally agree. I've seen people get away with it on modern bike engines but I would still never do it.

[dusterdude]

couldnt you align bore/hone the mains or would that be cost prohibitive?

[bill440cars]

I understand wanting a kickstart, but I'd personally keep the 650 lower half simply due to the vastly improved clutch... Especially since you're going for higher horsepower.

                        I know that the 550 clutch is better than the early 500 but, is the 650 clutch actually
             better and, if so, how is it better? Also, on the subject of the 500, weren't they improved by
             the time the 73' model came out? I hope so, cause if I get to do something like this later, I
             want to put the 650 parts in a 500 case and covers to bring a 500 up to the 736, 740 or
             whatever can be accomplished.  I am really digging this subject. I hope, when it's all said and
             done, that this will be saved for future reference.    Later on, Bill ;

[Tommy Neimeyer]

Dusterdude,
In theory, yes, you could align bore/hone the mains.  However, I have not heard of oversized main bearings for these engines (I'm not saying they don't make them). 

Paul,
  The oil feed comes from a drilled and tapped hole into the main galley behind the oil filter.  The supply galley is the same one that feeds the original oil passages.  It is not the size of the oil passage that restricts the flow, the original oil passages have restrictors in the alignment pins between the case and cylinders.

When you pull the cases apart, the bearing bosses will look the same, but they may actually be different.  I do not have my manual here but when Honda machines the cases, they measure the final hole diameter and assign it a number or letter designation.  This designation is used when you select bearings.  If the bearing is a "A" in the top case and the bearing is a "B" in the lower half, you may end up with more or less clearance that desired.  I understand these differences between bearings is roughly .0006"-.0008" so it may still work.  I would not mix and match cases unless it was a absolute last resort.  I think the bearing code is stamped on the back end of the cases.

Bill,
As far as clutches, the 650 clutch is retained by a nut and does not have to be shimmed like a 550 that uses a spring clip.  It also uses a different throwout bearing assemble much like a CBX/CB1100F.

Seems to be a lot of interest guys, keep digging.

Cheers, Tom

[MRieck]

 A friend of mine and I have mixed main and rod bearings as sets in an attempt to tighten squish on roadrace engines that don't allow decking. Every little bit helps when you're racing.

[Pinhead]

One of the more pesky problems associated with hot-rodded engines is the increased strain on all the hardware between crank and rear wheel. Honda's solutions to the problems are clever and numerous. The first is an oil feed pipe aimed right at the Hy-Vo type chain connecting the crank and primary-drive jack-shaft, which insures that the chain isn't going to fail for lack of lubrication. They lightened the load on the clutch by reducing the primary reduction ratio, trading a higher clutch speed for lower torque applied at the clutch plates. It's not the first time they've employed the same expedient. The original CB500's 3.25:1 primary ratio became 3.06:1 in the CB550, and now has been revised to 2.74:1.

The CB650's clutch performed in a manner beyond serious reproach. It had a little cold-oil drag on its first use in the chill of the morning, enough to get a clunk out of the shift into low gear and a forward lurch of perhaps an inch. Apart from that, the clutch was perfect. Honda built a new kind of low-friction release mechanism into the cover, the clutch springs are extremely light, and just one middling-strong finger can supply enough pressure to pull the lever right back against the handlebar grip. Best of all (especially for inexperienced riders), the clutch engages ever so gently, with a broad range of lever movement from first contact to full grip. It is a world easier to cope with than some of the toggle-switch clutches some motorcycles still have.

from http://sohc4.us/650/articles/79650rt

That's why I'd stay with the 650 clutch!

[paulages]

pinhead,
i've read such articles...the problem is, if you follow this line of reasoning you end up with a modern sport bike! if i really wanted everything to be as perfectly functional as possible with no regard to any other aspect, i would just buy a new bike. when i look at the 550 design, it looks sleek and graceful. when i look at the 650 design, it reminds me of every '81 honda civic i've bought for $200 and beat into the ground---works like a champ, but doesn't win too many awards in the classic department. i would gladly keep the 650 clutch if i could have the 550 kickstart and clutch cover. part of the idea here for me, after all, is to have a 740cc bike that looks like a 550. classic and beautifully designed.

in any case, i'm just having fun with it. i'm sure new clutch plates and heavy duty springs alone will help considerably.

[bill440cars]

                Hey there,
 
                            I just found, from a buddy (that I got the sidecar from), that I'm getting a
               basket case CB650 for free. I've seen it before (I don't remember what year it is or exactly
               what's wrong with it though) and while it's not in good shape, I think it's pretty complete
               except for maybe the gastank and the seat. Should be a pretty good donor for a "Long
               Term" 500/550/650 project motor. I have to do something with my garage. I absolutely
               have no room and no work bench to open up a motor on. I gotta do some rearranging.
               I'm kinda like some people who pickup stray animals except mine are bikes usually in various
               stages of disrepair. I keep telling my wife, "At least they're not cars or trucks" Ha!Ha!

                                                                 Later On, Bill

[scunny]

I know about the lack of room in the garage. I was pulling apart my spare 650 motor yesterday and had to do it on the floor. no shelf or bench space left due to 2 bikes already in pieces 

[paulages]

i have ample room...but i'm losing my shop this month. 

[bill440cars]

i have ample room...but i'm losing my shop this month. 

scunny,
            Floor space, what's that? I've got a path that will let me come into the garage (1-car), from the kitchen, go almost to the outside wall. At that point, I can either go to the left (which takes me through the utility room and then outside) or I can go to the right (which will, with some maneuvering, take me to the overhead door. Now, I can move the sidecar setup outside and gain that much space temporarily (because I don't leave that outside if it's raining or getting dark. I really do need to do a serious cleanup in my garage.   

Paul,
            Buddy, I feel for you losing your shop and all. How are you gonna function? I mean doing that 550/650 Hybrid work, you gotta have some space somewhere.

                                                 Later on, Bill

[paulages]

we're looking for another shop. worst case scenario, i can do the actual engine work in my basement, but i'll need a dry shop to actually put it in the bike. i'm crying over losing this shop. it's huge, perfectly located, and unbelievably cheap. they're turning it into "work lofts". #$%*ing yuppies...

[paulages]

i now have both engines disassembled, bagged, labeled, boxed, and ready for some dish soap and a scrubber.

i have a question for you 750 hotrodders (Mreick, samcr750 and the bunch): what do i really need, and what will just be nice to have? dynoman has 29mm cr carbs, can custom make pistons, can get carillo rods made, etc.  Depending on the price, i could see custom pistons being very nice...valve cutouts would match the head perfectly, etc. What are the major benefits of cr carbs? are my rods really going to be that inadequate? i've been told that honda really overbuilt a lot of #$%*...a local mechanic compared the cb160 gearbox to a 650 ninja in terms of ruggedness...but i don't want to underestimate the results of such a power increase.

any thoughts?

[MRieck]

 How much do you want to spend? The pistons are a real good idea. The stock rods should be fine especially if you polish the beams, shotpeen and balance them. Use new rod bolts. I'd balance the crank or lighten and balnce it...APE does it for short money and the work is OK. The head and cam are important. Porting and a Serdi valve job are a very good ideas as is a cam with good lift ( an extra .050 or .060) and moderate duration. Heavier aftermarket  valve springs would be nice or shim up some new/low mileage pieces. Off hand I don't know if Kibblewhite makes them. Stuff like undercutting the transmission is a good idea but once again it's a matter of money.

[paulages]

How much do you want to spend?

after i win the lottery? lots!

for now, i really just don't want to shortcut anything that will undermine the project. i figured on heavy duty valve springs. i'll look into ape's prices, and see if my local machine shop doing the other work can do it. what about SS valves? seems like polished stockers could do about as well. as for the cam, at least the 650 and 550 cams can be swapped out in the bike. so if i don't do it straight away, then i can always upgrade farily easily later. i plan to have it dyno'ed to help with sorting out the carburetion, so i guess doing it all at once would save some money there. how about the cr carbs, MReick?

[kayaker43]

First some quick thoughts. Don't mix cases, they are definitely match bored and graded for bearing sizes. even if you got lucky with the bearing codes matching, the bore centers would never match. It might be easier to machine the 650 cases for kickstart?? Finding big pistons are an issue, and its tricky to machine for valves and head clearance when you can't see inside. I was going to use a junk ebay head and cut a section away to allow visual inspection of the combustion chamber to help with piston mods.

I thought I was going to be the 550/650 hybrid pioneer, but my project will be delayed till next summer. I'm thrilled to see someone else pick up the ball and run with it first. I already had a couple of old 590 race motors full of Yosh parts and CR gearboxes. I recently picked up a low miles 650 engine, then later found a brand new one in a crate. so I'm set for engine parts.

I talked to a guy racing vintage at Mid-Ohio this summer and I'm certain this was the silver bike posted earlier in this thread. Here's what he had: 550 bottom end with yosh rods I think - 650 cylinders, re-sleeved - re-worked KZ650 65mm pistons - oversize? valves - total loss ignition. He claimed 700cc and said it was a torque monster. He also said he had to use the milder (Yosh?) cam because the big valves hit on overlap. It seemed very tractable with the mild cam. ,.. wish I got his phone number, but he was from the west coast i think??

My plans are to make sort of a retro looking bike with modern suspension and wheels. I have CBR600 F4i wheels and forks, and will run a re-worked F3 swingarm with the F4i single shock. My late 70's CB590 roadracer also had single shock rear grafted on. The CBR's ran regular forks up till 04, so I can keep the classic looks with modern function. I can't find the old 3 spoke Dymags like I used, but the later CBR wheels look similar and use modern 17 inch tires and brakes. My old racer weighed 350lbs, so figure a super light 740cc vintage sleeper with modern CBR handling!! It would be fun for a 50 yr old guy to show up at track days and spank a few kids on their new bikes. Not quite the horsepower (maybe), but on a tight track,.. who knows??

For motor I am going to use the 650 bottom end with 550 covers to disguise it. I wont need kickstart because the 5 speed Yosh close ratio trans won't fit with it. If I use the 6 spd CR trans, I can't use e-start either, so it will be bump start!! I'll use 650 cylinders, crank and head, but trim the fins a little to look like 550's, and use a 550 cam cover. I'll shoot for 65mm (740cc) with stock 650 valves so I can run the hotter yosh TT100 cam.  I've got to find some smoothbore or CR carbs??

It should be hard to tell its not a 550 except for the 650 clutch cover. I'm hoping the 550 cover will fit and there may be some way to still use the 650 clutch?? Paulages - please let us know about clutch and cover interchangability??

[Pinhead]

Very soon I will know if the 550 alternator will work on the 650. Parts are in the mail. I'll let you all know how it works out.