Topic: The snowball effect...or, how to maximize a stock 550

[Scott S]

 I was planning on building up an engine for my next 550 project. You know, MRieck head, cam, high CR pistons, etc. etc.
 After adding up the cost, I figured I was awful close to just getting the race engine that Justin has for sale. Justin was even kind enough to answer a bunch of questions for me (sorry for wasting your time, Justin ), but even after "de-tuning" it, it would still be pretty high strung for street use. Plus, I quickly surpassed the cost of the ZRX1100 I sold last year....you know, a 115HP bike with double the torque of a modded 550!

 I originally wanted to use a 550 based cam since I have a set of early style  small face gauges that were on my very first SOHC4. A bit of nostalgia. That means a hard weld cam, which leads to hard welded rockers, better springs, oversized intake valves, etc., etc. Then I need high CR pistons and an over bore. Machine shop work.  Might as well add in an adjustable cam sprocket now. It just goes on and on.....

 Then it hit me that I could easily buy a bike that would walk all over this modded motor for a lot less money. Yes.....I know we do it for the love of the bikes and as a hobby and the dollars spent don't really count.
 That's when I decided to just freshen up the stock 550 I have and spend the money on suspension, brakes, tires, etc. We're talking a couple hundred bucks for rings, lapping the valves and some gaskets and I can do all the work myself.

 But what about maximizing a stock 550? Maybe spend ~$500 for a Stage 1 head and keep the stock valves, no need for hard welding, etc. Have the head milled to tighten up the deck just a bit.

 Then I saw the Cognito Moto GPS speedometer and realized that's pretty cool, too. That would allow me to run a 650 cam and not need to swap tach drives.

 So....to make a long story longer....what about these things on a STOCK 550 engine? Worth it? A waste of time and money? Will I notice it?

1) Stage 1 MRieck head, stock valves, springs, etc. Should be plenty for a stock or CB650 cam.

2) Mill the head to tighten up the deck .038-.040" for better squish and a slight CR bump. Is this a good idea with stock pistons and valve reliefs?

3) Adjustable cam gear. It's only about $40 plus the time to learn how to dial in a cam. I've heard that these engines can benefit greatly from optimized/advanced cam timing.

4) 650 cam (dang it....I just sold one a couple of months ago). I've used them before and my butt dyno says that work. If doing the above mods and I don't care about the tach drive, is it worth spending ~$100 or so for a little more cam? Will it work if I tighten up the deck?

 So, basically, just optimizing and blue printing everything above the cylinders. Some fresh rings and gaskets. What do you think this would get me out of a stock engine?

[BomberMann650]

I couldn't tell ya, but I'm definitely interested in the results as that was kind of my pipe dream top end job.

If anyone has dyno comparisons of stock 550 vs 550 w/650 cam bolt on I'd like to see it!

[Scott S]

 I've done two with a home ported head, CB650 cam and over bore pistons. One was just a 1.00 mm over size, the other with Yoshimura 10.5 :1 pistons.
 Both ran great with stock manners until about 6K or so, when they seem to have more "oomph" than a stock cammed engine.

 That said, my 500+lb Tiger Xc would walk away from them like they're standing still. It's just so easy to get much more power out of more modern bikes.

 That's why I'm thinking about the above work. I bet I can do it all for half what a Stage 2 head and a hard welded cam costs, let alone any machining for pistons, etc. Just make a very efficient, crisp stock engine, more or less.

[calj737]

With a 650 cam, no need for an adjustable sprocket really. +1mm valves would be nice to wake up the motor. The balance of the machine work you mentioned is prudent.

[Steve_K]

Engine work can be fun, but for me, I would rather make my suspension the best it can be. That, I can use every time I ride her.  Put better brakes on and you got a good handling scooter.
Steve

[seanbarney41]

Engine work can be fun, but for me, I would rather make my suspension the best it can be. That, I can use every time I ride her.  Put better brakes on and you got a good handling scooter.
Steve

+1, I have never been unhappy to enjoy the gutsy oomph of stock sohc4's.  I agree that building engines for these gets expensive when you can buy a whole early 2000's cbr600 in good shape for less.   Chassis, suspension and brake improvements really make for a bike that is fun to ride at closer to legal speeds.

[Scott S]

 If I use the stock cam but deck the head to tighten up the squish, is there enough lift to worry about interference? Should I still clay it?

[bwaller]

Unless you've owned it since new you cannot be sure that someone before you hasn't already removed material off somewhere. Absolutely you must check clearances before doing that kind of work.

Forgive me but I always found the 500/550's were toads, but that's when I was young & they were new. Nowadays most people have something modern to scratch their itch and the 40 year old is for entertainment! One thing about the 550 the little engine is quite robust and can still be reliable at twice it's original HP offering. The small combustion chamber with it's 15 degree squish shelf can be used to advantage making power, especially with a piston dome to match, but even with a stock one. It's rewarding work Scott if you measure first what clearances it has piston/head. It's not uncommon to find the piston is down the bore 0.016" or so stock so you have a couple options. You can remove material from the deck to tighten squish or remove some & use thinner head or base gaskets to get to the same result but always measure. It means test assembling a couple times, but not doing so is reckless! The beauty is now (even 40 years on) we have suppliers offering lots of good aftermarket parts, gaskets included ....it's crazy! 

So if you choose to "not go nuts" you can still improve it with good build techniques. I would still suggest you at least do a home job in the ports and get a bit of a cam, tighten up that squish area and probably see low 40's hp. Six extra is certainly enough of a power difference to feel. 

[flatlander]

your plan sounds reasonable. what are you thinking of doing for pistons? most people who want more power out of the 550 on a budget seem to combine a 650 cam with cruzinimage bigbore pistons. if you need a rebore, might as well throw that in.

you're right about it all being a bit of a wasted effort compared to newer bikes, especially 10 or 15 years old ones that you can pick up quite cheap. but it's not about that. it's about picking a 40 years old bike that you like and turn it into something that you like even more and that makes sense to you, personally. if you want to compete with new bikes or want the performance of new bikes, get a new bike.

maybe ask yourself: why this bike, and what do you want to do with it, how do you wan to use it?
over here in the netherlands my impression is that most people, like 99% of them, keep them stock. they may rebuild them nicely but don't do all the performance work that seems to be more popular in the US, unless they're actually racing. they want a nice old bike to cruise around on weekends or summer evenings, maybe take part in some oldtimer meetings and such. no need for performance upgrades for this kind of use. they would probably call me an idiot who is throwing lipstick at a pig but hey, it's my pig and my lipsticks.

[Scott S]

Engine work can be fun, but for me, I would rather make my suspension the best it can be. That, I can use every time I ride her.  Put better brakes on and you got a good handling scooter.
Steve

 That's the plan. I've already collected most of the parts for an R6 front end swap with much better brakes in the bargain. I also just ordered a set of Koni shocks from NobleHops. I have bronze bushings for the swing arm and have been researching/daydreaming about bracing it and the frame.

[Scott S]

your plan sounds reasonable. what are you thinking of doing for pistons? most people who want more power out of the 550 on a budget seem to combine a 650 cam with cruzinimage bigbore pistons. if you need a rebore, might as well throw that in.

 

maybe ask yourself: why this bike, and what do you want to do with it, how do you wan to use it?
over here in the netherlands my impression is that most people, like 99% of them, keep them stock. they may rebuild them nicely but don't do all the performance work that seems to be more popular in the US, unless they're actually racing.  they would probably call me an idiot who is throwing lipstick at a pig but hey, it's my pig and my lipsticks.

 See....there's the snowball effect. If it needs boring, why not go for Wiseco pistons and get some compression? There are people who say the CruzinImage kits aren't really performance pistons, just an overbore. If I had to pick between cc's and compression, I'll take compression.
 And now that I have Hi-Po pistons, I need headwork to match. Which means hard welded cam and rockers....and on and on and on....like a snowball rolling down the hill.

 Why this bike? Because out of all the vintage (and not so vintage) makes and models I've owned, I have a real sweet spot for the 500/550. It's just "fits". Not too big, not too small. Plenty of smooth power (yeah....all the XS650's I've had were more powerful, but nowhere near as refined feeling). I have tons and tons of spare parts for them. I know how to work on them.

 And I don't feel bad about keeping this one "not stock". I mean, just look what I'm starting with!




 I have spare engines; two 500's (one locked up, one good) and two 550's (one locked up and missing a couple of parts, one good). But there's evidence of a little oil weeping around the head gasket on the 550 and if I'm going in there...... snowball effect.
 That's why I wanted to just "maximize" it but keep it relatively stock.

[Scott S]

Unless you've owned it since new you cannot be sure that someone before you hasn't already removed material off somewhere. Absolutely you must check clearances before doing that kind of work.

Forgive me but I always found the 500/550's were toads, but that's when I was young & they were new. Nowadays most people have something modern to scratch their itch and the 40 year old is for entertainment! One thing about the 550 the little engine is quite robust and can still be reliable at twice it's original HP offering. The small combustion chamber with it's 15 degree squish shelf can be used to advantage making power, especially with a piston dome to match, but even with a stock one. It's rewarding work Scott if you measure first what clearances it has piston/head. It's not uncommon to find the piston is down the bore 0.016" or so stock so you have a couple options. You can remove material from the deck to tighten squish or remove some & use thinner head or base gaskets to get to the same result but always measure. It means test assembling a couple times, but not doing so is reckless! The beauty is now (even 40 years on) we have suppliers offering lots of good aftermarket parts, gaskets included ....it's crazy! 

So if you choose to "not go nuts" you can still improve it with good build techniques. I would still suggest you at least do a home job in the ports and get a bit of a cam, tighten up that squish area and probably see low 40's hp. Six extra is certainly enough of a power difference to feel. 

 This.
 This is pretty much what I was thinking. Imagine that there's a race class that requires all stock stuff. What would people do to maximize the original parts? Blueprint the engine, so to speak.
 Is there anything to be gained with timing a stock or 650 cam? With a timing wheel and adjustable cam gear?

[calj737]

Head work and hi-po pistons dont require hardweld cam/rockers. A 650 cam in that head (+1mm intakes and porting) will be loads better than stock. Maybe not a firebreather, but plenty good for street.

[bwaller]

Is there anything to be gained with timing a stock or 650 cam? With a timing wheel and adjustable cam gear?


Probably not much, but it's good practice and you'll know for certain afterward it's the best it can be!

[Scott S]

Head work and hi-po pistons dont require hardweld cam/rockers. A 650 cam in that head (+1mm intakes and porting) will be loads better than stock. Maybe not a firebreather, but plenty good for street.

 MRieck's price sheet and Dynoman's page both suggest it when going with a performance cam. The core is hard welded up to make the performance cam, and that leads to hard welded rockers, etc.

 Kinda got my feelers out for a 650 cam ( I KNEW I should have held on to the one I had....), and I've been reviewing my notes and pics on head porting.
 I think milling the head for proper deck height/squish is a relatively cheap and beneficial option, too.

[calj737]

Yeah, you need to hard weld a performance cam, but a new/hard weld cam isn't required with Wisecos was my point. You can do this build in stages:

Wisecos and head work now.
650 cam now.
MegaCycle cam and rockers later (if desired) because you can sing all them without pulling down the motor.

***Just be certain of how much you mill now because if later you do use a performance cam, you want to be 100% on clearances.

[Steve_K]

I saw that tank and thought, maybe the gas cap could be saved.  First time I have seen a tank like that.  That is a good choice for what ever you want to do.  If you save that bike, good on you.
Have at it!!
Steve

[Scott S]

I saw that tank and thought, maybe the gas cap could be saved.  First time I have seen a tank like that.  That is a good choice for what ever you want to do.  If you save that bike, good on you.
Have at it!!
Steve

 Oh, I'll save it. I've started with less. Luckily, the P.O. wanted to keep that tank for some strange reason. I was glad...it was full of old gas and rain water and the mosquito's were eating us alive.
 Here's the bike as found, parked in 1983 as a running bike:
 


 I have a super nice tank I picked up at the Spring meet at Barber for $60, a set of side covers that have been in my closet for years, the seat is actually really nice, etc.
 I have carbs, Lester's, 400F bars and pegs, etc. I pretty much have enough spares to get it going again, easily.

[bwaller]

More to what Cal is saying, unless a change is requested in making custom pistons, aftermarket will/should come with the same compression height but the dome will change. So I would go ahead and set up squish clearance @ 0.040". Even if a change to different pistons is made, again there are options for different gasket thicknesses. Yes, ideally build it all at once but for a less expensive bump, AND for a few shillings..... 

[Scott S]

So I would go ahead and set up squish clearance @ 0.040".

 Is this covered anywhere on the site? I'd love to see a "how-to" and some pics.

[bwaller]

I'll try to get a couple pictures to save some typing.

[Lostboy Steve]

Before I read Hondamans advice on porting these heads, and I had mine off, I went kind of crazy matching everything up and removing material where I thought it would matter. Ultimately did it make a difference? No idea. I figured the head was off and I was lapping the valves and replacing the valve seals and everything anyway so why not? I was keeping the stock pistons with new rings and cerakoting on the skirts and faces. I figured my build was more about keeping the engine robust and economical. Both of which it has proven to be. I ride my 550 all over and I treat it like a goldwing, which is why I'm assembling a goldwing now, to have something to take the stress off of the cb.


Sent from my iPhone using Tapatalk

[bwaller]

Sorry Scott, I haven't found any pictures and don't have an engine at a point where I can take anything meaningful. Basically you want to install the pistons (no need to use pin clips) with the cylinder down on a stock base gasket (might as well be a new one) on the cases. Make sure both the cylinder bottom & upper case are scraped clean of any old gasket.

You want to "clamp" the cylinder down on the case. I use a couple pieces of 1.25"x 1/4" steel bar front to back on the 2nd studs from both ends with aluminum spacers between the bar & the top of the cylinder. Then just spacers in the middle near the chain tunnel one front, one rear. Don't over torque the nuts. The cylinder might twist with too much torque in just a few spots. Just cinch it down.

Then I bring a piston to TDC and use a dial indicator and magnetic base on the steel bar. Loosen the magnet & drag the zero'd indicator across the top of the sleeve flange then onto the piston to find how far the piston is below deck.

With only one ring the pistons will not center in the bore perfectly so check a few spots around the circumference to get an idea. Check each piston too. Short of a dial indicator I suppose feeler gauges & a straight edge might also work.

[Scott S]

 And once I find that measurement, how do I use it? How do I use that number to determine how much I can mill off the head?

 At this point, I'm thinking about just doing a minor amount for straightness and a slight bump in CR. I *doubt* that the 650 cam is wild enough to cause any valve to piston interference if I take off .010 or .015, no?
 Without claying the head/piston, is there a safe amount that can be done on the 550? I'm leaning towards milling the head vs. the cylinders so that I don't get into cam chain length/timing issues. I know all this stuff is somewhat easily overcome but, again.....snowball.

[calj737]

Taking off 0.01 - 0.015 at the block and another 0.05-0.07 at the head will not cause a cam chain issue. BUT, you will definitely need to trim the dowels so the head sits flush to the block. Best to do both surfaces for best, true and flat fit.

Once you determine the clearance of piston to surface, and piston/valve, you can decide on cam (650 is non-issue) and milling distances. Then you determine which head gasket thickness you use to achieve your finally "squish". Expect to find the piston sitting about 0.025-0.032 short of the block surface (at least mine was). This allows a great deal of milling before any conflicts arise between piston/valve with stock components.