Topic: Building a high-perf engine next winter. Lots of questions.

[Highwayhigh]

Hey everyone. I'm Logan, I ride a '78 550k, and as the title states, I plan on tearing my motor apart and rebuilding it solidly next winter. I know I'm going to bore it out, probably the 590 setup, but I am still entertaining the idea of using the 650 guts and head to make it a 718, though to me it doesn't seem as pure. Then again, I suppose a 590 isn't pure 550 either. Haha. I plan on making at or over 70hp with the finished product. That's my goal at least. Is that pretty unreasonable? If not, is that achievable with the 590 or will I need to do the 718?

So far on my bike I've gained progressively more knowledge. The day I brought it home, I had a very loose grasp on even the simplest procedures. Now I can pull, strip, and rebuild my carbs in my sleep. Just changed a cam the other day (for me, that was a big step), rebuild the brake system. I can do most of the stuff on the bike. The only thing is the clutch and Engine work. And on the engine work, I'm extremely inexperienced, so I am coming here to start getting a better picture of what I'm looking at doing in the winter. I know winter is a ways off, but I want to start learning and planning now. So here go my questions:

When doing head work, do it myself or have a shop do it?
Should I just smooth out the intake and exhaust ports, or actually make them larger, and increase valve size?
Hondaman mentions putting "pockets" above the intake valves, what in the world does he mean by that?
With my HP goals in mind, would I need new carbs? If not, aside from jetting, would the stock carbs need porting at all?
With my HP goals in mind, I intended to do head work, maybe new valves and springs, obviously new pistons, rings, sleeves, etc., but will I need to do some bottom end work too? Like connecting rods and crank work? Or could I get away with the stock stuff?

I know it's a lot of questions, and I'm sorry. I'm trying to do a lot of my own research as well, but these are pretty specific and I haven't found answers to them really. Again, I just want to know what I'm getting in to, so later I know WHAT to look for in a shop, and I'll know what to tell them to do to my motor. Thanks guys!

-Logan

[sangyo soichiro]

In case you haven't seen these, check out Paulages build in the project section, and check out livefastdieold's and Howell's builds in this section. 

I'll let the experts guide you further.

[paulages]

Turboguzzi's cb500 makes 65HP, but it's a race bike, likely very peaky, and like any race bike needs to be torn down and rebuilt often. I forget the member's name, but there's another on here from germany who has done the 550/650 hybrid, but is only 620 or so cc's. both his and mine make exactly 69.7 HP. i can't comment on his (which is also a race bike), but mine is very streetable. if you want 70 or more HP out of a 550 while maintaining broad torque and idle for street riding, i'd shoot for 10-11/1 CR, a REALLY nicely ported/flowed head, a nice cam, and likely a 650 head.

several in this racing section have built some 500s with nice HP numbers... getting them to give up tuning secrets is another story...  

[Highwayhigh]

Paulages! Thanks for chiming in. I've read about your bike. That's an incredible build man, definitely an inspiration. You mention using a 650 head, does that mean you recommend maintaining stock displacement or still use the 650 guts/jugs/head? I suppose I'm still inexperienced with motor builds and I want to make sure I end up with a quality product from someone who knows what they're doing. Maybe I'll send it to MRiek, I've heard he does magic with these engines.

Also, having done the swap, how does it ride? Obviously it's near twice the power of stock, but still not fast enough to beat modern sport bikes, but would you say it's a pretty strong bike? Thanks again for your help! I guess I still have a good deal of research ahead of me.

-Logan

[turboguzzi]

Turboguzzi's cb500 makes 65HP, but it's a race bike, likely very peaky, and like any race bike needs to be torn down and rebuilt often. I forget the member's name, but there's another on here from germany who has done the 550/650 hybrid, but is only 620 or so cc's. both his and mine make exactly 69.7 HP. i can't comment on his (which is also a race bike), but mine is very streetable. if you want 70 or more HP out of a 550 while maintaining broad torque and idle for street riding, i'd shoot for 10-11/1 CR, a REALLY nicely ported/flowed head, a nice cam, and likely a 650 head.

several in this racing section have built some 500s with nice HP numbers... getting them to give up tuning secrets is another story...  

Im @61 last time i checked, howell and col seem to be around 65... snif...

If its a street bike, I would definitely go with the 718 route for longevity and powerband width, wouldnt want to ride with my bike's 6k-to 10k powerband on the street.

fast enough to beat modern sport bikes? is that the point? In real twisties its 90% up to the rider. So leave some budget for advanced rider training, best go-fast tuning you can do.

TG

[Highwayhigh]

Thanks Turboguzzi. I appreciate the input. And I never intended to beat sport bikes by any means. I think that for these bikes to beat modern sport bikes is not really achievable by the average joe. So yes, my main focus when I ride is the twisties. Going fast in a straight line is fun for a little bit, until you realize it's never fast enough and you will always be pushing that. But I really do want to breathe life in to the engine. Modernize a bit. Obviously I want this to be a street bike so I think I will go the 650 route. Should I still port/flow the stock 650 head? Also, are the carbs adequate for a performance build like this? I just want to know if I should start looking for upgrades. CR's a touch out of my budget range. Anyways, thanks again for all the input guys. Your bikes have both been an inspiration to me in building mine. Thanks for showing people that the 500/550 can still be a force to be reckoned with.

[edit] - Also, does anybody know of a good place to buy velocity stacks? I want to ditch my pods and go that route.

[Duke McDukiedook]

How much money do you plan on spending on this engine overhaul?
Do you have a good grasp on what it will take money-wise to do it properly?

Is this your only bike you are riding right now because if you can afford the money to hi-po an engine properly, you have enough money to buy a bike and ride while you wrench on this bike. You will want a bike to ride while you work on this.

Is your engine working fine right now?

[Hannibal Smith]

Never mind the snobs in the "Racing" forum that have not realized that they are only heroes to about 5 divorced guys...............

Anyway, I am punching out my 550 to to 592 with 61mm pistons, and once I get my pistons in, will start a thread on the process.

My base mill was a flawless, perfectly maintained motor, and I am definitely well over $1000.00 in so far, and the bottom end is the only part buttoned up.

The top end is where money starts to go!

For starters budget $1500.00 minimum, and that is on a cherry base motor. Labor is the real killer. I own a full CNC equiped manufacturing facility, but send stuff out for some operations, because it is specialized like boring/honing etc. So some costs you simply cannot avoid if you want it done properly.

[paulages]

Turboguzzi's cb500 makes 65HP, but it's a race bike, likely very peaky, and like any race bike needs to be torn down and rebuilt often. I forget the member's name, but there's another on here from germany who has done the 550/650 hybrid, but is only 620 or so cc's. both his and mine make exactly 69.7 HP. i can't comment on his (which is also a race bike), but mine is very streetable. if you want 70 or more HP out of a 550 while maintaining broad torque and idle for street riding, i'd shoot for 10-11/1 CR, a REALLY nicely ported/flowed head, a nice cam, and likely a 650 head.

several in this racing section have built some 500s with nice HP numbers... getting them to give up tuning secrets is another story...  

Im @61 last time i checked, howell and col seem to be around 65... snif...

If its a street bike, I would definitely go with the 718 route for longevity and powerband width, wouldnt want to ride with my bike's 6k-to 10k powerband on the street.

fast enough to beat modern sport bikes? is that the point? In real twisties its 90% up to the rider. So leave some budget for advanced rider training, best go-fast tuning you can do.

TG

Boo hoo... ONLY 61 HP out of a 500cc bike.


HighwayHigh-

If you want to keep up in the twisties, first make sure you sort out your chassis/suspension. For what it's worth, I only spent $500 or so on my bottom end, and that included every bearing, chain, seal, clutch plates, etc, as well as seals up top.

If you want to go the cheapest 550/650 route, keep the stock liners and buy pistons from Soos. I can't remember the max you can bore, but the magic will mostly happen in the head and by having a nice compression ratio. If you can't find a local machinist to do the necessary case mods, PM me.

[Highwayhigh]

I figured I would build the engine up first, then handle the suspension next, but I may reconsider that now. I know the back shocks are garbage, I need bronze swingarm bushing, and maybe new springs in the forks, and I'm currently installing tapered roller steering bearing. Anything I'm forgetting?

My initial budget I'm hoping to hit is 1200-1500. I don't have a secondary bike but I plan on doing this over the winter. Here in Missouri there's absolutely no riding weather for 4 or 5 months. So that will give me something to work towards over the winter, and bring the bike out of hibernation as a whole new beast.

How much should I be looking at for bore/hone? What about port/flow the heads?  These are the only two thing I have NO clue as to how much it's gonna cost me. Also, I initially didn't plan to do much work to the bottom end, maybe a beefier clutch and the 650 crank, but that's it. Should I plan on more work on the bottom? I understand this is a big project and I may have a steep learning curve and a big reality check when I start the project, which is why I'm getting as much knowledge as I can now. Hopefully I'll have a more clear picture of what I'm getting into. Thanks again for all your help. It looks like I'll be going the 718 route, a la Paulage. I have read your write up and I probably will again to get a better idea of what that entails. Did you use the 650 cylinders? Is that required for the 650 head to bolt on? Anyways, thanks guys!

[paulages]

I figured I would build the engine up first, then handle the suspension next, but I may reconsider that now. I know the back shocks are garbage, I need bronze swingarm bushing, and maybe new springs in the forks, and I'm currently installing tapered roller steering bearing. Anything I'm forgetting?

My initial budget I'm hoping to hit is 1200-1500. I don't have a secondary bike but I plan on doing this over the winter. Here in Missouri there's absolutely no riding weather for 4 or 5 months. So that will give me something to work towards over the winter, and bring the bike out of hibernation as a whole new beast.

How much should I be looking at for bore/hone? What about port/flow the heads?  These are the only two thing I have NO clue as to how much it's gonna cost me. Also, I initially didn't plan to do much work to the bottom end, maybe a beefier clutch and the 650 crank, but that's it. Should I plan on more work on the bottom? I understand this is a big project and I may have a steep learning curve and a big reality check when I start the project, which is why I'm getting as much knowledge as I can now. Hopefully I'll have a more clear picture of what I'm getting into. Thanks again for all your help. It looks like I'll be going the 718 route, a la Paulage. I have read your write up and I probably will again to get a better idea of what that entails. Did you use the 650 cylinders? Is that required for the 650 head to bolt on? Anyways, thanks guys!

you want the 650 cylinders for the tensioner, for the most part. FWIW i use stock clutch springs with no preload, barnett friction plates, and the 650 basket/primary gear and get no slippage at all.