Author Topic: StrongPerf CB550 Engine Build - Gentleman's Express Style (Read 25584 times)

moham · « **Reply #50 on:** June 01, 2009, 06:31:57 pm »

Quote from: bwaller on June 01, 2009, 06:03:35 pm

Well moham although I never liked the Barnett clutches, but don't be too hard on them.

We're all a little guilty of forgetting these bikes are 30+ and I'm sure they don't sell that many parts for these, so them not being current is forgiveable I recon!

Don't get me wrong, like I said they were extremely helpful. Just off a bit. Only sucked for me because I didn't know the difference at first either.

Hopefully I like the clutch because I've heard both sides from different folks.

And you're right, anybody selling aftermarket bits for these bikes after all these years is going to get my support (well, not just Anybody....)

Beans · « **Reply #51 on:** June 01, 2009, 06:54:13 pm »

Just tuned in and can't wait to see the build. was thinking about doing the same thing to my 550 motor. anyone have the article I can read to get more info on the 590cc engine build?

StrongPerf · « **Reply #52 on:** June 01, 2009, 10:05:49 pm »

Thanks for the clutch answer Moham. I feel much better about it now.

Beans, I have the article. PM me your email and I'll send it to you.

Beans · « **Reply #53 on:** June 02, 2009, 12:30:09 am »

speaking of this 590cc big bore kit. When I was searching the net for piston rings for my 550 I found this. would this help with the kit. found some cylinder sleeves and pistons. here are the cylinder sleeves http://www.dynoman.net/engine/pistons/hondaSleeves.html and here are the pistons. http://www.dynoman.net/engine/pistons/custom.html I figure im needing some piston rings might as well just build the full motor.

StrongPerf · « **Reply #54 on:** June 04, 2009, 04:50:59 pm »

Quote from: texaninseattle on June 04, 2009, 02:37:11 pm

Im curious to see what its going to cost to have the 750 pistons cut.

I will do it myself. Free...

razor02097 · « **Reply #55 on:** June 17, 2009, 05:12:38 am »

Updates yet? Just found this thread. I imagine there would be applicable info for my 650

StrongPerf · « **Reply #56 on:** June 17, 2009, 06:37:57 am »

No updates yet. The trans/lower half is back together with new chains and seals. I've been very busy at work but plan to cut the pistons soon. I'll share all when done.

Shenanigans · « **Reply #57 on:** July 20, 2009, 01:21:36 am »

Hurry up and get to those pistons!

I have a CB550 overbore project and I already have the 750 pistons and like to see how well it goes...

MRieck · « **Reply #58 on:** July 20, 2009, 04:49:27 am »

I have a set of 750 pistons for the 550 at the machinist's now (waiting for the cylinders to be bored. I didn't modify them..... the customer did. I can take a pic when the work is complete. Domes were modified and the skirts cut a bit.

bistromath · « **Reply #59 on:** September 01, 2009, 02:44:09 pm »

Mike, I'd love it if you could take a pic or two.

Mind if I hijack a bit? It's on topic....

I'm setting up a GE-style build, and while blueprinting I found some oddness in the cut they recommend for the 750 pistons. The stock 550 pistons are flat-topped with small valve reliefs of around 0.3cc total volume, and measure 22.65mm from pin center to shoulder. They sit 0.4mm in the bore. The 750K pistons (marked "300") are spherically domed, 1.5mm higher in the center than the edges, and measure 24.3mm from pin center to shoulder. Modeling this up in CAD and then modeling the "Gentleman's Express" modifications shows a dome volume of 3.0cc (without valve reliefs), with a piston shoulder that sits 0.4mm higher than the 550 piston, or flush in the bore. The problem is I'm calculating a compression of 12.4:1 with this setup! Not even huge valve reliefs are going to take enough metal out to bring that down to the 10.0:1 they give in the article.

Now, I know math isn't a substitute for a burette, but since I'm so far off I'd like to know what the $%^& went wrong before I cut metal. Any ideas? Do we know if they used "F" or "K" pistons for the article? They sure look like "K" pistons to me.

Shenanigans · « **Reply #60 on:** September 01, 2009, 03:07:17 pm »

1+ on the pictures...

bistromath check out this thread, if I am understanding everything correctly you may be using the wrong style pistons. Even if they are marked 300...

http://forums.sohc4.net/index.php?topic=57528.msg622879#msg622879

bistromath · « **Reply #61 on:** September 01, 2009, 03:19:10 pm »

As far as I'm aware there is only one type of piston marked "300", and those are the ones I've got on my desk. I can take a photograph if it would help.

Shenanigans · « **Reply #62 on:** September 01, 2009, 03:29:50 pm »

Im an idiot, I was thinking that it was the 300 pistons that overlapped with two different piston profiles but its the 392

Kemp · « **Reply #63 on:** September 02, 2009, 03:16:41 pm »

On my CB500 "Gentleman's Express" style project I tried a mix and match of bits to improve clutch performance. The CB500 clutch would slip with just a fast shift and the clutch was hair trigger in or out (stock engine). I used friction plates from the CB550 series with an extra CB650 steel plate which was the same thickness as the stock CB500. This allowed me to get an extra steel and an extra friction plate into the basket yet retain the same stack height as a stock CB500 (the CB550/650 friction plates are thinner than the CB500's). I tried using heavier EPM springs made as a kit for the 500/550. They were 10mm longer than stock and made the clutch just too stiff for around town although the action was really smooth and positive. I went back to the stock springs and found the clutch effort just fine (basically stock pressure) with a solid, smooth engagement and no slip. The parts were all used but spec'd out as okay for tolerances.

HondaMan · « **Reply #64 on:** September 13, 2009, 08:32:59 am »

Quote from: bistromath on September 01, 2009, 02:44:09 pm

Mike, I'd love it if you could take a pic or two.

Mind if I hijack a bit? It's on topic....

I'm setting up a GE-style build, and while blueprinting I found some oddness in the cut they recommend for the 750 pistons. The stock 550 pistons are flat-topped with small valve reliefs of around 0.3cc total volume, and measure 22.65mm from pin center to shoulder. They sit 0.4mm in the bore. The 750K pistons (marked "300") are spherically domed, 1.5mm higher in the center than the edges, and measure 24.3mm from pin center to shoulder. Modeling this up in CAD and then modeling the "Gentleman's Express" modifications shows a dome volume of 3.0cc (without valve reliefs), with a piston shoulder that sits 0.4mm higher than the 550 piston, or flush in the bore. The problem is I'm calculating a compression of 12.4:1 with this setup! Not even huge valve reliefs are going to take enough metal out to bring that down to the 10.0:1 they give in the article.

Now, I know math isn't a substitute for a burette, but since I'm so far off I'd like to know what the $%^& went wrong before I cut metal. Any ideas? Do we know if they used "F" or "K" pistons for the article? They sure look like "K" pistons to me.

The 750K0-K6 pistons are flat-topped, and most have small valve reliefs in them. The K7-K8 (and "F") pistons are domed. The domed ones are for use in hemi heads. I have seen (and actually have one) aftermarket pistons that are marked "300", but are for the later engines. The later ones should be marked "392". Some aftermarket builders must have goofed...

Don't overlook the chance (I would call it a 'requirement' if I were building one of these GE engines-) to add the quench band to the head. This consists of a tapered ring (or donut) area all around the chamber that starts at the bore diamter and blends into the combustion chamber that now exists. It will significantly reduce compression while also reducing knock tendencies and will improve mixing and burn. It can easily add 1cc to the chamber volume. It will also greatly deshroud the valves, for much improved breathing. This change will also improve upon the famous 'flat spot' that these particular engines (500/550) have in the midrange.

Ecosse · « **Reply #65 on:** September 13, 2009, 08:57:29 am »

very cool hm!

cb550fcafe · « **Reply #66 on:** September 24, 2009, 04:31:44 am »

What head gasket is used? Stock or some other aftermarket? I'm rounding up the parts I need to do this.

fastbroshi · « **Reply #67 on:** September 24, 2009, 05:47:58 am »

Quote

This consists of a tapered ring (or donut) area all around the chamber that starts at the bore diamter and blends into the combustion chamber that now exists.

HondaMan, could you elaborate?

What you described almost sounds like one of those o-ring reliefs cut into a head for heavily turboed engines, except it sounds like you're talking about boring out the combustion chamber to match the bore of the cylinder.

razor02097 · « **Reply #68 on:** September 24, 2009, 07:12:59 am »

That is to get rid of the sharp ridge when using a head with a bigger chamber right? The ring is build into the head gasket?

StrongPerf · « **Reply #69 on:** November 24, 2009, 03:38:48 pm »

Ok guys, machine work on pistons is done. Pictures to follow soon. I'm in the process of mock up assemble to check clearances! They came out good and all the machine work was done on a lathe and drill press in my garage!

StrongPerf · « **Reply #70 on:** November 24, 2009, 06:19:40 pm »

pics here showing difference in crown heights. left stock 550, right stock 750 and middle modified 750.

also skirt being cut on lathe. I cut them shorter than the 7mm because I noticed 2 different lenghts on 2 different sets of 300 pistons. I cut until I was comfortable with skirt to counterweight clearance.

StrongPerf · « **Reply #71 on:** November 24, 2009, 06:26:34 pm »

dome cut in lathe. note the 4 jaw adjustable chuck and the fixture my machinist friend made for me.

StrongPerf · « **Reply #72 on:** November 24, 2009, 06:29:03 pm »

3 machined domes, 1 stock 750 piston still needing machining and 1 old 550 piston for comparison.

StrongPerf · « **Reply #73 on:** November 24, 2009, 06:31:55 pm »

On to valve pockets. I just used the old ones on the 550 pistons for reference making them the same depth and in the same location. I used a $13 fly cutter I bought at the local hardware store. I have a cross slide vise from Harbor Freight. I also have a drill press with a tilting table which I think is hard to find (I found mine in a dumpster!). Pics are worth 1000 words...

StrongPerf · « **Reply #74 on:** November 24, 2009, 06:35:58 pm »

pockets

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Author Topic: StrongPerf CB550 Engine Build - Gentleman's Express Style (Read 25584 times)