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A long time pro puller/engine builder just sent this to me.
<blockquote><hr size=0><!-quote-!><font size=1>quote:</font>
When boring the block, the bore must have equal clearance between all the head bolts. This is accomplished by shimming the boring bar on one side before the actual boring process begins. It's close, but if performed correctly, it can be done.<!-/quote-!><hr size=0></blockquote>
<blockquote><hr size=0><!-quote-!><font size=1>quote:</font>
When boring the block, the bore must have equal clearance between all the head bolts. This is accomplished by shimming the boring bar on one side before the actual boring process begins. It's close, but if performed correctly, it can be done.<!-/quote-!><hr size=0></blockquote>
D
dvogt
Guest
that don't mean much. actally if you want to do a good job you measure down between the cooling fins and center it off the theoretical center. theres nothing saying the headbolts are remotly close. I've seen some that cut into the outside of the bore , others don't come close. some is in casting thickness. you definatly don't want to center off headbolts. you'ld be better off centering off the flange that extends off the bottom of the bore than the headbolts. either way boring that much for anything other than pulling will probably give you problems. We always strp the cylinder down to the block when they are bored thin.
my 2¢
I would think (quit laughing) that the "ideal measure point" would be from the installed crank rod journal center. Since the piston / rod has to bolt to the journal then it would dictate the bore location. If you have to bore off center then would you mill off the equal amount (offset) from the rod and cap then shim the opposite side ?
I would think (quit laughing) that the "ideal measure point" would be from the installed crank rod journal center. Since the piston / rod has to bolt to the journal then it would dictate the bore location. If you have to bore off center then would you mill off the equal amount (offset) from the rod and cap then shim the opposite side ?
Ken-
The piston has quite a bit of play that can make that up, seems as though it's +/- .050, ideally it should still be centered like you were thinking . . .
Still with the casting of the time having tolerances somewhere around +/- .060 or likely more, boring the block is sort of a crapshoot IMHO . . . not that I'd discourage someone, but I'd think a head/jug restraint would be somthing to consider.
just thinking out loud . . BUT would it be possible to re-jug a single cylinder block with one like that of a K582 engine, or have I sat in front of the CAD station too much to have logical thought . . .
The piston has quite a bit of play that can make that up, seems as though it's +/- .050, ideally it should still be centered like you were thinking . . .
Still with the casting of the time having tolerances somewhere around +/- .060 or likely more, boring the block is sort of a crapshoot IMHO . . . not that I'd discourage someone, but I'd think a head/jug restraint would be somthing to consider.
just thinking out loud . . BUT would it be possible to re-jug a single cylinder block with one like that of a K582 engine, or have I sat in front of the CAD station too much to have logical thought . . .
D
dvogt
Guest
theres alot of people that go for offset boring & angle boring for a reason. Theres alot of different things you can do with bore location for various reasons
Ahhhhhh. You Guys have to stop thinking "ROUND Pistons" I think it was the Honda CX500 motorcycle from about 15 or so years ago had OVAL pistons? It was OHC as per typical Honda design so the oval bore had room for Huge valves, decent plug location. But before You Guys Flame Me too much just let Me say this that it must not have worked too well because Honda only made them for 2-3 yrs. I can imagine ring sealing was a REAL problem since the rings couldn't spin around the ring grooves. I imagine ring sticking was a problem.
KENNY - Yes, I know, Pistons are actually very precisely ground "Out-of-round" so when they heat up and expand they are round, and the skirt area will be a different shape & diameter than the ring land areas. But the actual difference in a three or four inch piston probably doesn't exceed .020". This Honda CX500 was a transverse Vee-twin like a BMW, and the heads actually were angled on the cylinders so the carbs were tucked in behind the cylinders, and the exhaust ports were way out in the breeze, and the bores measured something like 1-1/2" wide by 2-1/2" long and displaced about 250 cc per cyl. Pretty novel design, and rare enough I've never seen one in person, just pic's in magazines.
Ken - The spec's didn't say anything about Oval bore & pistons. I may have the wrong model. I'll have to check My old Cycle magazines! But that was the model I was thinking had the oval pistons. With gas over $2/gal. I wish I could find one in real good shape!
Hi Guys!
No- the CX500 didn't have the oval pistons... it was another Honda model, and it didn't go into large-scale production. They actually started the oval-bore bit on single-cylinder development motors. You're right that the design was based on the concept that it allowed larger valves in a smaller bore, and they actually wanted to put 'em in production for a racing-advantage, but they found that the production costs and tolerances were economically infeasable.
The CX500 was an 84-degree 499cc liquid-cooled V-twin, longitudinal with the frame. As noted, the exhaust ports were canted outward, with carbs tucked in towards the frame at about a 40-degree angle. This wasn't to keep the exhaust flanges cool, but more to put the carbs where they wouldn't interfere with the rider's knees. The cylinder heads were 4-valve pushrod-actuated jobs, with one pushrod opening two valves through a rocker-shaft, where each 'leg' of the shaft had a 10mm locknut and adjustable head, to allow adjusting valve lash.
The CX500 series was first shipped to the US market in 1978, and it's production ceased in 1985. It was available in several versions:
CX500D (for Deluxe... the 'typical' version)
CX500C (for Cruiser... had slightly different bodywork)
CX500T (turbocharged, fuel injected, lower CR, road-race bodywork and suspension)
CX650C (slight bore and stroke)
GL500 (Silverwing, with fairing & saddlebags)
GL650 (Silverwing, with fairing & saddlebags)
Unlike every other Universal Japanese Motorcycle of the time, the CX/GL 500/650's had ONLY TWO CHAINS in the entire motorcycle. One chain drives the camshaft, the other drives the oil pump. The cycle is shaft-driven. On early models (prior to mid-1981), the radiator is cooled by a mechanical fan. The camshaft is located in a valley between the cylinders (like a classic US V8), and the camshaft extends through the front of the block, to a fiberglass-reinforced-plastic fan with aluminum hub. After mid '81, Honda eliminated the mechanical fan, and installed an electric fan on the radiator, and put a temperature switch on the radiator tank.
CX500s were conservatively rated at about 45hp. CX650's were more like 58hp. CX500T's were about 118hp.
Discontinuance of the CX/GL-500/650 was less due to success, than it was saturation. The little V-bikes went phenominal distance in comparison to air-cooled competetors. They were svelte bikes, weighing in at about 470lbs dry. With floorboards, fairing, stereo, bags, and trunk, mine weighs 517lbs. Add a few more pounds if you change the original forks/steering/brakes to that of a GL1000 (which I did).
As testament to their soundness in design and manufacture, my '79 CX500D had 162,000miles on it when I parked it just under 3 years ago. I had three reasons for parking it: 1) summer was ending 2) Nick was due in December 3) the (original) water pump seal started leaking when running, and I haven't gotten it changed. So I filled the engine with new coolant, filled the motor (to the top) with oil, drained and cleaned the carbs, and tucked it away. If/when I ever get it out, I'll have to go through the brakes, change that pump seal, etc... alas, I probably won't get to ride again 'till my kids are out of school... and by then, I'll probably get a Moto-Guzzi, or a Boss Hoss... or mebbie a 2-wheeled Cub Cadet...
No- the CX500 didn't have the oval pistons... it was another Honda model, and it didn't go into large-scale production. They actually started the oval-bore bit on single-cylinder development motors. You're right that the design was based on the concept that it allowed larger valves in a smaller bore, and they actually wanted to put 'em in production for a racing-advantage, but they found that the production costs and tolerances were economically infeasable.
The CX500 was an 84-degree 499cc liquid-cooled V-twin, longitudinal with the frame. As noted, the exhaust ports were canted outward, with carbs tucked in towards the frame at about a 40-degree angle. This wasn't to keep the exhaust flanges cool, but more to put the carbs where they wouldn't interfere with the rider's knees. The cylinder heads were 4-valve pushrod-actuated jobs, with one pushrod opening two valves through a rocker-shaft, where each 'leg' of the shaft had a 10mm locknut and adjustable head, to allow adjusting valve lash.
The CX500 series was first shipped to the US market in 1978, and it's production ceased in 1985. It was available in several versions:
CX500D (for Deluxe... the 'typical' version)
CX500C (for Cruiser... had slightly different bodywork)
CX500T (turbocharged, fuel injected, lower CR, road-race bodywork and suspension)
CX650C (slight bore and stroke)
GL500 (Silverwing, with fairing & saddlebags)
GL650 (Silverwing, with fairing & saddlebags)
Unlike every other Universal Japanese Motorcycle of the time, the CX/GL 500/650's had ONLY TWO CHAINS in the entire motorcycle. One chain drives the camshaft, the other drives the oil pump. The cycle is shaft-driven. On early models (prior to mid-1981), the radiator is cooled by a mechanical fan. The camshaft is located in a valley between the cylinders (like a classic US V8), and the camshaft extends through the front of the block, to a fiberglass-reinforced-plastic fan with aluminum hub. After mid '81, Honda eliminated the mechanical fan, and installed an electric fan on the radiator, and put a temperature switch on the radiator tank.
CX500s were conservatively rated at about 45hp. CX650's were more like 58hp. CX500T's were about 118hp.
Discontinuance of the CX/GL-500/650 was less due to success, than it was saturation. The little V-bikes went phenominal distance in comparison to air-cooled competetors. They were svelte bikes, weighing in at about 470lbs dry. With floorboards, fairing, stereo, bags, and trunk, mine weighs 517lbs. Add a few more pounds if you change the original forks/steering/brakes to that of a GL1000 (which I did).
As testament to their soundness in design and manufacture, my '79 CX500D had 162,000miles on it when I parked it just under 3 years ago. I had three reasons for parking it: 1) summer was ending 2) Nick was due in December 3) the (original) water pump seal started leaking when running, and I haven't gotten it changed. So I filled the engine with new coolant, filled the motor (to the top) with oil, drained and cleaned the carbs, and tucked it away. If/when I ever get it out, I'll have to go through the brakes, change that pump seal, etc... alas, I probably won't get to ride again 'till my kids are out of school... and by then, I'll probably get a Moto-Guzzi, or a Boss Hoss... or mebbie a 2-wheeled Cub Cadet...
Dave -- I just knew with that windy post you were talking from experience
On filling the engine to the top with oil ... I'm not to sure about that ... when's the last time you changed it ?? I had a set of Crane needle bearing roller rockers back in around 74 - 75 and I didn't use them on the 327 I built so I put them in a jug and opened a fresh can (YES CAN!) of 40wt Racing Valvolene and dumped it on them. I let a guy take them to Dearborn to sell them for me , he ended up misplacing them and not finding them for 12 years !! He brought what was left of them back to me ... the oil had ate up the aluminum and it was flaking a part like slate.
On filling the engine to the top with oil ... I'm not to sure about that ... when's the last time you changed it ?? I had a set of Crane needle bearing roller rockers back in around 74 - 75 and I didn't use them on the 327 I built so I put them in a jug and opened a fresh can (YES CAN!) of 40wt Racing Valvolene and dumped it on them. I let a guy take them to Dearborn to sell them for me , he ended up misplacing them and not finding them for 12 years !! He brought what was left of them back to me ... the oil had ate up the aluminum and it was flaking a part like slate.
Yep- definately experience. Great motorcycles!
I think the oval-piston wonder was the Honda RE-5, but not positive...
Ken- the oil... yes, I changed it all out, and I used Spectro Golden synthetic... it's fine in there, believe me! (oughta' be... it's not called 'golden' for no reason!)
I think the oval-piston wonder was the Honda RE-5, but not positive...
Ken- the oil... yes, I changed it all out, and I used Spectro Golden synthetic... it's fine in there, believe me! (oughta' be... it's not called 'golden' for no reason!)
Gotta correct myself.
After doing some googlin', it's the NR500 and it's bretheren that had the oval piston.
http://www.v-four.freeserve.co.uk/nr750.htm
and also at the Honda website... just search for
Honda oval piston.
After doing some googlin', it's the NR500 and it's bretheren that had the oval piston.
http://www.v-four.freeserve.co.uk/nr750.htm
and also at the Honda website... just search for
Honda oval piston.
Hey Don-
On the K241... I've got my breather off, resetting valve lash, and I noticed this before, but didn't think much of it at the time, but I see when I roll the engine over, that the cam/tappet interface is cut to cause the exhaust valve to rotate... but my intake valve isn't rotating at all...
Were these cams cut to rotate just one, do I have a cam wear problem, or is what I'm observing related to the ACR function? other'n lack of visible rotation when I crank it over, the valve seems to be working okay...
When I checked lash before, the intake was a tad tight (0.015"), but exhaust was fine (0.018). I've been running 'em a bit loose for the last few hours (along with MMO) to get the crud out... it's running better now, but the ACR's not workin' great (with the valve lash so wide), and was gonna set 'em back to 0.018"...
On the K241... I've got my breather off, resetting valve lash, and I noticed this before, but didn't think much of it at the time, but I see when I roll the engine over, that the cam/tappet interface is cut to cause the exhaust valve to rotate... but my intake valve isn't rotating at all...
Were these cams cut to rotate just one, do I have a cam wear problem, or is what I'm observing related to the ACR function? other'n lack of visible rotation when I crank it over, the valve seems to be working okay...
When I checked lash before, the intake was a tad tight (0.015"), but exhaust was fine (0.018). I've been running 'em a bit loose for the last few hours (along with MMO) to get the crud out... it's running better now, but the ACR's not workin' great (with the valve lash so wide), and was gonna set 'em back to 0.018"...
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