Wilsons Sandbox

Where did you measure the piston? At room temp the clearance spec is usually only for the widest part of the skirt. Devon bkowalca wrote:

> I just took the head off the engine (A14, 22,000kms). The cylinder > looks fine, I can still see most of the honing marks, a few verticle > scratches in the bore, nothing serious, what you would expect. There > is no ridge at the top of the cylinder. After giving a quick check > of the piston to cylinder clearance it was at least 0.025". I was > shocked! I can move the piston around in the cylinder. This can't be > right, I think most engines should have around 0.005 clearance. Does > anybody have the shop manual to verify what KHI wants this clearance > to be? It is possible the piston is worn this much, but the cylinder > isn't? It is possible that the manufacturing tolerances are out that > much? I'm confused. I was going to put a new set of rings in, but it > appears I might need an overbore as well. I can't believe this is > normal. The bike ran fine, but did consume oil a little more than > normal. > > Bryan K > A14

Hi Bryan, Manual says piston/cylinder clearance 0.043 - 0.070mm Piston Diameter : 99.942 - 99.957 mm Hope this helps, Dave A12 bkowalca wrote:I just took the head off the engine (A14, 22,000kms). The cylinder looks fine, I can still see most of the honing marks, a few verticle scratches in the bore, nothing serious, what you would expect. There is no ridge at the top of the cylinder. After giving a quick check of the piston to cylinder clearance it was at least 0.025". I was shocked! I can move the piston around in the cylinder. This can't be right, I think most engines should have around 0.005 clearance. Does anybody have the shop manual to verify what KHI wants this clearance to be? It is possible the piston is worn this much, but the cylinder isn't? It is possible that the manufacturing tolerances are out that much? I'm confused. I was going to put a new set of rings in, but it appears I might need an overbore as well. I can't believe this is normal. The bike ran fine, but did consume oil a little more than normal. Bryan K A14 List sponsored by Dual Sport News at www.dualsportnews.com. List FAQ courtesy of Chris Krok at: www.bigcee.com/klr650faq.html Unsubscribe by sending a blank message to: DSN_klr650-unsubscribe@yahoogroups.com . Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ --------------------------------- Do you Yahoo!? U2 on LAUNCH - Exclusive medley & videos from Greatest Hits CD [Non-text portions of this message have been removed]

Bryan, How are you measuring the clearance? Are you measuring with the piston in the cylinder and using a thickness gauge? If so, that's not the measurement you're after. The area of a piston around the rings and above the rings is smaller diameter than below the rings. The top part of the piston is subjected to more heat and expands more, so more clearance is needed. The best way to measure the clearance is to measure the bore with a inside micrometer and measure the piston with a outside micrometer. Measure both several places to check for taper in the cylinder and "out of round" in the bore and piston. Since you can see hone marks, I doubt that you have any serious wear in the cylinder. You will still need the thickness gauges. Before you put the new rings on the piston, put them in the bore and check the end gap of the ring. Also, after the rings are on the piston, use them to check the ring to ring groove clearance.

>>> I was shocked! I can move the piston around in the cylinder.

Keep in mind, that piston is going to expand more than the cylinder. Have fun, and let us know how the job turns out. Allan A14

----- Original Message ----- From: "bkowalca" To: DSN_klr650@yahoogroups.com> Sent: Friday, November 08, 2002 9:40 PM Subject: [DSN_klr650] Piston to Cylinder Clearance out of Control > I just took the head off the engine (A14, 22,000kms). The cylinder > looks fine, I can still see most of the honing marks, a few verticle > scratches in the bore, nothing serious, what you would expect. There > is no ridge at the top of the cylinder. After giving a quick check > of the piston to cylinder clearance it was at least 0.025". I was > shocked! I can move the piston around in the cylinder. This can't be > right, I think most engines should have around 0.005 clearance. Does > anybody have the shop manual to verify what KHI wants this clearance > to be? It is possible the piston is worn this much, but the cylinder > isn't? It is possible that the manufacturing tolerances are out that > much? I'm confused. I was going to put a new set of rings in, but it > appears I might need an overbore as well. I can't believe this is > normal. The bike ran fine, but did consume oil a little more than > normal. > > Bryan K > A14 > > > > List sponsored by Dual Sport News at www.dualsportnews.com. List FAQ courtesy of Chris Krok at: www.bigcee.com/klr650faq.html > Unsubscribe by sending a blank message to: > DSN_klr650-unsubscribe@yahoogroups.com . > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >

As I understand it, below the ring grooves a piston is not round at all. It's oval, so at operating temp it becomes round when the different thicknesses of metal at the skirt and around the wrist pin heat up. Did you do a leakdown test? Was the only reason you decided to change ring due to oil consumption? A leakdown test should identify leaky valve guides as well. Devon Allan Patton wrote:

> Bryan, > > How are you measuring the clearance? Are you measuring with the piston in > the cylinder and using a thickness gauge? If so, that's not the measurement > you're after. The area of a piston around the rings and above the rings is > smaller diameter than below the rings. The top part of the piston is > subjected to more heat and expands more, so more clearance is needed. The > best way to measure the clearance is to measure the bore with a inside > micrometer and measure the piston with a outside micrometer. Measure both > several places to check for taper in the cylinder and "out of round" in the > bore and piston. Since you can see hone marks, I doubt that you have any > serious wear in the cylinder. > > You will still need the thickness gauges. Before you put the new rings on > the piston, put them in the bore and check the end gap of the ring. Also, > after the rings are on the piston, use them to check the ring to ring groove > clearance. > > >>> I was shocked! I can move the piston around in the cylinder. > Keep in mind, that piston is going to expand more than the cylinder. > > Have fun, and let us know how the job turns out. > > Allan A14

So after I got the piston out today, I took some more time looking at this piston clearance issue. From the top, it appears that the piston is a very sloppy fit, and it is. The top of the piston is about 0.043" smaller than the skirt diameter, this difference being the source of my discontent. With the piston in the bore, I can get a 0.006" feeler gauge in between the bottom of the skirt and the bottom of the cylinder. It appears to be larger than the recommended clearance of 0.070mm (0.003"), if I am measuring it correctly. The piston and bore look to be in good shape, so my decision now is should I spend the money on a new piston and overbore, or just a new set of rings to freshen up the engine. Measuring this stuff is not a simple, the piston is not round and has different diameters by design. I have never worked on a big single like this, so the piston slop was usual to me, most of my bike work has been with smaller 2-stroke dirt bikes. If you haven't taken the head off before, the first thing you notice is that this is one huge piston, bigger than a 350 Chevy V8 piston (my reference point, I used to work in a GM engine plant). Is 0.003" of an inch worth an over bore? Bryan K A14

--- In DSN_klr650@y..., "bkowalca" wrote: > I just took the head off the engine (A14, 22,000kms). The cylinder > looks fine, I can still see most of the honing marks, a few verticle > scratches in the bore, nothing serious, what you would expect. There > is no ridge at the top of the cylinder. After giving a quick check > of the piston to cylinder clearance it was at least 0.025". I was > shocked! I can move the piston around in the cylinder. This can't be > right, I think most engines should have around 0.005 clearance. Does > anybody have the shop manual to verify what KHI wants this clearance > to be? It is possible the piston is worn this much, but the cylinder > isn't? It is possible that the manufacturing tolerances are out that > much? I'm confused. I was going to put a new set of rings in, but it > appears I might need an overbore as well. I can't believe this is > normal. The bike ran fine, but did consume oil a little more than > normal. > > Bryan K > A14

I don't see why you took the engine apart in the first place. I mean like, my front yard has a few bad spots, but I'm certainly not going to rip it all out and re-sod. Mark B2 A2 A3 At 10:52 PM +0000 11/9/2002, bkowalca wrote:

>The >piston and bore look to be in good shape, so my decision now is >should I spend the money on a new piston and overbore, or just a new >set of rings to freshen up the engine. > >--- In DSN_klr650@y..., "bkowalca" previously wrote: > I just took the head off the engine (A14, 22,000kms). >The bike ran fine, but did consume oil a little more than >> normal.

Doing engine work for a bunch of reasons: 1) Fix the dohickey. 2) Check the cam timing, maybe modify it because of item 4. 3) Port the head, clean up the exhaust, possibly do a high-velocity version of the intake ( http://www.mototuneusa.com/homework.htm ). The middle of page http://www.mototuneusa.com/the_2007_superbike.htm says he got about 7% increase in power on a KLR. 4) Remove the cylinder base gasket, drop the cylinder 0.016" to increase the compression ratio, check to see if there is valve/piston clearance issues. 5) Clean out the oil pump screen. 6) New rings and valve seals to fix increase in oil consumption problem. 7) Give the valves a light lapping to clean them up. 8) Set the valve clearance. 9) New oil filter, spark pluc etc. 10) Check the general wear and tear on the engine. It's a bit of performance mods, maintenance and blueprinting of the engine, my winter project. I plan on do some serious riding next season and I want the bike in top shape with a few more ponies to boot, increase the fun factor. Also, I really don't want a breakdown out in the middle of nowhere. Bryan K A14

>From: Tengai650 >To: "bkowalca" >CC: DSN_klr650@yahoogroups.com >Subject: Re: [DSN_klr650] Re: Piston to Cylinder Clearance out of Control >Date: Sat, 9 Nov 2002 18:51:59 -0500 > >I don't see why you took the engine apart in the first place. >I mean like, my front yard has a few bad spots, but I'm certainly not going >to rip it all out and re-sod. >Mark >B2 >A2 >A3 > > >At 10:52 PM +0000 11/9/2002, bkowalca wrote: >>The >>piston and bore look to be in good shape, so my decision now is >>should I spend the money on a new piston and overbore, or just a new >>set of rings to freshen up the engine. >> >>--- In DSN_klr650@y..., "bkowalca" previously wrote: >> I just took the head off the engine (A14, 22,000kms). >>The bike ran fine, but did consume oil a little more than >>> normal.

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Bryan, I'm very skepitcal about this guys performance claims, and his blanket statement that all or most bikes have factory porting that is too big to flow. Yes ports can be too large to flow correctly, Hardly's superbike engine for example. But the KLR is not a high revving engine to begin with, so extreme velocity is not a major tuning point. I'd check with others experienced in porting before filling my ports with expoxy. Also, a if I were going for performance, I'd look for a high compression piston instead of milling the head or cylinder so not to miss with the timing. Porting just isn't something I would miss with unless I had some time to experiment and a couple of extra heads to test ideas. I'd rather send my head to White Bros. or someone thats done it before. I know some on the list recommend against many engine mods, but I can't believe its so far to the end of its development that it won't respond to normal hop-up mods: Higher compression, bigger displacement, more radical cam timing, bigger carb, and higher flow exhaust. Porting and flowing is part of the picture, and I think if it was as simple as making the ports smaller for more velocity the factories would have figured it out by now. Just want you to be careful and not screw your bike up following someone unproven claims. Dave A12 Bryan Kowalchuk wrote:Doing engine work for a bunch of reasons: 1) Fix the dohickey. 2) Check the cam timing, maybe modify it because of item 4. 3) Port the head, clean up the exhaust, possibly do a high-velocity version of the intake ( http://www.mototuneusa.com/homework.htm ). The middle of page http://www.mototuneusa.com/the_2007_superbike.htm says he got about 7% increase in power on a KLR. 4) Remove the cylinder base gasket, drop the cylinder 0.016" to increase the compression ratio, check to see if there is valve/piston clearance issues. 5) Clean out the oil pump screen. 6) New rings and valve seals to fix increase in oil consumption problem. 7) Give the valves a light lapping to clean them up. 8) Set the valve clearance. 9) New oil filter, spark pluc etc. 10) Check the general wear and tear on the engine. It's a bit of performance mods, maintenance and blueprinting of the engine, my winter project. I plan on do some serious riding next season and I want the bike in top shape with a few more ponies to boot, increase the fun factor. Also, I really don't want a breakdown out in the middle of nowhere. Bryan K A14

>From: Tengai650 >To: "bkowalca" >CC: DSN_klr650@yahoogroups.com >Subject: Re: [DSN_klr650] Re: Piston to Cylinder Clearance out of Control >Date: Sat, 9 Nov 2002 18:51:59 -0500 > >I don't see why you took the engine apart in the first place. >I mean like, my front yard has a few bad spots, but I'm certainly not going >to rip it all out and re-sod. >Mark >B2 >A2 >A3 > > >At 10:52 PM +0000 11/9/2002, bkowalca wrote: >>The >>piston and bore look to be in good shape, so my decision now is >>should I spend the money on a new piston and overbore, or just a new >>set of rings to freshen up the engine. >> >>--- In DSN_klr650@y..., "bkowalca" previously wrote: >> I just took the head off the engine (A14, 22,000kms). >>The bike ran fine, but did consume oil a little more than >>> normal.

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M7 first 97 KLR was dripping a bit of antifreeze off the little port under the water pump, with a mere 20kmiles. So I did the water pump, mech seal, oil seal, and gasket. Piece of cake,worked great, and no more leaks. Worst part was pressing out the old and in the new mech seal. Finally used a block of 2x4, a large C clamp and a socket. In my experience, the downside of doing several upgrades and fixes, is that there's usually a break-in period to get some of the fixes themselves fixed up. Prolly be different if I played a mechanic on the TV. So you ought to figure on a shakedown run of some sort, before the CC50 or whatever big ride you have planned. Mark. A11, and loads of opinion.

--- In DSN_klr650@y..., "Bryan Kowalchuk" wrote: > Doing engine work for a bunch of reasons: > > 1) Fix the dohickey. > 2) Check the cam timing, maybe modify it because of item 4. > 3) Port the head, clean up the exhaust, possibly do a high-velocity version > of the intake ( http://www.mototuneusa.com/homework.htm ). The middle of > page http://www.mototuneusa.com/the_2007_superbike.htm says he got about 7% > increase in power on a KLR. > 4) Remove the cylinder base gasket, drop the cylinder 0.016" to increase the > compression ratio, check to see if there is valve/piston clearance issues. > 5) Clean out the oil pump screen. > 6) New rings and valve seals to fix increase in oil consumption problem. > 7) Give the valves a light lapping to clean them up. > 8) Set the valve clearance. > 9) New oil filter, spark pluc etc. > 10) Check the general wear and tear on the engine. > > It's a bit of performance mods, maintenance and blueprinting of the engine, > my winter project. I plan on do some serious riding next season and I want > the bike in top shape with a few more ponies to boot, increase the fun > factor. Also, I really don't want a breakdown out in the middle of nowhere. > > Bryan K > A14 > > >From: Tengai650 > >To: "bkowalca" > >CC: DSN_klr650@y... > >Subject: Re: [DSN_klr650] Re: Piston to Cylinder Clearance out of Control > >Date: Sat, 9 Nov 2002 18:51:59 -0500 > > > >I don't see why you took the engine apart in the first place. > >I mean like, my front yard has a few bad spots, but I'm certainly not going > >to rip it all out and re-sod. > >Mark > >B2 > >A2 > >A3 > > > > > >At 10:52 PM +0000 11/9/2002, bkowalca wrote: > >>The > >>piston and bore look to be in good shape, so my decision now is > >>should I spend the money on a new piston and overbore, or just a new > >>set of rings to freshen up the engine. > >> > >>--- In DSN_klr650@y..., "bkowalca" previously wrote: > >> I just took the head off the engine (A14, 22,000kms). > >>The bike ran fine, but did consume oil a little more than > >>> normal. > > > _________________________________________________________________ > Tired of spam? Get advanced junk mail protection with MSN 8. > http://join.msn.com/?page=features/junkmail