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10-28-2012, 01:01 PM
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#31 | |
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Ivanych
Joined: Jan 2011
Location: St. Petersburg. Russia
Oddometer: 213
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Quote:
Good luck in your work.
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10-28-2012, 02:18 PM
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#32 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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chain info
http://www.reginachain.it/eng/produc...es/honda.shtml
might be handy for someone! lots of info on chains |
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10-28-2012, 04:01 PM
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#33 |
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bikaholic
Joined: Oct 2009
Location: southcentral PA.
Oddometer: 1,536
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These older radial valve heads had problems with the valve seats coming loose in the heads .Warm the head up without the valves in and check them out.
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10-28-2012, 09:14 PM
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#34 |
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Aspiring human
Joined: Jun 2007
Location: SE Portland/ Carrboroland NC
Oddometer: 2,132
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^^^ I got paranoid enough about that issue that I bought a brand spankin' new oem factory head. The one in the first engine on my XL got so overheated by a PO that a valve seat dropped and was rattling enough to cause wear in the aluminum. Later found cylinder sleeve dropped in the aluminum as well. I never got it started with that head in there. I wonder if it would have run at all if I had gotten the new stator it needed first. I think XRs only does that service. I heard they do it at the factory with a certain tolerance machined then use liquid nitrogen to shrink the steel insert. One machinist at the auto parts store I was using was talking about making little ding marks all around the head where the valve insert goes, then a bunch of ding marks (with a center punch) around the valve seat steel insert, then using red loctite, pressing it in. I asked my retired, formerly fulltime self employed machinist friend about this procedure and he said "those guys are kind of a bunch of yahoos", at which point he explained how that would fail in short order, and how they do it at the factory. That got me asking all kinds of questions, like, can any used head ever be trusted knowing this?
The point of my long story about my experience with bad valve seats is: 1) take the valves out at least to see if the valve seat has obvious signs of overheating or any wear around the outside, and to see if the valve seat just friggin falls out. 2) don't take the head to any yahoos. Use a motorcycle-specific shop. 3)Don't get too paranoid. It is most likely fine and will be unless you overheat the shit out of the engine. P.s. there is a test you can do to check valves too. Tilt the head with exhaust ports toward the sky and try pouring solvent in there and see if it leaks past the valves. You can try petroleum based liquids of various viscosities to see if they leak, do this for intake side as well. Hopefully you honed the cylinder and a new set of rings, that's pretty important once they have seated they can't really find their original seal again once disassembled. And of the valves one more time, bar minimum take them out and replace the seals, before that, lap them with valve lapping compound and check to make sure there are concentric wear patterns all around the valve. Better one step than this is replace the valve guides too, but IIRC you are on a budget. You can lap the head mating surface on a piece of double-thickness glass with very fine sandpaper and something wet like mineral spirits. Same for the cylinder, but that's (hopefully) already on with it's nice hone job and set of piston rings.
__________________
1987 Yamaha XT600 2KF (German) STOLEN: RED XL600 in Portland I do heavy-duty textile repair, upholstery, and design/manufacture bags. |
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10-28-2012, 10:00 PM
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#35 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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I appreciate all the advice!
Here's what I am doing for 2 reasons: 1) money, 2) nervous about what else may be wrong. I have repaired the gearbox and inner engine with new gaskets and the shifter shaft. However, because I haven't heard the bike run and have no idea what else may be wrong, I am going to reassemble with a new timing chain and gaskets. I pulled the filter basket out of the frame and inspected it. No particles of any kind. The oil filter area also looks fine (I'm going to use that filter for the first oil warm up then drain/change oil and filter). The top of the piston had no carbon on it, although the two exhaust valves did. I cleaned them. I'm not going to re-ring it or change valve seals or anything else until I hear it run. Even if it's smoking I can at least verify gears, knocks, carbs, spark, etc. If it has issues with using oil, smoking, etc. etc. I can pretty easily take down the top end and fix those problems - in the frame if need be. The main area I have a concern about is the small end of the rod. it did have a small amount of scoring. I did buy a new piston pin and it seemed to fit ok, but... If it has a knock, i.e. crankshaft/rod or whatever, then I have to reassess the whole project as I probably will have to wait until the 'money tree' has grown more dollars... At least by that time I will have the whole thing reassembled instead of sitting around in boxes and yogurt containers in my garage... Yeah, I know, not exactly an ideal situation, but I really want to 'prove' the engine before I continue to throw money into it. The bike (supposedly) was running fine when the chain guide broke in two. However, my latest guess as to why it broke is because the chain was worn out and flopping around. My Scottish roots of being cheap are fighting a battle with my Swedish roots of excellence in mechanical engineering. LOL |
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10-30-2012, 03:41 PM
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#36 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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more parts arrive, timing chain ordered
Well, I now have the cam chain tensioner spring and washer for the kick start in my possession. Meanwhile I ordered a timing chain. If all goes as planned, should see the chain toward the end of the week. THEN I can continue to reassemble. The tensioner spring was definitely at least 1/4 of an inch less tension than the new one. The tensioner itself feels good though.
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10-30-2012, 03:51 PM
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#37 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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timing chain stretch question
Has anyone ever either measured or heard of a (factory) measurement between a certain number of links, for a timing chain on this engine? Just out of curiosity I would like to know the measurement of a 'normal' brand new chain per link length (lets say 10 links or something) and compare that to mine. If nothing else it would be a reference number for verifiable chain stretch.
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10-30-2012, 11:40 PM
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#38 |
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Aspiring human
Joined: Jun 2007
Location: SE Portland/ Carrboroland NC
Oddometer: 2,132
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Not sure about that but you have a new unit on the way so that's good. May I also mention that several XL'ers on here have had the insight to make a point of polishing their cam chain tensioner pivot pins with fine sandpaper. It gets rid of the polished spots on it and lets it grab again like it should. I advise it. I might have that old froze-ass timing chain around from the XR600 engine I got for parts, give me a couple days to dig around for it...
__________________
1987 Yamaha XT600 2KF (German) STOLEN: RED XL600 in Portland I do heavy-duty textile repair, upholstery, and design/manufacture bags. |
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10-31-2012, 06:42 AM
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#39 |
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Beastly Adventurer
Joined: Jul 2007
Location: San Francisco,Ca.
Oddometer: 7,984
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Cam Chain Stretch
You will never get an accurate measurement on a cam chain. The sure way to check is to install the chain and cam. If the cam drive gear marks line up with the head then the chain is fine. If not and it looks like the mark is about half a tooth off (it's always the forward mark being up) then that right there tells you the chain is stretched. Even if the chain is stretched the bike will still run. The cam timing will just be off a few degrees. More low end.
__________________
Steve in SF BMW's 58 R26 79 R100s 91 R100gs 87 Harley FXRS-SP ~ 06 KTM 625 SMC ~ 72 Honda CB750/915cc ~ 92 XR600/654cc ~ 95 XR650l/675cc ~ 03 CRF450r ~ 05 CRF450x ~ 02 XR650l/675cc ~ 86 YZ490 ~ 93 YZ80 ~ 93 XR650l Project |
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10-31-2012, 07:43 AM
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#40 | |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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Quote:
Thanks, I can put my old chain next to a straightedge and keeping the links in a straight line, change the length of the chain almost 1/4 an inch - and that's just one side of the chain. Also, when I wrap it around the sprockets and pull it tight, it won't line up with the final few sprockets - or, if I hold it tight at the bottom of the sprocket, it is loose at the top. DEF stretched! I did what you said too, and was out by a long way. Just was wondering if there was an accurate measure of new vs. old. I'm assuming it's the pins wearing out in each link versus the actual stretching of metal. |
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10-31-2012, 07:47 AM
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#41 |
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Beastly Adventurer
Joined: Jul 2007
Location: San Francisco,Ca.
Oddometer: 7,984
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The cam chain starts stretching on day one. If it's stretched it's toast. Quit playing around and buy a new one.
__________________
Steve in SF BMW's 58 R26 79 R100s 91 R100gs 87 Harley FXRS-SP ~ 06 KTM 625 SMC ~ 72 Honda CB750/915cc ~ 92 XR600/654cc ~ 95 XR650l/675cc ~ 03 CRF450r ~ 05 CRF450x ~ 02 XR650l/675cc ~ 86 YZ490 ~ 93 YZ80 ~ 93 XR650l Project |
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10-31-2012, 08:10 AM
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#42 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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10-31-2012, 12:46 PM
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#43 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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10-31-2012, 01:00 PM
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#44 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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Thanks, will def. do this...
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11-04-2012, 10:32 PM
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#45 |
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Gnarly Adventurer
Joined: Oct 2012
Location: Canyonville Oregon
Oddometer: 134
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Chain here?
The post office is torturing me. Timing chain - Online says notice in box, but window wasn't open on saturday...had to take wife marathon shopping instead. However, am really enjoying "The XL600 thread". Its my daily bedtime read! Thanks guys!
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