Twincam.GTi Posted September 6, 2005 Share Posted September 6, 2005 Hello everybody, In my family we run a 1981 Yamaha XJ550 (black with the orange pin striping)which we have owned since 1989 and used since as everyday transport all year round (winter and summer). It has now reached roughly 90,000 miles without an engine rebuild as yet (but read more of later) and still on original clutch/drivetrain. Naturally during our time of ownership it has had a few replacement exhausts (thanks to all that lovely corrosive salt they put on the roads in the winter in the UK ), we've had to do a partial re-wire (original fuse box etc. carroded to bits), many tyres, many fork seals and many chain and sprocket kits plus many, many regular oil and filter changes. The panels/frame are still the original ones except the front mudguard which we replaced in '98 due to the original rusting (lovely UK Climate again). Only mods/Extras on bike are a JMC back suspension and engine protector bars. Not a minter but a well used and reliable mode of transport. However this week we suspect we have a burnt valve . So a top end strip down may be required, my mechanical apptitude is fine due to years of running old timers/Jalopies/bangers of various sorts but I will be asking little bits of info, so firstly here goes Does anybody here have the touque settings and tightening sequence for the cylinder head (Yes I know I should get a workshop manual ...and will be ...how I've managed till now I do sometimes wounder ). Many thanks and happy riding. Link to comment Share on other sites More sharing options...
Twincam.GTi Posted September 7, 2005 Author Share Posted September 7, 2005 I don’t need to take the head off (thankfully). As stated earlier I though internal damage had happen such as a burnt/chipped valve etc. because on number 3 cylinder petrol was going in but not igniting yet a sparkplug tester showed a superb spark on all four leads to the plugs, plus new plugs where fitted, the carburettors operated correctly (linkage etc.) So naturally you can understand my thought of some form of engine damage. So the rocker cover was removed and the engine just turned over to check that the cams operated the valves up and down etc. Then I thought even if valve was burnt it would still ‘fire up’ in the cylinder so rocker cover put back on and I decided to take the top off No3 Carburettor …and …believe it or not …but a good piece of fibre/cotton/cardboard was in the carburettor tube, stopping all movement of the carb piston, hence ‘neat petrol’ going into the cylinder and flooding everything. It would appear the air filter element has broken up and a few bits of its fibre went in the carb. The bike appears to be running fine now (famous last words) but for a short while did smoke a bit due to all the unburnt fuel that has gone down the exhaust. So my question to you all this time is …can anyone scan me an exploded diagram/picture of the carburettors. Although every thing is running fine I’m just a little concerned about the carb (rubber diaphragm at the top cause I’ve disturbed it for first time in 24 years etc.). Plus can anyone think of any damage that might have been cause by this? Link to comment Share on other sites More sharing options...
jimjam Posted September 8, 2005 Share Posted September 8, 2005 Just keep an eye on your oil level. It might have risen if petrol got passed the rings. Link to comment Share on other sites More sharing options...
Moderator YamaHead Posted September 9, 2005 Moderator Share Posted September 9, 2005 TwinCam.....If it were me, I'd change that oil after you get it good & warmed up BTW....I dug around out in my Garage & found my factory Service manual for the XJ550 I hope this helps just a bit ............. I think that rubber diaphram has to be bought WITH the piston valve assembly But they do tend to leak after years of use......sounds like you mighta got your money's worth out of it though Link to comment Share on other sites More sharing options...
Twincam.GTi Posted September 9, 2005 Author Share Posted September 9, 2005 Many thanks for picture, yes realised pistion is 'bonded' to diaphram (hasn't ripped, though, is fine, but just got concerned like anything when you disturb it for first time after a couple of decades). Oil change, yes did think about that, you're quite right. On a side note things done this year are: Replaced one of the igniter coils, which failed (second hand, came of 'Scrapper/Beaker' XJ550 , different size to original coil but does job!) Made own 'blade type' fuse box to replace well caroded (and breaking up) original fuse box I've fitted an 'O' ring chain for first time last month to bike (along with new sprockets), are these 'o'ring chains longer lasting? Replaced Tacho/rev counter cable (old one had stripped and leaking oil around seal where fits into engine). New sparkplugs (due to problem mentioned in first thread) An oil change Oh my I've spent over £90 ( $165 ) this year on bike thats more than i've spent in previous years (round where I live you can buy a 20 year old bike for that amount ) And i'm thinking of replacing the front mudguard again as the pattern one is getting rusty again (last replaced in '98) from everyday (including winter) use. Thanks once again to everyone for advice and help Link to comment Share on other sites More sharing options...
Moderator drewpy Posted September 10, 2005 Moderator Share Posted September 10, 2005 for reference you can get diaphram kits from NRP in Manchester UK for your bike http://www.cameron-site.co.uk/nrp/yamaha_c..._diaphragms.htm Link to comment Share on other sites More sharing options...
Twincam.GTi Posted September 12, 2005 Author Share Posted September 12, 2005 drewpy Many thanks for that, all info is greatly received Link to comment Share on other sites More sharing options...
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