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Messages - Johnwebley
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3181
« on: July 22, 2013, 03:05:39 PM »
hi all, are any of you going to Calne ?? would be good to see lots of classic SOHC, mine will be there, check out the link, John, http://www.calnebikemeet.com/about.html
3182
« on: July 17, 2013, 09:23:09 PM »
Thats not detanation as the cause, what happens is some idiot PO reved the nuts off it when cold and the rings expand to quickly so the top one shatters into pieces, this widens the ring groove then flame passage and heat finish it off.
Used to happen quite a bit on 250K4 and CB175's
I had exactly this on a 550 years ago. My friend bought a bike that had been standing for a year or so. Unfortunatley, the seller had taken the bike for a blast to make sure all working OK. My friend bought the bike but soon complained that it wasn't running properly and was smoking. When I investigated I discovered that there were broken rings on all four cylinders. Luckily, they had stayed in place and not scored the bore and a new set was all that was needed.
thanks for the hints !! I can't remember racing it when cold, BUT,from now on will keep it below about 5k for a couple of miles at least, thanks John
3183
« on: July 15, 2013, 10:18:43 PM »
update,
firstly thank you all for your help and advise,
the bike is back together,just over 600 miles,runs beautifully,got its top end back,
runs up to 9k very willingly,
oil change done,no issues,seems so much more in the lower gears,
I rev it in the 2nd,3rd , and 4th gears,dont slog it in top,
and I am really pleased
John
3184
« on: July 04, 2013, 08:29:00 PM »
they could contact me,
my CB500 is running ok now,
also has 4 pipes,
very original,un-restored ,52k miles
ask them to E-mail me for pics
John
3185
« on: June 25, 2013, 11:45:27 PM »
update, all back together, started first time. felt really tight,the new rings are steel,see link,look for motorcycle rings http://www.npr.co.jp/english/products/p_train/index.htmlI expect these to be stronger,less brittle,and more durable than old style cast rings after about 130 miles,gentle throttle no more than 5k under load,and 6k on overrun the motor feels much better,still a little tight,but very torquey will continue till about 500 miles before any serious throttle,increasing the revs under light load
3186
« on: June 12, 2013, 06:41:28 PM »
John,
I recently had some rings for the 550 from silvers. The rings are slightly different if you look at them one is square and the other slightly tapered. It tells you the installation sequence in the manual if you have one, the rings are marked with a "N" this needs to go to the top if I remember correctly. Hope this helps.
Regards,
thanks,I looked Very Hard,and found the "N"s,as luck would have it,I had fitted them correctly, as far as the cause, check out this link, http://www.motorcycleclassics.com/mc-how-to/project-cafe-rebuilding-a-1973-honda-cb500.aspx#axzz2Vx8B1Md3a CB500/4 with almost the same issue, my piston wasn't quite as bad,but the diagnosis is "detonation" ,I guess severe "pinking" ?? my bike never seemed to suffer this,but would over advanced ignition cause it ? I run Boyer electronic and also a much bigger plug gap,(0.033th) as it supports a bigger spark, also gives great low/mid range punch, maybe I should retard the ignition a few degrees ?? thoughts and comments please, John
3187
« on: June 12, 2013, 12:01:46 AM »
ok,further update,
new parts arrived from Mr Silver,
nice new piston,and 4 sets of rings,
slight query, the rings are 3pt oil,and two plain rings
one looks plain,no markings,seems to be coated in black teflon ??,guess its the second ring, and I guess the one with grey surface for the bore is a chrome ring?? and is fitted at the top,
again no markings,
do you agree ??
regards
John
3188
« on: June 07, 2013, 11:07:17 AM »
It's quite unusual to break rings on a 4 stroke engine if everything is normal, possibly more influenced by the assembly last time it was built.
Also a possibiltiy if it had been stored for a long time for the bore/rings to rust and cause damage when someone tried to start it.
the history,I have owned the bike since 1977, the barrels have never been disturbed,the head came off about 20k miles ago,after I damages a couple of valve stems while changing the cam-chain,the bike gets regular use,although only between 2-3,000 a year,
3189
« on: June 06, 2013, 07:35:13 PM »
OK,update,
so I took the head off,
looked like Foreign object damage in cylinder No4,
lots of marks both on piston,and head,
valves removed,good seals on inlets valves and seats,exhaust seats good,but valves in need of lapping,
not happy about state of No4 piston,so off with the barrells, result,top ring broken,and 50% vanished !!big damage to top ring groove,
and top land,
No3 piston also has broken top ring,???
1 and 2 pistons OK, no marks on bores, ordered new (std) piston, 4 X sets of rings,
waiting for them to arrive,
SQ, why do you think the rings went ??
John
3190
« on: May 27, 2013, 02:08:23 PM »
looks like a head-off job !!
just as summer is finishing!! LOL
3191
« on: May 26, 2013, 06:27:02 PM »
No Honda since the late 60's needs leaded fuel, if you have a sticking valve without you have the start of a mechanical problem mate
OK,its runs well,got just over 52K miles,great starter,etc, what could be the issue ?
3192
« on: May 26, 2013, 03:25:53 PM »
I have recently been forgetting to add "lead substitute" to the fuel,
and have got what appears to be sticky valve !!!
as the motor get warm/hot,after cruising around 6K rpm for several miles ,the engine runs rough,noisy tappets,and feels like its on 3 only,
spitting in the carb,and spitting in exhaust.I still have 4 - 4 pipes,
after checking,setting tappets at 3th inlet/4th exhaust,and re-using Morris lead substitute again,the bike runs well again,
is it common? if so,I hope you take notice,and use an additive as well,
John Webley
PS,I should say I have a '74 CB500/4. and the handbook does say it needs "some" lead in fuel
3193
« on: May 15, 2012, 09:12:41 PM »
Putting oil in the silencer would be okay IF you weren't using it, but it'll smoke like a 2 stroke when it warms up!
also,try never to ride for shorter distances than 10 mls,and always get the pipes very hot,I will make you smile as well, just a thought,both David Silver,and CMSNL,have the pipes in stock,at present I think the dutch site is the cheapest
3194
« on: May 15, 2012, 09:03:37 PM »
you can always try a reverse fill/prime,
detach caliper,remove piston,fill caliper with fluid,then insert piston,press in,and watch the bubbles appear on the mastercylinder,.
this may be a drastic last resort.
sometimes,if you use just one pad in the caliper,and pump it full,then push the piston all the way in,this also helps to dislodge air .
John
3195
« on: October 27, 2011, 07:59:52 PM »
thanks for the welcome,just for that,you get a pic of the LH side!!!
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