start up after new piston rings

[Nessism]

Maybe the buckets got bent when things started to bind up? I have spares if you are in need.

[turkish1961]

hi
thanks for promp reply

ill get some 240 ish grit on way home
its the inlets that had the grit in before

buckets are ok i think as they fit in the exhausts ok

vic

[tatu]

Just to ask, How are you getting on with this?

[turkish1961]

hi all

thanks for the reminder

it's running BUT

fill in later off to work

[Normk]

Haven't read the complete thread so may be off topic somewhat but two thoughts:

1) When honing, boring or using any abrasives it can be very difficult to remove the residue, especially if the grit embeds into the surface. Washing with kerosene or varsol is not very effective in removing honing debris from the surfaces. Anyone who does not believe this simply needs to flush & wash a freshly bored cylinder with varsol, kerosene, etc. until it wipes clean with a shop towel. Then brush the cylinder with hot soapy water or even engine oil and note the effects on a shop towel. I used to show second year apprentices this effect before we taught cylinder service because they never forgot.

Leave that embedded stuff in the cylinder walls or your lifter bores and you ask for accelerated wear. It's too late at night for more detail but the idea should be clear.

2) New piston rings need to be exposed to higher cylinder pressures in order for them to bed into the cylinder walls. The combination of burnishing and wearing away of high spots is most important to proper long term ring performance. This does not mean that very high RPM is warranted but alternating heavy acceleration and deceleration to move oil into the ring lands is required.

Install rings and leave the average engine idle or "baby it" and you'll likely have an oil burner. Another point is not to let an engine with a new camshaft or refinished valve train wear surfaces be exposed to low idle until the surfaces have burnished. Cam makers and regrinders always insist but some people aren't trained, don't pay attention, or know more so can't be told...

HIH, off to bed,

Norm

[turkish1961]

WORKED VERY WELL with my 180 grit then 240,400 last ogf all 800
it worked very well
with the sump of made sure wipped around the rest of the bottom of the crank case best i could and there was a couple of bits of grit there

i have flushed through with parrafin down cam chain tunnel ,alternator ,and clutch area all looks OK

rest of the engine bolted up OK
the only thing a little worried cam lobs 3 of them never noticed before but there where circles around the main contact area is it where they have got really hot ? your thought please
well I thought have i nothing to loose (i HOPE) so continued be rebuild

started OK no funny noises

on St ride just a round the block at 3000 rev had a funny noise vibration noise ,very happy when I remembered this from before it was the horn vibrating under the petrol tank

very gentle on for a bit .have now taken up to 6,500 at the moment

but did have another noise when going down the motorway so backed of
think i getting paranoid now

i have done about 70 miles now took of rocker cover the other evening and all looked well

so need to go on a longer run now

vic

[Normk]

Vic, paranoia is common amoungst most of us after a repair. Wish I could dispel it but still happens after 50+ years of wrenching.

You posted: "i have flushed through with parrafin down cam chain tunnel ,alternator ,and clutch area all looks OK "

Can't recall our equivalent term to your "parrfin", is it varsol or kerosene? Should recall but age..... Doesn't matter much, just curious.

The oval patterns are signs that your cam lobes are worn through the case hardening and are on the way out. Time to start looking for replacement or regrind.

Don't be too gentle with throttle during initial break-in because you will need significant combustion pressures in order to ensure that the rings and cylinder walls are properly burnished/run in. Seen many, many engines which burned oil after a re-ring when they were babied.

Hope all goes well with the overhaul.

HIH

Norm

[turkish1961]

parrafin = kerosene

another cam shaft great that's all i need ,

yes i do need to give the bike some stick,with large amounts of shutting the throttle down ,i have read the report http://www.mototuneusa.com/break_in_secrets.htm

may be bit late for that but i'll try

better start looking for a exhaust cam shaft i guess

apart from the oval patterns will i hear a particular noise before they give up the ghost ? or should i just change ASAP

vic

[Normk]

You may get away with using that cam for some time. If it were mine, I would start looking for a cam and pull the cover from time to time in order to assess whether the lobe starts to spall or peel. It's unlikely that it will fail rapidly so you will almost certainly have time to look around. I'm not trained on cam grinding equipment so don't have a feel for the metalurgy other than having seen lobes in this condition many, many times which required replacement. The lobe should have a slight crown so the presence or absence may be a clue as to the amount of wear.

If the case hardening were completely gone, it is usual for cam and rocker camshafts to begin to develop wear grooves but the shim provides a different wear effect.

Those things are very hard to assess as to how long you have because there's no way to determine how much of the case hardening remains. If it is a daily driver which you must rely on, or especially if you will be doing a long tour then the replacment is soon. Otherwise watch and wait intil you find a deal. You may also wish to check to see if there is a cam grinder in your area who does motorcycle cams as a price may be attractive.

HIH

Norm

[tatu]

Cheap cams come up on ebay from time to time.

[Nessism]

Cheap cams come up on ebay from time to time.

Make that all the time. The 750 - 1100G cams all interchange, and because of the super stable GS shim and bucket valve train, the cams rarely wear. Personally, I'd measure the lobe height and compare to the service manual spec, and if those cams are within the service limits, I'd run them and not give it another thought. I've seen worn GS cams before, but they didn't look like the photos here.

[tatu]

I've not seen the lobes wear, but I have seen the bearing journals worn badly.

[gshub]

Make that all the time. The 750 - 1100G cams all interchange, and because of the super stable GS shim and bucket valve train, the cams rarely wear. Personally, I'd measure the lobe height and compare to the service manual spec, and if those cams are within the service limits, I'd run them and not give it another thought. I've seen worn GS cams before, but they didn't look like the photos here.

Got 1100g cams in my 1085 motor they have bit more duration than stock Gs1000s gives
a nice torquey Gs for two up riding....

[turkish1961]

hi
normk i use the bike a SAS rider these days ,,, so i'm not going to be clocking up lots of miles,even more so now winter is here


i think we are all lucky on the set up with shims must help tp spread wear

Nessism (good to here from you again) so what do worn cams look like

so how do i measure for wear ,diagram would help

think 1 thing i will do is keep an eye out for ex cam shaft

??????? do exhaust cam shafts quicker than inlet ?


vic

[Nessism]

You can measure the cam lobe height and bearing journal size using a micrometer. The spec is in the service manual. If the height is too low, it is worn. You can not see this type of wear with the naked eye.

The exhaust cam runs hotter so it typically wears faster, although not overly fast in these GS engines.