Hello Guest User,

Please feel free to have a look around the forum but be aware that as an unregistered guest you can't see all of it and you can't post.

To access these 'Registered Users Only' areas simply register and login.

Is 115PSI serviceable compression ?

Need help restoring, building, or finding then try here.

Moderators: KeithZ1R, chrisu, paul doran, Taffus

Message
Author
User avatar
dwhitehouse
Regular Poster
Posts: 57
Joined: 18th Jan 2009
Location: Warwick

Is 115PSI serviceable compression ?

#1 PostAuthor: dwhitehouse » Mon Jun 29, 2009 4:06 pm

Did a compression test on the Zeb last night after a short ride round the block so it was warm. Not hot but hot enough for me to burn my fingers on the plugs :shock: Took the carbs off for the test and got:

cyl 1: 115 PSI
cyl 2: 110 PSI
cyl 3: 115 PSI
cyl 4: 115 PSI

Has been burning off oil when starting and showing signs of oil on the plug in cyl 1, hence I tried the test. Looks to me like it's worth lifing the head and checking the valves seals and head gasket. Also adjusting the clearances at the same time.

Bike has done 45K miles but supposed to have had a set of barrels last year after a cam chain tensioner went. Barrels were off a 25K bike but I couldn't see any evidence of rings being replace in the paper work.

115 psi seems a bit borderline to me; wondered what every one else thought? I seem to remeber being able to get stepped rings if reusing old barrles and pistons; does this sound right ?

Don't want to have to go the whole hog of new pistons etc if it's not necessary; since I'd rather spend the money on better brakes and getting the wheels rebuilt at the moment.

User avatar
tlc
International Rep
Posts: 5239
Joined: 6th Nov 2007
Location: Aylesbury

#2 PostAuthor: tlc » Mon Jun 29, 2009 4:19 pm

I would always do valve clearances first after the improvement in running I got.
Asphalt Cowboy

Phil Churchett award winner 2015

User avatar
PAULJAC47
Hardcore
Hardcore
Posts: 3266
Joined: 31st Aug 2008
Location: WOLVO WEST MIDS ENGLAND

#3 PostAuthor: PAULJAC47 » Mon Jun 29, 2009 4:21 pm

Try putting some light oil down plug hoels and re-test see if figures increase much, if do suspect rings, would check valve shims and if ok look at valve seats etc,115 is ok seem to recollect service limit is 100 psi,,,cheers Pauljac
PAULJAC47,,,,,"She may not look like much, but she's got it where it counts, kid."
-Han Solo

You can't polish a turd, but you can roll it in glitter

Salad is what real food eats.
Anon

PUM 673

User avatar
Pigford
Hardcore
Hardcore
Posts: 13314
Joined: 2nd Jan 2006
Location: North Dorset

#4 PostAuthor: Pigford » Mon Jun 29, 2009 6:53 pm

Bit on the low side...... Nice & even though :wink:

If the bike ain't smoking too much... and running OK, I'd leave it, could get another 10k miles out of her :twisted:
And on the 7th day... Zeds were created!

User avatar
dwhitehouse
Regular Poster
Posts: 57
Joined: 18th Jan 2009
Location: Warwick

#5 PostAuthor: dwhitehouse » Mon Jun 29, 2009 7:43 pm

That's what I was thinking. Maybe after doing the head it will be better and I can run it for an other year.

Runs OK, with no smoke after it's warm. Pulls OK if a little lumpy below 2000 revs but I think that might be clutch :|

paulmceleney
Chunks
Posts: 591
Joined: 29th Jan 2008
Location: milton keynes

#6 PostAuthor: paulmceleney » Mon Jun 29, 2009 7:49 pm

my smokes like a chimmney but runs okay leave it to the winter then fix it


Return to “Bike Help”

Who is online

Users browsing this forum: No registered users and 27 guests