Quantcast

loss of compression.

classic Classic list List threaded Threaded
28 messages Options
12
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

loss of compression.

shmopieo
This post was updated on .
hey everyone, im in a bit of trouble here.

picked up a 2003 royal enfield sixty-five 2 weeks ago.  had great compression (kickstart was supporting 80kilos jumping up and down no problem).  the bike has only 5500 miles on her, but has been sitting for the last 2-3 years.  the first week or so of riding the bike was feeling great.  a few troulbes with the carb here and there (dont think its tunned up right, previous owner switched out old style air filter).  2 days ago i took it out on a longer ride (4hours) with lots of hills.  bike seemed to be doing great except for oil slowly leaking from the head gasket which i thought was typical of enfields???  when i arrived at my destination and parked the bike, i realized there was motorcycle parking so i went to kick start the bike again (has electric start but would rather feel the engine),the bike kicked through as tho i had the decompression valve open.  i could hear the wheezing sound as it lost compression.  the block started up just fine as it was very hot and i thought the bike was just a little bit too warm and would settle back down after it cooled.  when i got back to the bike a few hours later there was hardly any compression, i could turn the kickstart with my hand easily.  i checked the decompression valve over and over again and it didnt seem to come from there.  you could hear heavy wheezing coming from the oil top up when turning the kickstart crank.  i checked the tappets from the tappet cover and they seemed to be fine.  the oil was quite low, just on the bottom mark.
after messing around for awhile trying everything i could think of i used the electric start and the choke and got it running.  it would not idle, not even while warmed up and i had to constantly keep the throttle up.  i didnt want to drive home but i had no choice, i was in the middle of nowhere with no other options.  i drove all the way home with the bike stopping many times to listen to the engine.  what puzzles me is that the bike was handling big and very steep hills in 3rd, 4th and 5th gear without much trouble.  im quite new to the bike so i dont really have much to compare too.  one thing i did notice, was when slowing down, when using the engine to slow the bike by downshifting there was zero effect.  the engine was not slowing the bike at all.  how is this possible if it could handle the steep hills?
where do i go from here?  would the bike loose compression due to having  low oil?  is oil leaking at the block normal?

i need to get this bike up and running asap as im going touring. any thoughts or ideas would be greatly appreciated before I pull the head off.

p.s. I'm in London, UK if anyone is around or can recommend any shops/dealers. Since I'm going touring on this bike I would like to fix it myself so I have the experience and confidence in it.



Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Pete Snidal

>when i arrived at my destination and parked the
>bike, i realized there was motorcycle parking so i went to kick start the
>bike again (has electric start but would rather feel the engine),the bike
>kicked through as tho i had the decompression valve open.  i could hear the
>wheezing sound as it lost compression.  the block started up just fine as it
>was very hot and i thought the bike was just a little bit too warm and would
>settle back down after it cooled.  when i got back to the bike a few hours
>later there was hardly any compression, i could turn the kickstart with my
>hand easily.  i checked the decompression valve over and over again and it
>didnt seem to come from there.  you could hear heavy wheezing coming from
>the oil top up when turning the kickstart crank.  i checked the tappets from
>the tappet cover and they seemed to be fine.  the oil was quite low, just on
>the bottom mark.

You need a good manual.  Mine is available at Hitchcock's or direct
through www.enfield.20m.com
It covers all this in detail, but basically, here are the possibilities:

1) (Best) Tight valve.  Set valves to pushrods just spin at TDC on
compression. (the whoosh place)

2) (Harder) Poorly-sealing compression release.  You should hear air
leaking out the pipe on this
      one, but it could also be coming from a burnt exh valve.  DO
NOT take out the cotter pin in the
      top of the CR when removing to clean and lap-grind.

3) (Hardest, but certainly not impossible) Burnt Valve(s) or bad
rings.  In either event. check
     either by wet/dry compression testing,  or better still by
leak-down testing.  (Shop job unless
      you have a leak-down test rig.) Pop for my manual before
attempting.  Best 30 pinds you'll ever
      spend!

If 1) and 2) are busts, you need to do a top end job.  Valve refacing
and piston ring replacement.
  DO NOT hone!  That's a job for a machine shop, done ONLY as part of
a rebore/fresh piston
  If/when you do a top end, check the piston bottom ring land very
carefully.  See manual.

Good luck with it!
ps




Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

shmopieo

2) (Harder) Poorly-sealing compression release.  You should hear air
leaking out the pipe on this
      one, but it could also be coming from a burnt exh valve.  DO
NOT take out the cotter pin in the
      top of the CR when removing to clean and lap-grind.

3) (Hardest, but certainly not impossible) Burnt Valve(s) or bad
rings.  In either event. check
     either by wet/dry compression testing,  or better still by

When you say leaking out the pipe you mean exhaust pipe yes?

how do i check the exhaust valve?  do i need to remove the head for this?
would I need new gaskets in order to check this?
what work could I do to minimize costs?  i literally just quite my job to go touring on this bike so my budget is extremely limited.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Sali Rostami
In reply to this post by shmopieo
 If I understand your description correctly, your loss of compression seems ocuur when the engine hot/warm. This suggests to me that valve action is suspect. One of the rocker boxes may seize when a hot engine is shut down or the closure of one of the valves may be impeded by heavy gum deposits in the guide.

 These suspicions are reinforced by your claim that while kick-starting fails to re-start the engine, the starter motor does succeed. This, I rather suspect if my theory holds true, is because the more rapid turning if the engine in some way enables the valve to close because the binding or the rocker or resistance caused by gum deposits is overcome by the higher inertial forces brought about by more rapid movement.

 A binding the rocker action  might be detected by removing the tapet cover and checking the pushrods at the top dead center of the compression stroke. At this point in the 4-stroke cycle, the rods should have little detectable up and down movement. However, a considerable movement would indicate a rocker box that fails to permit the valve to return to the closed position.

 While I've yet to find heavy gum depsoits causing the failure of motorcycle valves to close, in small engines used in gardening, pressure washers, and snowblowing it is quite common. In some cases I have dealt successfully with the problem by adding ATF to the engine oil in a proportion of 1:5, that one part ATF to 5 parts engine oil. The ATF is detergent laden and will remove gum deposits.

 Good luck in tracking down your problem and let us know of your progress.


  Al in Philadelphia  

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

shmopieo

<What is ATF? Transmission fluid?

Just started the bike up this morning.  It dosnt "sound" bad at all and actually started quite easily.  A bit of blue smoke out the back at higher revs and still not much compression.  I looked at the tappet rods again and noticed that the exhaust tappet rod, while spinning freely, is completley unifrom.  There seems to be a small wobble in the rotation as if its not rotating on a perfect axis.  could this be the source of my problem>?  would this allow oil to be burning up?
also, is there anyway it could just be the rings and not the cylinder as well?  I dont have the funds to have the cylinder re bored... is there any way this could be the case?
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

cjayheff
--- In [hidden email], shmopieo <split005@...> wrote:

> I looked at the tappet rods again and
> noticed that the exhaust tappet rod, while spinning freely, is completley
> unifrom.  There seems to be a small wobble in the rotation as if its not
> rotating on a perfect axis.  could this be the source of my problem>?  

No, not if the rods are spining freely. The wobble can be an optical illusion caused by the fittings being a thou off or so. And even if it were a bent rod (not at all uncommon in REs) as long as it spins freely all the way round and does not bind up at any point your valve action will be OK.

I've just read your first post of the problem and have not read any of the subsequent ones but from your first post I'd say you burnt an exhaust valve running up those hills.

We can speculate all day on this. Your only solution is to pull the head (or do a differential compression check if you have that equipment and know how to use it). With the spark plug and decompressor in, turn the head upside down level on the bench. Fill the combustion chamber with gas (or kerosene if your not good with fires) and peer into the the exhaust and intake ports with a flashlight looking for leaks.

If there are no leaks in the head then it may be time for new rings, eh.

CJay

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Sali Rostami
In reply to this post by shmopieo
 ATF is automatic transmission fluid.

 The apparently bent exhaust push rod could be the cause of your problem. The bent rod, as it rotates in use, causes the effective length to vary. If the initial adjustment was made when the rod was in the "short" position, it will prevent the exhaust valve from fully closing when in in the "long" position. 





--- On Sat, 7/25/09, shmopieo <[hidden email]> wrote:


From: shmopieo <[hidden email]>
Subject: Re: [Enfield] loss of compression.
To: [hidden email]
Date: Saturday, July 25, 2009, 7:45 AM


 





<What is ATF? Transmission fluid?

Just started the bike up this morning. It dosnt "sound" bad at all and
actually started quite easily. A bit of blue smoke out the back at higher
revs and still not much compression. I looked at the tappet rods again and
noticed that the exhaust tappet rod, while spinning freely, is completley
unifrom. There seems to be a small wobble in the rotation as if its not
rotating on a perfect axis. could this be the source of my problem>? would
this allow oil to be burning up?
also, is there anyway it could just be the rings and not the cylinder as
well? I dont have the funds to have the cylinder re bored... is there any
way this could be the case?

--
View this message in context: http://www.nabble. com/loss- of-compression. -tp24625272p2465 7211.html
Sent from the Royal Enfield mailing list archive at Nabble.com.

















     

[Non-text portions of this message have been removed]

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

cjayheff
--- In [hidden email], Al <k3eax@...> wrote:
>
>  ATF is automatic transmission fluid.
>
>  The apparently bent exhaust push rod could be the cause of your problem. The bent rod, as it rotates in use, causes the effective length to vary.

You can rule out or confirm the push rod as the problem by simply removing them (or backing the adjuster way off so as to make them useless) and kicking over the engine. If you still don't have compression, look elsewhere for the problem.

CJay

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Sali Rostami
In reply to this post by shmopieo
 CJay, this is an excellent bit of diagnostic advice.




--- On Sat, 7/25/09, cjayheff <[hidden email]> wrote:


From: cjayheff <[hidden email]>
Subject: Re: [Enfield] loss of compression.
To: [hidden email]
Date: Saturday, July 25, 2009, 11:16 AM


 



--- In royalenfield@ yahoogroups. com, Al <k3eax@...> wrote:
>
>  ATF is automatic transmission fluid.
>
>  The apparently bent exhaust push rod could be the cause of your problem. The bent rod, as it rotates in use, causes the effective length to vary.

You can rule out or confirm the push rod as the problem by simply removing them (or backing the adjuster way off so as to make them useless) and kicking over the engine. If you still don't have compression, look elsewhere for the problem.

CJay

















     

[Non-text portions of this message have been removed]

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Pete Snidal
In reply to this post by shmopieo
At 05:42 PM 7/24/2009, you wrote:
>When you say leaking out the pipe you mean exhaust pipe yes?
>
>how do i check the exhaust valve?  do i need to remove the head for this?
>would I need new gaskets in order to check this?
>what work could I do to minimize costs?  i literally just quite my job to go
>touring on this bike so my budget is extremely limited.

I hate to say this to you, but I wouldn't recommend going touring on
a Bullet judging by the questions you ask.  These are the bike that
makes a mechanic of you, and it would be best to
spend some time at home with it, becoming one, before hitting the open road.

Start with my manual - that's what i wrote it for: www.enfield.20m.com

Begin, though, but slacking off your valve adjustments as described
in an earlier post.




Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

shmopieo
Thats why I bought this bike.
To learn mechanics and enjoy something I independently maintain.  I just wish I wasn't faced with such a massive problem so soon.  But I am learning loads, so all is not lost.  I was hoping to get accustomed with the bike and then eventually do a diesel conversion.  I'm definitely not afraid to dive in and get my hands dirty.  The first stop on my "tour" was going to be at a friends place where I was going to spend a month or so working on the bike and getting accustomed with it during my spare time and in between little day rides, but I guess I will have to spend some time here before heading out.

I've ordered an engine overhaul gasket set but am going to take it into a shop for a quick diagnostic before I move forward.  I dont have the best working space at the moment but will have to make due.  If the head needs to be removed then I will do it myself.  If the cylinder is scored then I will take it to a machine shop and get a quote.  If its more than I can afford after new piston and rings etc.  Then I will either sell the engine as is and start the diesel conversion, or I will buy a new barrel.
How difficult is it to install a new barrel?
I have already purchased the manual, and planned to take it on my laptop so I could always reference it.
What are the chances that I just need new rings and exhaust valve?

As good as the manual is, I feel its not quite complete to the absolute beginner.  But as a teacher, I understand how hard it is to put yourself all the way back at the starting line.  I had already made a few ajustments to the bike with the help of the manual and found it to be priceless.

Will keep you guys updated as things progress... I hope to get this moving quickly as London is money to the power of time.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Sali Rostami
 Mike, your attitude and philosophy is commendable!

 I've never been one to put much trust in the diagnostic capability  of motorcycle shop mechanics --- good luck.

 I would suggest that you request they perform a cylinder leak-down test. This should take about an half hour of shop time, requires no disassembly other than the removal of the spark-plug, and so is a good valud value for money. This test will reveal and identify the compression sealing ability of the rings, intake valve, exhaust valve,and headgasket. even a semi-competent mechanic should be quite able to provide accurate results.

   Al in Philadelphia --- the center of the universe for incompetent motorcycle mechanics



--- In [hidden email], shmopieo <split005@...> wrote:

>
>
> Thats why I bought this bike.
> To learn mechanics and enjoy something I independently maintain.  I just
> wish I wasn't faced with such a massive problem so soon.  But I am learning
> loads, so all is not lost.  I was hoping to get accustomed with the bike and
> then eventually do a diesel conversion.  I'm definitely not afraid to dive
> in and get my hands dirty.  The first stop on my "tour" was going to be at a
> friends place where I was going to spend a month or so working on the bike
> and getting accustomed with it during my spare time and in between little
> day rides, but I guess I will have to spend some time here before heading
> out.
>
> I've ordered an engine overhaul gasket set but am going to take it into a
> shop for a quick diagnostic before I move forward.  I dont have the best
> working space at the moment but will have to make due.  If the head needs to
> be removed then I will do it myself.  If the cylinder is scored then I will
> take it to a machine shop and get a quote.  If its more than I can afford
> after new piston and rings etc.  Then I will either sell the engine as is
> and start the diesel conversion, or I will buy a new barrel.
> How difficult is it to install a new barrel?
> I have already purchased the manual, and planned to take it on my laptop so
> I could always reference it.
> What are the chances that I just need new rings and exhaust valve?
>
> As good as the manual is, I feel its not quite complete to the absolute
> beginner.  But as a teacher, I understand how hard it is to put yourself all
> the way back at the starting line.  I had already made a few ajustments to
> the bike with the help of the manual and found it to be priceless.
>
> Will keep you guys updated as things progress... I hope to get this moving
> quickly as London is money to the power of time.
> --
> View this message in context: http://www.nabble.com/loss-of-compression.-tp24625272p24662545.html
> Sent from the Royal Enfield mailing list archive at Nabble.com.
>


Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

malfisher500
In reply to this post by shmopieo
--- In [hidden email], shmopieo <split005@...> wrote:
>
 would the bike loose compression due to having
> low oil?  is oil leaking at the block normal?
>

Too low oil is allways bad, but as to whether it would lose compression, maybe but I dont think so.

Ive had this happen a time or two to my bike, the compression was so low it wouldnt kick start, so I used the electric, it cleared itself both times so I dont know what causes it Im afraid!

You dont need to take the head off to check the valves Mike, just the rocker covers, remove tank, and then remove the two rocker covers on top of the head, 4 nuts each.

Then you can turn the engine over and watch the valves work. This may tell you something.

The oil leak is a pest, and is usually from the right side of the engine where the pushrod tunnel is. This can be cured by using sealant to make like O Rings round that part of the gasket. Mine was fixed this way and did 12000 km's with no sign of leaks.


Malc

www.midlandbullets.co.uk


Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Pete Snidal
In reply to this post by shmopieo

>'ve ordered an engine overhaul gasket set but am going to take it into a
>shop for a quick diagnostic before I move forward.

You want a Leakdown Test.  That's where they insert compressed air
through the spark plug hole and monitor how long it takes to leak
down and where it goes.  Here's a quote from my manual:


Checking Compression

The very best way to check compression is by the Leakdown Method. The
piston is brought to TDC on the compression stroke - both valves
closed. The spark plug is removed and replaced with an air fitting
connected to an air source with a pressure gauge teed into the line.
Air is introduced into the cylinder via a valve from the air source
(a tank of compressed air is good), and once the valve is closed, the
combustion chamber should hold air pressure for some time - the
shorter the time period, the worse off the engine. While the air is
being applied, it is often helpful to listen at the carburetor intake
and at the exhaust pipe , as well as at the crankcase breather, for
escaping air - a hiss from any of these will tell you what's leaking.


>  I dont have the best
>working space at the moment but will have to make due.  If the head needs to
>be removed then I will do it myself.  If the cylinder is scored then I will
>take it to a machine shop and get a quote.

Could be a leaky valve - you should have your valves and seats
refaced - and guides checked if you take the head off.

If the leakage is piston to cylinder, it will be past the piston
rings.  Ring replacement usually does wonders.  You want to check the
piston and its clearances carefully as well.  All in the manual.

>If its more than I can afford after new piston and rings etc.  Then
>I will either sell the engine as is and start the diesel conversion,

i would be VERY surprised if you tried a diesel "conversion"
(actually a total engine switch to a non-Enfield utility engine) and
still wanted to go that route.  My advice: fahgeddaboudit!

>or I will buy a new barrel. How difficult is it to install a new barrel?

Don't worry about it at this point. 9/10 cases just need new piston
rings.  Failing that, you get the barrel rebored to a fresh oversize piston.

>I have already purchased the manual, and planned to take it on my
>laptop so I could always reference it.

Read the sections on top end work. A great investment of a half hour
of your time...

ps

>What are the chances that I just need new rings and exhaust valve?



[Non-text portions of this message have been removed]

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

shmopieo

i would be VERY surprised if you tried a diesel "conversion"
(actually a total engine switch to a non-Enfield utility engine) and
still wanted to go that route.  My advice: fahgeddaboudit!

The royal enfield service mechanic wants 80quid just to take the head apart and have a look.  New piston and rings are going to be around 100quid, and to re bore and reface the valves will probably be a couple hundred.  A guy gave me an estimate of around 300quid.  So, for 300quid, I can buy a superior diesel engine and for another 200 or so in work and extra parts I can have it up and running.  Not to mention I can still sell the RE engine and a few parts of the diesel.  My original intention with the bullet was to convert it sooner or later, so now seems to be a good time.

Taking it in tomorrow morning to have a compression test done.

Thanks for all the advice and guidance so far.  I will let you all know the "fate" of my lovely RE.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

Sali Rostami
- Nay, nay, nay not compression test but a cylinder leak-down test is what is needed!

  Al



-- In [hidden email], shmopieo <split005@...> wrote:

>
>
>
> i would be VERY surprised if you tried a diesel "conversion"
> (actually a total engine switch to a non-Enfield utility engine) and
> still wanted to go that route.  My advice: fahgeddaboudit!
>
> The royal enfield service mechanic wants 80quid just to take the head apart
> and have a look.  New piston and rings are going to be around 100quid, and
> to re bore and reface the valves will probably be a couple hundred.  A guy
> gave me an estimate of around 300quid.  So, for 300quid, I can buy a
> superior diesel engine and for another 200 or so in work and extra parts I
> can have it up and running.  Not to mention I can still sell the RE engine
> and a few parts of the diesel.  My original intention with the bullet was to
> convert it sooner or later, so now seems to be a good time.
>
> Taking it in tomorrow morning to have a compression test done.
>
> Thanks for all the advice and guidance so far.  I will let you all know the
> "fate" of my lovely RE.
>
> --
> View this message in context: http://www.nabble.com/loss-of-compression.-tp24625272p24670854.html
> Sent from the Royal Enfield mailing list archive at Nabble.com.
>


Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

shmopieo

I could't find any bike shops that could do a leak down test.  They were either all booked up, or didnt have the equipment necessary.  I did however find a highly experienced mechanic who popped the head off in a mater of minutes, checked all the clearances, and determined that the exhaust valve wasnt seated right and needed to be reground and that the decompresser piston was bent.  He wasnt sure how the decompresser could have gotten bent the way it did, maybe from the previous owner.  Anyways, we are ready to reassemble as soon as my gaskets arrive and I source out a new decompresser piston.  Hopefully will be on the road today.  Great news.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

malfisher500
--- In [hidden email], shmopieo <split005@...> wrote:
>
>
>
> I could't find any bike shops that could do a leak down test.  They were
> either all booked up, or didnt have the equipment necessary.  I did however
> find a highly experienced mechanic who popped the head off in a mater of
> minutes, checked all the clearances, and determined that the exhaust valve
> wasnt seated right and needed to be reground and that the decompresser
> piston was bent.  


Thats good news mate! It shouldnt cost a lot either!

Malc.

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

ric450classic
In reply to this post by malfisher500
--- In [hidden email], "Malcolm Fisher" <malfisher@...> wrote:
>
> Ive had this happen a time or two to my bike, the compression was so low it wouldnt kick start, so I used the electric, it cleared itself both times so I dont know what causes it Im afraid!
>
> Malc
>
> www.midlandbullets.co.uk
>

Possibly build up on the exhaust valve stem keeping it stuck open ?

Can be avoided by leaving the bike on TDC (compresion)  :0)

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: loss of compression.

malfisher500
--- In [hidden email], "ric450classic" <longstrokeclassic@...> wrote:

>
> Possibly build up on the exhaust valve stem keeping it stuck open ?
>
> Can be avoided by leaving the bike on TDC (compresion)  :0)
>

Thats a possibility Ric.

It was very strange as it did it when really quite new, still under warranty, and another time or two ages later.

As I say, all it took to clear it was the electric start so I never investigated.

Malc.

12
Loading...