[kris]

57plate version that has 15k on the clock.
Gets ridden thirty miles a day through town lots of short shifting so doesn't get a blow out that often.
Then had her flat out down motorway last week and since then been very wheezy at mid revs and only runs well at high rpm. Historically have used standard unleaded. Got mechanic mate to help take out carb and clean out with airline. Also set jets two turns as per manual (they were out by quarter turn in opposite directions. This didn't seem to help and was still very lumpy. Changed both plugs as front was coroded. This defo helped but when cold the bike is awful and pops and bangs more than usual. Have akros with no baffled.

Any suggestions as what could have caused the bike to go from normal purring to lumpy cementmixer just by getting it flat out in top ?

Once I understand what caused it might be easier to know what to look at next.
Yours riding a mixer
Kris:frown:

 

[Jhon]

It sounds like you have water in your float bowls, but if they've been dismantled and cleaned that probably rules that out (unless there's residual still in the tank.) Try draining your tank completely and look for evidence of water - if there's any, drain the bowls again.

The other thing to check very carefully is the sealing of the carbs on to the inlet rubbers. Any leak at all here and it'll run really poorly mid range and pop and fart as it draws too much air.

Unlikely at this time of year, but carb-icing causes similar symptoms too (particularly if you're at altitude and there's high humidity - it doesn't need to be that cold.)

 

[king karl]

Once I understand what caused it might be easier to know what to look at next.
Yours riding a mixer
Kris:frown:

Have you put petrol in rather than diesel, easy done

check the glo plugs, and the points are clean :smokin:

 

[Locksmith]

Sounds like carb , you must be sure youve gave them a proper clean , a air line dont always clear the jets .Have another look at them

 

[kris]

The other thing to check very carefully is the sealing of the carbs on to the inlet rubbers. Any leak at all here and it'll run really poorly mid range and pop and fart as it draws too much air.

now you might be on to something ...

one of the small rubber o rings wasnt at the end of the spring .. and was only found when we used a fine air line (finiest nozzle ..we were very thorough when doing this) ... did the rubber washer come out ...

now given we re-used this rubber o ring... perhaps this is why we still have the same issue ...

painful tho it is ... get 2 new rubber o rings ...take the damn thing out again ... and refit with new rubber o rings ...clean the carb again with air line (how else should we do it ..any suggestions ?) ...

my question is ... is there any other possible suggestions of what could be wrong (other than the carbs) .... when the bike is on the table having open heart surgery ... would really be grateful if I have all teh suggestions in hand ... so we have hte right bits ready ..

cheers

kris

 

[kris]

have tried super unleaded and when the bike is warm it feels better ...but from cold its a shocker ..wont idle and feels very lumpy ...

any suggestions on what is wrong and what to check ..

summary so far ..new spark plugs ..carb has been out and carefully cleared with air ...(suspect that the rubber washers on jetsprings might be moody)...

bike goes back to get a check out next saturday so I'd welcome any suggestions on what else to check when the bike is in bits ..

Yours in hope

Kris

 

[kris]

latest update ... valve clearances needed doing ... but more worryingly ... the compression was tested ...and the front cylinder was very low ....rear cylinder was fine ...

does this indicate and issue with front cylinder ...valve issue

(reminder the bike would start very rough when cold ... then seem to run normally when warm).

the engine is out of the bike so would be really glad of any good advice on what to check ..

had a look on these sites ....

The Anti Pyndon Engine Rebuild - ADVrider

but any advice on any special tools if we take the head off to look at the valve stems etc etc

 

[KevInYorks]

Rough when cold would back up the suggestion of lean mix. Did you say you have checked that the O rings are in place on the fuel screw?

Compression will vary depending upon auto decomp working. Loosen the exhaust valve clearances to make compression greater cos the decomp cant work properly then.

 

[protea6]

just read this thread and heres my story lots of short rides locally then one day ride to work 22miles there no bother then 18 miles into the return home bike pops and farts feels like its running out of fuel then cuts out pushed it 3 miles mostly uphill(wont leave it on motorway,it would be stole)any way thought it was carb cleaned it then decided to check for spark found i had a weak spark bike would not fire up so decided to think about it ie bike would backfire on decelaration and light throttle reason being unburnt fuel in exhaust ordered new ignition coil lead and plug and fitted it and started on the button and does not backfire and is a lot smother than it ever was.have had the bike for 4 months with the backfiring issue thought it was normal as its a 640 with titanium akrapovic system now i know it was the ignition coil gradually breaking down so this could also be a possible option to your running problem, pull spark plugs and check for a nice blue spark . diffrent bikes but simalar problems hope this helps

 

[kris]

while the engine is out .. we are going to check the front cylinder and check it out ...but got a problem ..

Now according to the manual ..

Disassembly section 4.2 ... it says

" Loosen the bearing bolt 1 on the double timing gear and pull out of
the cylinder head together with the needle bearing. The double
timing gear will slide down slightly, relieving the timing chain.
"

Now the bolt comes out but the gearing is stuck in ... see the 2 pictures I have attached...

What is the advice to get this sucker out ..can't move forward and loosen the cam chain ...worried that we could do harm at this point ... so far we have tried to :-
-use a flat headed screwdriver and turn the thing out (no joy)
-use a reverse hammer and pull the thing out (really gently) ...

Any advice oh wise ones ?


Cant upload the images so here they are on photobucket..

Pictures by c1tru5 - Photobucket

Cheers Kris

 

[FIREY950]

cant you make up a hook to insert then pull it out , like the manual suggests

 

[Ell Tell]

I assume given that you have Akros with the bafs out, that you have put appropriate jets, fuel mix, needle and air box mods etc.

I have free flow exhausts on mine but have not yet done the mods. After running the bike with the bafs out it runs like a bag o shit. Fine if your nailing it but its still gutless throughout the range. Also surges when cold and pops like a mofo.

Bafs immediately back in till I get the kit from XBikes.

Basic stuff but I normally overlook the obvious.

Edit - perhaps I need to read the entire post.

 

[kris]

ok so spoke to dealer today .. regarding the problem with the "double timing gear" being stuck ....

Pictures by c1tru5 - Photobucket

they have a special tool (not mentioned in teh book for this) ... but said patience and some kind of pliers (safety?) would do the job ...

anyone got any ideas of what tool they talked about .. need something to pull out the "double timing gear"

 

[Rikki]

is the chain off?
sorry if thats a daft question (cam chain, obviously)

 

[natrat]

low compression, will new rings sort this?

 

[Rikki]

low compression, will new rings sort this?

Low compression,

Worn rings and bore is an obvious but could be valves not seating. Either need lapping, springs knackered, or burnt away.

Taking the butt clearance of rings would indicate condition of them.