If you are concerned that the cams on the vertical have not been timed correctly when you last did the belts, take the covers off and recheck the timing marks. No need to touch the heads for this unless you have other problems regarding the low pressure. Steve
Makes sense, however I'm not sure of the engine capacity and of possible twicks on the cams (see my other post), hence why I am concerned as to what the correct position should be, but I guess if i get them to the 748 stock settings it shouldn't hurt, right?
I've seen your other post, whether you have a big bore kit (853) or not won't alter your cams, if they have been tweaked to give maximum performance in any way it will only be by a small amount with an offset woodruff key or adjustable pulleys which in the case of the pulleys you would have noticed when you changed the belts, if you are concerned take the covers of and check the timing marks, if they are out remove the belts and reset correctly. If you have fitted the belts wrong in the first place there is a possibility a valve may be slightly open or worst case you may have bent a valve which would cause your lack of pressure on the vertical cylinder. Steve
Right, checked the timing: TDC: (didn't take a picture of the window on the left hand side of the engine, but was spot on) Horizontal Cylinder: Verical Cylinder: now I know the intake cams are (or at least appear to be) offset by 1 tooth, and I am 90% sure that is how I found them when I replaced the belts as I remember having this exact doubt back then, and the reason why I left them as they are is found on the cylinder head cover, that reports 01T on the intake side (see below)
I also have noticed the temperature of the exhaust gasses is significantly different from the left (Vertical Cylinder) to the right (Horizontal Cyilnder) exhaust. I initially thought it was because of the greater distance gasses must go to get to the right exhaust from the front cylinder, but then I went on measuring them and : I've left the bike idling all the way up to 80 degrees and I measured as follows: engine temp. 50 degr.: left exhaust: 38 right exhaust: 27 engine temp. 80 degr.: left exhaust: 44 right exhaust: 27 ... is this normal? both heads are similarly hot, checked about 30' after I switched the engine off..
I can't think of any reason for the cam on the vertical to be one tooth out, I would be inclined to refit the belt with the cam marks lined up correctly and turn the engine by hand to make sure there is no contact and if OK start it up. This could well be the reason for low compression and poor running on the vertical cylinder. Steve
Just noticed your temperature readings, as it is the vertical cylinder that has the low compression and a black (rich) plug, I would expect that one to be running cooler than the horizontal which is running correctly. Steve
Urto, looks to me like your horizontal cylinder is timed OK and the vertical one is a tooth out. Also the markings on the cam box could easily read +10 perhaps a cam timing adjustment in degrees. Not sure anyone would be adjusting cam timing at the belt and even if they were surely both would be set the same. Curiously enough many years ago a friend of mine bought a 2 year old Morris Marina as a spares or repairs car for £200 which had 30k miles on the clock, was pristine but was a really bad runner. 5 minutes looking at the engine revealed the timing to be one tooth out. That too had sooty plugs and had been 'serviced' by unspecified persons only three months before. He went on the fix the timing issue within 90 minutes and ran the car for 10 years then sold it on for spares and repairs for £200!
I just realised only one exhaust has been "emptied" (i.e.: the end of the can hasonly the outer pipe, not the inner) .. the left one! I'm sure this explains it. I'm currently in the garage resetting the pulley, but as soon as will be back home I'll show you what I mean. Ridesafe, Matteo
This bike is teaching me an awful lot, and you guys too, obviously! I've spent the last couple of hours re-setting the timing .. put everything back together after spinning the wheel in sixth gear to check there was nothing obstructing or no flowing as it should have. pushed the bike out of the garage, put it on the side stand, switched the ignition on and hit the start button. The prompt response, the perfect ignition, the noise, much clearer, cleaner.. a smile started forming on my face from what was initially a grin. I leaned forward whilst I was kicking my leg over the passenger seat, and in that exact moment I saw it... Right in front of my eyes! I couldn't believe it. I reversed my movements, crouched on the side of the bike and reached out to touch it. I needed to know what that was, very quickly! PETROL!! Dripping from the fairings, in copious amount! I've been spending the last few weeks trying to figure out what was the cause of this rough running of my 748, and to do so I removed the tank several times. Logical consequence to it was that the o-rings, already very old, didn't survive! Luckily I had a spare set from when I replaced the fuel filter and I used them straight away, otherwise it would have been pretty annoying not being able to use the bike straight away, now that she's cured! At least I hope, but honestly it seems that all previous bugs were gone after this timing mistake was amended. Fingers crossed, and thank you guys ever so much for all your assistance and patience!!!
The intake cam is definitely not right, it's one tooth retarded so the intake valve is opening and closing too late. Hopefully it hasn't caused any damage (I doubt it would hit anything being retarded) so it maybe a case of setting it right and away you go (fuel leaks excepted).
Feedback on this: Just rode from North London to Basildon, Essex ... She's a mean machine... A completely different bike to what I've been riding for the past few weeks... I'm in love again. Thanks to you all for your patience and kindness. Glad I've ended up in this forum.
?? In the absence of knowledge of previous engine work/knowing what cams were fitted, there was nothing more to be gleaned from Matteo's posts Steve and it all pointed to a simple timing mistake - your replies covered everything. another happy ending. :smileys:
