So, i did a valve clearance reading today, after 35k km. It may have been done when i bought it at 25k as well. Anyway, the result worries me. Right cylinder is 100% in spec. Left cylinder gives zero clearance on all 4 valves... Im now struggling how to calculate which shims i need (simply -0.25mm for i.e. exhaust might not be enough?), and i'm wondering what could be the cause. Should I inspect/replace the valves and springs? Maybe damage is done to the cylinder? Any tips for this amateur mechanic very eager to learn?
May be a silly questions but are the cam lobes definitely pointing away from the buckets on the cylinder with tight clearances ? Is it possible the clearances have never been checked? If you are correct I would think best to inspect . However to sort clearances on over tight valves you would need to substitute thinner shims first to get an accurate reading . Check the basics first ! What is thinnest feeler gauge you have ? Check cam lobe position not just the position indicators . May be best to get a mechanic to check it..
Some early T595s suffered from soft inlet valves that caused the clearances to disappear. When I took the head off the edges of the valves were like razor blades!
Yes zero valve clearance can lead to burnt valves depending on how the geometry is set up and matirials some clearances open up with heat some close so best to get it sorted ASAP. As for cause it could be a variety from badly cut valve seats to seats that are badly fitted and get hammered home, also wrong shims fitted from the outset....but dont panic yet just reset them and see how it behaves.
Not the sort of thing you can take a guess at if you can't work out which shims to use get them done professionally cheaper than a blown engine
Hi Reggie, thanks and fair questions. I checked the position of the lobes about 10 times. I can feel the lobes going into the right position, and the markers are set right (dots and stripes). There is no position in the whole cycle where the clearance is not zero.. My thinnest feeler is 0.03mm. I suspect the clearance is never checked, but i will validate tomorrow, and call the garage that used to do maintenance.
Thanks, but honestly, I feel I at least have to open up and try with smaller shims. Then take another reading or two. Once in spec, ride it, and inspect regularly. If things go out of spec fast, then I'll leave it to the mechanic...
Take out the cam and use the thinnest shim, if there is one, on the other 3 valves to hopefully get a min gap?
Thanks! Good idea to use only one for that. I dont have a small shim (the good ones are bigger..), but i will ask the local dealer tomorrow to sell me a shim.
Dont need to go to a dealer they are pretty standard 9.48 (9.5mm) shims any bike shop should have em?
The procedure I have used for years is to check the clearance with feeler gauges. Use several sizes until you find the exact fit. Lets say the clearance is .002" less than specified. Remove the shim and check it with a micrometer or dial caliper. Then install a shim .002" thinner than the one you took out. Reassemble and recheck. If it is still not right, do it over. If the valve has .000" clearance, start with a shim that is thinner and the one you took out by the amount of of the required clearance. You may have to do it over because in the case of zero clearance, you cannot tell how tight it is. Repeat the process for each valve that is out of spec.. It is tedious work, but necessary. If you do not have the tools to do this right, I recommend you take it to a professional. ...J.D.
Yes the early sprints used to do that as well they closed up rather than loosen. As I found out to my horror when the valves went through the pistons and shattered the engine cases. Regards Joe.
During the 1970's I was in the mechanic's trade. I did some work for a couple of Fiat-Lancia dealerships. You get lots of practice with shim an bucket valve adjustments. These days I send my bikes in when it is needed though. I don't have enough work volume on just my own equipment to keep a shim kit and tool around. ...J.D.
Thanks for the tip, the dealer didn't have them in stock. But the garage around corner found a cup full of 25 mm shims in his drawer . They were thin enough (2,7mm), and I borrowed them for free. Installed them, and now I have a clearance on all! Calculated my optimum thickness, and ordered 4 new shims. I'm releaved. The initial reading I was able to calculate now, was around 0,2-0,3 mm below the zero, so the valves were definitely never fully closed. Hopefully can install next week, bring back the borrowed shims, and drive around like a happy duck.
It's a lot of work, I agree. But hey, I work from the home office nowadays, so I have some time . And the satisfaction is about 10 times bigger if it works out the right way!
Didn't realise you were talking about an air cooled with 25mm shims, probably got a few in the garage from my Speedmaster.
