tankygsy Posted September 19, 2012 Report Share Posted September 19, 2012 (edited) Squish is the distance between the ***top of the piston*** at top dead center and the ***combustion chamber top cap***. You can use soft solder but I prefer to use blue tack or even better a piece of clay as it has very little elasticity (done it this way for years on engines at the engineering company I work for). Put a small sausage of blue tack or clay about 3mm diameter by 10mm length approx 5mm from the edge of the piston. Attach the cylinder head and top cap to the crank case and set the piston to an inch below TDC (dont torque the nuts and bolts up just nip them up hand tight) put everything together except for the base gasket. Use your old orings in the top cap for now, fit the new ones after you have the correct squish height. Now rotate the crank so the piston goes past TDC squashing the blue tack / clay (I like to rick it back and fourth a couple of times to remove any elasticity in the measuring media). Disassemble and carefully measure the thickness of the blue tack / clay - digital verniers are great for this. Ok, if for example your blue tack measures 0.3mm thick then you need a 0.7mm gasket (0.7 +0.3 = 1.0mm) - however gaskets also squash approximately 1/6th of their own thickness when you tighten things fiwn so bearing this in mind the most appropriate sized gasket would be one that is 0.8mm thick. Gaskets come in a range of thicknesses to allow for correct squish. Sometimes one gasket will do, sometimes you might need to use 2 or even 3 to get the correct thickness. This is no problem, just layer them up with the ***thinnest one closest to the cylinder head***. You do not and should not need to apply any sealant to the gasket. Fit them dry unless you have pitting on the mating surfaces that you think may cause you problems in future. Pitting will mainly be around the cooling water jacket ports. As a side note seeing as the head is off you may as well check the piston rings and if you access to a bore gauge check the cylinder for wear and keeping it as a reference for future use. Check the piston ring end clearance which should be 1 thou of an inch per inch of piston diameter as a general rule of thumb IIRC. Once all the work is completed and the engine is running retorque the cylinder head nuts after it has had a full heat cycle. Edited September 19, 2012 by tankygsy Quote Link to comment Share on other sites More sharing options...
tazz229 Posted September 19, 2012 Author Report Share Posted September 19, 2012 (edited) Is that amount of squish really that important? I mean what's the worst that can happen by using the wrong gasket? Loss of power? Please forgive my ignorance and I really appreciate your input thank you I'm just curious! It's all a learning curve ya know! Edited September 19, 2012 by tazz229 Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted September 19, 2012 Report Share Posted September 19, 2012 Squish height has an effect on compression ratio which affects power. The higher the compression the more power but also the more likley you will have pre-ignition (pinging or pinking). Higher compression also makes for harder starting. If you use too thin a gasket, it might be possible to have negative clearance. In other words, the piston will hit the head. You do not want this to happen. Expensive parts break when the piston hits the head. Quote Link to comment Share on other sites More sharing options...
tazz229 Posted September 19, 2012 Author Report Share Posted September 19, 2012 Squish height has an effect on compression ratio which affects power. The higher the compression the more power but also the more likley you will have pre-ignition (pinging or pinking). Higher compression also makes for harder starting. If you use too thin a gasket, it might be possible to have negative clearance. In other words, the piston will hit the head. You do not want this to happen. Expensive parts break when the piston hits the head. Ahh I get it thank you just didn't realise half a mm could make so much difference! Quote Link to comment Share on other sites More sharing options...
jse Posted September 19, 2012 Report Share Posted September 19, 2012 As a side note seeing as the head is off you may as well check the piston rings and if you access to a bore gauge check the cylinder for wear and keeping it as a reference for future use. Check the piston ring end clearance which should be 1 thou of an inch per inch of piston diameter as a general rule of thumb IIRC. Actually, that should be .1mm per inch of cylinder bore, not .001". The dial bore indicator will give you a measurement of cylinder wall taper, usually the highest wear area is about 3-5mm below where the upper ring stops and relates to peak cylinder pressure on the power stroke. I've used clay before for squish clearance but find the solder method more accurate. The clay need to be a certain type to get good readings, as too soft or pliable will often distort and a release agent should be used on the head or the clay will thin when pulled between the head and deck, giving a bad measurement. You must also be absolutely sure to lift the head straight up as any side movement will distort the clay layer. I like clay for combustion chamber profiles, but as I mentioned, you have to be very careful, which may be a problem for a first-timer. Jon Quote Link to comment Share on other sites More sharing options...
sting32 Posted September 19, 2012 Report Share Posted September 19, 2012 (edited) Tazz, I think you would be well served to just change the tranny fluid a few times. I have lost the seal on the WP on many bikes, over the years. it seems to take about 3 oil changes after you refil the 1st time. when I have this happen, I used the cheapest ATF for those 3 changes, then I went back to my better (and slightly more $ per quart) yama-lube. But a quart of oil is so cheap, lets not risk the crank bearings running without oil for ANY reason imaginable. But I guess it is your bike. maybe you can blow everything out before you fill and start the engine? I dont know, JSE might tell US, but the bearings dont get pressured oil, they more or less just sit in, below the fill level of the transmission fluids, aka gravity fed or submerged mostly? I dont have one torn down to look at atm, you know.. Edited September 19, 2012 by sting32 Quote Link to comment Share on other sites More sharing options...
tazz229 Posted September 19, 2012 Author Report Share Posted September 19, 2012 Tazz, I think you would be well served to just change the tranny fluid a few times. I have lost the seal on the WP on many bikes, over the years. it seems to take about 3 oil changes after you refil the 1st time. when I have this happen, I used the cheapest ATF for those 3 changes, then I went back to my better (and slightly more $ per quart) yama-lube. But a quart of oil is so cheap, lets not risk the crank bearings running without oil for ANY reason imaginable. But I guess it is your bike. maybe you can blow everything out before you fill and start the engine? I dont know, JSE might tell US, but the bearings dont get pressured oil, they more or less just sit in, below the fill level of the transmission fluids, aka gravity fed or submerged mostly? I dont have one torn down to look at atm, you know.. As it goes ive flushed it through a couple of times with some oil watered down a little with some parrafin. Seems to have taken pretty much all the gunk out. Ive also got the clutch case off too to replace the water pump seal. I managed to drill the 2 bolts in the end just enough to release the bolt head from the casing. The threads were fine it was just the bolt head that was stuck so thats a relief i can tell ya! The water pump seal does look in bad shape tbh and the little spring that goes round the center hole to keep it tight too the shaft is just kinda floating around. There doesnt seem to be any tension on it at all! Fortunately the shaft it self looks fine so i just ordered a new seal hopefully that'll get here soon! I took all the clutch plates out too while i was at it and cleaned them up to get all the milky crap off them! The bike is leant over a bit on its side so with any luck any last remaing dribbles of crap will drip out overnight. Many thanks for the input on this thread and hopefully i can get this seal fitted and be back up and running soon! Fan motor tomorrow! Ill update the other thread cos i found the prob! Thanks guys Quote Link to comment Share on other sites More sharing options...
jse Posted September 19, 2012 Report Share Posted September 19, 2012 Tazz, I think you would be well served to just change the tranny fluid a few times. I have lost the seal on the WP on many bikes, over the years. it seems to take about 3 oil changes after you refil the 1st time. when I have this happen, I used the cheapest ATF for those 3 changes, then I went back to my better (and slightly more $ per quart) yama-lube. But a quart of oil is so cheap, lets not risk the crank bearings running without oil for ANY reason imaginable. But I guess it is your bike. maybe you can blow everything out before you fill and start the engine? I dont know, JSE might tell US, but the bearings dont get pressured oil, they more or less just sit in, below the fill level of the transmission fluids, aka gravity fed or submerged mostly? I dont have one torn down to look at atm, you know.. Mitch, The crank bearings have a short dedicated feed hole machined into the bearing boss where oil thrown up by the gears makes it's way into the bearing. Jon Quote Link to comment Share on other sites More sharing options...
sting32 Posted September 20, 2012 Report Share Posted September 20, 2012 As it goes ive flushed it through a couple of times with some oil watered down a little with some parrafin. Seems to have taken pretty much all the gunk out. Ive also got the clutch case off too to replace the water pump seal. I managed to drill the 2 bolts in the end just enough to release the bolt head from the casing. The threads were fine it was just the bolt head that was stuck so thats a relief i can tell ya! The water pump seal does look in bad shape tbh and the little spring that goes round the center hole to keep it tight too the shaft is just kinda floating around. There doesnt seem to be any tension on it at all! Fortunately the shaft it self looks fine so i just ordered a new seal hopefully that'll get here soon! I took all the clutch plates out too while i was at it and cleaned them up to get all the milky crap off them! The bike is leant over a bit on its side so with any luck any last remaing dribbles of crap will drip out overnight. Many thanks for the input on this thread and hopefully i can get this seal fitted and be back up and running soon! Fan motor tomorrow! Ill update the other thread cos i found the prob! Thanks guys Make darn sure that there is NOT any groove on the shaft, that is the reason for the "kit" but maybe our newer bikes have a harder shaft, I don't know. Glad youre getting this sorted. :thumb Quote Link to comment Share on other sites More sharing options...
jse Posted September 20, 2012 Report Share Posted September 20, 2012 Make darn sure that there is NOT any groove on the shaft, that is the reason for the "kit" but maybe our newer bikes have a harder shaft, I don't know. Glad youre getting this sorted. :thumb True! Use your fingernail to slide over the shaft, it is amazingly sensitive and if you feel any groove it would be wise to replace the shaft. I also use the fingernail technique to check for imperfections on fork tubes. I learned suspension theory in one of the best shops in the U.S. and we found the fingenail worked better than any other tool we had for uncovering pits. scratches etc. The newer WP shafts have a better heat treatment and last longer. I think that certain anti-freeze products have a higher silicate content and this may contribute to slightly faster shaft wear. Jon ps. Mitch, I'm going to try to make the Peru event! Quote Link to comment Share on other sites More sharing options...
sting32 Posted September 20, 2012 Report Share Posted September 20, 2012 True! Use your fingernail to slide over the shaft, it is amazingly sensitive and if you feel any groove it would be wise to replace the shaft. I also use the fingernail technique to check for imperfections on fork tubes. I learned suspension theory in one of the best shops in the U.S. and we found the fingenail worked better than any other tool we had for uncovering pits. scratches etc. The newer WP shafts have a better heat treatment and last longer. I think that certain anti-freeze products have a higher silicate content and this may contribute to slightly faster shaft wear. Jon ps. Mitch, I'm going to try to make the Peru event! Hope to see you there, bring lots of bug spray! I know around my house the bugs must have taken the hot summer off, now they are like making up for lost time! Quote Link to comment Share on other sites More sharing options...
tazz229 Posted September 20, 2012 Author Report Share Posted September 20, 2012 Yeah Thanks guys I'm pretty convinced there is no groove there I've had a real close look, and funny enough I also rely on my fingernails quite a bit for various things, it's amazing how much ya can feel with them lol Quote Link to comment Share on other sites More sharing options...
tazz229 Posted September 22, 2012 Author Report Share Posted September 22, 2012 All sorted!! New fan motor New WP seal New head gasket And a fresh change of oil Fan now cycling as it should and no more water in he gearbox GOOD TIMES! Thanks for the help and input people much appreciated! Quote Link to comment Share on other sites More sharing options...
sting32 Posted September 25, 2012 Report Share Posted September 25, 2012 (edited) Yep, good! now what I have learned from having gassers pro's since 04, I always look at my dad's & all of our bikes' oil level portal, a LOT I seem to be drawn to check when riding, I check everyone's around me, lol, whenever it hits me, and it seem hit me to notice it, a lot. It is just what I habitually do, and i've caught seal failures quickly this way, on mine and friends bikes. Edited September 25, 2012 by sting32 Quote Link to comment Share on other sites More sharing options...
tazz229 Posted September 25, 2012 Author Report Share Posted September 25, 2012 Yep, good! now what I have learned from having gassers pro's since 04, I always look at my dad's & all of our bikes' oil level portal, a LOT I seem to be drawn to check when riding, I check everyone's around me, lol, whenever it hits me, and it seem hit me to notice it, a lot. It is just what I habitually do, and i've caught seal failures quickly this way, on mine and friends bikes. Good advice mate!! Fortunately im quite anal about oil levels having owned a couple of superbikes,because on those things it really matters. Don't get me wrong i know it matters on these too but these bikes aren't doing 10k+ revs! And funny enough i just had to ring my mate today to let him know there is none in his bike . Its in my garage and i just happen to have a look. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
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