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Post by BritPete on Jun 27, 2023 18:13:58 GMT
While doing the base gasket CTB was explaining how the TDC mark on the flywheel and the 2 indexation marks on the cam sprocket, when the cam was lined up the TDC mark was a few mm out So thought I would do some analysis The cam goes round 1/2 turn for a full turn of the fly wheel  The cam has 46 teeth so 1/2 turn is 23 teeth The Fly wheel is 143mm diameter  Using pie x diameter this makes the circumference = 3.14 x 143 = 449mm So for every tooth of the cam the fly wheel moves 1/23rd of a turn so dividing the circumference by 23 we get 19mm movement per tooth 
Apologies Buster this is your area of expertise |
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Post by buster on Jun 28, 2023 9:40:14 GMT
please dont apologise, great info because the timing lines on the sprocket tend to look a bit wrong even when they are right. I'v even gone as far as to deliberately put the sprocket a tooth out in either direction just to see what it looks like, its very obviously wrong if your interested  as an aside I'm partly plotting to get on with the cafe racer engine. for that I'm going to see about having the moriwaki cam profile copied onto another cam shaft. I'll also get the DTI on the pistons at assembly time and calibrate exact TDC, then I'll ask the cam shaft people if they can slot the sprocket for me so I can degree the cam in exactly. |
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Post by BritPete on Jun 28, 2023 14:17:29 GMT
So part 2 This should be the perfect setup of the cam chain - Cam marks horizontal and T mark opposite the triangular arrow  My bike has done 46k miles so I expect the cam chain has stretched, hence Honda build in a tensioner So (Buster Correct me if I am wrong) the stretch will be taken up by the tensioner and the rear of the can chain will bow inwards - hence the T mark would move slightly anti clockwise  This is what my flywheel looks like  which is 8mm of the circumference |
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Post by BritPete on Jun 28, 2023 17:56:30 GMT
please dont apologise, great info because the timing lines on the sprocket tend to look a bit wrong even when they are right. I'v even gone as far as to deliberately put the sprocket a tooth out in either direction just to see what it looks like, its very obviously wrong if your interested as an aside I'm partly plotting to get on with the cafe racer engine. for that I'm going to see about having the moriwaki cam profile copied onto another cam shaft. I'll also get the DTI on the pistons at assembly time and calibrate exact TDC, then I'll ask the cam shaft people if they can slot the sprocket for me so I can degree the cam in exactly. Well above my pay grade |
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Post by buster on Jun 28, 2023 18:51:35 GMT
so basically I'v got to do exactly the job that you and Carl have just done. these arrived today  I'll try and get a load of pics as I go through it |
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Post by buster on Jul 1, 2023 15:44:33 GMT
what was going to be a quick and easy job soon got a bit harder when I saw the state of the pistons, clarted up doesnt even get close  . theres no way I'm putting an engine back together like that so off with the slugs and raid my supplies of NOS for a couple of gudgeon pin clips.  then a load of donkey work, scraping old gaskets off and degreasing parts  definitely not the recommended way to remove the carbon/oily lip but if your very careful you can get away with it and finish with a bit of scotchbrite  trying to be optimistic at least all the cleaning has shown that there are no visible signs of detonation, something that I could very easily suffer if I were to push the advance too far on the CDI   |
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Post by buster on Jul 2, 2023 16:05:31 GMT
so rails in and ring clamps on  barrels on and I decided to see how accurate honda's T mark on the mag wheel actually is. so checked it with the DTI and it turns out its spot on  my method for the next bit is to fit the guide and the tensioner then pull the tensioner right up and nip it in place with the nut behind the barrel  then its cylinder head on and the joys of fitting the cam, probably the easiest way is to fit the sprocket to the chain with no cam shaft and align the marks at TDC. then with your fingers where the cam shaft goes inside the sprocket, rotate the engine until you can slide the cam shaft in from the back brake side, you can then bring the engine back to TDC and everything should be aligned. then torque it down  fiddliest bloody bit of this job is getting the pattern rubber seal on the rocker cover to behave while refitting  |
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Post by buster on Jul 2, 2023 16:13:48 GMT
looking at the cam shaft after the tensioner was released it looked as if the notch at the bottom was slightly out of line but I'm fairly convinced that its not. theres no way I could see the rear sprocket line with all the rocker gear in but I could see the front one and I checked that by rack of the eye (get right down to the level of the rocker cover) and I also checked it with the straight edge of an engineers ruler. I did try and take a pic of this but not enough hands and it just came out as dark. so the tensioner (combined with the guide) should just be taking slack out of the chain, it shouldnt be affecting the cam timing and relative crank position unless the chain is slack.
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Post by buster on Jul 2, 2023 16:44:56 GMT
one more little aside job, checked the balance of the mag wheel. spun it 5 times and landed at a random position each time so I'll take that as balance is ok  |
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Post by buster on Jul 9, 2023 14:36:24 GMT
got about 100 miles on it now so time to check the torque on the cylinder bolts (1st job that) then double check the valve clearances. if your too lazy to take the mag wheel cover off you could put the bike in top gear and gently use that to turn the engine over with the rear wheel and use the front cam sprocket alignment mark as TDC to set the tappets.  and I'm pleased to report theres no sign of any top end oil leaks |
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. theres no way I'm putting an engine back together like that so off with the slugs and raid my supplies of NOS for a couple of gudgeon pin clips.