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Timing camshafts on spada causes valves to hit pistons

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by kaldek, Jul 23, 2005.

  1. Ok this is a wierd one.



    So I'm fitting the camshafts back onto my mate's Honda Spada, and following the manual on timing the camshafts. Problem is, following their advice the valves hit the pistons. Don't worry - we tested this verry sloowlly before doing anything else so there is no damage.

    The manual says to use the "T2" timing mark to time the cams on the rear cylinder, which is what we did. So can anyone tell me what the "T1" and "T2" marks mean, or if I should be using T1??

    Kaldek
     
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  2. Well, are the T1 and T2 marks about 90 degrees apart on the ignition trigger wheel? If so, then it's pretty definite they're TDC indicators...

    Can you rotate the crank so both the T1 and the T2 indicators can have a turn at the timing mark? If so, do the cam lobes on the rear cylinder with the crank at T2 look the same as the cam lobes on the front cylinder with the crank at T1?

    What about the IN and EX notches on the camwheels? Do they look like they're oriented identically with respect to the cam lobes on both the front and rear cylinder camshafts?

    Precisely to avoid this sort of arseache, if I'm pulling cams out, I'll daub a bit of liquid paper across the camchain and the camwheels, so, when the time comes to put the cams back in, all I do is match the liquid-paper daub on the camwheel with the one on the camchain. The motor doen't even have to be at TDC, or anyfink.
     
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  3. Yeah the T1 and T2 marks are exactly 90 degrees apart. And I actually took pictures of the timing but wasn't smart enough to mark the parts. In hindsight, I should have bloody done that.

    After putting it back together, I noticed that if I placed the crank in the position it was in when I took the picture, the cams were in totally different positions compared to my digital photos. Truth be told they are out by about 30 degrees by the looks of things. What's also interesting is that if I try to do the proper alignment, I cannot get the cam sprocket alignment marks to be exactly parallel to the head. Again, this makes me suspicious.

    All I can think of is that these camshafts aren't the original ones that came with the bike, and they don't match what the book is telling me to do. I noticed that the cams on the bike have paint dots on them - perhaps this is where the previous owner marked the cam to list where the "actual" index mark really is.

    The bike is a grey import....literally *anything* could have happened and I could be pulling my hair out for ages at this rate, especially if some monkey has made it non-standard.

    Kaldek
     
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  4. Turn the crank 360 degrees & reset the cam timing from there. Its a 4 stroke -takes 720 degrees to complete 1 cycle. Sounds like you are 1/2 a cycle out
     
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  5. Yeah but since the cams run at hald the speed of the crank, if I align everything correctly I would either be totally in cycle or 180 degrees out. And since it's a wasted spark system, that shouldn't matter.

    I'm seriously starting to think these cams aren't the right ones and it's been "fudged".

    Kaldek
     
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  6. I'm only guessing here but do the cylinders fire in the same 360 degree cycle? If it is a 90 degree V twin & the timing marks are 90 degrees apart then I would suspect each cylinder would fire in different 360 cycles. As the cams are running at 1/2 crank speed they would not line up if you are 1/2 a cycle out -I think. Will look at my V4 manual as it is basically 2 v twins together
     
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  7. Can you picture me saying those very things to myself in a dank garage some time back? ;)

    On both cylinders? Or just that problematic rear cylinder?

    You've pulled the rubber cam cover gaskets off and you're aligning the camwheels to the top edge of the head, not the rubber, right? :)

    ...and what you're talking about is that, if you align the T1/T2 indicators down on the crank, the IN/EX marks on the camwheels are a few degrees out from being exactly parallel with the head?

    Yeh?

    If so, dunworrebaudid. That's just mass-manufacturing tolerances coming into it.

    Not likely. You see it on most bikes.

    Again, not likely. It might be a grey import, but it's a grey import 250. Few people are so bored as to have time to tweak them.

    Might be worthwhile posting up these pics you've taken someplace.
     
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  8. Definitely on both cylinders.

    Yeah it's to the top edge of the head - everything else is removed.

    Yeah, in fact we came to the same conclusion that it wasn't a big deal ourselves...until the valves hit the piston that is....

    I've just noticed in my pics that the exhaust cam looks like its index mark is opposite to that of the intake cam. Would that be correct or should both the cam's index marks line up?

    Kaldek
     
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  9. OK then. Just had a quick look at my 750 V4 manual & strangely enough you line up the T2 mark for the front cylinder cam timing & the T1 for the rear. Can't say this would work for the 250 but worth a shot. Explains valves hitting on one cylinder but. Also check you have the front cams in the front & vice versa. Should be marked. Also #1 cylinder is at the rear on the 750 -where on the 250?
     
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  10. Here are the pics from the engine before I pulled it apart. Smart me took all these pics at a random point rather than pointing at the timing marks. Duh!:

    Timing
    http://members.optusnet.com.au/~edwardluck/Timing.jpg

    Rear Cylinder intake cam
    http://members.optusnet.com.au/~edwardluck/Rear cylinder intake.jpg
    Rear Cylinder exhaust cam
    http://members.optusnet.com.au/~edwardluck/Rear cylinder exhaust.jpg
    Front cylinder intake cam
    http://members.optusnet.com.au/~edwardluck/Front cylinder intake.jpg
    Front cyliner exhaust cam (taken from other side of bike)
    http://members.optusnet.com.au/~edwardluck/Front cylinder exhaust.jpg

    Note that the cam sprocket alignment marks are all at the same position on both cylinders.

    I've also just noticed that the front cylinder cams are flipped 180 degrees out of phase from the rear cams - you can tell by where the sprocket meets the cam there is a small bump in the middle of the front cams, whereas on the rear cams that side is facing down.

    I have not - as yet - even attempted to put the front cams in since the pistons hitting the valves on the rear cams definitely made it "beer time".

    Kaldek
     
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  11. Bugger me, you're right. I just found it. The specs for the Spada in the service manual say "Rear Cylinder is #1", but the camshaft alignment pages say to use T2 for aligning the rear cam.

    There's a guy named Chris who has done this task and I noticed in his docs that T1 should be used. I've asked him if this was just a typo but he's not read the E-mail yet, obviously.

    I think we've mos likely found the problem then. If that's the case, I'll put an edit into the service manual PDF document I created and then send that off to the guy who is hosting it online.

    Wait for further news tomorrow!

    Kaldek
     
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  12. Well I've just returned from fitting the camshafts and I can definitely confirm that the Honda service manual is WRONG. Timing of the rear camshafts must be performed using the "T1" mark, not the "T2" mark.

    The manual also gives you nonsense directions on how to then time the front camshafts based on what you see on the rear camshafts. The directions are rubbish. The correct procedure is to:

    1. Time the rear camshafts by using the "T1" alignment mark, with the rear camshaft index marks facing up and hteir sprocket alignment marks parallel to the head.
    2. Turn the crankshaft to where the "T2" mark is aligned and the rear camshaft index mark is facing down (so that you don't see the "INR" or "EXR" marks).
    3. Fit the front camshafts, with the index marks facing up and the sprocket alignment marks parallel to the head.

    After that, all the motions of the cams made perfect sense and the valves do not hit the pistons.

    Thanks to everyone for helping me find this solution!

    Kaldek
     
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    • Informative Informative x 1
  13. Good lesson here for all of us that the manual is not always right. If it doesn't make sense, then maybe the translation from Japanese to English wasn't as good as it should have been or the proof-reader stuffed up somewhere.

    Great to hear that you sorted it though. Perseverance pays!
     
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  14. Perseverance does indeed pay. And the Internet has to be the best invention ever for getting help for these things.

    Having said all that, the proof will really be in the pudding when I crank the motor and it fires. We didnt get around to doing that, because we wasted yesterday d*cking around with the camshaft timing and didn't buy an oil filter!

    Kaldek
     
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  15. Since fitting the cams properly, I should say that the alignment marks on the camwheels are perfect and exactly parallel to the head. So, I guess them being a "tad out" previously was just one more piece of evidence that the timing was way wrong.

    Kaldek
     
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  16. Well, Finally fitted the oil filter and filled the Spada up with oil today. Cranked her over - and she fired up no problems. A bit rattly to start with (no oil in the camchain tensioners probably) but once warm no rattles apart from a couple of valve clearance ticks (we knew that we rushed this a little bit and left them maybe with too much clearance).

    All in all, a pretty easy job if you make sure you ignore the service manual. :)

    Kaldek
     
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