Cam-swap/engine won't start

[Biker Biggles]

I think Northwind has done this.Might be worth a PM and pick his brains?

Managed (after a lot of persuasion) to get the timing cover off. Success. Still lack a 17mm socket. Fail. Will continue this later this week...

Dont know if its any help but i have a digital copy of the curvy haynes manual, assuming you havent already got it.

I've got a hard copy in the garage. It's very helpful...as long as you can get the timing cover off Now that it's off, things should be ok - I just need to get a 17mm socket so I can turn the engine over by hand.

[Red Herring]

I've not done a swop before but I'd have thought the markings on the new cam would be completely wrong for where you have moved it to. Inlet and exhaust cams are timed differently so why should the markings be interchangeable? An easy way to check would be to pull the cam cover off and position the new cam with the lobes at a particular point, then put the one you took our next to it and compare where the references are with the lobes in the same position. Oh and an easy way to turn the engine reasonably accurately (at least with the plugs out) is to put it in gear and turn the back wheel.

The cam swop is easy enough to do and those diagrams you are using are definately correct - I think they are pretty much what everyone uses.

A couple of things though - it is easy to get the timing 180 degrees out if your distracted by other stuff whilst you are doing this - more than a couple of people have done this so don't definately rule it out.

Theres not much to disturb when you do the rear (assuming you did it with the tank still on) so as Sid Squid said I'd just go back and double check everything you've done for correctness.

Finally - I find the tensioners a nightmare too - especially the rear for some reason, but I've always taken them out so the chain is nice and slack. I would definately recommend marking up the cam chain somehow before you start moving things though just as some sort of insurance policy incase it does slip.

[rictus01]

unhitch your horse and go buy a socket for a start...., don't cut corners, basic logic will show it's timed right or not.

It's not a complex job, and I'll admit I haven't done it for a number of years now, but can't remember any problems.

Cheers Mark.

Originally Posted by Neeja

I've got a hard copy in the garage. It's very helpful...as long as you can get the timing cover off Now that it's off, things should be ok - I just need to get a 17mm socket so I can turn the engine over by hand.

put it in gear - take the spark plugs out and turn it over using the back wheel..

Good luck with it all

[jambo]

Neeja,
To try and clarify the point Sudoxe and Spoon have made. The cams (as I'm sure you know) move half the rotational rate of the crank. This means it's possible to have the front cylinder at TDC, (F mark visible in the timing cover), and all the points line up correctly but have the crank one full rotation / the cams 1/2 a rotation out of sync with the other cylinder. Everything will turn over fine, but instead of the cylinders now trying to fire 270 degrees apart, they will try to fire 90 degrees apart, this doesn't work out well.

I would also suggest that using the starter motor to turn the engine once the cams have been out isn't a great call. Simple reason being the starter motor's very strong and can bend a valve if you've got the timing wrong. Turning by hand you should be able to feel the resistance and stop if you're concerned.

Jambo

Edit: My understanding of the process is that K3+ intake cams should replace curvy intake cams, and the curvy intakes should be moved to the exhaust. If this is not precisely what you're doing (I can't remember what year of bike you have) then it's worth clarifying.

Just to clarify, I've not got a set of K3 intake cams, but I do have 2 sets of curvey intake cams after taking my lunched engine apart. Instead of replacing intake with intake from K3, I'm just swapping out my exhaust cams for intake ones. Should make a difference, although nobody's sure how much.

I always thought that if the cylinders were trying to fire at 90 degrees that the engine would still fire, just badly. When the first attempt was made to start it, only the rear cylinder had a plug in it, so it should've been running on just the rear cylinder, with the front doing nothing but spitting out fuel-smelling air from the spark-plug hole Unfortunately it didn't fire at all.

And the only reason I turned it over with the starter was that I rolled it forward in gear first and didn't hear any clunking or feel any resistance - I was pretty confident that it all went back in in the same place as I left it, but apparently not. Picked up at 17mm socket on the way to work this morning, so should have this sorted tonight or tomorrow, depending on what time I get back home after a trip out to see a friend.

Re: above comment on removing the CCT - I was planning on taking the front one off because it's reasonably accessible. The rear one I had difficulty taking the cover bolt off...didn't fancy trying to remove it completely because I had a premonition of the nightmare I'd have trying to get it back in. Oh the irony. Hindsight, people...it's a wonderful thing