Engine timing, advice needed please ?

[Soprano69]

I wondered if someone can enlighten me with some technical info with regard to the above ?

I've recently stripped the top end of a curvy engine to give it a once over and grind the valves etc. I'm now ready to put the thing back together.
As its the first time I've done this, I've been following the letter of my haynes manual but, unless I've missed something, it seems to me there is a gap in the info supplied in the book.
When you align the timing mark on the flywheel to Tdc, how do you know if its on the ignition stroke or the exhaust stroke if the camshafts have been removed ? I think I should have probably marked the camchain before removing the shafts, or done one cyl at a time, but it didn't occurr to me till later.
I know the valve timing is determined by where you set it when the camshafts are re-fitted and I don't have a prob with that but is it possible to get the ignition 360 degrees out and hence firing on the exhaust stroke ?
I'm probably missing something really obvious here and about to be ridiculed for being a numpty but can someone put me out of my misery ? I need to get it reassembled now, I want my dining table back !:confused:

[dizzyblonde]

The haynes manual seems somewhat limited on a lot of info. ....have you ever thought of a 'Clymer manual'.....its a lot more informative. you can buy them off ebay quite frequently.
I can't help you with your question, I'm afraid, but the Clymer is better IMO. I have both

[charlie13]

There are some manuals that you can view from the www.sv650.org (http://www.sv650.org) page, but I can't seem to get on it right now to view them. I've got workshop manuals for both pointy and curvy in pdf format. The files are quite large but I can split it down and mail you the relevant sections if you can't find them anywhere else.

Edit
ps - have you tried a search on "engine timing" or "cam timing" or similar, sure I read something a while back that had some good advice of checks to do before you hit the starter button.

[yorkie_chris]

Well, I've never done this so please bear in mind I could be talking ****e...

The cylinders are 90 degrees apart, so if you know the firing order then you can work it out from that I think.

Is front first or rear? If you got it wrong, does the engine waste spark? if this would run, would it damage it?

[Soprano69]

Chris, this is my question, does the engine spark on both strokes anyway, in which case it wouldn't matter but I can't find any reference to this.

[yorkie_chris]

This is the wasted spark I refer to.

The black box gets triggered at crank speed, so correct me if I'm wrong but it can't actually tell whether its on compression or exhaust.

However like I say I'm really just speculating, I've never done this job.

P.s northwind is probably the man to ask

[jamesobrady]

The position of the cams tells you what stroke your engine is being set up to

http://img101.imageshack.us/img101/9030/enginetdcexpansionxl1.th.png

[yorkie_chris]

You can figure that out, but how do you know whether you're on compression or exhaust when the cams are out?

[zadar]

if cams are out there is no compression or exhaust stroke,just stroke.
when you put cams in you basically tell engine which stroke is what.
in other words it does not matter,you can start anywhere you want,front or rear,any crank revolution.you just make sure where ever you start next cylinder is one crank revolution apart and both cylinder cams are set at F mark(not R for rear).R is TDC but not where you set cams at.cams are set at F mark for both cylinders(one revolution apart).R mark is only to check valve clearance.

[yorkie_chris]

:notworthy:

[zadar]

This is the wasted spark I refer to.

The black box gets triggered at crank speed, so correct me if I'm wrong but it can't actually tell whether its on compression or exhaust.


right.black box only knows piston is at top of stroke.
reason is crank turns twice for each cam revolution.

[yorkie_chris]

So as long as you set the rear cams to firing position a revolution after the front then all's well?

Which timing marks do you use on the cams when the crank is aligned to "F", obviousy front is normal ones like you would when doing valve clearances, what about rear?

[zadar]

yes.
starting mark on cams is arrow with F for front(exhaust cam)and arrow with R for rear(intake cam).you align this arrow with head surface and than next cam is 16 pins away.pins counted between number 2 and 3 stamped on cams.

[Soprano69]

Thanks for clearing that up guys. I kind of suspected something like that but the haynes book confuses matters by stating that the front cyl has to be on the compression stroke when re-inserting the cams and I didn't know if the ignition was timed to a certain crankshaft revolution. Its clear now that compression or exhaust stroke are determined by the valve position.
Thanks again.

[yorkie_chris]

Don't forget to rotate the engine by hand a good few times and check for interference or anything that doesn't look right.

[Richie]

manuals (http://www.sv650.org/sv_manuals.htm) for the curvy and the pointy.

I replaced the gearbox complety and rebuilt the engine and top half just using these.
hope it helps you out too.

[Soprano69]

Everything back in place and looking ok so far. Next step is to get the engine back in the bike and fire her up.
Cheers chaps

[zadar]

the haynes book confuses matters by stating that the front cyl has to be on the compression stroke when re-inserting the cams and I didn't know if the ignition was timed to a certain crankshaft revolution. Its clear now that compression or exhaust stroke are determined by the valve position.
Thanks again.
there is reason for that.in case you working on 1 cylinder only you do have to pay attention to compression stroke.
if not you may end with big bang motor :).it will run fine,just make about 10hp less :)