Cam Timing for GPX250

[Childs' Play]

Hey Guys,

I've just given a mate a hand fixing up a leaking headgasket on his 1991 GPX250, and tried putting the cams in the way I'm used to on the old Z500 and we keep getting valves collide with pistons when turning the engine over by hand.

The procedure has been:
- Cylinder 1 (left) at TDC (visual & timing mark inspections)
- Exhaust cam goes in first, line up 'EX' marker with head and install cam caps
- Install the intake cam so that 'IN' marker lines up with head once the chain tensioner is installed.
- Turn engine over by hand using the alternator bolt
- Valves collide with pistons.

I'm guessing at the valves colliding, but the crank spins freely with the cams out and the chain held taught by hand. I can't think of any other explanation.

Has anyone got the correct procedure for the specific bike, either in the form of a full PDF base manual (have the PDF supp. manual), or a scan of the relevant pages?

Cheers,
Jon.

[Lainie]

I have the Manual I just need an email addy to send it too

[Tack]

If I remember correctly, you have to line up with number 2 TDC timing mark and if my memory is working...there are 33 links between in and ex cam timing marks.

However I can't remember the procedure for setting valve clearences, which is straight forward but you must have the cam lobe in the correct position to check the clearence correctly.

I made a tool for doing the tappets which just a long socket with a bit of flat welded to the top and drilled it for screw driver access.

Probably best to read the manual to get it 100% right because of all the things I've lost, I miss my mind the most.

[Childs' Play]

Thanks for that Track - the cams did look 90 degrees out from where they 'should' be. I'll give that a try for him on the weekend and see if that sorts things. I'm not interested in doing the valve clearances as Dan only wants the bike until July when he gets off his 250 restriction.

Lainie - Haven't seen anything for the manual come through yet on my end...

Jon.

[Lainie]

I sent it as soon as u gave me your email addy, cause of the size of it I had to send it through "YouSendIt" any emails from them? I got an email to confirm it went... Check junk mail if nothing let me know and will resend

[MiG]

Lainie, do you have the GPX supplement or the GPZ base manual? I hope it's just the supplement, or else I wasted $40 and a lot of time photographing each page. I expect to have a PDF ready by the end of the week.

[Lainie]

I have both... and would of only charged you $39.95

[Lainie]

Jon did the manual go through

[MiG]

How come you haven't uploaded it to the KSRC manuals section?

[Lainie]

Cause I dont know how to

[Childs' Play]

Thanks for emailing that Lainie, it worked this time. The file you sent is the Supplementary manual - gives basic info for the bike, but doesn't have cam timing in there. Have you got a copy of the full manual (EX250 model I think?)

If there's no copies floating around, I'll try #2TDC. Only reason I haven't tried so far is because there's no '2T mark on the alternator, just the '1F and '1T timing marks...

Screwdriver down plug hole, here I come!

[Lainie]

Yeah I have sending it now

[Childs' Play]

Looks like you sent the Supplementary Manual again!

[Lainie]

Have u had a look through it It may have what u need. Thats all I have

[Childs' Play]

Thanks for trying Lainie.
Look on Page 4-1 (engine top end) and you'll see things like Cam Timing refer you to a "Base Manual"

The bit of info Tack gave us should be heaps anyway, I've always done it with #1TDC, but looks like it's the other way around.

Cheers,
Jon.