660 Build...Cam Timing Question

[LuckyStriker86]

I have almost completed my 660 build following the write ups on this site, with much acknowledgement going to reelrazor.

The setup consists of :

FZR crank and case
YZF cylinders
YZF pistons
YZF Head
YZF Carbs
FZ600 Fazer Connecting Rods
Yamaha OEM YZF top and bottom head gaskets

I adjusted the cams following the FZR 600 manual, taking the slack in the chain up on the exhaust side and aligning the exhaust cam mark with the cam cap mark.



Following this, installed the intake cams, aligning the mark on the intake cam with the mark on the cam cap. (Hard to see in photo, but the mark on the cam is a hole right above the white paint mark)



All seems well, but notice that on the YZF head, the mark on the exhaust cap is dead center and the mark on the intake cap is OFFSET from center.
However on the FZR head, the mark on the exhaust and intake cam cap are BOTH dead center.

What the hell should I do!?!? I havent fired the engine yet, but am extremely hesitant as I don't want to bend valves.

Should I align with the offset YZF caps, or align dead center like the FZR head was?

If anyone has done this build with the YZF head and can shed some light, please advise. Thanks.

[LuckyStriker86]

This is how she currently sits. 400 frame btw.

[reelrazor]

FZR or YZF cams...

According to megacycle, they are interchangeable...but maybe timing mark is offset as well on the OEM YZF cams as well?


If YZF cams, align to mark..if FZR, align to center?

[LuckyStriker86]

They are the cams that came with the YZF head. I have also read that they are interchangeable, so was unsure. The motor is already in and ready to rock so I may just hit the red button and pray. I'll report back with results. Thanks for the reply.

[DonTZ125]

Pull the plugs, put it in gear, and push it - GENTLY. Any sudden resistance means piston and valve are rudely introducing themselves.

[LuckyStriker86]

ya, good call. I think i may be able to rotate the wheel on the rear stand if I click it into a higher gear. Thanks.

[LuckyStriker86]

Well I rotated the engine with the current cam timing setup, and there doesnt seem to be any interference. I tried starting the bike, but cannot get it to fire. I am wondering if it has to do with the intake cam opening too early or if it is carb related. I am having trouble with the YZF carbs. They keep flooding. I have cleaned these things so well, and have been messing with the float height but keep getting flooding and leaking issues. There is not much info about float height. The leaking occurs at the top of the carbs at the T-fitting for the float bowl air equalization setup, which makes me think that the floats are not closing properly. Any input would be great if you are also running the YZF carbs.

[DonTZ125]

You have one or more stuck floats or damaged needle valves or obstructed needle valves (crap between needle and seat holding it open). Turn off your petcock until you get this sorted, as you are drooling fuel into your engine oil.

[LuckyStriker86]

Thats what I was thinking too, but I have literally gone through these carbs with a toothbrush multiple times. I replaced the float valves with ones from donor FZR600 carbs, which seem to be the same dimensions (actually about 1/5 mm longer). You are talking about the float valves, not the vacuum controlled needles right?

The floats seem smooth, although when i blow air through the fuel line into the carbs with my mouth I do feel like I can pressurize it enough to pass some air through with all valves closed. I dont know if the fuel is pressurized this much or if gas can pass as easy as air. But they do seem to be operating ok otherwise.

I think I'll adjust the float height really high so that it pretty much wont let any fuel in and see if they still overfill and leak.

[LuckyStriker86]

Discovered the difference between the FZR and the YZF cams. They are essentially the same, however the alingment holes on the cams are different spacing. This is why the YZF cam cap has the alignment mark offcenter. Not a big deal, just dont align the YZF cam in an FZR head using the FZR alignment marks.



YZF Cam


FZR Cam