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Discussion Starter · #1 ·
doing my belts for the first time. Hanyes left me with some questions.

thinking on memory, when the crank pulley was aligned w/ the mark on the case both my vertical and horizontal cylinders cams were aligned with their respective V and O marks. is my memory wrong?

do i have to do TDC on horizontal, put on the belt, and match the O marks then rotate the crank the 270 degrees to get the TDC on the vertical cylinder to match the V marks with the cams? in that case a 2 part timing process.

or can i do what i remeber i saw and set the crank pulley at its mark...and flywheel mark, and put on both belts on without rotating the crank and with the cams properly V and O'ed? which would be a 1 step timing process.

please tell me its the 1 step TDC
 

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Discussion Starter · #2 ·
and for tention i'm trying to pass a 5mm allen key between the nonadjustable pulley and the belt?

i know some of you geeks know the answer, and i know your names...and i'll say them.

anyhow, will somoene help me out with this and the previous post? preez
 

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The below assumes you are working on a 748/916/996 series superbike (non-testastretta motor).

You've got 5 points to deal with. The crank and the 4 cams.

Set the crank as you've described and leave it alone. Don't pay attention to the flywheel mark, either.

The cams have timing marks on their timing gears. BOTH cams on the vertical head should point to 12:00.

The intake cam on the horizontal head should also point to 12:00. The exhaust cam on the horizontal head should point to 6:00 (180 degrees from the intake cam). That sets your 5 points.

Make sure the vertical cams don't turn as you are setting the belt. The cams will be under load and will want to turn. If they do, the timing will be off.
 

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Discussion Starter · #4 ·
very much thanks, yes its the non testastretta, modestly powered 748.


i set everything as you described but have a single concern regarding the vertical cams. the intake cam is loaded yet the exhaust is not, if its not an issue i'm going now to crank the engine.
 

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Yes, the V.I. cam will be loaded by the closer spring at that position. It's not a problem, just turn the pulley against the spring to get it lined-up as you do that belt.

You only need to turn the motor to the V cylinder marks when you're ready to tension the V cyl belts, but it's not necessary to turn the motor just to install the belts.
 

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Discussion Starter · #6 ·
OldBaldy said:
but it's not necessary to turn the motor just to install the belts.
i meant i'm done, just need to start the bike to affirm a job well done. then find out about the 5mm tension.
 

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I'm not sure if you've already found your answer about the belt tension. Obviously the safest bet is to have this backed up by a pro after you're done. The way I read it: What you're doing first is to set the belt taunt and then scribe a light line on the head along the non-toothed side of the belt between the intake and exhaust cams. Then while applying a "modest" amount of pressure with a 5mm allen wrench start to loosen the tensioning pulley until you can deflect the belt toward the crank enough to make the opposite side of that allen wrench line up with the line you've made. That gives you 5mm of deflection

The same process is repeated on the vetical cylinder but substituting a 6mm wrench due to the higher operating temps of that cylinder.

I hope that helps. I pulled my vertical cylinder off today. The horizontal is ready to go too, but the front wheel's in the way! Since I can't seem to split the head from the cylinder and don't want to screw anything up I'm just going to go pick a front stand to create the room I need. Been meanin' to get one anyway! I haven't really gotten in for a thorough look yet but it appears as if at least my vertical intake and exhaust openers are flake-free!

Cheers,
Gavin
 
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