Yamaha V6 link and sync

[phantomyamaha]

im wanting to link and sync my 1984 yamaha v6 175, i have fitted the motor with milled pro v 200 heads, epoxied front half, reed stuffers, ported 8 hole reed blocks, boyesen power reeds, ported inlet and 34mm carbs from the pro v, i want to link and sync the motor to make sure every thing is set correctly before i start jetting etc.
Does anyone have the correct link and sync procedure for my motor as i have trawled the internet with no luck.
Thanks in advance, Andy.

[DoktorC]

Unhook the oil pump arm
unscrew the idle stop
unsure the throttle cam isn't touching the roller
loosen the link arm on the two carbs (LEFT HAND THREAD) and re-tighten
reset idle
hookup oil pump arm

[Mr. Demeanor]

I always double check with a piece of wire as a feeler gauge right in the center under each throttle plate because there can be a little variance with them closed vs. slightly open when the slack/play is taken out of the linkage.

[phantomyamaha]

I may have replied twice I don't post much on hear so I'm a bit of a novice, firstly thanks for the rapid reply, the link sync is much simpler than i was led to believe so shouldn't present me any problems, secondly since you guys no your stuff whats the best method to set the timing at idle and wot, and how much advance should i run, also if theirs any other advice you can give me on my setup i would greatly appreciate it, thanks again, Andy.

[DoktorC]

http://www.screamandfly.com/showthre...amaha-V6/page2

Ray has some good info at the bottom of pg2 on this thread in terms of timing.

The manual has the proper method of setting the timing...I've never really played with it to be honest.

[Mr. Demeanor]

My motor is 3/4 of your V6 bu very similar otherwise. Ive played with timing without seeing a whole lot of change. Ive run a max of 26 degrees with 160 psi of compression and jetted very safe.

I set my max advance with the boat on the trailer. Start it up with the throttle linkage disconnected and have your timing gun ready. Pull the advance arm to full advance and see what your timing is. It will rev up but not to fast with the carb linkage disconnected. You see the timing go up on the flywheel and then come back down slightly as revs increase. Marking your flywheel with white paint whee you want the timing makes things easier.
Before you set timing you must make sure your pointer is set to TDC. I use a piston stop and made a spacer to stop the piston at 10 degrees before or after depending on which way your turning the flywheel. The flywheel should read the same before or after TDC when the piston hits the stop. If it doesnt, the pointed needs to be adjusted. There are other methods but the piston stop IMO is the easiest and most accurate. Once you have the spacer made so it screws in just far enough to stop the piston around 10 degrees.its quick and easy to check it at any time.

[phantomyamaha]

Ok brilliant thanks for the advice i will crack on with it this week, should hopefully get it to run nice and smooth, thanks again for the tips.

[Mr. Demeanor]

Most carbs have air bleed holes in the throttle plates but Yamaha doesnt. The ones with air bleed holes are very accurate and idle nice. The Yamaha carbs have to have the throtle plates cracked open slightly to idle and for this reason the sync is critical to get a nice idle.

[phantomyamaha]

Yea it used to idle really well with the original 27mm carbs on, i have only just fitted the 34mm carbs and didn't want to mess around with them and loose the settings before i fitted them so i just soaked them in new fuel, but the idle is rather rough so I'm going to take them back of and go through them, I'm fairly handy in the machine shop, i nocked up this flywheel and ported reed cages for it on a quiet day at work.



i lapped the reed faces and cleaned the insides of the cages with a dremel after this photo was taken, the boat is a Phantom 18 its a british built race boat.

[Mr. Demeanor]

Very nice! Need more Yamaha guys around here :-)

[hydro]

According to Bob Kottmann "THE YAMAHA GURU" you are better off jetting a v-6 Yamaha almost perfectly and running moderate advance 22-23.Than jetting it too safe and running more advance.

Yamahas don't like excessive advance.