79josh81
XS650 Addict
So today I went outside to (in this order) set timing on my points ignition, then sync the carbs, and then set my mixture screws. I decided to do all this because I went up a size on my pilots and 2 sizes on my main jets for the Uni filters and open headers that I'm running. I had already did my valve lash, cam chain tension, and breaker point gaps to spec and also re-set my mixture screws to the factory spec to give me a good starting point. My timing went well with the light and everything was right on with both cylinders and my advance.
I then moved on and hooked up my DIY manometer to sync the carbs. I have aftermarket carb holders without the vacuum barb but I used the 2 vacuum ports on the sides of the carbs by removing the screw and threading in barbs that I actually pulled off of the old vacuum petcocks that I'm not using anymore (they fit perfect in the carbs in case anyone is curious). I notice right away that neither cylinder was pulling more vacuum than the other enough to suck in fluid but the vacuum readings being shown on my manometer were erratic, where each side seemed to pull harder at different times.
After messing with the sync screw for a little while, I noticed that the closer I got to getting the fluid levels to be even with each other in the tubes, the shittier the bike ran and the fluid levels would still jump around where one side would pull and then the other side would pull. So at that point I decided to just adjust the sync screw by sound/feel and I watched where the fluid in the manometer ended up when it sounded good.
When I got the engine running good (meaning the sound/feel from each exhaust was identical), the fluid levels were no where even to each other. I wanna say that the manometer fluid level for the right cylinder was probably 12 inches higher than the fluid level for the left cylinder. BUT...the fluid stopped being erratic at that level and it did not move at all, even when throttling up to the higher RPM's. That tells me, regardless of where the fluid levels were in the tubes, that the vacuum being pulled on both sides was equal because neither could budge the other. So that's where I set it.
My question is, what is a better method to go by (and this is going to cause a shit storm), the DIY manometer or by sound and feel? Now after doing this with my DIY manometer, I'm smart enough to understand that the reason why my fluid wasn't even on both sides when I got it running good was probably because by the time I found the sweet spot in the sync, the fluid was already out of whack in the hoses and when I finally hit equal vacuum it just locked the fluid levels in their current positions (because of the equal vacuum on both sides). But most of the videos I've seen using the DIY manometer method, seem to show guys who have their fluid levels completely even to each other at perfect sync. I just wonder how many people chase getting the levels even like that and, in-turn, run their bikes slightly out of sync. Thoughts???
I then moved on and hooked up my DIY manometer to sync the carbs. I have aftermarket carb holders without the vacuum barb but I used the 2 vacuum ports on the sides of the carbs by removing the screw and threading in barbs that I actually pulled off of the old vacuum petcocks that I'm not using anymore (they fit perfect in the carbs in case anyone is curious). I notice right away that neither cylinder was pulling more vacuum than the other enough to suck in fluid but the vacuum readings being shown on my manometer were erratic, where each side seemed to pull harder at different times.
After messing with the sync screw for a little while, I noticed that the closer I got to getting the fluid levels to be even with each other in the tubes, the shittier the bike ran and the fluid levels would still jump around where one side would pull and then the other side would pull. So at that point I decided to just adjust the sync screw by sound/feel and I watched where the fluid in the manometer ended up when it sounded good.
When I got the engine running good (meaning the sound/feel from each exhaust was identical), the fluid levels were no where even to each other. I wanna say that the manometer fluid level for the right cylinder was probably 12 inches higher than the fluid level for the left cylinder. BUT...the fluid stopped being erratic at that level and it did not move at all, even when throttling up to the higher RPM's. That tells me, regardless of where the fluid levels were in the tubes, that the vacuum being pulled on both sides was equal because neither could budge the other. So that's where I set it.
My question is, what is a better method to go by (and this is going to cause a shit storm), the DIY manometer or by sound and feel? Now after doing this with my DIY manometer, I'm smart enough to understand that the reason why my fluid wasn't even on both sides when I got it running good was probably because by the time I found the sweet spot in the sync, the fluid was already out of whack in the hoses and when I finally hit equal vacuum it just locked the fluid levels in their current positions (because of the equal vacuum on both sides). But most of the videos I've seen using the DIY manometer method, seem to show guys who have their fluid levels completely even to each other at perfect sync. I just wonder how many people chase getting the levels even like that and, in-turn, run their bikes slightly out of sync. Thoughts???