Odd vacuum levels after thermostat change 1999 VFR800

So I changed out the stuck thermostat in my 5th gen and that part of the surgery appears to have been fine. When I fired the bike up on the fast idle lever all seemed normal UNTIL I blipped the throttle, then the bike developed a high idle; I think I got a hose caught in the stopper for the front butterfly shaft on the right side. I rectified that but now I have some odd vacuum levels at the starter valves. I had balanced these before the thermostat surgery without any issue, but now I'm finding #1 (fixed cylinder) has a high vacuum, and the other three have their SVs mostly closed and I can't get them any higher. I did have a bit of a struggle removing the vacuum lines to the flapper solenoid, but don't think I messed that up; my mouth suction test held vacuum just fine in that line.

So what are the likely things that I need to check? The throttle boots all seem pliable and leak free.

 

Hi Terry.
Wish I could offer you a definitive answer to your issue and I feel like I'm talking to the educated. Your problem has only happened since removing the TB's . The vacuum arrangement seems far more horrendous compared to the 6 and 8gens. I have heard that once the TB clamp bands have been disturbed they require quite amount of re tightening to properly seal them. I can only suggest revisiting the clamps and rechecking every vacuum hose that it's routing is correct, no cracked hoses, kinks and every hose properly terminated at its source and destination. Are all four butterflies closing properly and perfectly in synch. Sorry to state the obvious and I've no doubt you'll sort it out, stay focused on exactly what you've done to do the T/stat replacement. Good luck mate hope you have it sorted ASAP.
Cheers and best regards.

 

Thanks Graham; I was coming to a similar conclusion. The idle speed seems to have varied a bit, I had to back the adjuster out initially as it was too high, but after riding yesterday it dropped down and I had to wind it back in a touch. I actually think that may be a good thing as lower idle means less air entering, so I'm hoping the rubber boots etc have settled back into a better seal. I'll get the balancing gauges out again today and take a look.

I do have a set of fresh rubber boots and vacuum hose to hand so I will contemplate doing that if I can't get the throttle body balance right. In the meantime the bike is starting and running as it should. I know others have commented that unless the SVs are balanced just so, the bike surges at low revs. My bike, or the rider, is not that sensitive!

I feel that I should know the answer to this; I'm sure I've read where others have had the same issue.

 

I'm with Grum, I'd kinda start all over and check all the hoses.

As for starter valve sync, follow this direction for a proper sync. Makes a significant difference.... (after you get the vacuum fluctuations settled down).
https://vfrworld.com/threads/starter-valve-synch-revisited.53524/#post-620387

 

I just went and re-started and warmed up the bike, the idle was low again (1000rpm) but had been 1200rpm when I tweaked it at the end of yesterday's ride. I raised that, then fitted my balancing gauges. Low and behold, they were more even than they'd been, and I was able to reset them as per the revisited guide above (1=2, 3=1+20mm Hg, 4 = 1+10mm Hg). It certainly seems like the heat cycling from riding has helped re-seat the inlet rubber boots (or something like that). I will monitor and check that over the next few days.