CiprianStoica Posted April 14, 2021 Share Posted April 14, 2021 This winter I was thinking of doing some proactive maintenance of my 6th Gen VFR. Among others, I was thinking of changing the throttle body insulators given that they are made from rubber, and due to old age who knows how good they still are. Due to lack of time, I didn't manage to do it, but a question pops up in my mind from time to time. When do I know that my insulators are bad? Last time when I checked them it was around 1 year ago when I replaced the cooling thermostat and they seemed in pretty good shape. I don't really have a bad fluctuating idle, maybe only a little bit, but that may well be the throttle valves being a bit out of sync. So how will a small leak in the insulators manifest itself? Link to comment Share on other sites More sharing options...
Magneto Posted April 14, 2021 Share Posted April 14, 2021 My thinking was in line with yours when I was restomodding my ZRX of 1999 vintage. After I checked the price for them buggers they suddenly looked perfect for me. Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted April 14, 2021 Member Contributer Share Posted April 14, 2021 They're pretty thick, and tough material. I've had both my 5th and 6th G ones off - both looked fine. My $.02 is that your maintenance money is probably better spent elsewhere. Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted April 14, 2021 Member Contributer Share Posted April 14, 2021 A leak at the insulators will result in *continuous* high idle because on a fuel injection system any air that gets past the throttle bodies the map just adds the corresponding fuel... the result is high uncontrolled idle... After you remove the throttle bodies check the hoses and O rings of the coolant system... Link to comment Share on other sites More sharing options...
Member Contributer DannoXYZ Posted April 14, 2021 Member Contributer Share Posted April 14, 2021 3 hours ago, Magneto said: My thinking was in line with yours when I was restomodding my ZRX of 1999 vintage. After I checked the price for them buggers they suddenly looked perfect for me. I've re-conditioned them with mixture of alcohol + oil of wintergreen. Soak completely submerged for 24-hrs. Nice and soft, pliable, easy-to-install and seals better for same clamping pressure as well. Link to comment Share on other sites More sharing options...
Member Contributer DannoXYZ Posted April 14, 2021 Member Contributer Share Posted April 14, 2021 On 4/14/2021 at 8:54 AM, CiprianStoica said: Due to lack of time, I didn't manage to do it, but a question pops up in my mind from time to time. When do I know that my insulators are bad? Last time when I checked them it was around 1 year ago when I replaced the cooling thermostat and they seemed in pretty good shape. I don't really have a bad fluctuating idle, maybe only a little bit, but that may well be the throttle valves being a bit out of sync. So how will a small leak in the insulators manifest itself? While leaks can manifest as higher-than-spec idle, due to alpha-N load-sensing (combo TPS+MAP), idle can be stable. Yet transitions between throttle-positions may have slight lag and hiccups with leaks. Alpha-N uses higher weighting of TPS-position and less on MAP at idle and low-loads. This is why you can start bike and idle OK with leaks, or even with MAP-sensor hose completely disconnected. As throttle is increased, TPS-position has less weighting and more of MAP signal is used. Since leaks causes improper MAP signal, going to higher throttle-openings depends more on MAP signal and leak causes more improper air-fuel mixtures and you'll end up with lags and stumbles. If you don't have any of those symptoms, then don't worry about the insulators leaking. https://www.vfrdiscussion.com/index.php?/forums/topic/97100-hesitation-and-occasions-pop-when-grabbing-full-throttle Link to comment Share on other sites More sharing options...
CiprianStoica Posted April 15, 2021 Author Share Posted April 15, 2021 I appreciate all answers, thanks. Well, given that they looked liked new and that I don't really get any idle related issues or lags when I change throttle positions, I think I am safe to say that the money can go on a different operation. I will double check them along with the coolant hoses when I replace the vacuum lines. Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted April 16, 2021 Member Contributer Share Posted April 16, 2021 I don't know what it is with the o-rings on the water necks that come out of each cylinder head - those things become absolutely fossilzed. Other o-rings in the system can be fine - but those . . . Maybe it's because they get hotter than the others - probably. At any rate, that's a good service to r&r those. Link to comment Share on other sites More sharing options...
CiprianStoica Posted April 22, 2021 Author Share Posted April 22, 2021 That's very interesting, Great idea, I will order and have them replaced while I have the throttle bodies out. I suspect it's P/N : 91331MCP900 ORING, 21.2X2.4 Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted April 22, 2021 Member Contributer Share Posted April 22, 2021 The ones on mine were stiff when I first got it. Came apart OK, so I lubed them with engine oil on reassembly. Been apart a few times since & lubed each time on reassembly, now they are quite soft. If you take a look on the tube, there are videos on how to soften rubber parts that have hardened with age & heat. Link to comment Share on other sites More sharing options...
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