Member Contributer Skids Posted February 3 Member Contributer Share Posted February 3 Good morning all. My 01 has been sat in the garage since last Sep and I've just completed the annual oil & filter change. Started the bike up to let the oil warm up and pass through the filter so I could top it up accurately. Idle was around 2k rpm, which I guess is about right since it needs to warm up??? Then, as the temp gauge hit 70° C (158° F), the idle increases to a steady 3k rpm and wont reduce. Moving the bars makes no difference so the throttle cables are not snagging, I've tried to reduce the idle by turning the idle screw but that makes no difference, the throttle has the requisite slack on the cables so I'm thinking wax idle unit??? Before I purchased it, the bike spent the last 6 years not moving and over the previous 10 years only competed 400 miles. I have yet to lift the tank to check the throttle cables, SVs and idle screw but before I do that, I thought I'd ask the knowledgeable folk on here for their thoughts. When I last rode it, I had fitted new Iridium spark plugs, deleted the PAIR setup, balanced the SVs, new air filter and it was running beautifully. It's been stored in the garage over winter on a trickle charger with a full fuel tank topped up with fuel stabiliser. Any thoughts welcome please. Quote Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted February 3 Member Contributer Share Posted February 3 My thought is the same as yours, but that's all I got! Let us know what you find out. Ciao, JZH 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Presson Posted February 3 Member Contributer Share Posted February 3 I confess I've no actual experience of the wax unit, but could a stuck wax unit piston cause the problem you describe by keeping the SVs wide open? From reading around it sounds as though the wax units normally last over 100k miles. Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 3 Author Member Contributer Share Posted February 3 2 hours ago, Presson said: I confess I've no actual experience of the wax unit, but could a stuck wax unit piston cause the problem you describe by keeping the SVs wide open? From reading around it sounds as though the wax units normally last over 100k miles. Me either, it's all Honda magic to me. They should last but I wonder if the history of the bike with so much time doing nothing has led to an issue with it. Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 3 Author Member Contributer Share Posted February 3 IF it is the wax idle unit, is it possible to just replace the inner bit (part 17) or do you have to buy the whole lot (17 & 18) and the washers? Quote Link to comment Share on other sites More sharing options...
Member Contributer Presson Posted February 3 Member Contributer Share Posted February 3 Others will have to advise on that. However if it was working before it was parked for winter wouldn't a stuck bit that just needs easing be the most likely fault? I suppose the other scenario could be failure of an o-ring and leakage of the wax and there might be telltales if that were the case. Bloody irritating and quite expensive for a new unit I see. Fingers crossed it's an easy fix; even if it does mean taking off stuff on top of the engine. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted February 3 Member Contributer Share Posted February 3 General info... Trouble shooting Chris's RC45 continuous high idle the culprit proved to be air leaks... you see that on a fuel injection engine *any* air that bleeds past the throttle bodies the map just increases the correct amount of fuel... the result is high continuous idle... make sure all the rubber hoses are connected and in good shape... make sure all the intake boots are tight and in good flexible shape... if the rubbers are hard and cracked its time for replacement... 1 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted February 3 Member Contributer Share Posted February 3 As a suggestion, you may have a blockage in the thin water tubes that lead to/from the wax unit. This means the wax unit does not see the high water temps and so keeps the idle high even when the coolant is hot. Eventually heat soak from the engine should allow the idle to drop but it might take a while. If you’re lucky you maybe able to blow the blockage clear without major surgery. 1 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 3 Author Member Contributer Share Posted February 3 19 minutes ago, BusyLittleShop said: General info... Trouble shooting Chris's RC45 continuous high idle the culprit proved to be air leaks... you see that on a fuel injection engine *any* air that bleeds past the throttle bodies the map just increases the correct amount of fuel... the result is high continuous idle... make sure all the rubber hoses are connected and in good shape... make sure all the intake boots are tight and in good flexible shape... if the rubbers are hard and cracked its time for replacement... I did check everything you say when I had the tank off after I bought her and everything was like new. None of the gubbins beneath the injectors has been removed or disconnected so an air leak is a difficult one to imagine. Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 3 Author Member Contributer Share Posted February 3 18 minutes ago, Terry said: As a suggestion, you may have a blockage in the thin water tubes that lead to/from the wax unit. This means the wax unit does not see the high water temps and so keeps the idle high even when the coolant is hot. Eventually heat soak from the engine should allow the idle to drop but it might take a while. If you’re lucky you maybe able to blow the blockage clear without major surgery. What, blow with my lips? 🤔 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted February 4 Member Contributer Share Posted February 4 Hi Skids. Excellent advice already there for you. Just to add one more for a snippet of info. Any damage to the Molybdenum butterfly seal coating, will cause additional bypass air resulting in high uncontrollable idle. Bottom line is the main cause of Hi Idle is either the Wax Unit (or blocked coolant flow through it as mentioned), additional air into the throttle bodies (vaccumm hoses, throttle body mounting boots) or perhaps a dud TPS or ECT signal. Assume you don't have any Fi Flashing Codes. Terry raises a good key point here, if your idle very slowly returns to normal just relying on engine temperature heat soaking the WU then that is a good sign coolant flow through WU could be restricted or blocked, this could be within the WU itself or the hoses. Cheers. 1 2 Quote Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted February 4 Member Contributer Share Posted February 4 23 hours ago, Skids said: What, blow with my lips? 🤔 Yep, the same way you blow up a bus. A more delicate soul might employ a compressed air line but honestly, if you are that risk-averse then motorcycling may not be for you. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted February 5 Member Contributer Share Posted February 5 Any resolution on this issue? I went to see if I could help a fellow 5 Gen owner with the same issue. I tried looking/listening for air leaks but the bike wasn't at my place to do a more thorough go through. I took the wax unit out of the equation (adjusted it to not effect the idle), just to see if it was the culprit and although it seemed to keep the RPMs down, the problem still exist. I want to bring the bike to my place to have a better and more thorough look but thought I'd check in here first. My gut says air leak but until I can "strip the part off the heads to get a better inspection, thought I'd look on the forum first. Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 5 Author Member Contributer Share Posted February 5 Hi. No, I've not had time yet and won't for a little while. There's no rush though, she won't be back on the road until April. Please let us know how you get on with your mates bike. Quote Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted February 5 Member Contributer Share Posted February 5 2 minutes ago, Skids said: Hi. No, I've not had time yet and won't for a little while. There's no rush though, she won't be back on the road until April. Please let us know how you get on with your mates bike. Will do, may not be able to get to it until March, work will have me traveling this month. I want to have him bring it to my place so I can have a better and longer go at with all my tools at my disposal. Definitely chime in once I get a chance to look at it closer. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 5 Author Member Contributer Share Posted February 5 Great. And of course my fuel tank is full from over-winter storage 🙄 Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted March 5 Author Member Contributer Share Posted March 5 Finally have an hour or so to take a look at this. Drained the fuel tank, started the bike, idles around 2k rpm as it warms, temperature gets to about 70° C (158° F) and the idle shoots up quickly to around 3k rpm. I backed the idle adjuster out until it no longer touches the plate that moves the SV assembly so that it is not affecting idle - blue arrow in photo The screw/nut adjuster with the yellow arrow, which I think leads to the wax idle unit, can be pulled outwards a little and that reduces the idle so I'm wondering if that is not adjusted correctly. I've looked through the Haynes manual and there is no reference to this adjuster (bronze coloured tube with green dot on it) but it definitely moves the whole SV assembly and thus affects the idle. When I had the bike apart, I didn't knowingly disturb this, I didn't remove the fuel rail assembly at all, just disconnected and removed the PAIR system. Is there a procedure somewhere to adjust the yellow-arrowed nut to move the whole assembly without disturbing the wax idle unit? Or is this factory set and should not be moved, in which case why has the idle adjuster run out of movement and is therefore unable to reduce the idle speed? Or am I barking up the wrong tree here? Any help appreciated. Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted March 5 Author Member Contributer Share Posted March 5 Picture from parts catalogue, blue arrow pointing to yellow-arrowed adjuster in previous post. Image from Honda SM. Can't find any reference to adjusting here either. Quote Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted March 5 Member Contributer Share Posted March 5 Hey Skids. Am I seeing something strange?? Does that look like a broken Wax Unit shaft circled in Red?. Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted March 5 Author Member Contributer Share Posted March 5 No m8, but good spot. It's a scribe mark on the thread exaggerated by the angle of the light. Quote Link to comment Share on other sites More sharing options...
Member Contributer raYzerman Posted March 5 Member Contributer Share Posted March 5 There is no adjustment procedure and the manual just describes replacing the wax unit. So, one has to figure out the adjustment. If it were me, warm up the engine to operating temp, wax unit should have no influence, it if does, back it off.... Then Sync the starter valves, set the idle to 1200-1300 (or you preferred hot idle). Then let it cool down and see what your cold idle is... 2000-2500 is fine (to me), and typically where I put it with mine that has the throttle cable instead. Even then, it will creep up as the engine warms up, all normal. In your case, when hot, it should drop back to where you have your preferred not idle. I'd think the wax unit at that point may have a little slack to the starter valves, i.e., no influence on them at all. Are you using the proper starter valve sync procedure?? Check that no starter valve is sticking.... Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted March 5 Author Member Contributer Share Posted March 5 Hi raYzerman, thanks for that. When you say "back it off" for the wax unit, do you mean move the adjuster (yellow arrow) until it no longer has an effect when moved by hand? Quote Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted March 5 Member Contributer Share Posted March 5 The nut on the end of the wax unit op rod, sets the SV position relative to the wax unit temperature. If the wax unit & its lever brass bearings are operating correctly it should NEVER need adjustment. If the wax unit is NOT operating correctly you can adjust this nut to compensate, but it may not cure your issue. If I were you I'd measure the rod protrusion length, then remove the nut & brass bearing & clean it as it looks like it may be corroded! Reassemble after cleaning & test again. All the wax unit does is push pull the SV (choke) lever based on the coolant circuit temperature. When cold it closes the choke to make the AFR rich, when warm it opens the choke to allow main air control for idle to be by the SV/throttle plate idle screw setting. So if engine cold idles as expected (2-2.5k/rpm) then increases rpm when engine reaches nominal operating temp, the wax unit/SV plate is NOT returning fully to the Open position. The ECU does NOT have a monitor for WAX/SV position, but does have an engine temperature monitor for AFR compensation, hence the high idle speed. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Presson Posted March 5 Member Contributer Share Posted March 5 Like Mohawk, I'd strongly recommend cleaning up the brass slider and the plates either side. IIRC You did say it was working correctly before winter. Most likely that corrosion is causing the actuator to stick and as the engine warms expansion of the rod increases the idle further. Perhaps measure from the end of the rod to the nut before disassembly to give you a starting point when you put it back together. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer raYzerman Posted March 5 Member Contributer Share Posted March 5 Yes, what they said, perhaps better. I meant move the nut so it has no effect on the SV's when hot...... and see if your idle creep is still there..... although somewhat explainable as Mohawk says. Once the engine is at full operating temperature, I have not noticed any idle creep with my manual lever backed off... 1 Quote Link to comment Share on other sites More sharing options...
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