No need to reply to this; just covering the couple of points raised earlier:
There isn’t a lot of colour difference from crank now, and when I first split Old Faithful, and given your comment about heat marks being from assembly, I’ll stop worrying about that. I will still check it over and compare it against the other spare crank though. Here’s a photo of this same crank from Old Faithful split May 2014:
I’ll update with all the details, and maybe a few photos when I’ve got all the jobs done. My SIP order is due tomorrow, which leaves me just a few jobs left, and a few days to get it all back together in the hope of having engine back in on Saturday morning, for firing up and a ride on Sunday. I’ve done my engine mounts whilst waiting, rebuilt gearbox with NEW standard Piaggio crux, and cleaned everything up for rebuild.
Main jobs outstanding (for next few days): · Dremelling longer Secondary transfer slots in NEW piston to match previous one (5mm), and chamfering all ports. · Threadlocking new studs where needed (carb, selector box, crankcase, and cylinder – all now thoroughly degreased where loose, waiting for new studs where needed). · Reinstalling crank (after crankcase studs done). · Pressure test. · Jetting overhauled carb, and replacing with new gaskets, which I've made. · (I also need a new clutch and rear brake cable before riding).
I think you (pxguru) might advise against this next bit, so I’m putting it here in case you really think it’s a bad idea, but I intend to reinstate the 0.2mm copper base gasket with the 2mm packer. I think it will put my squish back where intended, return my compression ratios to where intended, and help my temperatures as a result. I also intend to have it, as much as possible, back to where it was in June 2016, before the tweaks that caused the seize. I was very happy with it as it was there, and any further improvements that might have been gained in performance/efficiency/economy are not of interest to me at the moment; I’ll keep it more on the safer-side of optimum this time. I feel I should have left it there then. It’s roughly the same ambient temp now as then, (13°C), so should be close to good enough for the Summer with not too much messing about; I’m not spending all Summer setting-up carb again. I know there’s more, maybe with bigger AC, BE2, maybe with smaller carb drilling etc., but it isn’t important to me for now.
With that in mind, I have to decide on running-in procedure and jetting (with reference to the notional target jetting I had before the tweaks that caused the seize); they were:
Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, and.... 42/160, MJ135, BE3+2, AC160, #04 slide (8750rpm (99kph/62.0mph) in 3rd, and 7410rpm (112.5kph/70.4mph) in 4th. – max temp 150°C)
I’ve considered running-in without vortex (opinions welcome), but as my best idea of running-in jetting, if I keep it on: Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, and.... 55/160, MJ145, BE3, AC160, #04 slide
I’m unsure how much running in is needed for new piston and rings in old barrel (ring-gap now 0.35mm), so I’ll have a go below, and be prepared to be corrected: · Extra 1% for first 2 tanks (100 miles) · Two 10-minute spluttery runs, and cool fully between runs. · 200 miles spluttery running in (with more-open mixture screw as well as richer jetting), staying mainly in 3rd. · Strobe timing after 200 miles (should be spot-on as before, but worth a check). · Rejet after 200 miles (to near notional target jetting above), bit more 4th, extending periods and a bit of WOT when happy – for another 300ish (or Easter, whichever is sooner). · A bit of plug chopping at various revs (hopefully after about 500 miles), to make sure I’m good if I go anywhere at Easter.
I’ll take on board any comments, but I am serious about not spending the rest of the Summer on it.
Been a lot going on behind the scenes. You will be the small block engine mount expert before long, if not already. As I remember the beast never went right after the last rebuild. Maybe the top piston ring was cracked since near then? Now you have your compression tester it will be much easier to keep an eye on it.
The main reason for taking out the 0.2mm copper packer was to reduce the max rpm. It was revving too high which means that the bottom end would be flat and it wouldn't pull 4th so well. 0.2mm has no great effect on the compression, not sure it would even notice. Either way its not permanent and will be as you liked it pre re-build, so least it will be running fine for the Summer.
Did you buy a new piston or re-using the original scuffed one from the very first build?
There are a lot of opinions to running in just rings. No additional oil and just the three heat cycles is all I ever do. Nothing bad ever happens and they seem to last plenty long enough. I am not usually running in cast rings though so I suggest not too much prolonged high rpm stuff for the first few tanks or petrol.
I think you will find this time round the jetting in will be confined to a weekends work. Once its running great again it won't be such a chore.
Engine mounts were easier second time around; still not my favourite job though. Not sure when the problem with rings first happened; my guess is about the time I was first having trouble idling in Autumn, whilst trying to set up Pilot, which was shortly before fist isolated starting problem, then extended over-Christmas break. But it was still starting OK again in February, for a while, and, as film shows, running OK at higher revs, but then definitely gone during those last, or the final film I made; finding a satisfactory theory to suit all evidence is difficult. My main reason for reinstating the copper gasket was that it might help bring my temps down again (though that could be my CHT gauge anyway), and that maybe, combined with the reduced squish, it might have been a factor in the ring failure. I do remember that I was revving to just short of 9,000 in 3rd, and that 4th wasn’t great, though bottom end was good after AC/BE mods. Hmm; I mentioned it because I doubted my decision, and I’m still not sure which is best. But I do know I was happy with it in June. It isn’t permanent, as you say; still time to make best decision though. Yes, a new piston. Given that I’ve had two near-misses with this barrel now, which has a lot of my time invested in it, and the recent experience of re-using parts in critical areas, and the scuff and that the ring channels had hard black deposits possibly affecting ring seating, I decided I’d be happier playing it safe with a new (£50) piston. That old spare (which is still a spare – part of the reason I got a new one was it leaves me a spare), wasn’t from any re-build of mine, it was from a previous seize before I was doing stuff for myself, and had been replaced then, and I’d kept as a paperweight. Other than engine studs (just where necessary), and general hardware, the other main new item was a standard Piaggio crux; I decided on standard because I still can’t convince myself that I’d rather be beating my gears up than my crux. I have several that I could have turned over in the spirit of Vespasco, but, in the hope that these casings stay together for a while now, £20 on a new one seemed a sensible decision. You’d probably have gone for re-used piston and hardened crux, but I had to make some decisions last week to get my order in on Friday, and SIP got it picked and dispatched within 2 hours, so well done them – if it’s correct when it arrives……. I’ll reign-in my running-in plans a bit, but it is new piston and rings, and putting in miles locally isn’t such a chore, especially if it stops raining for five minutes. Disappointed the weather has been so poor; I don’t mind getting cold and wet really, but there’s been no opportunity to do any rear-end rust while the engines been out, so had to put that job off – again!
I wrote a quick reply early this morning (above), but during the day, and since my SIP delivery I’ve had a couple of developing thoughts - I have two theories; both might be nonsense, but I thought I’d see what people think.
Firstly, cast your mind back to how tight the gudgeon pin was when I tried to dismantle the top-end after the seize. Also recall that inside the piston, I had cut away one side only of the piston, around the casting holding the gudgeon pin, to aid airflow through the piston to those two boost (secondary) transfer cut-outs. I wonder if the piston might have warped (due to there being more metal one side than the other) when it got hot. I wonder if that was why my gudgeon pin was so tight, and maybe also why the rings, maybe bulged and snagged before failing. Just a thought, but one worth airing before I do the same mods on the new piston on Thursday morning. I started wondering because the gudgeon pin on the new piston is just a nice smooth slight interference fit just like the uncut piston on Old Faithful.
Here’s another, which will either be a valid point, or will show me up to be a tit; I’m thinking about these cylinder studs: · I’ve always thought the shorter-threaded end goes into the casings, (to give more thread-length at head-end for packers/skimming etc). · I’ve also thought that the casings end should be threadlocked, but the cylinder head end should be torqued (nut, washer, spring washer) but not threadlocked. The last two sets of ‘kosher’ Piaggio M7 cylinder studs I’ve bought (last time from Wasp and this time from SIP) have had pre-threadlocked (blue) threads, but applied to the long-threaded end. Either this is intended to go into the casings, or Piaggio are intending the head end to be threadlocked (hence my problem with studs keep coming out), or Piaggio have made a mistake, or they aren’t ‘kosher’ Piaggio (I think they are though; they feel and sound right), or I’m wrong to think the short end goes in the casings. Whatever turns out to be correct, this is why the cylinder studs keep coming out – their threadlock (on the wrong end?) is stronger than mine (in the casings end)!
As it happens, I’ve just got myself some Loctite 270 (green), which is stronger than 243, which is what I intend to use on all the engine studs this time – I’m intending to do that tomorrow, so do say if it’s too strong; I’m trying to get them in to stay this time and look after my casings.
Here’s the previous piston mods, which I’m intending to do to the new piston tomorrow (thurs):
Those mods to the inside of the piston don't need to be done on the inside. And I cant imagine they would make the pin tight. Chamfer the piston ports from the inside too though. Before fitting a difficult piston put the wheel side circlip in, then give it 30 minutes at gas mark 5 and the pin will just slide straight in.
The loctite 270 will do the trick. Just make sure this is the last time any of those studs ever come out again. When you wind them in stop with a few theads showing.
Surprised you didnt get the thin ring Grand Sport DR piston. Is double the money but there is always the 1st oversize option for much later on.
SIP say that the hard crux doesn't wear the cogs any more than usual. I have no idea if that wizardary is true but I have one in mine with a new set of gear cogs, so we will see how it looks in a year or so.
Be sure to get a good pressure test result before fitting the clutch.
I would imagine you are looking forward to starting with half a kick again.
Excellent; I’ve a big bag of bits and a list of jobs, no more questions and no more parcels – all clear for final push. Thanks for your replies; I’ll update in a couple of days……………… Just to keep it tidy: · Noted re piston work · Loctite 270 is my new friend · G.S. Piston; not so much the money (but that’s a factor), more that 1st o/s (Ø63.5mm) is up my sleeve for later, when we have more time to discuss piston windows, as compared to those on D.R. piston. · I read SIP blurb about hard crux; I know you wouldn’t use one if you didn’t rate them; if I get a decent season or two out of Beast this time, I’ll be more inclined to part with more of my hard-earned next time. · Engine will not leave the building without a good pressure test; if there’s any problem, I’ll find and sort it here first.
The main thing is all jobs are done and pressure test is good; only slightly down on new build figures when everything was brand new. I have loads of data, photos, film etc., but my main priority now is to get all my tools tidy again, and get engine complete (carb, clutch, flywheel etc. back on), to have a couple of hours putting engine back in the frame tomorrow (Saturday) morning. No time for more now; lots to check and organise to get ready for tomorrow…………..
Here’s pressure test comparison; it’s all that matters for now:
New Build Pressure Test (Oct 2015): 10psi to 7psi in 1st 5 minutes = 0.6psi/min 7psi to 5.5psi in 2nd 5 minutes = 0.3psi/min 5.5psi to 4psi next 10 minutes = 0.15psi/min
Spring 2017 overhaul pressure test (today): 10psi to 6psi in 1st 5 minutes = 0.8psi/min (was 0.6psi/min new build) 6psi to 3.5psi in 2nd 5 minutes = 0.5psi/min (was 0.3psi/min new build) 3,5psi to 2.5psi next 10 minutes = 0.2psi/min (was 0.15psi/min new build)
07:20 Sunday (In and out before the neighbours knew what hit them).
Happy to say she's running again!
Started 3rd kick with newly rebuilt engine, couple of (deliberately) spluttery runs with no problems, but (not-deliberately) no decent back brake, and grabby clutch. She even nearly idled without a tweak, and started first kick when she died - lovely. Anyway, film and more sordid details later.............
.....Film (nothing of note really - she started, she went up and down the lane, no problems - good enough for now) Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, and.... 55/160, MJ145, BE3, AC160, #04 slide
First run after engine rebuild – 12th March 2017
I’m busy for next few days, but plenty of time to play later in week, and good weather for doing a few jobs and putting in some gentle miles before a few carb/jetting tweaks. Intention is to get jetting back to around (June 2016): 42/160, MJ135, BE3+2, AC160, #04 slide …for the Summer, then maybe fiddle again when it gets cold again.
Option 2: One way trip to the seaside if she plays up again this Summer
Don't think there is any danger of you getting the train home. Sounding like she's running well again. Pulls quite hard from low rpm. A few more of these runs and it's time for a long ride out, maybe to the seaside but just for a look.
Beginning from a clean sheet with 55/160, MJ145, BE3 and AC160 will get the job done quicker. Tweek only what needs it. Get the pilot and mixture set up first and if it revs out enough the MJ can stay where it is until run in.
All in all, I think you got away with this one quite cheaply
PX200E with 221 Malossi, max power at 8300rpm, VHSH30CS, 175 main jet PX200E Tourer, tuned original barrel, SIP road II, SI26/26 135 main jet, vortex 1050cc Triumph ST 600cc Honda CBR
Quick update – nothing exciting to report, been pretty busy. I’ve done enough spluttery kms to be thinking about jetting and carb tweaking now. She’s starting 1st or 2nd kick and running sweet – no worries. I’m still a little concerned it’s too hot, but I know my CHT gauge is suspect, and it will possibly be better when my revs are up anyway (still on 6500rpm so far), so concentrating more on plug this time. I’ll have a retorqueing session sometime soon as well, but just slowly increasing my revs and staying in 4th more - but need the revs for the cooling, like before. I'm happy just to do it myself in my own time – no hurry or worries at the moment. Think of no news as good news for now, until have some results to share anyway……
Was wondering what you were up to. Seems like it is all going fine. Will be very slightly hotter with the running in. As before, the plug colour and how it feels says it all. The reading can just be used for known reference once you know what reading gives the right plug colour. Suppose you can't tell how the performance is yet? Hopefully somewhere near last summer's glory.
It feels great again; there’s plenty there, but I’m not near pushing it up to WOT yet. I have no doubt it has the potential to be the same as last Summer (pre-seize) when my jetting is sorted. Now I’m ready to tweak my carb, I can wind my Mix in, reduce my Idle and get a decent tickover, and change my Pilot as necessary, all of which will generally settle it all down a bit; it’s running rich and idling fast at the moment. I’m still trouble-shooting non-engine scooter stuff as I ride too, and my time is limited. I got distracted by the (suspect?) indicated CHT temps last year, so I’m definitely relying on plug and feel this time. I know 170°C indicated was still giving me a good plug last year, which made me conclude that this gauge is now reading at least 20°C too high, but I’d still rather not be seeing 150°C whilst gently running in, and it’s reading correctly at ambient with a cold engine, so I don’t really know what it’s doing – I’ve got my eye on it. The fact with this CHT gauge now is I think it’s pretty useless, but I also don’t want to waste more money on another, so I’ll see if I can make use of it as a benchmark to show sudden changes later, but for now I have to proceed with caution with what it’s telling me at the moment to know what indicated temps are OK. It seems to be mainly when revs drop as I go into 4th that the temp jumps up, so there is a definite increase, and maybe that’s just because my running in revs aren’t high enough for adequate cooling yet – I’m sure it’ll iron out as I open it up more and tweak the carb at the same time as knowing my plug is OK. I want to be cautious because of what happened to the rings before. I’m still aware of those ‘V’ shaped bridges I Dremelled in the barrel, which you weren’t keen on, and might be creating a hot/high wear spot on the rings. That doubt wasn’t lessened by Jim’s post yesterday about ‘ring speed’, which I’ve read now in the context of the whole thread over on Modern Vespa here:
My 57mm stroke 2mm rings doing nearly 9000rpm sounds a bit like ‘redline’ if the source of this info is reliable (I have not waded through Jennings to find it). Up to now, and if that isn’t a red herring, I hadn’t realised I was anywhere near any rev limits with my DR, although obviously I knew you felt my fat cast rings were limiting, but I took that to be limiting performance, not what it could handle.
I should note that I’m at the same point as I was after the seize, when running in/setting up again last August (specific detail on 16th August on thread linked to below); I’m running in at my own pace, I have the same indicated CHT gauge temp issue, and I already have the advice I had last time to refer back to. It got to a point where we seemed to be in a discussion loop that wasn’t going anywhere before, and which, whilst I must re-read it to see if I’ve forgotten anything, I don’t want to drag up for discussion or continue with again, other than to note the same issue exists. Progress was halted then when eventually I could no longer idle at all, which must be about the time the rings problem happened. – So now I just want to do my running in and tweak my carb with reference to the plug, and hopefully get past that point this time, so I can have the scoot good and reliable this year. Here’s the last page of the previous thread, which I’m going to go back over quietly myself (it’s the same issue, but now with a freshly rebuilt and checked engine, I’m even more inclined to doubt indicated CHT gauge temps, BUT lets not forget that sometime soon after this something made the rings go wandering round my barrel uninvited):
This weekend, after a carb tweak and a few general scooter jobs to keep it road-safe now I'm on the road again, which I neglected over Winter, and time permitting, I’m going to widen my route to take in a few big hills to see how she likes it. Seagull chasing will have to wait a few weeks, but there’s plenty of young bunnies up the lane that need an early morning wake-up!
Sime66, if you have ' tuning vespas the Norrie Kerr way' the first edition is the one I've got, on page 24 he give a mention to projected speed of the piston and piston ring flutter, it may be of interest? I can try typing it on here later if you wish? Or someone who knows how to copy it on may do it, with a bit of luck 😉
All the best and hope you get a great summer out on the Beast😉😀 Jim
I’ll follow all this up on your thread sometime, but just to tidy....
For now, so as not to get distracted from the job-in-hand here with my running in, I had a quick squizz at Norrie Kerr, then checked how to calculate Mean Piston Speed, did a little table, and referenced rev/mean piston speed for 57mm crank against a (for now, until I’ve had a better read elsewhere to get a proper figure) limit of 3500fpm (17.78m/s), which is slightly over my 9000rpm (getting close though):
Good it is making sense. Nothing much for you to worry about but you did end up with a touring tune (usually circa 8000)that revs too high. This is why the 0.2mm packer came off but just don't prolong the 9000 rpm action. The fat 2mm rings are not suited to high rpm as they lose power, they don't necissarily break. If it pulls 4th gear acceptably, once jetted in just leave the packer alone and ride it.
Should be a lot easier to jet in this time. I think the top ring cracked soon after the last re-build and was making it difficult. Do a short post each time it changes for the record.
PX200E with 221 Malossi, max power at 8300rpm, VHSH30CS, 175 main jet PX200E Tourer, tuned original barrel, SIP road II, SI26/26 135 main jet, vortex 1050cc Triumph ST 600cc Honda CBR
It’s very unlikely that I’ll ever ride for long at 9000rpm, if at all, and if it even still reaches it. Before I was tending to favour keeping at high revs in 3rd more than low in 4th for two main reasons: · It saved me much changing between 3rd and 4th on dual carriageway for hills, wind etc. – the 3rd that just keeps giving! · The high-revs cooling was better in 3rd, and the indicated CHT was possibly a problem, particularly in the revs I was achieving in 4th, which we didn't get round to sorting. Probably there is still a tweak there, with packer height and gearing, to get 4th better, and revs and cooling better as a result, but that can wait until I’ve had a decent season really getting used to it, and when my enthusiasm is restored to tweak it again; I am a bit drained from the constant tweaking, then the seize, then the rings aggro, then this rebuild, and now the prospect of running-in and jetting again…. I need to get it close and safe, and just ride it for a while, even if not at absolute optimum performance and efficiency. For those reasons I just want to quietly tackle this bit in my own time – without it being the only thing I’m doing with my spare time, or the only thing I’m constantly thinking about. Of course I’ll keep the thread updated; it’s common courtesy, especially after the time you’ve also invested in it as well, and it’s all good data for future reference too. – Being brief is not a strong point of mine; I realise that. I do also realise that the 0.2mm spacer was removed to reduce my max rpm, and also, as it reduced my Exhaust duration, was improving my low-end torque a bit too; I just felt the need to have it as close to pre-seize, best results set-up as possible – as my jetting benchmark for what was good before. Subjects like this piston speed, ring float/flutter etc. are very interesting, but they can become very time consuming; it’s too easy to get too drawn in and spend too much time on stuff that probably doesn’t matter – I got lost in max piston velocity and acceleration calcs over this morning’s coffee, only to run out of time and put it away unresolved, and not much wiser really, other than to appreciate some knowledge of it would be wise, but it can get complicated. Anyway, back to the script; hoping for some tweaking and riding over the weekend, and I’ll post anything interesting afterwards.
Sime66, that sounds like a good plan for your weekend☺. Sometimes my heads felt it's going to burst when I've had an engine that needs a lot of tweaking and fettling and I have to remind myself this is supposed to be fun, when I get to that stage, I try to reset myself with a cuppa or 20😉 and say, this will do, for now! and I may or may not revisit it, days weeks or months later! This is all, if it's my engine in my scoot.
Not saying your at that stage and hope you don't reach it.
Very quickly. Just had first look at plug, after a couple of week’s gentle running-in, before I start carb and jet tweaking. This is just what I’d hoped to see, and strengthens my belief that CHT is reading high; which means I can lean it and push it a bit more now.
Tomorrow I’m going to warm it up, then tweak Mix/Idle to see if I can drop the Pilot and get a decent tickover, which will make it all a bit more settled and easier to ride. Then I'll start to get a better idea how the Main is looking.
So, rest assured, all is well, and no news is good news for now…..
It doesn’t feel so bad to ride, because I’m being gentle anyway, and I know I’m deliberately rich. When I’ve got it ticking over I’ll be able to do a couple of electrical jobs that need sorting; that’s important too. I’m uploading a film from last weekend now, which I wasn’t going to bother with because it’s pretty boring, but will give an idea of how she’s running(-in). As far as CHT is concerned; before I venture on to dual carriageways, there’s a bit of road between the villages where I like to see 125°C when I’m riding fast with the best jetting we had before (that was then giving me 150°C ish WOT on dual carriageway). Now with this rich jetting, and me taking it easy with the throttle, it’s already showing 150°C on the film on that bit of road I use as a reference. That suggests at least 25°C too high. Anyway, it’s something I’ll get a feel for by proceeding with caution, but I was glad to see the plug that my jetting and gentle riding should suggest, rather than what might be expected from those now highly-suspect indicated CHT gauge temps.
This film goes with the rich running-in plug above.
I’ll sort the Pilot, get the revs up higher, try to get more in 4th now I know the plugs OK, and do some hills on the weekend to liven things up a bit………
Good evening, and here is the weekend news update ….
Saturday: Up to 6850rpm, still showing a dubious 150°C, took in a few hills, all felt fine. Plug was wet, but that’s probably because I had a little fiddle with Idling, which was at 1600rpm, but now tweaked. Because it took a few kicks to start, and because of wet plug, I’m going to 50/160, MJ142, BE3, AC160, #04 slide for next run; this was still with previous jetting. I wouldn’t worry too much about watching the films; they’re more there for me to keep it all tidy and in one place for when I download forum pages to archive them – pretty boring for anyone else I should think:
21-04-17 - Very quick update: I’m still running in, but really riding pretty normally except for keeping off the WOT for a while longer yet. Over Easter jetting was 50/160, MJ142, BE3, AC160; splutter in low/mid-range (did the BE tweak to overcome that before), revving to 7200rpm in 3rd, CHT still showing high, but not seeming to get higher as I increase revs or downjet, but I’ve got my eye on it, and will see what happens now I’ve gone to 48/160 & MJ140. I don’t believe the CHT gauge, but I’m still wary of letting it go too crazy without checking plug regularly. Not plug chopping yet, but previous (Easter) plug showed less black and oily, but still safe, so I’ve now dropped both jets for next session. Now intend to concentrate on Pilot first, and see if I can get 48/160 spot-on before going down more on either jet. I also checked my compression, just as a benchmark for any future suspect ring aggro; I only did it cold (will do it again warm when I think of it) – I’ve got 130psi now.
Sounds like it is all going well. If after after adusting the pilot and mix so the tickover and progression are great and there is still a splutter as the revs pickup, then you will need the AC180 and BE3+2
Those plugs look dark for those temperatures. Another thing to ponder is that your cylinder head just may not be able to cool that much power, even when it is jetted correctly. If this is happening the only thing to do (even without signs of detonation) is back off the timing. If she is really getting near the 172C then there will be an over heating type smell when you stop, which could help confirm the temperature reading is more correct.
Thanks chaps; I’m still trying to update this just enough so you don’t think I’ve died, rather than wanting to keep this thread bubbling at the top.
The invasion starts at Easter really, H; before that the roads and beaches are pretty quiet. Anyway, Cornwall can get as busy as it likes; hopefully I’ll get my tent on the back, and have a couple of weeks away exploring somewhere later in the Summer; it’s been a busy last six months for me, and I’m thinking about a scooter touring holiday, if all keeps progressing to plan, and she behaves and earns my trust. – If she doesn’t, I’ll go without her; I’m not wasting another Summer on it.
Now to this CHT issue; this has been a stumbling block since last running-in, and is being a bloomin’ nuisance, but I’m going more by plug, feel and the previous known jetting to get past it. I think that’s the first time you’ve said CHT might be more correct; I asked a long time ago if anything other than lean combustion (so not showing on plug) could be giving me genuine high cylinder head temps that the plug itself wasn’t showing. Since then I’ve been trying to convince myself to disregard the CHT gauge as an actual temperature; that’s how I’ve been proceeding….. Those dark plugs above do correspond to my jetting and running-in gentler riding (but not CHT), with what I’d expect from where I am relative to previous jetting; I’m still rich as expected, and I’m still 1000rpm+ below previous max, but not intending to jet that lean this time anyway. I know my previous sensor ring/thermistor/lead was reading low at the time of first seize; that’s why I changed it. Always, since fitting this new sensor, the CHT has been reading high; last time I was running-in it halted my progress, this time it’s making me proceed with caution, but I do now believe it’s reading high, rather than actually being high. I could buy another CHT sensor and gauge, but I don’t want to waste my time and money on more TrailTech stuff, and haven’t given much thought to alternatives, since I last decided TTO was my best option; I’d prefer to get an idea of by how much this one is out, Which I sort of have got, once I’m without doubt that is the case, rather than waste more time and money on gauges. To a degree the CHT failed to warn me before the seize, so failed in its job; and has been a hindrance to running-in/jetting since, so is a bit of a waste of space now too. You old-hands told me not to rely too much on gauges, and I’m getting used to doing that now. Nothing about the ride, other than CHT gauge, suggests anything is wrong; I’m pretty convinced nothing is wrong (but I’m still cautious). I think the high CHT reading was, and is continuing to be (but to a lesser extent this time), a red herring – but I’m not certain of it. I did have a hot smell last weekend, but I put it down to my back brake adjustment, after I’d changed the pedal because it was permanently sticking on (that’s the sticking pedal keeping the brake light on, not keeping the brake on). It corresponded with a noise I was getting when wheeling the scoot. I didn’t notice the noise or smell this weekend, I guess because the high-spot on a shoe had worn away, but if I notice it again, I’ll make sure I know whether it’s coming from brakes or elsewhere – I’ll lift up the side panel and check the cylinder cowl after next indicated hot run. I’ve made a mental note that I could adjust the timing to improve cooling, but I don’t see much to suggest that 19° was ever giving me a problem before. What it boils down to is that I’m happier progressing slowly and carefully towards, rather than making big changes away from, what I had before, which remains in my mind as a known good point – that does include the BE3+2 and AC170 I had before for the low-end splutter, which I expect to return to; or possibly BE2 and AC185, which was suggested earlier, but in my mind as something for later - an improvement on before, building on your findings with your tourer. I’ve just replaced, rebuilt and pressure tested all known problems with this engine; I’m running-in without issue; compression test, performance and starting all suggest the new rings are good. I’m pretty happy with how it’s going; nothing other than that silly bit of LCD and plastic is bothering me.
...so I'm ignoring it
(but still keeping an eye on it, and my plug, and recording it all).