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Post by sime66 on Jul 25, 2014 5:20:21 GMT
Reading a thread on Facebook about CHT sensors, remembered earlier post where Vespasco mentioned his CHT ring, remembering my own sieze and plenty on here since; putting these things together and beginning to think CHT Sensor might be a good idea. Question on FB was what temp is safe limit? – FB chaps state 350 (F?), and post link to a gauge that goes 30-500F, 0-260C, so it must be F. This is the link: www.trailtech.net/digital-gauges/tto/temperature/722-et3Anyone got any light to shed on the subject? – Good idea or another gimmick gadget? I know temp at top of head is too late really, but as an indicator maybe worthwhile. Might help prevent a lock-up accident or an expensive seize?……………. Also thinking that anyone plug-chopping now should be aware that much colder, denser air in the winter will mean it needs checking again – that caught me out before when I seized in the snow.
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Post by coaster on Jul 25, 2014 6:35:06 GMT
A CHT is a useful tool, I have one on my Lambretta along with an Exhaust Gas Temp (EGT) gauge. The temps from the CHT will be in the 150 - 250 degree Centigrade range. The sensor ring should ideally go under the spark plug (you need to remove the sealing ring on the plug). The problem with the sensors is that they are prone to failure and don't take kindly to frequent removal. Koso gauges (SIP) use a replaceable sensor ring but others especially the cheaper ones require the complete lead to be changed. Some people bolt the sensor to a fin or put it under a cylinder head nut but that will give a lower reading and delay the reading even more.
The temps you quoted look more like Exhaust temps picked up from a prove inserted into the exhaust manifold. Both gauges have their uses but are best when used together. As you say, the CHT reacts a little slowly, it will take several seconds to respond to temp changes whereas the EGT is virtually instant but requires a fair amount of interpretation of the readings to tell if you actually have a problem.
Hope that helps
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Post by sime66 on Jul 25, 2014 7:23:02 GMT
Thanks for the info – very helpful. It seems, like most things, that the cheap and cheerful option is probably not worth bothering with, but the CHT gauge (maybe with EGT, but that’s probably more than I need) is a good idea if done properly. I work in Celsius too, but for comparison, you reckon the 350F should be more like 300Fmax (150Cmax). I emailed the manufacturer of the 722/et3 last night, and I have a few doubts about it, especially when combined with your comment about sensor failure on cheap ones: 1) The lead/sensor is only 530mm anyway. The lead/gauge is 150mm. 2) A replacement lead/sensor is most of the cost of the unit ($31.95/$42.95). 3) The gauge itself has a non-replaceable battery anyway, with a 5-yr life. All in all this looks like a cheap ‘use it and chuck it’ option, so probably worth more investigation of options before jumping in. I’ll have a look at Koso later. What have you got if you read this vespasco? I’m aware of the SIP speedo with CHT, but not keen on it. (I’m quoting the dollars, rather than the sterling because USA replied to my email and UK didn’t – that says something too. There are UK suppliers, but I'm not really looking at 722/et3 now anyway).
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Post by pxguru on Jul 25, 2014 11:33:26 GMT
You will not regret having a CHT gauge. They are a lazy way to get the jetting right. And if you keep an eye on it, it might just prevent a seize up, dodgy fuel issues or forgetting the 2 stroke!
I also go by 300F as the maximum with the sensor on the spark plug. I think this to be quite hot enough for the road. I have the SIP speedo one and have the sensor on one of the head bolts which is a bit cooler than the spark plug but doesn't get broken quite so often.
Here is the theory bit. The basic idea of a Carburetor, is to supply a constant ratio of fuel air mixture regardless of the position of throttle or quantity of air drawn through it. The ratio of fuel to air determines how hot the flame will burn. More fuel to air (bigger jet) will make the CHT colder and less fuel to air (smaller jet) will make it run hotter. This might be opposite to what anyone first thought.
When you find the right one and have the CHT gauge all set up, try riding at each of 1/8, 1/4, 1/2, 3/4 and full throttle for at least 30 seconds or so each. And you are looking for better than 250F and near to 300F across all the throttle positions. This is especially useful with a needle carb where there are many more adjustments.
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Post by sime66 on Jul 25, 2014 12:14:33 GMT
I hadn’t thought of it as an aide to jetting, but I see what you mean, and although I’m happy with my jetting at the moment, it would be interesting to see what temperatures I’m getting testing it as you say. I do follow your explanation of the theory, and it seems the logical way to me – more air to fuel=leaner=hotter (so too hot needs bigger jet-at its simplest). So I’m hooked on the idea, more so now that I’ve had a quick squizz through Koso and SIP sites, and got a better idea of a better, and slightly more expensive option, something like this: Koso KO0414 & KOBA003030/5*: - 1.4M cable - 5 removable sensors in pack - 0-150°C/0-250°C* - CR2032 (watch) battery - (backlight off 12V if req.) - £65 inc. p&p (SIP) The SIP speedo, aside from being pretty pricey, seems to be a lot of stuff that can (and does seem to) go wrong. But it’s a much neater idea to have CHT gauge within the speedo where it can’t be knicked. – Still pondering my options…….. Thanks very much for both replies; this is something that I reckon, after a little more investigation, will go pretty high up on the wish list. Cheers Chaps.
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Post by vespasco on Jul 25, 2014 20:17:18 GMT
I think that if you have a stock motor then a cht would be more of a gadget, albeit a worthwhile one to a certain degree. On a kitted motor then id say go for it. Especially if youre still setting it up. Along with an egt sensor you will eventually know your sweet spot. An egt would tell you more accurately and quickly whats going on with the cylinder gases. Im using the SIP speedo/cht one for various reasons. Plug chopping was a pita so i moved the sensor under a cylinder stud. Yes the temp reading was about 15c lower. On my kitted pinasco my max readings under the plug were around 220-230c depending on the weather/ambient temp. I do tend to ride quite hard once its warmed up. Usually WOT wherever possible (dual carraigeways/motorways) and it never reaches more than 230c when under the plug. Compared to other kitted 200s this was quite low! Around town would be below 200c After a cold start it soon reaches 100c and quickly goes up to max temp after about 2-3 miles. 1/2 throttle cruising reads around ? Cant remember, it does not normally go that slow just below 200c Other kitted motors can read upto / around 250c+ without problems. 150c is not even fully warmed up! If youre going to compare readings of different scoots in different places on different days then various factors need to be taken into account. Its best to forget what readings others have and find out what yours reads when its running well and check if it ever goes abnormally higher. Or try and get it lower by re jetting /timing/changing fuel etc Ive read that people have ridden upto temps of 350c which would be quite a critcal temp to reach before a likely seizure. But cant remember if thats on an ali or iron cylinder They are handy, for eg, i was out on my scoot. It was fully Warmed up. I noticed my readings were 250c (20-30c more than normal) Alarm bells rang. I eased off the throttle. Temp dropped. Then it sputtered. I pulled over. Low and behold there was a problem. Id forgotten to tightened my carb down properly after some work. Fuel mix was lean and it over heated. So they do work. Sensor was under the plug at the time. Best bet is to use one with a cheap replacement wire/sensor ring and to weld one direct on the head. Koso/sip would work On my sip speedo, by sheer chance, the anologue needle on the rev counter on the sip speedo also doubles as an accurate speedo! i.e. 70(x100) rpm = 70mph! 30(x100)rpm = 30mph But only when im in 4th gear! Everything works on my sip speedo but the clock doesnt always keep time. Probably just a battery issue. I dont need that function anyway. And yes im using Celcius ! EDIT - And yes i mean Fahrenheit!! Oh fk thanks sime
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Post by pxguru on Jul 26, 2014 4:22:01 GMT
vespasco, I am sure you mean degrees F. Sounds to me your Pinasco is very cautiously jetted. Running hotter is more powerful but dangerous over 300F. Probably not a bad thing to be careful but measured at the spark plug, you could take it to over 200F round town and 250F on the motorway and still be in the cautious limit. It is important to check CHT accross all throttle positions carefully. Even running perfect wide open can still seize up when you shut the throttle at speed, if its lean in the middle.
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Post by henri on Jul 26, 2014 6:20:29 GMT
i hadnt realised that cht had dropped in price to be comparable with the cheaper exhaust gas analysers, think 1 is def going on my chrimbo list ,just for setting up/jetting, take the guess work/worry out of the job ,an also give a truer reading as can be used under load out riding ,dont think it will stay on when set-up, it would be 1 more thing my eyes couldnt focus on in time to not be dangerous .H
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Post by sime66 on Jul 26, 2014 7:42:00 GMT
I’m definitely having a thorough look into it before deciding which way to go SIP/Koso, but here’s a few first gleanings from having a quick read with my coffee this morning:
- The temp range for SIP Speedo is “Maximum temperature: 250°C or 32-482°F for cylinder head”. This might help us agree on max C/F temps, or range (acknowledged it depends on scoot, but it would be good to agree). It also means that the Koso model is the KOBA003035 (250°C) not the KOBA003030 (150°C). - The SIP one is now Speedometer SIP2 (#50000220-£150SIP-£137Wasp-£……?), which is probably why there are a lot of the old ones floating about on Ebay etc – careful if buying. “The SIP Rev counter/Speedometer 2.0 possess the following extra functions : • As an alternative to an analogue rev counter, the speedometer needle can also display maximum speeds of up 140 kph/mph • Maximum speed: 199 kph or 140 mph. • Maximum rpm. • Maximum temperature • Maximum 'B' stage distance: 9999,9 kph/mph. • Maximum 'B' stage journey time 99.59h. • Maximum average 'B' stage speed 199 kph or 140 mph. • Adjustable total journey distance. • Five back-light brightness settings. • Fuel reserve warning.” - Got to wonder if the tiny digital temp reading on the SIP is adequate, but SIP don’t explain what “warning” is shown at maximum temperature. I saw you mentioned setting speed on SIP, vespasco – what happens; does it flash, or go red, or buzz? - I’m looking at all the extra wires hanging out the back of the SIP speedo and wondering what they do (and a little box-where’s that go?). Would like to get my hands on installation instructions; will look around on Internet when there’s time. - Prefer the cost and simplicity of the Koso, and I think the SIP speedo is pretty ugly, even in black, but the little Koso gadget would be so easy to nick off my scooter.
Early days, lots to investigate and understand. Excellent info from you lot though; cheers chaps.
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Post by sime66 on Jul 26, 2014 8:22:38 GMT
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Post by henri on Jul 27, 2014 6:37:32 GMT
ya need to get to the seaside n see the sip speedo in the flesh ,the 1's ive seen on scoots look much nicer in the flesh than in the catalogue (they aint got your flair for pretty piccys), ive always been put off them as there more expensive coz of all the add-ons ,which honestly would you use that often ,if they did a straight/simple speedo n temp gauge with remote switching ,so ya cud toggle between em with a thumb,i'd be seriously interested in one .i like the black faces on them. the koso is more simple an my kind of speed ,have seen them plumbed n flush fitted into top of glovebox which would be safer than just on a external bracket ,as they do look very nickable there .would mean cutting a viewing window in top of glovebox tho. H
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Post by vespasco on Jul 29, 2014 23:40:22 GMT
Yeh degree f ! Oops!
I use celius normally but due to the smaller increments degree f is more precise.
Ive got my jetting running a cooler engine as possible at all ranges, especially the throttle range i use the most, and where it used to detonate. 220f for a pinasco 225 is quite low apparently. But maybe thats just because with the cht gauge i could fine tune it more to how i want it. And i have all the power i would ever want on a 40 year old vespa
Sounds like you just need the cht gauge, not the expense of the sip speedo. There are no 'warnings' not on my mkl anyway. You just keep an eye on it For reading cht temps a small gauge with large read out is way better than the small sip display.
But yes, you need to fit a seperate gauge somewhere. I had a similar dilemma with an egt gauge. Decided i didnt like a gauge sticking out/fitted in somewhere. Needed an accurate speedo anyway. Kaboom! That was my wallet dying. On my mkl speedo the heat reading is very small.
The little box just fits inside the headset behind the light. But thats on my Rally 200
There is also a toggle button, switching the tiny display from this to that.
When i was talking about setting up the speed, You need to calibrate and input your tyre circumference, along with which gear ratio to use, all easy enough, but variable. Meaning, i could, if i wanted, set my sip speedo to read higher mph, just to try n sound cool? by adjusting the tyre circumference variable. Its definitely more accurate than my piaggio one anyway.
I know that riding in the snow reads lower temps than summer by 10-15f ( but that might just be because i daren't open it up)
If sip included an egt gauge option built in too that would be good. One nice neat little package.
Im not entirely sure running hotter would create more power , not after it detonates and overheats anyway!
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al
1st Class Ticket
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Post by al on Aug 16, 2015 14:19:12 GMT
I fitted my SIP speedo around 2 months ago and love the features especially the clock(that does loose time)But comes in handy on runs out when I've promised the misses I will be home on time.I use the CHT rings as instructed and doing around 50 to 60 it gets up to around 130c sometimes about 135c and I tend to back off the throttle.For the life of me dare not WOT.Am I just chicken?P200 running a 140 jet and plug is a light chocolate brown.
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Post by vespasco on Aug 16, 2015 15:49:45 GMT
A p200 on a 140main jet!? Im guessing its not really a stock p200???
P200 can be ridden WOT all day long if set up stock/correctly.
I used to max out at 230°f (wot) with those crappy sensor rings under the plug.
Ive now drilled the sensor direct in the head, much faster readings, now, if i get to around 33ly0°f i wonder why its so hot and ease off the throttle.
My CHT gauge (on a sip speedo) is definately worth the expense (at least on a tuned motor) Add a EGT and happy days!
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al
1st Class Ticket
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Post by al on Aug 16, 2015 16:10:23 GMT
Not sure if it's standard as the lad who rebuilt the engine is no longer with us unfortunately.The only visible mod is a Simanini exhaust and been up jetting to get a nice looking plug.It goes well but anything over 60 its territory I feel nervous at.
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