Messages

1

Tech Talk / Re: Aircooled cylinder head temps?

« on: February 06, 2023, 10:37:21 PM »

hi James, as a sparky what type of thermocouples are you using (J, K or other) can you post some pics.

Hoony,

The thermocouples I use with the Westach system are 712-4WK (CHT, Type J https://www.westach.com/product-page/712-4wk) and 712-4D6K (EGT, Type K https://www.westach.com/product-page/712-4d6k). The instrument is a 2DC1-2 (metric scale https://www.westach.com/product-page/2dc1-2). Of course, the instrument is calibrated for the aforementioned types of thermocouple.

The first system I ever tried was from MGL Avionics - it was very good, but had a lot more features than I really needed. It required a fair bit of 'setting up' compared to the much-simpler Westach system (e.g. had to solder thermocouple wires into a multi-pin plug connector for the instrument) and it also required a DC supply. I thought that the instrument was a little more fragile than it should be for motorcycle use (so I mounted it on Mackay Multicushions), but I imagine it is fine for panel-mounting in aircraft (for which it was designed). It used Type K thermocouples for both CHT and EGT.

The Westach system is much more 'plug & play' (all plug connections ready-to-go, no soldering) and is self-powered. I made some bosses (OD 15, ID M8x1.0 thread, length 12) which are welded to the exhaust front pipe in an appropriate position to take the EGT thermocouple. The thermocouple itself has an adjustable sliding fit so as to locate the tip shallower or deeper into the front pipe, as the user sees fit.
The CHT thermocouple ring is 1mm thick, so it spaces the spark plug 'out' by the same amount. However, this should be nothing to worry about if the plug thread depth in the cylinder head is correct in the first place.

Regards,
James

2

Tech Talk / Re: Has anyone ever welded a piston, and used it?

« on: January 20, 2023, 08:43:02 PM »

I know of someone who (in the 1980s) welded up the reed intake holes in DT175 pistons to use them in Lambretta piston-ported racing engines, so it can work. However, if it is only exhaust-bridge-lubricating holes you are dealing with, I wouldn't bother. I have been running a PE250 piston in a non-PE cylinder (with a single unbridged exhaust port) for more than 10,000km and the lubricating holes don't seem to cause any trouble.

Regards,
James

3

Tech Talk / Re: Aircooled cylinder head temps?

« on: January 20, 2023, 08:21:31 PM »

I monitor both CHT and EGT on my bikes. When I researched the topic of temperature monitoring about 15 years ago, the consensus seemed to be that EGT was useful for tuning (carb jetting etc.), while CHT was better for running.

I set up my thermocouples the same way on each bike; The CHT thermocouple is attached to a ring terminal under the spark plug seat, while the EGT thermocouple is screwed into a welded-on boss on the exhaust header pipe, within 100mm of the piston skirt. As Pokey mentioned, putting the EGT thermocouple closer to the piston skirt will give a higher temperature indication. However, it takes some experience to interpret readings.

For CHT, I have adopted an absolute limit of 250degC. If it looks as if the CHT will reach that figure, I change riding style or let the engine idle until the temperature reduces. Of course, some lower limit may apply if the thermocouple is located in a different position. However, the ring-under-plug-seat location seems to be fairly standard and seems to allow the most plausible case for comparison between different engines. I have found that my air-cooled engines generally operate in the 125-200degC range for varied types of riding, whereas the water-cooled ones generally operate in the 100-130degC range. The usefulness of CHT on a water-cooled bike is that the gauge should respond a lot quicker than a water temperature gauge (although obviously a lot of off-road bikes don't even have those!).
I have found EGT to be a much less definitive parameter than CHT and it seems difficult to apply an absolute limit. There are a lot of factors which will affect EGT (although not necessarily indicating a problem), so the best suggestion I can offer is to get some experience with it on a known 'good' engine and see how it varies with carb jetting, fuel and oil types/mixtures, riding conditions etc. Once you have a good general idea of how it varies and the figures which are obtained with normal running, it will be a lot easier to spot trouble from air leaks, dodgy fuel and the like. Although the thermocouple is mounted within 100mm of the piston skirt on each bike, I haven't been able to achieve exactly the same distance in each case, due to the proximity of frame tubes, radiators, slip joints and other obstructions.
All of my experience is with two-strokes - temperatures normally obtained from four-stroke engines (particularly EGT) may be different.

Most of my bikes have a Westach 2DC1-2 dual CHT-EGT gauge. These aren't perfect, but are fairly robust and the system is self-powered (i.e. no battery - the analogue gauge just responds to the voltages generated by the thermocouples). I would probably find a digital electronic gauge easier to read, but these are frequently more fragile and need batteries (or rectified supply from a magneto) to operate. Also, I haven't yet found one which offers the simplicity of the Westach system.

Admittedly, one problem with monitoring temperatures and other engine operating conditions is that you may have to take your eyes off the road/trail/track/course to look at the gauge(s). This is not usually a problem on roads or smooth trails, but could spell disaster in other circumstances. Mounting the gauge(s) in an appropriate position may lessen the risk. 

With some experience and care, monitoring CHT and/or EGT should give sufficient early warning of impending melt-down to allow large-scale engine damage (due to overheating, whatever its cause) to be avoided.

Regards,
James

4

For Sale / Suzuki PE400 clutch cover - new old stock

« on: August 01, 2021, 06:13:25 PM »

I'm fairly certain this is a PE400 clutch cover:





I bought it years ago as a spare for my early PE250, failing completely to notice that it had no hole for the clutch actuating shaft . It came in a plain plastic bag but without any label or tag. However, somebody had written the part number 11341-40900 inside, which is correct for PE400. The cover on the 1980+ PE250 looks very similar, but (according to photos of the 250 cover I have seen), one of the locating dowel holes is in a slightly different position. I am therefore assuming that this cover is indeed a proper PE400 item.

It was sold to me as 'NOS' and it appears that it has never been fitted. I'm not sure what it is 'worth' - apparently they cost A$257...when you could still buy them new (see Mick Hone parts database). On that basis, I am inclined to offer it to fellow enthusiasts for $150 before resorting to Ebay.

Collection is available from Inner West Sydney, or I will post it anywhere in Australia at cost. Payment by cash, COD or PayPal (if buyer pays the fee).

If anyone would like any more details (more photos, measurements etc.), please let me know. Please register interest by replying under this topic and send me a PM to follow up.

Thanks & regards,
James

5

Wanted / Re: 1980 PE400

« on: July 04, 2021, 08:08:50 PM »

PM sent.

Regards,
James

6

General Discussion / Re: DT 200R Piston question

« on: October 03, 2020, 02:43:20 PM »

The engine is back together with the blaster piston and all works. 

Good to know its working OK. For background info; The DT200R had cylinder reed intake from 1984 to 1987, then crankcase reed intake from 1988 onwards.

Regards,
James

7

General Discussion / Re: Any recommendations for machinery movers in Sydney?

« on: October 03, 2020, 02:39:48 PM »

The best known ones and they have all the gear is Johnston’s at Smithfield. A mate used them with no dramas but they were not cheap.

Thanks - I had that firm on the list already, but more positive reports will make the choice easier!

Regards,
James

8

General Discussion / Any recommendations for machinery movers in Sydney?

« on: September 26, 2020, 02:51:24 PM »

In the near future, I need to move some workshop machinery (400kg lathe, 1000kg milling machine, pedestal drill, tool & cutter grinder, band saw, power hacksaw, hydraulic press and some sundry items) from one place in Sydney's inner west to another - a distance of about 10km as the crow flies.

With the smaller items, I would be reasonably confident just hiring a small to medium flatbed/dropside truck (equipped with a basic crane) myself and roping in a friend to help. However, mistakes due to my inexperience with transporting machinery may be costly where the larger items are concerned! I would therefore be glad to know whether anyone can offer any testimonials in favour of transport firms or individuals who are particularly experienced in moving this sort of machinery.

This should not be a big job for someone with the right gear and could likely be completed in three trips...or less if the truck is big enough. I'd prefer recommendations based on personal experience, but any leads may be useful.

Thanks & regards,
James

9

Yamaha / YZ125 cylinder head O-ring groove

« on: September 21, 2020, 08:56:18 PM »

Anyone got a YZ125 cylinder (1986 or later) lying about from which they could take some measurements?

I'm looking for the dimensions of the O-ring groove for the combustion chamber (ID, OD, depth).

There are/were different O-rings used for sealing the combustion chamber, depending on the year of manufacture:

93210-65721 - YZ125 1986-1993
93210-63442 - YZ125 1994 onwards

If anyone is in a position to supply measurements, please let me know the year and/or model code of the cylinder you have measured.

Thanks in advance & regards,
James

10

Suzuki / Re: PE250B Vintage Supermotard

« on: January 28, 2020, 09:37:11 PM »

maybe this type of pipe could have the outlet aimed at the chain to keep it lubed

Now there's an idea!

To answer your questions; I've not ridden it much so far in this configuration, as there is still a small amount of work left to do before registering. However, the silencer exit is angled slightly away from the bike and is below the level of the foot rest, so no smoke in the face and I don't expect any unburnt fuel-oil mixture on the left boot or rear tyre. Still, these are aspects I will be watching out for when the bike gets on the road. Whether it blows any dust remains to be seen - if it does, I might be able to use the bike for clearing the footpath outside the house as well .

Regards,
James

11

Suzuki / Re: PE250B Vintage Supermotard

« on: January 22, 2020, 08:35:37 PM »

Have you got any more photos or details of that TM pipe Leith? I'm struggling slightly to comprehend which bit is which !

Regards,
James

12

Suzuki / Re: PE250B Vintage Supermotard

« on: January 04, 2020, 01:12:49 PM »

Why did you do it then ?

Sorry, maybe I didn't make it very clear. The prime objective for modifying the exhaust was to reduce the noise. If the performance remains unchanged, I'll consider it a bonus!

the whole point of the centre bleed is to have a complete pointy cone end to the pipe which sends a complete reverse wave back to the exhaust port therefore giving better performance by holding more charge in the cyl instead of loosing a tad through the stinger hole in the wave. a block should have some effect i guess but who knows. a dyno before and after is the only real answer and its probably a gnats difference anyway..looks way cool!

Thanks . I can't argue with the theory, but am hoping (as you suggest) that the short length missing from the reverse cone will make little difference to the performance compared to the previous set-up, where the cone was also 'incomplete'. The reverse cone is still the same length as before and it remains to be seen whether my 'seat-of-the-pants dyno' will detect any difference - hopefully not!


Regards,
James

13

Suzuki / Re: PE250B Vintage Supermotard

« on: December 30, 2019, 09:40:35 PM »

...is an okay youtube video that explains it not bad. https://www.youtube.com/watch?v=n5AvG-hDvY8

I thought I should have another look at that video (I'm pretty sure I saw it while researching the internal stinger concept previously). I don't necessarily disagree with anything the narrator says, but stingers arranged as per the second or third drawings will lead to lower performance if Gordon Jennings' findings are to be accepted (and if I have understood them correctly ) - he found that stinger exits which start anywhere in the reverse cone caused a drop in performance compared to the standard set-up (the first drawing in the video). Jennings stated that an internal stinger should start about an inch ahead of the reverse cone, which I take to mean 'in the parallel-wall belly section'. In the absence of contradictory evidence, I have assumed that an outlet anywhere within the boundaries of the parallel-wall belly section will perform in similar fashion (i.e. same performance characteristics as standard set-up, but with less noise).

Two-stroke pipes are a minefield and I have so far avoided designing my own in preference to buying (or sometimes building and/or modifying in accordance with) known/proven designs. I just don't have the time to experiment by continually chopping and changing pipes...only to end up with something which may be the same as (or more likely inferior to) an existing product.

However, all of this does not mean that I'm not interested in the design aspects...but I know enough about them to realise that I don't know enough about them!

Regards,
James

14

Suzuki / Re: PE250B Vintage Supermotard

« on: December 30, 2019, 08:57:36 PM »

interesting, can you explain the concept of the pipe and if you noticed the diference in power delivery ?

There is a brief description of the concept in the Diffrent Strokers write-up (http://diffrentstrokers.com/phpBB2/viewtopic.php?t=2511). Since modifying the exhaust, I have only ridden the PE around a concrete car park for about 15 minutes. It felt pretty much as I remember from a 'response' point of view, but I'll have to wait until it is officially 'back on the road' for a proper evaluation. In theory, there should be no difference in performance compared to the previous set-up. However, dyno runs before and after would be the only way to be sure if the theory is good in practice.
The first (and only previous) time I tried out the 'side-bleed' stinger concept on another project bike did not provide any info on performance difference - I made that first exhaust up from a pair of pressings and fabricated the header pipe and stinger from standard bends - I didn't have any previous experience of that particular pipe in the form for which it was originally designed. Having said that, the characteristics of the finished product were very agreeable...not valid for a comparison though.

did you end the pipe cone to a point?

No - I just blocked it at the end of the reverse cone (i.e. at the start of the existing stinger) with a plug, which also served as a sleeve for joining the original stinger/tailpipe back together. I did it the same way on my only previous side-bleed attempt. I'm not sure if this is the 'correct' approach, but I couldn't think of a better way to do it which would satisfy both technical and practical considerations. With the standard stinger arrangement the 'true' end of the reverse cone is an imaginary point...and trying to manufacture a small cone extension/plug/sleeve would have been a bit fiddly. I don't recall seeing the reverse cone of any expansion chamber end in a closed-off sharp point, although I'm not claiming this as technical justification of my method! If anyone has any input on this particular aspect, please let me/us know!


Regards,
James

15

Suzuki / Re: PE250B Vintage Supermotard

« on: December 28, 2019, 01:30:33 PM »

Thanks Leith. Is that 'proboards' forum new? I wasn't aware of it until now.

Regards,
James