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Discussion Starter · #21 ·
Since I have moved to flat top KTM 64mm piston I needed a new head profile, luckily its modified to acept inserts, so a new insert in order.

old one:
IMG_20211121_145729 by Milos Balunovic, on Flickr

divorced
IMG_20211121_145959 by Milos Balunovic, on Flickr

new one
IMG_20220524_220751 by Milos Balunovic, on Flickr

made it 13.5 compression. 0.7mm squish and 50% squish area. (old one was 11.5 comp and 40% squish)
also notice how the sparkplug outer part is shortened, on picture not finished but basically you cut of all the way to thread, that exposes the "sparking" part more in to the stream and makes it ignite cleaner/faster (a Moto GP trick shared by FOS - who knows who he is will know :D )
IMG_20220524_220751 by Milos Balunovic, on Flickr

some videos after starting as soon as I get it on YT.

ps check the older posts, I updated some info and added more pictures.
 

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Discussion Starter · #23 ·
oh, it has been a long road...

I have been running a quick fuel line connector, that I found is limiting the flow in to the bowl, which in combination with running marginal jetting (was testing the jetting at sustained WOT) I got a seizure :)
it has been a good minute of ringing it between 10 and 12.5k rpm. there was no power drop even at 12.5k rpm and is ringing so nice :D
noticed it in time and all went well. Piston just scraped no sticking rings etc. however my old tired crank developed a week knock... it was quickly rebuilt with a reinforced conrod and bearings once again :) (now that I got back home from vacation) should be back and running in few days.

I started hating the VHSB34LD as needles are difficult to source, and I could never get it to work as it should... it is just to sensitive to temperature etc.. I decided to switch to a carb wanted for LONG time,IE, the PWK 36...

IMG_20220808_062948 by Milos Balunovic, on Flickr

so if anyone has a big carb (bigger than the 28mm) DONT use a quick connector how ever it is appealing.
- this one in particular


I'm also putting back the oil pump and making a cable splitter where the PV actuator will hold the pump maxed out (or close to) when the valve is open no matter the throttle position.
throttle by Milos Balunovic, on Flickr
 
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Discussion Starter · #24 ·
A happy sad weekend for me :)
Got a new idle jet delivered finally (I went with BGJ in particular)

see compared to the N1AL what came with the carb,
299592586_778742640104791_8153323841323514991_n by Milos Balunovic, on Flickr

compared to a new BGJ one:
299637819_597831772046851_8663490615175282029_n by Milos Balunovic, on Flickr

and got the main jet adjusted, right on the edge so added a little on the MJ.


Than my battery decided to crap out... The mito is killing AGM batteries, and I cant find any simple flooded ones here.... I have changed to a diferent voltage regulator of Piagio, that is providing 14.3V already at 3000 rpm (a huge improvement )


now ill try to get a LiFePo as it has a 3 year warranty..

IMG_20220821_164638 by Milos Balunovic, on Flickr
 
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Discussion Starter · #26 ·
decided to switch to a Castor/Ricinus oil as a Pre-mix (only 2% as I have the metering pump working with sintetic)

some writeup as to why for anyone that wants to learn :) (in short, not advised for low load engines. you have to be ringing the engine)


By Bert Striegler.

Back in 1983 there was quite a controversy in magazines about the tests that were necessary to measure the "lubricity" of various oils that might be useful in engines. Castor oil was used as the benchmark, but it was obvious no one knew why this was so. They apparently got a lot of info on various industry tests of lubricants, but these were really designed for other purposes. This was my answer. I will remind you that I was a lubrication engineer and not a chemist, but I drew my chemical info from Bob Durr, the most experienced lubricant scientist in the labs at Conoco.

Bob worked with my group on many product development projects and I can tell you that he is one smart hombre! Small changes were made in the text, but surprisingly very little has really changed since this was originally written. Here goes with the answer:

"I thought I would answer your plea for more information on castor oil and its "film strength", which can be a very misleading term. I have never really seen a satisfactory way to measure the film strength of an oil like castor oil. We routinely use tests like the Falex test, the Timken test or the Shell 4-ball test, but these are primarily designed to measure the effect of chemical extreme pressure agents such as are used in gear oils. These "EP" agents have no function in an IC engine, particularly the two-stroke model engine types.

You really have to go back to the basics of lubrication to get a better handle on what happens in a engine. For any fluid to act as a lubricant, it must first be "polar" enough to wet the moving surfaces. Next, it must have a high resistance to surface boiling and vaporization at the temperatures encountered. Ideally the fluid should have "oiliness", which is difficult to measure but generally requires a rather large molecular structure. Even water can be a good lubricant under the right conditions.

Castor oil meets these rather simple requirements in an engine, with only one really severe drawback in that it is thermally unstable. This unusual instability is the thing that lets castor oil lubricate at temperatures well beyond those at which most synthetics will work.

Castor oil is roughly 87% triglyceride of ricinoleic acid, [ (CH3(CH2)5CH(OH)CH2CH=CH(CH2)7COO)3(OC)3H5 ], which is unique because there is a double bond in the 9th position and a hydroxyl in the 11th position. As the temperature goes up, it loses one molecule of water and becomes a "drying" oil. Another look at the molecule. Castor oil has excellent storage stability at room temperatures, but it polymerizes rapidly as the temperature goes up. As it polymerizes, it forms ever-heavier "oils" that are rich in esters. These esters do not even begin to decompose until the temperature hits about 650 degrees F (343 deg C). Castor oil forms huge molecular structures at these elevated temperatures - in other words, as the temperature goes up, the castor oil exposed to these temperatures responds by becoming an even better lubricant!

Unfortunately, the end byproduct of this process is what we refer to as "varnish." So, you can't have everything, but you can come close by running a mixture of castor oil with polyalkylene glycol like Union Carbide's UCON, or their MA 731. This mixture has some synergistic properties, or better properties than either product had alone. As an interesting sidelight, castor oil can be stabilized to a degree by the addition of Vitamin E (Tocopherol) in small quantities, but if you make it too stable it would no longer offer the unusual high temperature protection that it did before.

Castor oil is not normally soluble in ordinary petroleum oils, but if you polymerize it for several hours at 300 degrees F (149 deg C), the polymerized oil becomes soluble. Hydrogenation achieves somewhat the same effect.

Castor oil has other unique properties. It is highly polar and has a great affinity for metal surfaces.

It has a flash point of only 445 degrees F (229 deg C), but its fire point is about 840 degrees F (449 deg C)! This is very unusual behavior if you consider that polyalkylene glycols flash at about 350-400 degrees F (176-204 deg C)and have a fire point of only about 550 degrees F (288 deg C), or slightly higher.

Nearly all of the common synthetics that we use burn in the combustion chamber if you get off too lean.

Castor oil does not, because it is busily forming more and more complex polymers as the temperature goes up. Most synthetics boil on the cylinder walls at temperatures slightly above their flash point. The same activity can take place in the wrist pin area, depending on engine design.

Synthetics also have another interesting feature - they would like to return to the materials from which they were made, usually things like ethylene oxide, complex alcohols, or other less suitable lubricants. This happens very rapidly when a critical temperature is reached. We call this phenomena "unzippering" for obvious reasons.
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So, you have a choice. Run the engine too lean and it gets too hot. The synthetic burns or simply vaporizes, but castor oil decomposes into a soft varnish and a series of ester groups that still have powerful lubricity.

Good reason for a mix of the two lubricants! ( " 927 " is a mix as described here!)

In spite of all this, the synthetics are still excellent lubricants if you know their limitations and work within those limits. Used properly, engine life will be good with either product. Cooked on a lean run, castor oil will win every time. A mix of the two can give the best of both worlds.

Like most things in this old life, lubricants are always a compromise of good and bad properties. Synthetics yield a clean engine, while castor oil yields a dirty engine, but at least now you know why! "

Bert Striegler

Bert was the Sr. Research Eng'r. (ret.) at Conoco Oil Co.
 
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Discussion Starter · #27 ·
A short acc take. Imnot sure it was constant WOT as I filmed it with one hand/phone and other on throttle.
 
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Discussion Starter · #31 ·
Next on the list of improvements

A yamaha boost bottle as I have a very stupid drop in torque 6 to 8 rpm. And its same even with the CTS is fully closed or open. Have the formula on how to make it good:
15cm long 22mm ID hose connecting it to a 0.5L bottle. By changing the hose length the rpm it is effective changes.

The mixture gets very lean. at WOT, EGT eill spike all the way to 670°C which is max limit for a short duration... And my high rom EGT is ~600°C which is very safe but not exclusively rich.

And a quick shifter :)
 
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