RE: YS 170 DZ CDI
Hello All,
I have had a very helpful E Mail from Naohisa Yamada. I’m sure that Richard Verano will also have been active behind the scenes.
Yamada san is very well aware of the high temperature issues with the current pump design. He has carried out tests that have indicated that the temperature peaks after 8 minutes (he didn’t say whether this was 8 minutes after starting or 8 minutes after landing). He also acknowledges that when the temperature peaks, the engine can become difficult to start.
Yamada san has replaced the bottom plastic pump cap with an alloy pump cap and has found that this lowers the operating temperature of the pump and also speeds up the rate at which the pump cools down after flight. He has also experimented with fitting stainless steel valve inserts into the pump body to help prevent premature wear of the valve seats.
As Amram has already mentioned, YS are also intending to fit a re-designed regulator diaphragm to the next generation of pump in order to make the setting easier to adjust.
Yamada san has not yet tried increasing the diameter of the existing cooling fins on the valve body or fitting new cooling fins on the pump body housing, but he acknowledges that these modifications might be also be worthwhile. His E Mail also includes the statement “The carb temperature must be down too” though I am not sure whether this points to the need for better insulation (slightly thicker paxolin?) between the crankcase and the carburettor body.
Yamada san was about to leave for the European F3A Championships in Austria when he wrote, but he said that he would start doing some further work on the re-designed pump as soon as he returned to Japan.
It is YS’s intention that the new pump should be available on the forthcoming YS175.
I thanked Yamada san for his very full and very helpful reply and suggested that it would be good if the redesigned pump was also available as a separate item for retrofitting to existing YS 170 glows and YS 170 CDi’s. I also said it would be helpful if the new YS175 CDi was available as a glow version as well as a CDi !
In summary, I think that Yamada san is well up to speed with our concerns and is adopting the usual meticulous YS approach to improving and refining his product.
Hope this helps
Regards
Bob