lundi 30 juin 2014

Kaw Power Up

After much searching here on the site for quite some time, I've not comg across an answer to my specific inquiry, so I thought I'd post it directly. As a moderator on another forum, I do try to make sure I "search" for answers before asking a question that has been asked 1000x before, but I cannot locate any direct info on my question, so here goes ...





I have a Tiger Cub (shown in sig line) that I'm happy with; it's been reliable and done a great job. However, I'd like a bit more power from it. There are times when it loads up a bit in heavy grass, and could use a touch more "oomph". It has the Kaw FH601V engine. After looking over countless parts manuals and shop manuals, I've come to the conclusion that I'm unable to tell how they differentiate the HP models in how they achieve that power differential. As I recall that TC chassis and series of engine was available in 19hp, 21hp, 23hp, 25hp, all from the same identical long-block per the shop manual. When visiting the Kawpower site, I can see there are slight variations in carbs from revision to revision, but I cannot tell if these are the SOLE means of upping the power or not. And since there are so many variations, I'm not sure which one I'd need to select.



In fact, according to the manual, page 3-14 for the fuel system, here is the info I see:

FH601V, FH641V, FH661V, FH680V, FH721V

Carburetor Specifications:

Nikki 621266

Throttle Bore Diameter 26 mm (1.02 in.)

Venturi Diameter 21mm (.83 in.)

Main Jet (MJ) L: #122, R: #128

Pilot jet (PJ) L: #46, R: #44

Main air jet (MAJ) 1.7

Pilot air jet (PAJ) 1.1,

etc, etc ...

The above info shows me that even the carbs are the same for all those five engines.



Is there a throttle restriction plate behind the carb that is different?

Is there a different setting in the max throttle travel when the govenor opens up, allowing more WOT flow?

In short, just what makes a 25hp engine out of a 19hp engine, when it appears that the entire long block and carb are essentially the same?????





Does anyone have direct, specific info as to how I can "up-power" my Kaw? Got a site link with specific parts numbers or tuning procedures, etc? Perhaps an older script on sandstone that was done back in the good ol' days? It would be presumably far cheaper for me to simiply upgrade the induction system than to "repower" the chassis with a new engine.




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