dombush Posted June 25, 2011 Report Share Posted June 25, 2011 Being a bit of a tinkerer i decided to replace my Dellorto PHBL 26 with a Keihin PWK 28 on my 06 250 pro. I'd read a number of existing posts and decided i wanted some of the advantages on offer. I thought i'd summarise the results as i found them. Why Compared to mates Sherco's and Beta's my pro has quite a strong pickup, great for wheelies but not as good on loose cambers or slippery climbs. The other major reason was lack of confidence in the tickover during tight turns or steep drops. I often clutched more than necessary to avoid a stall. I was guessing that an overall richness was part to blame. Lastly... it was a pig to start (however this was improved partly by reducing the dellorto float-tang height from 19mm to 16.5mm) Carb setup Carb was a PWK28 LH tickover and Airscrew model. Settings as reccommended by Kevin Hipwell of GasGas UK Main Jet 122, Pilot jet 45,Needle JJH- middle clip, Slide 3.5, Air Scew 1.5 turns out Other stuff GasGas Raga Reed block, flange, spacer, 3 gaskets,longer screws, flange rubber and 2 jubilee clips (reliably informed these parts arent strictly nesessary but provide a more proffesional "fit") Keihin specific throttle cable and angled cable entry for the carb top. Fitting Apart from awkward access to the reed valve flange screws its fairly straightforward procedure. Removal of the rear shock may be necessary if you havent got necessary tools to access these screws. Results Cold starting was a choke-second kick affair.. same as the Dellorto PHBL Hot starting could be achieved using any throttle opening. The Dellorto wanted no throttle:- hot or cold. The tickover rpm could be set slightly lower on the Keihin whilst remaining reliable/stable. Out riding, the snatchy pickup was gone, replaced with a much smoother linear initial power delivery. The bike was smoother/quieter and sounded slightly weaker. Higher up the rev range the bike was more comforatable and happier to rev out.. An unexpected bonus was significantly better fuel consumption, comfirming initial fueling thoughts. Conclusion Overall i think the bike is more forgiving and progressive for a novice like me. Would i do it again?? probably yes but its a bangs per buck thing... At Quote Link to comment Share on other sites More sharing options...
dan williams Posted July 4, 2011 Report Share Posted July 4, 2011 This somewhat parallels the experiance I had replacing the DellOrto on my '95 Beta with a Mikuni. It ran strong with the DellOrto but it was a beast to ride because I could never get the DellOrto properly tuned so it went from running lean to suddenly making olts of power. The Mikuni made the power delivery consistant across the entire range so the bike felt "weaker" but was actually just building power linearly instead of with a big step. Quote Link to comment Share on other sites More sharing options...
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