This will be my review of the Diaphragms available from Legend motorcycles
First, we are entering a time when replacement OEM parts are nearly non available and we are forced to rely on good people trying to build good parts to help us keep these beasts alive. Who are these people and do they know what they are doing?? Who knows. It's almost as bad as 30 years ago when a lot of "aftermarket" products were coming out of China. Quality was dismal to say the least although in the past few years things have gotten better and sometimes worse. It's a crap shoot. So buyer beware and thank God for sites like this where we can share information and experiences.
The diaphragms from Legend Motorcycles in the United Kingdom
As of this writing Legend sells these individually at $17.91 USD each and comparing that price to the offerings at www.z1300.de
priced at 29.90 Euros each ($32..29 USD) , or the other EBay offering from DJIN 1378 who offers a set of 3 for $74.99 USD ($24.99 each comparison price only).
Bottom line Price wise, pretty good.
Neither Legend or DJIN1378 would outright tell me what material their product was made from and both told me that they sold hundreds of these diaphragms and no reported problems. I have not contacted Z1300.de for any information and all I wish to do here is comment on the Legend Motorcycles product.
I also want to bring to your attention that the Legend Motorcycles diaphragm does not have any reinforcing material in the diaphragm like the Kawasaki OEM diaphragm. Now the elastomer has to perform the work of controlling the throttle plunger as opposed to the Kawasaki OEM diaphragm which relies on the reinforcement to do the work of controlling the plunger and the rubber portion of the membrane to seal the reinforcement
Bottom line- I have concerns about the ethanol compatability and I have a concern about the lack of reinforcement.
At first glance I really like the way the diaphragm sits in position in the relaxed position. BUT when I went to install the top cap, I noticed that I had metal to metal contact between the cap and the carb body. Hmmmm, No pinch on the diaphragm?? Measured the depth of the outer groove in the carb body and then measured the thickness of the diaphragm that fits in the groove and the groove measured .082" and the diaphragm is only .072" thick at the same point, This means when all installed, the diaphragm is not sealed to the top cap and there will be air leakage from atmosphere outside the carb, through the seam between the diaphragm and the cap reducing the vacuum applied to the cavity and this will likely cause the plungers to not rise as they should.
This could be overcome by trimming down the carb body by .015" to create a pinch on the diaphragm and properly seal the chamber under the cap but in my mind this is a big problem that was overlooked when they manufactured the diaphragm. I measured up the thickness of the OEM Kawasaki diaphragm at .085" and at the very least, Legend should have had the replacements made to the same standard as the originals, so no Brownie points here. I have a concern about the OEM diaphragm since at .085" thick installed in a .082" deep groove, there is only .003" of pinch. Considering that O-rings require a 10% compression to achieve a seal and the diaphragm is .085" thick where it sits in the groove, the OEM diaphragm should have been .090" thick to meet the standard and it's not, so even the OEM diaphragm is questionable in my mind. Standards are standards for a reason.
Another issue I confirmed- There were reports of these aftermarket diaphragms having the locating tab out of place and this is another problem. when installed the locating tab on the outer diameter is off by about 5 degrees and it's impossible to install the diaphragm/plunger assembly and the only way to make this diaphragm work is to cut off the locating tab and assemble as carefully as possible so as to not invoke a twist in the diaphragm which might bind the plungers. Another faux pas.
This pic shows how far off the locating tab is to the locating spot in the carb body.
this shows a straight edge across the carb body to indicate the recess on the inner diameter that allows the diaphragm to relax inside the groove. So no pinch of the diaphragm inside the lip on the outer diameter. In a nutshell, the diaphragm is located and pinched in the groove only as if the groove was filled with an o-ring.
Bottom Line- it's a viable product. Cost wise not bad, Material undecided and only time will tell. Fitment, If you're willing to shave down your carb bodies to create a pinch on the diaphragm, I see no reason why these won't perform. But if you're not capable of trimming down the carb bodies, I would suggest these diaphragms are not for you.
Hopefully you'll find this information useful