650/X-2 Thinking carb problems, help

Location
iowa
1989 X2 with 28mm carb. Poor idle problems and bogs above throttle. I know my low speed air screw is damaged but trying to compensate with different adj. the choke plate has been removed and all FA screens missing. I can get it to idle good and run crisp on trailer if I put restriction (sponge) to take the place of FA screens. Fuel pump is working. I know I should scrap this 28mm and go larger but doing small steps. Under load in water it idles but doesn't develop any power with (sponge) restriction. Won't idle or Rev at all without restriction. Acts like its starved for fuel. Good spark both cylinders , haven't checked compression yet. How critical are these 28mm for having choke plate and FA screens removed. Acts like it needs better carb signal. If anyone has a good working 28mm carb and FA willing to sell I might be interested.
 
Location
iowa
Currently I don't have my pop off tester. Can someone tell me what baseline pop off pressure should be on the 28mm. Thinking I'm waaay too high.
 
Location
SWFL
carb screw not working correctly, overcompensating on mixture, no FA's, then trying to ride it (basically choking it out) with a sponge, and no throttle power under load (in water).
These are all contributing factors to your problem. also, bad/low compression will run on a trailer, but will always cause stalling issues under load.

not worth the time and headache of trying to get it to even run like that. First thing I'd do is check compression. gauges are cheap and a must have ig you own a ski. you can even rent one for free from your local auto store (or for a minimal fee).

Then after that, you can get a GOOD used carb for less than $100, or even cheaper if it just needs a $40 rebuild kit. like this one for example is $20 and its a 38mm.

http://www.ebay.com/itm/Mikuni-38mm-carb-Kawasaki-X2-/142398391307
 
Location
iowa
My thoughts exactly. So why did I not do all that? I'm helping a buddy out weekend at lake miles from home. Most 2-strokes are the same, I'm an owner of 2 701 blasters and love them. Since the carb is so small I figured asking thinking the window to make the engine work was so small that I might be missing something. Not my ski so just making the best of it away from my well equipped shop full of appropriate tools. Thanks. I might keep posting our results for others.
 
Location
iowa
So I installed the 38 but its got a flat spot off idle. Thinking pilot jet too small or pop off too high. Can someone give me specs on a 38 kiehn pilot, main and pop off to start with. I turned out the low speed 2-1/2 turns and it helped. Only mod is pipe and waterbox. And now larger carb and intake.
 
View attachment 336291 View attachment 336292 Might be time to go up a jet size or two. Makuni has a graph that explains what does where, it will help you find your "flat spot." For me lowering pop off seemed to help. It would take effect right after the low speed jet. Building a pop off tester is easy buy a gauge that reads 0-30psi (or something close to that) use a vacuum tee and some short pieces of hose. Some people use a small hand pump but I just use a regular air compressor and a good regulator to drop the pressure to around 20psi and a small ball valve right next to the gauge and crack it to bring the pressure up slowly. Here is a .pdf manual too. Hope this helps
http://www.mikuni.com/pdf/sbn_manual.pdf
 
Location
iowa
Thanks. Yes I have all that and very familiar with tuning at what throttle position I need to make adj to jets and pop off. This is not my ski and I have limited time to assist a buddy so was hoping for a benchmark on kiehn 38 carb. I was hoping to buy a few pilot jets and springs but wanted actual pilot jet sizes and spring tension numbers to get started. I'm pretty sure the last guy that owned this ski lost the pop off spring and put in a ball point pen spring. Now u c what I'm dealing with. I need a base line.
 
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