Kawi2strokes.com Forum

I'm looking into modifying my later cylinders to work with a 3 hole pump. I'm mounting 34mm flat slide carbs which don't have provision for oil lines. So it seemed fairly straightforward using the method outlined in the following link from Kawatriple.com.

http://kawatriple.com/tips/casecyl_swaph2.htm

In there they recommend using a #30 Mikuni pilot jet in each cylinder. First question (sorry if it's obvious) is any 30 size jet going to work? There are a number and some seem better for the application. The Mikuni N100/606 Slow Speed Jet in 30 size seems like it would work well.

Also, if anyone has made this mod, did you have to remove the cylinder studs to be able to drill the case?

Thanks,

Dave

download/file.php?id=2571
I have TM34s, look through my thread to see how I added check valves and lines to the TMs for carb oil injection, in addition to crankcase injection. Some tricky work, but it works well for me.
Here's the page... viewtopic.php?f=13&t=12577&start=170
Also, here's the crankcase oil banjos modified as you are doing viewtopic.php?f=13&t=12577&start=50

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1974 Kawasaki H2B 750, 1981 Yamaha XV750 Cafe, 1986 Kawasaki KDX200, 2003 Honda XR100, 2004 SDG140. 2006 Ninja 500R Turbo intercooled fuel injected.

Thanks for the reply. Looks like it was a lot of work, was it worth it? I picked up the flat slides because I'd heard they were an upgrade and the price was right. I haven't started any of the real modifications yet. Just want to know if it's worth the trouble. I'm not racing, just want a good performing bike.

By the way, I couldn't see any of the images, said I didn't have enough permissions to view them.

Thanks,

Dave

Was a lot of work, yes. The LH carb hits the crankcases, and I find it sacrilege to cut the cases so I machined the carb instead, some off the bowl drain flange and some off the drain plug too. The oil check valves in the carbs were tricky, as was the added vacuum port for the fuel tap. It does make more power though, and the best thing, it throttles off an idle better than I could get the stock VM30s to. Seemed like I had to grab a second clutch release off a standing start to save the bog it had, but the TM34s, the bike pulls away much more smoothly from idle. I spent as much rebuilding and tuning the stock VM30s as I did buying the TM34s, so if you are starting with old non rebuilt VM30s, that is a good place to go to TM34s instead.

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1974 Kawasaki H2B 750, 1981 Yamaha XV750 Cafe, 1986 Kawasaki KDX200, 2003 Honda XR100, 2004 SDG140. 2006 Ninja 500R Turbo intercooled fuel injected.

I don't have pictures, but I drilled my 75 cases to mate with my 72 cylinders. I don't recall having to remove the either of the rearward studs. Drill slowly since it is aluminum, but be certain you are drilling straight and true as shown in the link's images. My first hole drilled was misaligned and had to have a local guy repair it before I correctly drilled a second time. Note that I was utilizing the 72 carbs and oil pump as well as the cyls, and only needed to match the cases to these.

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"Only cheat the cheaters, boy - you can't cheat an honest man!" Mordecai Jones - The Flim Flam Man.

DGA, I checked out the thread you posted above, I like the idea of drilling the port for the manometers. I already have a set and would like to use them. Do you remember what size drill you used to drill the vacuum port?

Did you have to do anything to port before mounting the pushloc onto it? It has a rough surface like the rest of the carb body, don't know if you need to make it seal a little tighter. Looks like an easy way to connect the oil lines and less trouble that drilling the case. I'm getting some jets to mount inside the body.

Thanks for the advice,

Dave

Not sure what size the vacuum port was, it only really needs to be small, .063" or so.
For the carb oil inlets, i used a (I think) 5mm hex die and threaded one of the carb vent nipples, yes they are cast, but it worked great. But, don't forget, you have to either have check balls inside the carb, or some other method of shutting the oil off from draining from the oil tank. I tapped the carb vent port inside and used the small mikuni main jet for the oil outlet into the bowl, but above that i slid in a piece of hypodermic stainless tubing, then a small ball, then a small spring, then screwed the jet in to hold it all in place. I tuned the check ball for about 4psi opening, by changing the length of stainless tubing.
I am heading to Road America tomorrow morning for a race event, but can see if i have all the sizes written down for all this when i get back.

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1974 Kawasaki H2B 750, 1981 Yamaha XV750 Cafe, 1986 Kawasaki KDX200, 2003 Honda XR100, 2004 SDG140. 2006 Ninja 500R Turbo intercooled fuel injected.

Be sure you read and follow the FDM on the Resources page as to the O Ring crush in the rear chamber. It is specific on O Ring crush sealing.

The CORRECT factory air only check valve pop-off pressure is 4.6 PSI. I just CAREFULLY stretched the stock springs to get there.

Just checked, I do have a M5x0.8 die. Looks like I'll be fitting some oil lines. The vacuum ports will be easier. I have some jets ordered, the hard part is fitting the check ball and spring.

Dave

Anyone use the Yamaha check valves, p/n 8ch-1316a-00-00?

Dave