All 2st PWK swap and hydraulic clutch issues...

I swapped the TMX for a 38mm Keihin PWK yesterday. Went really well except the extra length of the PWK is causing the airboot on my WR300 to touch the shock spring. I've tried and tried to position the carb in such a way that the boot is clear of the spring but it is still touching. I've seen others have the same issue but I've not seen the solution.

Also had a problem with the Magura hydraulic clutch. They sent the kit with an adaptor barrel thing to reach across the case to the clutch arm. However, that adaptor scrapes on the engine case and the bottom of the reed block. Can't use it like that as it will destroy the adaptor and eat a hole in the case, the reed block, or both.

Adaptor installed on end of slave. The sucker hits the case close to the slave and the reed block toward the clutch arm.


Adaptor off the bike




Any help is appreciated

Heath

I had the same problem.
I mounted the adapter in my vice & hand filed it until I had an acceptable clearance.

if you place the carbs side by side what is the body length difference
possibly trimming the boot will fix it?

I've got to call Magura and see what in the world they were thinking with this kit and if they have any better answers. There just isn't room between the cases and the reed block for that big adaptor. If they can't fix it, I'll have to figure out some other mod to make it work. The dang rod on the slave is nowhere near long enough to work. I'm stuck with the stock cable for my big riding trip this year if I can't get it solved in the next week.

The Mikuni and Keihin are roughly 1/4 inch different in length from front to rear. I guess I could cut the boot up, but I'd rather not do that. I'd certainly loose the band clamp groove on the boot, and likely have air leaks for the life of the machine.

I've read old posts here about a good number of guys having this issue when swapping on the PWK. But, no solutions... Do they just ride with the spring kissing/rubbing and doing other nasty things to their air boot??? Seems like a good way to destroy the boot.


Heath

This is my problem with the longer PWK.


Would cutting the boot fix the problem? Read where Lectron owners have done this with good results. What about guys that have put on Keihin's? I don't want to cut the air boot on my new WR only to gain nothing.

Heath

Spoke to Peter at Magura USA yesterday. I got some more measurements for him last night and called him back today. I'm sending my unit back to him. He is going to send a kit with a different slave cylinder. It will have a longer actuation arm to reach beyond the tight spot between the cases and the reed block. Hope to have that back to test in a week or so. Will post back when I have more info.

On the PWK fitment issues.... I guess people just say screw it and let the shock spring eat the air boot. If I had a spare boot, I would try trimming the carb end off a bit and see how well it works. Bill's or Hall's or somebody have those boots for sale?

Heath

if the spring eats the boot, it's after the filter so dirt, sand or water could go in the intake

I'd find someone with a lathe and turn the carb body down 1/8 inch off of each end flange if necessary but it doesn't look like that amount is really needed just to gain the space for clearance.
Your photo with the "K" from the Keihin logo looks like there's plenty of meat there for the air boot to allow it to fit on further. It would easily go on to the rear of the carb further if this rear flange was just shortened a bit.

I have a 14 inch lathe and wouldn't even think twice about it.

I Had to do the same only opposite fitting flat slides on my old Maico's. Going from round slide Bings and Mikunis to flatslide, smooth bored Mikunis and D slide Keihins
I had to make the flange longer on the front to reach the rear boots and slip a matching aluminum sleeve into the front silicone rubber flange. The rear boots were accordion style and then they would fit without crumpling.

Exactly!

There is no way to move either the intake or reed boot further on the carb. They are both smashed against the float bowl on the bottom of the PWK. The float bowl wouldn't allow the boots to slide further onto the carb even if the intake and output horns were machined down.

This is my dilemma.

Heath

Heath,
Sorry for the suggestion of using the lathe. I couldn't see that your flanges were in contact with the floatbowl in the picture.
Try using a heat gun on the air boot yet?
Or should I just step out of this one? Probably so.

Buy an intake (reed side) from a 2008 or earlier wr 250 . They are shorter because they used the longer older mikuni tmx. I did that with my lectron on my 2009 wr 250.

Wow. Sounds like a great way to get more room for the carb. Where did you find the reed boot? Bills? Any photos? Have to do any more mods to fit the lectron?

Sorry for all the questions man. I really appreciate it. Hoping this will let me use the PWK on riding trip that starts in 2 weeks.

Heath

Yes, my 07 clears no problem. Air striker and now non shortened Lectron.

Dave

how much shorter are the older reed boots? the magura set up(hymec 186 I think) on my 300 uses a 520 chain joiner link to extend clutch rod to actuating arm

Seam Grip! Go to your local outdoor retail store, like REI and get a tube of seam grip. I had/have the same issue. Just is what it is when you do the carb swap. I disconnected the top of the sub frame and shock bolt and swung them back to give me clear access to the rubbed area of boot. Apply a generous helping to Seam Grip to the area and let dry. Then reassemble and don't think about it ever again. I have had it on there for 4 years and it is still 100%. Seam grip is a urethane that comes in a tube and can patch holes and do all sorts of amazing things.

As a temporary fix, can you slip a piece of Delrin in between the boot and spring? I.e. attach it to the frame or boot. That will buy you months to figure out what you are going to do to shorten it.

BTW, on my WR 250, the stock clutch cable was rubbing the reed block. That got fixed when I extended the actuating arm because the piece of metal I added was under the actuating arm. If you can't get the Hydraulic Clutch to work, I can definitely recommend the actuating arm extension mod. Combine that with a Teflon coated clutch cable (or highly lubed stock cable) and you get one heck of an easy clutch for about $10 in parts and an hour or two of fiddling around in the garage.

I've currently got a piece of aluminum bolted to the arm, but at some point I'm going to make it official and weld a piece of steel on it instead.

Don't worry about the boot rubbing on the spring after the swap. I've had my pwk on my '11 wr 300 for 3.5 years with no fixes to address the rubbing and the boot is just fine. The shock moves away as it's compressed as Kelly says. Go ride. Did you remember to use the curved brass cable fitting from the tmx? If not you'll need that. Otherwise you'll kink the cable when the tank is on. Cheers!

08 and earlier WR250 reed boot is ordered. $35 and change with shipping from Bill's. Should be here next week.

Heath

The early style WR reed boot is on it's way from Bill's. Peter at Magura shipped the different hydrualic clutch kit yesterday. Hope these parts work out. Leaving for a 5 day ride in a week.

Will post up results when they arrive and are installed.

Heath