After riding to work this morning, the problem has lessened a bit but not disappeared.

 

Invaluable information.. Can you imagine buying a nice used KLX and never getting it to run right because of this shaft seal ?

 

neon, I did a quick search, even looking on the Keihin site and didn't find where that part is available as a single item. Have you done a more extensive search on the net for that item? Quite a few KLX folks have changed carbs to pumpers, so you might be able to find one for a reasonable price.

 

After googling I have found several cases of the same issue, all seem to be caused by harsh solvents or carb cleaners drying up that felt seal. Information is scarce and sources for this part even more. I have found an ebay seller that has 3 different types of these seals that should fit based on the measurement of the shaft and seal carrier.

http://www.ebay.com/itm/MIKUNI-CARBU...189866&vxp=mtr

I will try to find it locally first. I'm confident I can find this other type of seal that is rubber.

http://www.ebay.com/itm/MIKUNI-CARB-...ef1c8f&vxp=mtr

I guess the o-ring muyst have sealed the contact with the hard plastic black piece, but not the inner contact with the shaft due to less sealing surface area or maybe to large for the shaft. I bought the proper size for the seal carrier, never thought about having it tight to the shaft. I will try a size smaller if I can't find the other seals. This one is size 11 o-ring.

You know, even with this mess, the bike feels really good, probably due to the new cam chain and valve adjustment, as well as the manual cam chain tensioner. It pulls real strong and smooth except for 4k to 6k rpms. Can't wait to get it sorted out and get riding again jaja.

 

TNC, I wish I had funds I'd get a pumper myself jaja. Got a friend coming down in a week luckily so if nothing local works I'll have her bring me one from ebay.

Here is what I found locally: size 10 and 11 o-rings and corresponding size seals. I hope the seals work.


Yesterday I was overconfident and lowered the jetting from 132/5N/2.5 turns which I was using to compensate for the air leak, to 128/4N/2.25, thinking for sure the fix would work. Realizing that last time I tried that jetting with the air leak, the bike had terrible driveability. Now it's even better than the 132 setup, so I want to believe that validates at least my analysis of the source of the problem.

Update and more pics to come later. cheers

 

The larger seal was a perfect fit to the seal carrier and the shaft. Too perfect as the throttle shaft was unable to turn freely nor easily with it. The smaller seal was obviously too small, I didn't even try it.

So I tried the number 10 seal to see if it could get a tighter seal to the shaft, and then the felt seal between the o-ring and the hard plastic part. This did get a tighter seal with the shaft but not with the seal carrier, but I went ahead and tried it anyway.

On first review it seems to have worked. Even with the #11 o-ring I installed yesterday I had massive decel popping. Now I have next to none, even less than before. Letting off the throttle at 9k rpm from WOT to closed had very little, very subdued, barely noticeable popping. Moderate to aggressive riding had no decel popping, before I used to get some at least.

On the rest of the rev range the bike is running as good as ever or better. I get no stumble from cruising at 3k to WOT like I always did before. Getting hard pull all thru the mid. This fix is the first time I experienced the bike with new chain and adjusted valves correctly and it sounds better, deeper and feels stronger and smoother.

I don't know how long this fix will last so I'll order the original seals to have on hand if the problem arises again. For now I'm going to confirm the fix tomorrow then start jetting up again based on Klxsters findings, corrected for my altitude.

cheers

 

That's been a strange deal. I can't recall of anyone ever having those items fail in CV carb, but stuff dies...it happens.

 

Tell me about it, I didn't even know there was a perishable seal there that didn't like carb cleaner or solvents. Heck I didn't even know carb cleaner was bad for the rubber parts inside the carb. Luckily I just never used it for the diaphragm because it wasn't dirty, just wiped it with a soft cloth.

This guy had the same issue on a KLR: CVK40 - Air leak around throttle shaft... - ADVrider

 

I will tell you a fair amount of metric hardware, including O-rings and seals, can be had from Fastenal. You may have to buy a bag of 100 on O-rings, but it usually is not that expensive. The seals, and any bearings (wheels, etc) can usually be by the piece. Bolts are usually by the piece, but nuts/washers are by the bag, 50-100. I picked up a full set of seals and bearings for my KLX650 hubs, although I think All ***** is probably cheaper for those without a wholesale discount.

Just saying go on www.fastenal.com if you cannot find an item and see if they have it.

 

Or McMaster-Carr

Ride on
Brewster