88 kdx leaking oil

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Aug 19, 2003
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#1
Ok I've been all over the forum and can't find anything on this problem. My bike has been leaking oil from a small angle valve at the base of the cylinder. What could be causing this and could it cause the bike to run rich. I've had more than a couple of macanics tell me to replace the old carb becase the needle seat wears out and can't be replaced, and that I probably just over filled the bike with oil. Any help would be great.

Tim
 
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#2
Ok problem 1 I have no idea what you are talking about. Is it part of the ‘kips’?

Re the carb the float needle & jet can leak, on an 88 not sure but think you have a Mikuni carb so new float jets would be easy to get. But first thing is pull the float jet out, replace the o-ring. Drop a ball bearing down the hole & give it a decent tap with a punch to make sure it’s even & check the float jet. If it is really badly ridged a new one is easy to get or 2nd hand same size.

Also the fuel tap should be turned off, if it still leaks (in off position with hoe pulled off) an aftermarket rebuild kit is cheap & easy to fit.

Still in the dark about your oil leak & where you are talking about but as far as running rich do make sure the air filter is not past it’s best. On these old carbs you should look at the needle jet (as the needle passes through) as these do wear oval, & the needle itself - happened to a friend of mine & was much improved when he replaced it.

Ahh, was that what you were talking about when you said needle seat? I assumed you meant float seat.
 

kdxtaz

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#4
He's talking about the crankcase vent. It's in the top of the case just under the cylinder. Also, what's a good way to make an Air Striker carb work on that bike? Yunno, the 'justment screw's on the wrong side.
'taz
Hey Tim guess who? :think: :confused: ;)
 
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#6
No the vent tube is missing. And after looking more closely it may be over filled. But I still need to figure out why its running so rich. I have a new airstriker to put on it but I have to modify the carb or the bike. I just need to find out if I may be pulling oil into the gas mix from the case or not. Is there an easy way to test bottom pressure to see if it is leaking. I don't mind putting the carb on to see if that is the problem. But if it isn't then I can't return it. And then I have to do all the modifications becase the air srew and the throttle adjustment srew are behind the air filter. Stuck in a strange predickament. Tim
 
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#8
Well, After looking at the oil level it looks pretty high. Haven't had a chance to drain it yet though I plan to tomorrow. The air striker was a good deal for $200 and some change. The stock replacement was $350. I got it through Carb parts warehouse; 1-216-635-1099. Its the only one that is available as an upgrade for an 88. You may or may not have the same problem. I was under the impression that the 87 had a mikuni. I talked to the sales guy who said I may be able to have the other side of the carb machined. The new air striker has stub outs for both the air srew and the idle adjust. I think it would just be easier to drill a 3/4 inch hole and then plug it back up with a rubber plug. First I have to find the plugs to know if it will work. i'm just hoping the new carb will solve the problem. The old carb has already been rejetted leaner from a stock 154 to a 134 main; and it still pukes oil and has no top end. tim
 
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#9
Um, that’s a huge change on the mainjet & is probably why it has no top end -it could well be way lean. The needle & pilot are probably where it is rich & as you spend quite a while there will contribute to the spooging.
 

MX175

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#10
After you have drained the oil from the transmission/clutch, refill with about 3/4 to 7/8 or a quart. Do not watch the the sight glass while you are filling as it can be very delayed. Under no circumstance should you ever have more than a quart in there. And get a hose on that vent. It will help prevent water from entering the case. It's a good idea to run that hose to the airfilter box, if you can.
 
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#12
Well I finally just put the new carb on and it seems to be better. It still seems a little rich but it came with a second leaner main jet so I will put that in to see if it stops spitting black. I did look into E-bay but didn't want anyboby elses problems so I decided to go with the new one. It was still not wanting to open up untill I took the spark arrestor off then it all seemed to just open right up. Time to repack and try again. The bike is green with all original plastic so it's pretty ratty to. Its all I got for right now but I'm looking for something new. So here's the big question Do I stay with the KDX or go for a KX? Dessisions, dessisions. I like the looks and idea of the power of the KX; but don't know about a new KDX. I have ridden a newer KDX and like the power but need to know how much different the KX is. I can get an 03 KDX 220 with a fmf pipe and spark arrester for $3999.00 but I don't know if the power is comparable. Tim.
 
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#14
Things seemed better today. I rejetted from the 162 main that was in it to a 160. Less mess out the pipe. I'll ride the heck out of it this weekend and see how it does. The issue of KX vs. KDX is only in my head. I trail ride only as well and have read of people converting the KX for trails. It seems like a win win situation with the power but is it to much or not. No big deal I'll just have to find someone with one, nock him off it and give it a try. This weekend should be good though lots of friends lots of riding and my bike works. Tim.
 
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#15
Well after a good long weekend of riding with KDXTAZ my bike is like a totally different beast. I'm still working on the jetting, but I'm real close now. I really appreciate all the help. It helped me enjoy my old beat up bike that much more. I will probably hand her down to my 15 year old when I get my new one. He rode it for a while and liked it better that his 81 CR 125. But then who wouldn't. Thanks again . Tim