Engine reving way too high --- Help please!

[gbruno21]

88 KDX 200. Quick background. Engine seized up mid ride. Took it to a motorcycle mechanic. He dismantled the entire engine just to find out it was the classic KDX rotor problem. He wanted $2200 to replace everything he could think of. I took home a box of parts and put it all back together. I bought and installed a new rotor and new stator. The bike now only starts with the aid of starter fluid and the engine is running only at a high RPM like I am turning the throddle. The throddle cable is not in a bind, and I loosened the tension on it. I loosened the idle screw at it is still racing at idle. Saw black oil leaking from the head gasket - new head gasket is in the mail. I will also replace the piston rings.

I am not a mechanic at all. I am an amatuer at best. Could it be at such a high rpm because of a bad head gasket or bad rings? Could it be the governor? Could it be a problem in the carburetor. Please help. :bang:

 

[whenfoxforks-ruled]

See if the slide is in the carb backwards? A round bore has a slot in the slide, and a pin in the bore of the carb. Either way, that slide needs to close all the way!

 

[gbruno21]

not sure what you mean by the "slide." If that is the throddle valve then no it is not backwards. On the 88 the throddle valve is flat on one side and round on the other. It would only fit in one way.

 

[whenfoxforks-ruled]

I would stop trying to start it with starting fluid. Something is really wrong. A head gasket leak will cause a lean condition, any air leak between the carb and exhaust will. Did he have the crank out?

 

[gbruno21]

Yes. He split the case and had the crank shaft out. I put it back together and it seemed to go back in pretty smoothly. I froze the crank shaft with the bearings attached and heated the case in the oven at 200 degrees per another thread on this site. The piston and rings appeared to be in pretty good shape (the bike ran great prior to the rotor magnets breaking loose). Now the engine races out of control at idle and then the RPMs drop quickly and it stalls out. I can keep it going for a few minutes by manipulating the throddle but the RPMs stil sound out of control. When I tried to ride it for a few minutes the RPMs jumped way up with only 1/2" or so of movement in the throddle. I am just trying to get it running properly so that I can ride for recreation with my sons. No racing or anything like that. I don't want to spend a fortune to fix a bike that I just use for fun trail riding.

 

[whenfoxforks-ruled]

When you put the engine back together, perform a leak down test to confirm its sealed up properly. A crank seal improperly installed? Way too many places to leak. And then it could be the carb. Anything that mimics a lean condition. Do you have a shop manual, or equivalent?

 

[gbruno21]

yes. I have the Clymer manual.

 

[sr5bidder]

it sounds like you put her back together with the old crank seals

did you use honda-bond 3 on the case halfs or did you bolt the together with no sealant at all?

BTW why did the cases get split anyhow? upon finding the rotor jacked up he should have stoped

 

[gbruno21]

yes, I used the old crank seals. I used Yamabond (or the equivalent) on the case halves before I put them back together.

I agree, why did the mechanic split the case if it was not necessary? I did not have a flywheel puller at the time so I could not pull off the rotor to find the problem, nor would I have known to do that first. But the mechanic should have known. When it froze up my kick start lever would not move, that is how I knew there was a problem. The rotor would turn about 1" but made a crunching sound. Took it to the mechanic and he disassembled the whole motor. What a freakin mess.

I am not a mechanic at all. I am learning as I go from threads on this site as well as youtube instructional videos.

 

[sr5bidder]

If the piston was removed from the crank you are going to want to order new circlips and install them thry are one time use and can come out if reused.

did you order a new base gasket too?

 

[sr5bidder]

http://servicehonda.com/look-up-parts/03

I would get every gasket you can see in the pic


and get a couple 92049 seals from this pic

http://servicehonda.com/look-up-parts/03

to put the seals in you are going to have to split the cases again, once all that is done properly there should be no more air getting in the crankcases

 

[gbruno21]

When you say circlips are you talking about snap rings, piston rings, or something else?

No. I did not order a new base gasket. Sounds like I should, right?

 

[whenfoxforks-ruled]

He had the crank out, he did not remove the seals or bearings? And you should not reuse, gaskets, circlips, or rings, by the way. When you put the cases in the oven, did you turn the oven off? It never got over 200 f.?

 

[gbruno21]

No, I did not turn it off. Did not know to do so.

 

[gbruno21]

I guess I learned not to go back to that mechanic. Does anyone know a good, and HONEST mechanic near Charlotte, NC. Don't go to the one I went to in Iron Station, NC!!!

 

[whenfoxforks-ruled]

Did he take any crank seals out?

 

[_JOE_]

http://www.harborfreight.com/cylinder-leak-down-tester-94190.html

Go buy this and quit guessing. A bunch of us could give you possibilities but none will be much more than a guess. Learn to be your own mechanic, it's not terribly difficult if you make a small investment in tolls and can save you a ton of money and aggravation. There's a couple people on here that might be able to help you out if you get stuck on something.

 

[gbruno21]

I will check the cylinder compression. Thanks for the help.

 

[sr5bidder]

I know someone in Boone N.C that likes working on kdx's. I live a bit north of atlanta Ga if you wanted to bring it down I would get her fixed up for $100 plus parts, just because I like being in the garage. Some of the best work comes from people who like to r/r motorcycles and not from people trying to make money fixing bikes.

let me know I would love to wrench on an 88 as long as you don't mind me "field testing" it

 

[julien_d]

Would that be me?

I've been quite busy up here, but I could probably be talked into having a look at it if you could bring it up, or send me the motor. Bottom end rebuild is not a problem. I have acquired all the necessary tools. We slapped my buddies KTM200 back together last night in 4 hours. Fresh top and bottom. Not too shabby....

 

[sr5bidder]

Would that be me?

I've been quite busy up here, but I could probably be talked into having a look at it if you could bring it up, or send me the motor. Bottom end rebuild is not a problem. I have acquired all the necessary tools. We slapped my buddies KTM200 back together last night in 4 hours. Fresh top and bottom. Not too shabby....

10-4 that would be you, but did not want to go any further in
Volunteering your services. :cool:

 

[whenfoxforks-ruled]

Less the 10% kick back to the fallen riders fund? And details as to why it would not run!

 

[sr5bidder]

Less the 10% kick back to the fallen riders fund? And details as to why it would not run!

??? :whoa:

 

[julien_d]

Well sure :)

 

[whenfoxforks-ruled]

??? :whoa:

Soon enough, he may have his own forum to sponsor?