Yet another rebuild thread

Discussion specific to the various air-cooled KDX models sold in the USA
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Re: Yet another rebuild thread

Post by KDXGarage »

Guys, when cylinders are stripped of plating, paint gets stripped also. Again, that looks great to me. Clean it, then clean it again and again.
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Re: Yet another rebuild thread

Post by kdxsully »

KDXGarage wrote: 04:47 am Aug 04 2019 Guys, when cylinders are stripped of plating, paint gets stripped also. Again, that looks great to me. Clean it, then clean it again and again.
Yes and yes. I didn’t know they coated it too though. I thought I was getting a sandblasted cylinder back 🤷🏻‍♂️
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Re: Yet another rebuild thread

Post by kdxsully »

5459B6F8-F2A1-407D-9942-D5E86C66CCB1.jpeg
5459B6F8-F2A1-407D-9942-D5E86C66CCB1.jpeg (1.54 MiB) Viewed 4265 times
Had to modify my head gasket to get it to fit. My kit was for an 84, and I’d assume the stud pattern would be the same for an 85 cylinder but I guess not. My old gasket barely fit, but some of the gasket hung over the exhaust side of the cylinder. Shaved some material off of my new gasket and I got it to fit just right.
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Re: Yet another rebuild thread

Post by KDXGarage »

Looks great!! I see it is black again. :bravo:
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Re: Yet another rebuild thread

Post by kdxsully »

KDXGarage wrote: 03:40 am Aug 05 2019 Looks great!! I see it is black again. :bravo:
2 tone motors aren’t my thing :lol:
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Re: Yet another rebuild thread

Post by KDXGarage »

Ir's whats inside that counts.
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Re: Yet another rebuild thread

Post by kdxsully »

Got to start breaking it in today. I did a couple heat cycles. I'm trying to figure out if the pilot is rich or not. I'm thinking I'll do a couple more heat cycles and see how it runs. I might do a video another time.
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Re: Yet another rebuild thread

Post by kdxsully »

She doesn’t want to idle. I can’t even start it on choke, it fired up with no choke though (cold). I’m running it 32:1 for the break in, and I plan on going 40:1 after, which is even richer. Stock jet for an 84 motor is 40, I’ve got 35 in. Now, my Mikuni carb is off of the 1987 model, and Wikipedia says they switched to the Mikuni in 85? Is that right? Are the stock jet figures for 84 for a different carb?

Stock pilot in an 87 is 25 it looks like.
In the meantime I’m gonna pull the spark plug and see if there’s any goop.

Edit: spark plug had a small deposit of spooge on it (it was new), I suspect it was starting to foul. I upped the idle speed and it still idled for a bit then cut out. Upper range is fine though
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Re: Yet another rebuild thread

Post by kdxsully »



Before



After

Note that I did switch phones between these two recordings. And excuse my messy workspace :oops:
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Re: Yet another rebuild thread

Post by KDXGarage »

RPM is a little lower. Is 1983 - 1985 a 32 mm carb or 34??

Is that "just" a silencer?
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Re: Yet another rebuild thread

Post by kdxsully »

KDXGarage wrote: 12:51 am Aug 07 2019 RPM is a little lower. Is 1983 - 1985 a 32 mm carb or 34??

Is that "just" a silencer?
Idle screw was only about one turn to one and a half turns out. I think it was two in the top video. And, I really don’t know. Guess I’ll measure. I assumed the Mikuni carb was the same until they switched the the keihin in 88. What do you mean by just a silencer? It’s the full expansion chamber and Answer silencer hooked up. It does sound thumpy
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Re: Yet another rebuild thread

Post by KDXGarage »

Is it an Answer S/A-Pro silencer/spark arrestor or the Answer S-II or whatever they called the silencer?

If you are not sure, see how far a metal rod will go inside. If it stops early, it's the S/A-Pro.
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Re: Yet another rebuild thread

Post by kdxsully »

KDXGarage wrote: 08:22 am Aug 07 2019 Is it an Answer S/A-Pro silencer/spark arrestor or the Answer S-II or whatever they called the silencer?

If you are not sure, see how far a metal rod will go inside. If it stops early, it's the S/A-Pro.
I know it’s answer, but I can’t find an example online anywhere. The sticker was kinda thrashed, and it was scuffed, so I just slapped paint on it. I’ll check next time I’m over there. In the meantime, I ordered a leaner jet to see how that works out. I don’t wanna put the 20 back in there with the new top end and risk running too lean.
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Re: Yet another rebuild thread

Post by kdxsully »

https://rover.ebay.com/rover/0/0/0?mpre ... 3300337357

It looks a lot like this.

Update: i believe it’s the Answer Equalizer. This link looked much more familiar.

https://rover.ebay.com/rover/0/0/0?mpre ... 2537202415

Otherwise known as the “S-II” or whatever KDXGarage called it. I stuck something in there and it went all the way down.

By the way, the bolts to take it apart look like rivets, how the heck do you repack this thing??
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Re: Yet another rebuild thread

Post by kdxsully »

Thought I’d add more stuff about my actual rebuild for your entertainment..

Image

The bracket for mounting the chain guide was busted off of the swing arm. Don’t ask me how, it was never there. Insanity. I bought a piece of steel bracket from Lowe’s, drilled and tapped into the bottom of the swing arm, bolted the cut-to-size bracket on the bottom of swing arm with blue loctite. I left some space in the bracket so I could adjust as needed and maybe even do additional mounting to it. Notice the thick washer "spacers" inside the chain guide to accommodate the wider o-ring chain. The whole assembly cost me less than $35 - the chain guide was $27 with a chain slide.

Image

Used a piece of scrap from work as a support for the chain guard, rather than paying $10 for the dumb bracket thing.

I also made a custom front sprocket guard from scrap metal. I forgot to take a picture, so I’ll post that later.

Image

Noticed little hairline cracks in my gas tank. Not sure if this is just from age or from being in the sun at some point. I’m wondering if I should be shopping for a replacement. I did some scraping with a razor just to see how deep down they are and whether they go away. Not sure if I should even concern myself. What do you guys think?

Image

Here’s another woe of mine. The kickstart scuffs the rear brake pedal. I’ve shimmed the kickstart with a washer (which I don’t like), and I set up my stopper bolt upside down so I can let the brake pedal hug as close to the frame as possible. I might just have to live with this, being that my frame and motor are mismatched. Any ideas on this?? :hmm:
I don’t think I can heat and bend the kickstart out a bit because it is cast. I’m worried I’ll break it. Maybe shave it down a tad???

Also, I replaced ALL of the grease fittings (4 in total I think). They're M6, if you want to do yours. I got a pack of assorted ones at Harbor Freight (I know) for like $8
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Re: Yet another rebuild thread

Post by kdxsully »

KDXGarage wrote: 12:51 am Aug 07 2019 RPM is a little lower. Is 1983 - 1985 a 32 mm carb or 34??

Is that "just" a silencer?
83-85 carb

You might have put me onto something. My 87 carb looks different, so maybe I should be jetting 25/320 (from memory) as stock. Thanks.
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Re: Yet another rebuild thread

Post by KDXGarage »

W, L & J (later FRP) used to sell an angle piece to brace the part that came down from the swingarm to bolt the plastic chain guide to. Teenage me was like, what the hell is red Loctite??

I'd be a little nervous on that tank. Not real bad, but not real good, ya know?

Kickstarter issue sounds like mismatch to me.

I remember losing one of my fittings back in the late 80's. Dealership sold me an SAE one. THANKS!!

Check the OEM diagrams to see about the jetting differences. I know 1986 - 1988 had the lever for the choke mechanism.

EQUALIZER! That's it! MAN! I wish Answer still made all the KDX parts. They made pipes and silencers and spark arrestors back in the 80's and early 90's. They even had a few for some of the KDX250 air-cooled.
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Re: Yet another rebuild thread

Post by kdxsully »

About the Kickstarter. My other theory is that it’s scraping because it is sloppy. It wiggles on the boss, and that might be enough to scrape. I did a test where I held the kicker in place, and it didn’t scrape. How do I fix this? Welding?
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Re: Yet another rebuild thread

Post by KDXGarage »

Well, yeah, if it is sloppy, then that will be an issue. I think people build it up with welded material, then sand it down.
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Re: Yet another rebuild thread

Post by kdxsully »

KDXGarage wrote: 04:12 pm Aug 08 2019 Well, yeah, if it is sloppy, then that will be an issue. I think people build it up with welded material, then sand it down.
I looked at the parts diagram for the heck of it, noticed there's supposed to be 2 orings under the kicker on the boss shaft. I don't remember having any, so I'm gonna put a couple on there and see if that helps.

Update: Kickstarter is tight as a drum now. It still has a tiny bit of wiggle because the o rings are rubber, but it’s not excessive at all. Definitely acceptable. I just put 2 thin o rings on the base of the boss shaft. I also pulled the balls out of an old bearing, and found a small spring to fix the small lock mechanism. Found a set screw at Lowe’s for less than a dollar. Total cost: under $4.
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