1987 project questions

[bprolo28]

I’m new around here and I just picked this 1987 KDX up last week and I’ve got some questions for the smart folks here.

First: I pulled the pipe on this bike after I got it and the cylinder and piston look ok, and the bike has really solid compression according to the compression tester in my leg. That said, there is one vertical mark on the cylinder that caught my eye, and I think after this season I’m going to want to do a top end and re plate that cylinder. Most of the sources of pistons for these bikes say they’re the same for our c series bikes as the newer ones, is this right? I don’t want to stick the wrong piston in it, but I also wouldn’t mind a newer coated piston.

Second: I see RickyStator sells a 65W lighting coil for these bikes, would that get me into the range needed for a 12V conversion. My understanding is that these come with a 35W lighting coil from the factory? I assume a regulator is needed to do the 65W and 12V?

Lastly: The flywheel magnets. Seems like I’m going to want to address these sooner rather than later. Looks like I should be encasing them in epoxy, does anyone have any pics of this process from when they did it? Is it really just as simple as filling the voids between the magnets and calling it good, or is it more involved than that?

Anyways, glad to be part of the air cooled kdx crowd!

[KDXGarage]

Welcome to kdxrider.net. Congratulations on the '87 KDX200.

As far as Wiseco pistons, 1986 - 2006 are the same.

Ricky Stator once told me that they sell a regulator to go with the updated stator. It was 12 volt, so headlight and taillight would need to switch I guess.

There is a post here from a Mr. Swinehart, I think. May he RIP. He actually had some magnets made. I think his posts showed the encasing of the magnets.

Again, congratulations on the '87. Grease the swingarm and linkage fittings!

[Kipsy]

I have no experience with the Regulator Rectifier ignition kit, but I plan to buy this when I get to the motor portion of my KDX build. It comes with an 11 oz. flywheel. What was the stock weight?

It also has a 60 watt lighting coil. Nice feature. Again, though, I don't know of anyone who bought this so I have no idea if it all actually works. It would be nice if it does...

https://www.regulatorrectifier.com/prod ... r-cdi-coil

Nice bike. I have an 87 and an 88. The 87 putters around the property just fine. I ride it in first and second gear with my 5 year old on his little electric dirt bike. It has beautiful putting manners! An 85 KX250 seat puts the ground even closer. It'll get restored some point further down the road, with an 88 KX cartridge fork and 86 KX rear disc set up I have sitting in a corner. My 88 KDX is white and is completely disassembled on my work stand, as it has been for years. Progress is slow, especially since an 84 IT200 shoved it's way in line and is getting refurbished first.

Ask any questions you have and good luck with your build. These bikes are a fun piece of history, and although they are not as fast or well-suspended as a newer bike, they have a friendly low-to-the ground light-weight feel that is great for tight trails or riding with 5-year olds.

[Kipsy]

PS - the magnets are still on ebay I think, listed under the title of "Tecate" magnets I think.

[KDXGarage]

I have no clue on the flywheel weight.

Thank you for mentioning that about the magnets. It is great that she is continuing with them.

https://www.ebay.com/itm/235151245802

[bprolo28]

Bike has been running nicely, starts easy and pulls hard. I do have some fine tuning to do though and have a couple questions. When the bike is cold, idle is very high on choke, I’ve been turning choke off right after start up. This may be normal, not sure. Idle is still a little high when cold off choke, but settles down when warm. However, when it’s good and hot, the bike idles high coming off of a rev(maybe 500rpm high) for a few seconds, then comes back down to normal. It isn’t really a rev hang, as it comes down off the rev pretty normal, but just sits a little high for a few seconds after.

For reference, I’m running 32:1 amsoil interceptor, 91 no ethanol. Stock main and pilot, needle all the way lean. If the needle isn’t all the way lean it doesn’t like to rev out, although it seems odd to me that it’d need to be on the last needle clip. I have not checked float height as I can’t find the spec(if anyone has a pdf of the c series service manual let me know). This seems like a lean condition to me, but I’m no jetting expert. I have checked for air leaks as well and found none. I did try a 310 main(stock is 320), and I liked the 320 better.

If anyone has some wisdom let me know, otherwise I’ll just keep fiddling.