Found it! The ATC250SX/ES Cold Start Kit

[madmax]

Well after a dozen or so phone calls I found a Honda dealer that had part # 06161-HA0-305 in stock. This kit has been discontinued by Honda, so the only way to get one is to find a dealer that still has on the shelf. I found this at Vernes Honda in Antigo, WI. The kit comes with no instructions but Scott at the dealership was cool and made a copy of the bulletin for me. For those that arent familiar with this kit it was the subject of a service bulletin dated November 1985 and updated in February 1986. It addresses a hard start when cold condition on the 1985 ATC250SX and ES (Big Red). It consists of a new starter jet and a number of vacuum hoses, tees, clamps and a bracket. The trickiest part of the upgrade is trying to pull the old starter jet out of the carb without damaging the carb body. This is done by screwing a sheetmetal screw into the old jet and slowly working it out of the carb. The new jet is tapped in, the hoses and tees are added and voila you have (or should have) a good cold starting carburetor. The difference in jet hole size is obvious. I saw a post once where sombody mentioned drilling out the jet. The hole is still small enough that drilling the old one out to a larger size would be a crapshoot. Also, there would be debris from the drilling that would get in the carb. Anyway, enough of me, heres some pics of the kit.

[madmax]

Heres all the parts...

[madmax]

Heres page 1 of the bulletin...

[madmax]

Heres page 2...

[250sx]

I NEEDS that for my big red

[madmax]

Dan,

I'd suggest calling some Honda dealers in northern (cold) states (like minnesota, wisconsin etc) since they may have been shipped more of these kits than the dealers in other states. You can get phone numbers/addresses from Honda's website. I called some dealers around me (Kansas, Oklahoma, Missouri) but they didnt have it. I installed it last night and it works great, starting is almost instantaneous now. Too bad the original owner of my SX didnt get it done under warranty or a goodwill policy (as noted on the bulletin) I wouldnt be out $52.00!!! :)

[Glenn]

Wow! That's a very cool find!

[likestrikes]

Originally posted by madmax
Dan,

I'd suggest calling some Honda dealers in northern (cold) states (like minnesota, wisconsin etc) since they may have been shipped more of these kits than the dealers in other states. You can get phone numbers/addresses from Honda's website. I called some dealers around me (Kansas, Oklahoma, Missouri) but they didnt have it. I installed it last night and it works great, starting is almost instantaneous now. Too bad the original owner of my SX didnt get it done under warranty or a goodwill policy (as noted on the bulletin) I wouldnt be out $52.00!!! :)

SH!T

I just saw this post - I wondered if you had a set of vernier calipers to see how many thousandths of an inch that old jet versus the new jet was. I was truly advised by KEIHIN just to "drill it out" but they were speaking of the main jet after I tossed on a Cobra pipe and tossed off the air box lid.

I was just curious how much larger it was than stock. The hose kit is nice but truly does nothing more than tie the vents all together - that little jet does everything and it will work great for you.

I can only suggest that the 350X models may have been cold blooded also as Honda ditched the original model 05 carb and changed it to a Keihin 10 model with a modified starting circuit (essentially identical to the 08 87 250SX carb).

Glad you got your kit!!!

[madmax]

'trikes.. unfortunately I cant say for sure how much bigger the replacement jet was, but I can say that it WAS a visible difference.
The replacement also has a shoulder on it (the original dosent) so you can install it. Heres a pic of the original after I pulled it out (dont think I'll be able to re-use it :) )

[likestrikes]

Did you happen to see all the other service bulletins??

They had SX snapped cranks from over revving.
SX leaking swingarms.
250R ignition problem on aircooled models

and a few more....

[madmax]

Nope, I havent seen the other bulletins. I remember you posted once about the swingarm but the cranks breaking is a new one to me. BTW thanks for all the good carb interchange info over on 3ww.

[250sx]

I just won a book on ebay that arrived yesterday. It has ALL the factory service bulletins in it. :D :headbang:

Now if I only had a faster/better scanner.... ;)

[madmax]

Dan,

did you get the scans I emailed you?

[250sx]

got 'em. thanks!