How to plug hot start on 450r carb?

[bk111]

What's everyone doing? Silicone?

[CJM]

RTV silicone, can buy it practically anywhre auto parts are sold.

I prefer the grey one myself since its good on aluminum as well as steel but whatever floats your boat.

[bkelley]

From zrpilot's 450r carb install thread:

Originally posted by zrpilot
This is how I sealed off the hot start. I simply used some black RTV gasket maker and filled the cable adapter until it oozed out the back. Then I re-installed the hot start plunger and the spring to seal everything off.

http://i94.photobucket.com/albums/l97/zrpilot/IMG_0599.jpg

[gt400ex]

Buy the hot start plunger. Most people have problems trying to plug it any other way. If its not plugged right it will rev funny and it will make tuning harder.

[Wheelie]

Don't silicone it, buy the proper hot start plunger.

[island400ex]

Where do you buy the plunger?? Is it a part of the cable? The carb I bought did not have the cable and I am not familiar with the function, I phoned Honda today and they had no idea what I was talikg about when I said plunger? Should I just buy the cable and cut it down???

[slightlybent47]

Any Honda dealer can get the part number for you and order it as well.

[slightlybent47]

Here ya go. HO HHP Valve set Part # 16019-HP1-671 $25.94 + tax

[island400ex]

Thank you very much! Nothing worse than talking to the parts guy at honda without a clear description, he didn't seem to keen on helping me since I was putting a 450r carb on my 400ex!!

[slightlybent47]

No prob, glad to help.

[JOHNDOE83]

Really you dont need the stuff for the hot start all it does is open the passage to the little hole on the top of the carb hole on your intake boot side of your carb. all you really need to do is block that little tiny hole but i still filled mine all the way with rtv without any internal hot start parts and mine runs like a champ. dont waste your time buying the parts.

[riotact]

If you dont buy the plunger and parts you are just asking for trouble when you go to jet that thing.Follow ZRpilot's how to thread and you will be good to go.

[Wheelie]

That's bad advice Johndoe, there have been countless members on this board that have had unusual issues due to plugging the hot start hole with silicone.

Do it once, do it right.

[JOHNDOE83]

well its not "bad advice" take your plastic cover off your carb where your throttle cable is and look for yourself. you can see where that hot start goes and what it connects to. all it actually is a hole and all the hot start does is open that hole so as long as its blocked off by rtv it will not mess anything up go ahead and waste time and money on the extra parts but in the end ill be right. you also dont have to block off or drill any new holes for the vent lines.

[JOHNDOE83]

also your just filling it with RTV then installing the hot start parts with RTV to block it off anyway rendering the hot start parts useless...all you did was block it off anyway... so really whats the difference if the parts are useless anyway and serve no mechanical purpose on a 400ex so whats the difference from blocking with or without useless parts in there. just fill it ALL the way with RTV and let it dry and you wont have problems.

[island400ex]

So talked with Honda and found the part! That's the good news, $44.00 here in Canada WTF!! I ordered it, despite your advice John doe, I am sure the silicone will work but if it doesn't and there is a small vaccum leak it'll be a pain to get it all out to put the proper plunger in! I appreciate everyones opinions this site has helped me in huge ways with nodding my quad! This is the first time I posted any questions but will not be the last!! Oh and by the way just for fun I priced a new 450r carb, here in canada a special price of just $780.00!! I don't get it!!

[JOHNDOE83]

check out the parts when you get them, "technically" and if they serve their purpose, you wont even need to fill it with RTV cause the plunger and spring will take care of that. cause thats what it does block off the hole....im not trying to argue just trying to expand technical advice. if you think of the concept of what your doing when blocking of the hot start, no matter if the hot start parts are there or not all your doing is blocking it off with or without the internals. they would only serve a purpose if they held it open, which they dont they hold it shut. so filling it throughly without the internal parts is the same as doing it with the enternal parts. i only did not use mine cause it did not come with the parts for a hot start so i did the research, checked the parts out, inspected the carb and openings, and came to the conclusion that all you do is block it off.....and mine runs better then ever.

[riotact]

Why you running the stock carb then?Is it because you couldnt get the 450r carb working on you 440?Maby air leak,jetting?You could seal it with chewed up bubble gum for less then .25 for that matter.

[JOHNDOE83]

carb is new and havent changed the info yet.

[riotact]

I figured you had it on there and had to switch it back to the 400 carb.If thats what happened I was gonna say it was probly from the hotstart hole.Those have been giving people fits on here for a while.Sometimes its just best to stick with what is known to work.

[JOHNDOE83]

well if you do it right this method is also known to work. its common knowledge. you just have to make sure its filled. read my other posts on this page and if you disagree then you disagree. but it WILL work the way i described buy the parts or dont buy them anyone that fills it the right way will agree that you do not need the hot start pieces. and next time your installing the hotstart pieces and filling them with rtv anyways, ask your self if its really needed.

[gt400ex]

The reason you put rtv or what ever on top of the hot start is because after you thread the retainer on there is an open area where the cable can snap in and the rtv will help keep everything in place and dirt out.

[JOHNDOE83]

exactly!

[slightlybent47]

I used the hot start plug and the only rtv I used was on the very tip of the plug on the outside top just to keep the dirt out of the hole. It had no bearing on how the plug works; the actual way it works is if you look down into the hot start hole you will see a small hole down at the bottom. The hot start valve is kind of like a small needle valve and the little point goes down in the hole and plugs it. Then it has a spring that holds it down kinda like a little pressure valve. Just putting rtv down in the hole will not and I repeat, it will not push the little plunger down in the little hole at the bottom.

It's a cheap part, use it and you should not have a problum.

[riotact]

Originally posted by gt400ex
The reason you put rtv or what ever on top of the hot start is because after you thread the retainer on there is an open area where the cable can snap in and the rtv will help keep everything in place and dirt out.

X2,but you still need to buy the plunger and retainer that is what everyone keeps saying.So if you follow ZR's thread there will be no worries.

[gt400ex]

Thank you Slightly I think you said it better then me lol. With the hot start parts you do NOT have to use rtv it just helps keep dirt out.

[JOHNDOE83]

yes you guys are right, absolutly right.... what im saying is with the hot start parts yes all you have to do is cap with rtv where the cable goes exactly right. ..to the keep dirt out ....all the hot start parts do is plug the hole with the needle type valve and spring yes exactly....they plug the hole also the passage way into the carb which is the tiny hole on the inside of the carb on the top by the intake boot side of the carb....most people fill the big hole with rtv and not the one inside the carb hole which is where there problems occur. because the hole inside the hot start that plugs that tiny hole with the needle type valve and spring is left open if you dont have those parts, if you fill the hole thuroughly inside the hot start and fill the hole inside the carb on the top side of the carb port by the intake boot you will have no problems with leaking and will not have to order the extra parts.

[slightlybent47]

The first thing that goes in the hole is the little needle valve and then a spring then a little plastic plunger then a cap that screws on to hold it all in. then a rubber boot goes over the top of the valve where the cable would go. I only put the rtv in the hole in the boot so dirt wouldn’t work its way down into the valve assembly.


It’s an easy mod just take your time and if you run into any problems just pm me and I’ll try to help.

Good luck

[JOHNDOE83]

and when the cables in there all it does when you pull on it is lift that needle and let air/fuel mix go through the little hole into the intake port on the carb correct????? with the cable.

[slightlybent47]

Originally posted by JOHNDOE83
yes you guys are right, absolutly right.... what im saying is with the hot start parts yes all you have to do is cap with rtv where the cable goes exactly right. ..to the keep dirt out ....all the hot start parts do is plug the hole with the needle type valve and spring yes exactly....they plug the hole also the passage way into the carb which is the tiny hole on the inside of the carb on the top by the intake boot side of the carb....most people fill the big hole with rtv and not the one inside the carb hole which is where there problems occur. because the hole inside the hot start that plugs that tiny hole with the needle type valve and spring is left open if you dont have those parts, if you fill the hole thuroughly inside the hot start and fill the hole inside the carb on the top side of the carb port by the intake boot you will have no problems with leaking and will not have to order the extra parts.


You may be right but it’s a cheap part and with it I had no problems and for me it was worth it. Mine worked the first time I fired it up and seems to run just fine with it the way it is. Is it perfect probably not but like I said it runs fine and it pulls great all the way through the rpm range.

If you go back through all the post on this mod you’ll see a lot of people had issues with just using rtv to plug the hole.


You can also make a cheap adapter for the intake tube using a rubber hose coupler from lows for $4.00.

[slightlybent47]

Originally posted by JOHNDOE83
and when the cables in there all it does when you pull on it is lift that needle and let air/fuel mix go through the little hole into the intake port on the carb correct????? with the cable.

You are correct.

[JOHNDOE83]

mine also.