HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
mediumdaddy

what a nightmare!

11 posts in this topic

Hey all, i've been creeping this site for a few months, and finally signed up so i could ask this question. First a little background - i havent been on 2 wheels for about 12 years, until a month ago when i took a ride on a newer 450, and was instantly hooked. So knowing my budget, i started watching the classifieds, and i came across what i felt like was a fair deal. It was a 1999 yz400f, with a new top end and new plastics, clark desert tank (which i hate btw) and a Boyesen quickshot accelerator pump(if somebody can please tell me what the heck this is, i'd be very grateful) It also has protaper bars, and a couple other small extras not worth mentioning. SO! I went and looked at it, test rode it, she fired right up, was fast, i talked the owner down 150 bones, and loaded her up. The owner told me that she needed rejetting, as she was running a little lean. It did idle a little funny, and bogged just a little every once in a while, only on the bottom end. A little carb adjustment, i thought. Filled the tank and went for about a six hour ride on it. Discovered that she bogged more than a little, and that there was something definately off about the decomp lever. But she'd start first kick almost every time. I have a good friend that works on bikes and is very good at it, so i took it over to him that same day after the ride. He tore into the beast, and here is what he found (so far! UGGHH!) whilst trying to time her, he tore into the top end, and the exhast cam had been twisted, and rewelded back together, and was so far outta spec that he couldnt time it, and somebody had disconnected the decomp lever in the head. (how it even ran is beyond me) Valves were at least in spec. Replaced with a new one, timed. Idle was still erratic, so he tore open the carb, and found a pilot jet that was not even close to anything that should be in there. replaced with correct jet. Still idling weird, so he tore into it deeper, and found that several of the gaskets and o rings were MELTED, and there was a crack in the carb body itself! So now, almost a month later, he still has my bike, and is apparently having a hard time finding parts to replace the melted stuff. ANYONE ever hear or the freakin carb getting too hot and melting gaskets?!?!? if this is from that big fuel tank , ima scream. I just want to ride my new bike! anyone?

Share this post


Link to post
Share on other sites

Well from reading around here when i got my own 400 last year, people was putting 450 carbs on the old 400 with great results, so i found one for mine too, and gotta say its the best thing i ever did to the bike, all i did was put it on and adjust the fuel screw (it had stock 450 jets). The old carbs is just getting too old, and parts isnt cheap. Search the forum and there should be more info.

@ greyracer. Would it be an idea to make a sticky post about this or put it in the faq?

Cheers, Hope to help..

Edited by RasmusDK

Share this post


Link to post
Share on other sites

Auto carb cleaner was used on the carb, which melts the inner rubber parts.

Contact JD Jetting regarding replacing the rubber parts and the main body seal gasket.

Share this post


Link to post
Share on other sites

Hey brother i have a 99400f as well and i just went threw some carb trouble. My problem is a little different i took mine apart so i could clean it and three weeks later i finally got to ride again im not shur what the problem is with these carbs besides there 13 years old. My bike ran great untill i cleaned the carb and i did it by the book and put everything back together exactly the same way it came apart and the bike wouldnt run at all so three weeks of taking the carb off taking it apart checking and recheking everything i have it ridable its real lean a lot of backfiring when i let off the throttle. So if you want to save yourself a lot of wrench turning so you can get to more throttle twisting ditch the carb get a newer model from a 450 just plug and play iv seen them on ebay pretty cheap that is what im about to do and i think its the only way to bring the reliability back to these bikes. good luck with what ever you decide to do

Share this post


Link to post
Share on other sites

Most of the carbs on ebay are trashed, or they want $500.00.

If you can't get a picture of the inside of the float bowl and slide, don't buy it.

Share this post


Link to post
Share on other sites

Most of the carbs on ebay are trashed, or they want $500.00.

If you can't get a picture of the inside of the float bowl and slide, don't buy it.

Mine was perfect I got for 180$

Share this post


Link to post
Share on other sites

The one I sold to a fireman in central California for $250 was perfect and included cables and levers. I paid $200 for it to begin with. Don't miss the point that the recommendation being made is to replace the original carb with a newer, more sophisticated model from a 450. Don't waste money buying another copy of the same old POS that's already there.

I know of no one who installed a YZ450 FCR-MX on their 400 or 426 who didn't think it was more than worth the money.

Share this post


Link to post
Share on other sites

My buddy has an edelbrock carb on his WR400 he put on there a few years ago. His carb was cracking and was told there's no real fix for it. The edelbrock works great, starts super easy every time, and has a cool feature to adjust the jetting without tools in about 10 seconds. Not sure if they still make them, but my buddy absolutely swears by his and it was cheaper than a replacement Keihin.

Share this post


Link to post
Share on other sites

My buddy has an edelbrock carb on his WR400 he put on there a few years ago. His carb was cracking and was told there's no real fix for it. The edelbrock works great, starts super easy every time, and has a cool feature to adjust the jetting without tools in about 10 seconds. Not sure if they still make them, but my buddy absolutely swears by his and it was cheaper than a replacement Keihin.

Edlebrocks are made of pot-metal and start corroding the day you install them. 3-5 years is typical.

Plus, you can't tune for correct AF ratio on both the partial and wide open throttle positions. One or the other.

Share this post


Link to post
Share on other sites

BS! Its plated aluminum, and he's had it on there 7 years and 3000 miles of single track and dual sport rides. It looks like new.

Edited by upnorthbacon

Share this post


Link to post
Share on other sites

I have purchaed many Carbs off e-bay in the past never had any problems with them.

You have to rejet them in most cases to get dialed in but no big deal.

Then most of the bikes I have built in the past beeen one off stuff Aluminin framed CRf 450 with CR 500 motors stuffed in to them Ect there custom hand built from the ground up.

You can buy great used parts off e-bay and then you can buy someones elses junk if you'r not careful , sometimes if there chepper than everyone elses there a reason for it buyer beware.

Edited by marv02

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0