• Welcome to the Two Wheeled Texans community! Feel free to hang out and lurk as long as you like. However, we would like to encourage you to register so that you can join the community and use the numerous features on the site. After registering, don't forget to post up an introduction!

New Project Bike: '99 YZ400f

Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Cool project! - If you decide to keep the bike and ever need a strong bottom end for the YZ400F I have one sitting under my work bench that you can have anytime.... I think I even have the exhaust header and a few other bits.
Thanks man! I'll keep you in mind.

Sent from my Moto Z2 using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
That bike might do better at my place than the wr!

Sent from my SM-G965U using Tapatalk
Both bears though. I guess I have been stocking up on big heavy bikes lately first the wr and now this...
Oops

Sent from my Moto Z2 using Tapatalk
 
Joined
Feb 10, 2015
Messages
4,112
Location
Stockdale
First Name
Samuel
Last Name
Hastings
Both bears though. I guess I have been stocking up on big heavy bikes lately first the wr and now this...
Oops

Sent from my Moto Z2 using Tapatalk
True, mudslicks dad has an 06 wr450f and It was pretty tame around the trail

Sent from my SM-G965U using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Well I did a lot tonight.
After throwing a timing chain on and reshimming my crf today I felt like I had more energy so I turned to the yz.

-Installed a new timing chain
-Installed new left hand crankcase cover gasket
-Installed 5 new valve shims
-found a yz125 fuel valve in my parts that was a perfect replacement for the leaky one so I installed it. (Check out the gross ethanol effects on the old one)
-Took right crankcase cover off, cleaned it and installed a new gasket - I was having coolant get in the oil so new seals and gaskets in this area should help.
-filled it up with fresh coolant and oil
-Threw the header pipe on but I don't have a good silencer... And it's 2:51am.

With that last bullet point, it looks like I'll be waiting to try and start it tomorrow. I kicked it a few times with no life but i wasn't trying too hard.

I'm itching to get the motor squared away, that way I can focus on other stuff like the frozen front brake caliper, leaky fork seals, and the like. I just want to know I have a good power plant, and so far the insides look great.

The bike definitely had a bad seal causing coolant and oil to mix, and I think either a leaky head gasket or overfilled oil caused it to puff that into smoke. Either way I'm going through and swapping gaskets and o rings.
IMG_20200108_024731977.jpg
5011012e9f1d5d223c6b7214c05bfda8.jpg
0c5300e9b21d56bb35b08a4a9a4f0eec.jpg


Sent from my Moto Z2 using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Kick-starts were promising but lead to no success... Bump starts down the driveway always seem to work though! Got it running, a bit Smoky but I'm cautiously optimistic that that's residual oil in the exhaust from before.



Sent from my Moto Z2 using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
I rode it around the yard for maybe 30 seconds just to feel the power. Sure is scary with no brakes! The motor feels strong though. It's got more grunt than my 250 for sure

Sent from my Moto Z2 using Tapatalk
 
Joined
Feb 10, 2015
Messages
4,112
Location
Stockdale
First Name
Samuel
Last Name
Hastings
Put an air filter on it! Lol. Will it kickstart now?

Sent from my SM-G965U using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Put an air filter on it! Lol. Will it kickstart now?

Sent from my SM-G965U using Tapatalk
I did I did haha. Subframe is now on the bike so it has a seat and air filter. I'm gonna go see if it'll kickstart.

Sent from my Moto Z2 using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
It won't even bump start, let alone kick start now. Something changed, because earlier it started to run worse and get more difficult to start. Now it's not starting at all

Edit: managed to get it bump started but the moment I let off the gas it died. It's running really badly.

Sent from my Moto Z2 using Tapatalk
 
Last edited:
Joined
Feb 10, 2015
Messages
4,112
Location
Stockdale
First Name
Samuel
Last Name
Hastings
It won't even bump start, let alone kick start now. Something changed, because earlier it started to run worse and get more difficult to start. Now it's not starting at all

Edit: managed to get it bump started but the moment I let off the gas it died. It's running really badly.

Sent from my Moto Z2 using Tapatalk
I'd start with double checking valves. It sounded okay in the video

Sent from my SM-G965U using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
I'd start with double checking valves. It sounded okay in the video

Sent from my SM-G965U using Tapatalk
I really don't want to but i think I'll pull off the tank and check valve clearance along with timing.

Sent from my Moto Z2 using Tapatalk
 
Joined
Feb 10, 2015
Messages
4,112
Location
Stockdale
First Name
Samuel
Last Name
Hastings
I really don't want to but i think I'll pull off the tank and check valve clearance along with timing.

Sent from my Moto Z2 using Tapatalk
Better safe than sorry. I learned the hard way by dropping a valve on a 07 yz250f
If it doesn't kick start in a few kicks, something is wrong.

Have you been through the carb?
Sent from my SM-G965U using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Better safe than sorry. I learned the hard way by dropping a valve on a 07 yz250f
If it doesn't kick start in a few kicks, something is wrong.

Have you been through the carb?
Sent from my SM-G965U using Tapatalk
I cleaned the carb this morning yep. Just checked and the valve clearance is good too.

Only thing I'm unsure of is the timing. I did as people say to do with the 450f auto decomp cam. I set the intake cam as close to perfect as possible, and put 14 pins between the 12 o clock marks on the two cams. Even with a brand new timing chain and good tensioner, I can't get the intake cam to be perfectly timed. It's off by a degree or two but if I were to move it one tooth different, it would be the same problem in the other direction. See pics for better explanations... The dots on the cam are just not quite parallel to the head. Others seem to have no trouble though using these cams.

(Pics exactly at TDC)
26be6cc910a091084c6e8a4ce088198d.jpg
c2686afdfddf74d5b93514b28e2c5d0b.jpg
7f3d0c649af3fb1ebafa8047c31a3c3b.jpg


Sent from my Moto Z2 using Tapatalk
 
Joined
Feb 10, 2015
Messages
4,112
Location
Stockdale
First Name
Samuel
Last Name
Hastings
Back of cams look like this?

Timing looks close compared to what I've googled about the swap
a0f6be91f9fb4fe5f4dddb149d490c45.jpg


Sent from my SM-G965U using Tapatalk
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Here's where I'm at:
-valves in spec
-timing looks fine to me. It at least hasn't changed from where I set it and it was running fine at first
-has spark and a decent plug
-carb is clean and getting fuel
-oil level is in range

I've gotta figure out what exactly is causing it to run badly after a little bit of run time and heat got in to it.



Sent from my Moto Z2 using Tapatalk
 

bwdmax

Forum Supporter
Joined
Oct 20, 2010
Messages
2,035
Location
Victoria
First Name
Gary
Last Name
Turner
Did you turn it through by hand with plug out before you tried to fire it? If so was there a hard spot?(Piston to valve clearance probably isn't much.) I would lock it a TDC firing stroke not exhaust stroke and do a leak-down test. You can pressure it up with compressed air and just listen even if you don't have a true leak-down checker.

Do the cams turn clockwise or counter clockwise on that engine?
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Did you turn it through by hand with plug out before you tried to fire it? If so was there a hard spot?(Piston to valve clearance probably isn't much.) I would lock it a TDC firing stroke not exhaust stroke and do a leak-down test. You can pressure it up with compressed air and just listen even if you don't have a true leak-down checker.

Do the cams turn clockwise or counter clockwise on that engine?
Yep I did that with the plug out. No hard spots.
I could try sticking my air compressor down it but I don't have a leak down tester. It has very good compression and power by feel for what that's worth.

Cams spin counter clockwise on it.

Sent from my Moto Z2 using Tapatalk
 

bwdmax

Forum Supporter
Joined
Oct 20, 2010
Messages
2,035
Location
Victoria
First Name
Gary
Last Name
Turner
Do you get any response if you spray some carb-cleaner in the intake and kick it?
 
Joined
Jul 15, 2018
Messages
166
Location
US
First Name
Trevor
Do you get any response if you spray some carb-cleaner in the intake and kick it?
I don't have any carb cleaner or starter fluid here, just wd 40 and I'm not sure if that's a good idea hehe

Sent from my Moto Z2 using Tapatalk
 
Joined
Feb 10, 2015
Messages
4,112
Location
Stockdale
First Name
Samuel
Last Name
Hastings
I don't have any carb cleaner or starter fluid here, just wd 40 and I'm not sure if that's a good idea hehe

Sent from my Moto Z2 using Tapatalk
Not flammable enough

Sent from my SM-G965U using Tapatalk
 

bwdmax

Forum Supporter
Joined
Oct 20, 2010
Messages
2,035
Location
Victoria
First Name
Gary
Last Name
Turner
WD will usually get a response. Just need to know if fighting fuel or something else... You can get a soda cap worth of gas and splash into the carb and do the same, aerosol just easier.
 
Top