ex issues

[slightlybent47]

I have a 07 ex that is giving me some trouble and I'm looking for solutions.

Back story.
Last year my ex started having transmission troubles, 3rd gear was slipping out of gear.
The bike ran fine, but I stopped ridding it so I wouldn't destroy what was left.
The motor has thousands of hours on it and has never had any issues to speak of.

Parts.
In 08 I had a friend punch it out to a 416 with 12:5 to 1 and put in a stage II cam and some port work.
It also has a 450 carb and a WB slip on with the stock head pipe that has the welds smoothed over.
Stock CDI box
The bike ran flawlessly for years.

Then last year it started having the 3 gear issue.

When I pulled the motor it was running fine.
I took it to a well known builder and had him fix the transmission issue and ring it.

Well he replaced 3 gears, the shiftier forks and decked the head (because it was warped) and put a new timing chain and new valves.
He did clean up the porting a bit but very little.

So now I am having some issues.
It started rite up (even with a weak battery)
I rode it around for 10 min and stopped.
I let it sit for an hour and tried it again, but it was harder to start. But it did kick over and start.
I ran it for another 10 min and shut it down.
It ran fine on the low rpms but would sputter at high rpm.

I took it back to the builder and we trouble shot it for 4 hours.
We finally got it going and put it in the dyno.

She ran pretty good on the dyno, putting out around 38 HP without the dyno tires, (just my 18" knobbies)
She did have a little wavy thing going on on the top end but she sounded strong.

After talking with a few ex owners
I am thinking it's one of a few things.
Could be the battery is too weak to keep the spark hot enough and the fire is going out.
Or the CDI box has issues, or my stater is weak or going out.

When it runs, it runs pretty good except for the top end.
Could it be it needs a hot battery to keep a good hot spark?

Yes I could just buy new parts till it's fixed. I'd rather fix the problem and not what is not.


Any ideas?

Thanks.

[KKiowaTJ]

Mine will have dim lights and sputter around if the battery cables are not clean and great contact. My battery is many years old and every time I had related issues, it always turned out to be a dirty connection.

If you have more compression you might need a busa battery to turn it over. You can always put a jump pack on it and see if that changes starting. Or take back plastic off, strap down jump pack and see if it is battery related through the gears.
The weak spark could be the cdi as well. If you know another with a 400, throw his cdi on and go for a ride and see if any change. Could also be a weak stator not putting put enough for the cdi and battery.
I'd start with small and swap able parts and work my way up.

[slightlybent47]

Mine will have dim lights and sputter around if the battery cables are not clean and great contact. My battery is many years old and every time I had related issues, it always turned out to be a dirty connection.

If you have more compression you might need a busa battery to turn it over. You can always put a jump pack on it and see if that changes starting. Or take back plastic off, strap down jump pack and see if it is battery related through the gears.
The weak spark could be the cdi as well. If you know another with a 400, throw his cdi on and go for a ride and see if any change. Could also be a weak stator not putting put enough for the cdi and battery.
I'd start with small and swap able parts and work my way up.

That thought has crossed my mind.
I put the charger on it yesterday to top off the battery.
She started but I didn't get a chance to ride it.

Gotta be something simple, I've overlooked.

[DragonGunner]

Well it probably started easy the first time since the rings and cylinder were oiled when put back together.

Tried a new spark plug? I run the Splitfire 416C for years, they burn a little better than stock IMHO. Make sure your air filter has been cleaned recently, and spray some carb cleaner in the intake and I put some in the tank every now and then, any gas a few months old anymore tends to tarnish, could be a little tarnish on the main jet. These are the easy, cheap things I would look at first, even when my batteries got old and had to be jumped all the time once they were going they ran great, until the next start up.

[slightlybent47]

Well it probably started easy the first time since the rings and cylinder were oiled when put back together.

Tried a new spark plug? I run the Splitfire 416C for years, they burn a little better than stock IMHO. Make sure your air filter has been cleaned recently, and spray some carb cleaner in the intake and I put some in the tank every now and then, any gas a few months old anymore tends to tarnish, could be a little tarnish on the main jet. These are the easy, cheap things I would look at first, even when my batteries got old and had to be jumped all the time once they were going they ran great, until the next start up.

Thanks man, But yeah did all that. I've done all the standard trouble shooting.
Yes it has a new plug, and the spark looks good. (visually that is)
We swapped out the main jet a few times when it was on the dyno.
Next time I'm by a store that carries it, I'll pick up some contact cleaner and clean all the electrical plugs and connectors.
Everything is exactly like it was when I took it out. And it ran perfectly.
The only reason for the rebuild was the trans issue.
I changed nothing, on the bike itself.
I didn't even have to adjust any cables or anything.
It all went back just like it came apart.

I have a friend that still runs a 400ex and he is going to let me try his rev box to see if that helps.

Like I said, I can always just start replacing parts, but that is to expensive.

I haven't had a chance to mess with it yet. But I have done all the standard trouble shooting with no improvement.

Thanks again.

[Wingnut]

Have you checked the valves? Mine usually come out of adjustment a few hours after a rebuild. Have you unplugged the reverse wire at the case? That actually fixed an issue i had at one time. Are you running without an air box lid?

[slightlybent47]

Have you checked the valves? Mine usually come out of adjustment a few hours after a rebuild. Have you unplugged the reverse wire at the case? That actually fixed an issue i had at one time. Are you running without an air box lid?

Yeah we checked the valves again and the timing. We even pulled the fly wheel and checked the key to make sure it didn't shier.
I did check the reverse/neutral plug to make sure it was correct. I didn't try unplugging it.
The air box is exactly the same as it was. It shouldn't be the problem. But yeah, it's clean and oiled properly.
I cleaned out the fuel tank when I pulled the motor and put new fuel in when I installed the new motor.

I have been over it many times and everything is plugged in correctly and seems to be solid.
This bike has always been "VERY" easy to start. I can't stress that enough.
I've always just needed to bump the starter, and that it.
Even on the first build when all the HP stuff was added.
It was never hard to start.

[slightlybent47]

Have you checked the valves? Mine usually come out of adjustment a few hours after a rebuild. Have you unplugged the reverse wire at the case? That actually fixed an issue i had at one time. Are you running without an air box lid?

Yeah we checked the valves again and the timing. We even pulled the fly wheel and checked the key to make sure it didn't shier.
I did check the reverse/neutral plug to make sure it was correct. I didn't try unplugging it.
The air box is exactly the same as it was. It shouldn't be the problem. But yeah, it's clean and oiled properly.
I cleaned out the fuel tank when I pulled the motor and put new fuel in when I installed the new motor.

I have been over it many times and everything is plugged in correctly and seems to be solid.
This bike has always been "VERY" easy to start. I can't stress that enough.
I've always just needed to bump the starter, and that it.
Even on the first build when all the HP stuff was added.
It was never hard to start.
All the lights work and the R/N lights work correctly and kill switch on the bars works properly as well.
I disconnected the tether switch, thinking it might have gone bad. Nope! That's not it ether.

What I don't get is, when I first put the motor in, it started just like before.
It was only after I rode it did it start getting hard to start.
The oil was filled correctly and it was oiling properly, because I checked before I rode it.
I checked the oil cooler to make sure it was hot and I checked the oil filter to make sure it was oiling.
And when we pulled the top cover to check the valves, it had plenty of new oil up there too.
I just don't get it.
It was supposed to be a simple plug and play build.

[Wheelie]

Have you done a leakdown or compression test when the engine is cold, and then again when it's warm. You stated the builder ported the head, maybe a valve got damaged during removal or installation. Check the ports thoroughly as well, the casting may have cracked or split if he got too aggressive with the porting.

[slightlybent47]

Have you done a leakdown or compression test when the engine is cold, and then again when it's warm. You stated the builder ported the head, maybe a valve got damaged during removal or installation. Check the ports thoroughly as well, the casting may have cracked or split if he got too aggressive with the porting.

No I haven't done a compression test on it.
The porting was done on the first build 6 years ago. He just roughed up the intake a bit. He really didn't do much with the porting.
Once it starts it seems to run good, but it still studders a bit on the top end.
The valves and guides are new.

[slightlybent47]

I put the battery on my battery charger the other day and I forgot about it till the next day.
When I checked on it, the battery was boiling.
She fired right up.
But I cooked the battery so I'll have to get a new one.
Maybe she will run better with a fresh battery in it.

[slightlybent47]

I picked up a new battery today and it still didn't start.
I got to messing with the carb and noticed the choke closing and sticking in the closed possession.
It's somehow closing on it's own for some reason. It's never done that before.
Now mind you I am running an 05 450 carb.
The choke has never been connected to anything.
It's always stayed in the open possession and I've never needed it.
I may have to hook up a cable to it so it will stay open.
It took a min for it to pick and run and it started several times with no problem.
I have to wait to get a ride in and see how it does with a load on it.
Anyway, I'm making progress.