Need opinions/info on 400ex to "650ex" ?

[MisterGraphic]

Hello Everyone,

For the past 4 years I've owned a stock 2001 400ex.
I've added a few things to improve handling (kfx450
front shocks, burgards + 2 a-arms and rear wheel
spacers, gncc holeshots, protaper bars)

Believe it or not, the motor is completely stock.
(I don't get to ride that often)

It recently started to burn oil and I've been itching for more power.
I've seen a couple of ex with the xr650L motor and thought
that maybe a good solution for me.

What do you guys think about that motor swap ?
Would it be better than putting money to improve the 400's power ?

Random details : I mostly ride trails and am looking
for reliability. (example: last year we did a rally and
drove almost 400km in 3 days) I still like to go in pits
fool around on jumps and climb hills.

Thanks for the help and opinions,

[tayyo789]

You said you wanted to do the 650l correct? Not the 650r?

The L is a weaker motor, but is very reliable and has electric start. It is liquid cooled and would be much, much easier to put in the 400's frame. The L would make an excellent sleeper motor because it looks similar to the ex powerplant as well

[MisterGraphic]

Thanks for the replies
Yeah, I was thinking of the 650L.

I like the fact it looks similar to a 400ex, but
I kinda wonder how it responds to mods.

I know the stock 650L has 4 - 5hp more than
the stock 400ex, but I was hoping it would respond
better to the basic mods, (pipe, cam, jetting).

After the motor is in, it would be the same price
for those mods, and I would get "better results"
than on the 400 ?

I guess the real question is :

Would it be worth it to swap the 650 + pipe
and how would it "go" compared to a bored 400 + mods ?

[tayyo789]

Well, I haven't messed with the L motor at all, but I do know that both the L and the R are EXTREMELY choked up from the factory. I have seen a few drag racers use the L and have good results.
I am not sure of the dimensions of the L motor, and how easily it would fit in the frame, but I have seen this conversion done before. You really wouldn't get much as far as horsepower gains, but the torque comparisons would be unreal.

[MisterGraphic]

Good information,

I'm gonna have to do more reading about different
engines before settling down on the 650L.

After a little bit of research, I guess the Xr600R Motor
makes stock HP in the 40's, that's a huge difference,
and I bet I could get that motor for less $ (older bikes)

I'll keep you guys updated if I can find something to
settle in. I'm hoping to work on that during this winter.

[tayyo789]

I still would do the L over the 600.
Its got more potential, I think. Its just super choked up to pass California emissions. When you put it in a quad frame, you'll end up getting rid of all the emissions crap anyways. Plus you get electric start.
Trust me, you don't want to be kicking these big singles for long. When I was getting my first carb dialed in we had 4 people rotating turns to kick it over until we got it close enough where it would start first kick.

[tayyo789]

Look through this thread:

http://www.exriders.com/vbb/showthread.php?s=&threadid=261366&perpage=10&highlight=xr650&pagenumber=1

Theres quite a bit of info from XR650 who builds the L motor hybrids. There is a little info about the R as well, but you arent interested in that.

[MisterGraphic]

Thanks for all the great information Tayyo.

From what I'm reading in this thread and the one
posted in the Hybrid section, I'm thinking you
may be right about the electric start.

Especially since I ride mostly trails and
want something practical.

Starting with the 650L would also give me some
experience with motors. (Would do my own mods
and learn from that)

The 650L are also more popular around here,
and I don't think we have the "Smog" things
on the side of the motor. (that less to remove)

I'll certainly document the swap and make a
build thread when I decide to start the project.

Thank again for all the input :)

[Langbolt]

If you go with an older motor 'cause they're so cheap...shy away from the Xr's that had the double Carburetors.

My 600XL--->400ex was a nightmare to jet and it would never start when HOT.

My XR650R has the Edelbrock carb and it's Awesome!

The Torque is phenominal!

:devil:

[tayyo789]

Don't mean to jack the thread, but are you using the Quicksilver II?
I had one and hated everything about it

[Langbolt]

Hey Tayyo789.......yeah I'm running the Quicksilver II

I hated it at first too!!!

The Needle & Seat kept sticking -horizontal design not very good

The Accelerator pump shaft was BENT!!! Made the throttle really stiff

Once I got the right needle in it - #21 it really worked good

The Spring is pretty stiff so I backed it off one revolution and it helped

I also switched to a MOOSE Throttle......HUGE improvement as the lever ratio is greater.

What Carb are you running ? FCR ?

:devil:

[tayyo789]

I ditched the Eddie and had a 46mm Lectron for a few days, as a temporary fix. I couldnt start it, so I had to pull it to get going, but man, talk about top end.
So then I tried an FCR, and it was too physically large to fit, because I built the bike around having the Eddie in there, so the pipe and chain tensioner hit the FCR.
So I ended up with a Mikuni TM40. I really like it, the throttle wasn't even funny it was so stiff, so I backed it off all the way and have a moose throttle, its bearable now. The carb runs great, but Im getting a big bore kit and a stroker kit, with some other internal goodies, so I'm going to go with another Lectron actually very soon.

[Langbolt]

Yeah I know exactly what you mean about the Spring pressure.....it was a real workout to ride it

I would NOT recommend the Stroker package for the XR650R

I have a +2mm Stroker Crank & Falicon rod .....I removed it because once it was setup the compression was around 13:1 and my 200lb body couldn't kick it over fast enough to start it.

If you talk to the guys at XR's Only they'll tell ya to just run the big-bore and the stock head.

My head was ported & fitted with oversized valves....I went back to stock and it works better.

STOCK with a BIG-BORE 680cc is what i'm running, with a Stage 2 Cam and it's crazy fast enough!!!

It's reliable and no issues starting.



:devil:

[tayyo789]

Was starting your only real issue with the stroker? I have multiple motors. I have a stock one, and two bottom ends, with two top ends, so I can mix and match to see what's best. I'll have a stock bottom end, a stroker bottom end, a stock top end, and a big bore top end.

[Langbolt]

Yes! It was just the stroker that was painfull to start.....usually 20-30 kicks

I felt it was because of the higher compression and I couldn't kick it over fast enough

If only HONDA came out with Electric start for that motor.

That Motor doesn't need high compression.....it makes tons of torque as I'm sure you already know.

But let us know what your findings are with the stroker.

:devil:

[tayyo789]

Well the stroker would be for my drag set up. There is an electric start kit you can get but I don't have a place for a battery anymore.
I'm only going up to 11:1 as far as compression goes. I have a 10:1 right now, and it's not bad at all