I will have to dismantle the carb to take a look. I had the bowl off once but I don't remember what pilot and main jet it is. I would also need to take a close look at the Jet needle and needle jet. as jetted it is slightly rich.

the carb itself came from a 1976 IT400C.

for the time being, I need to get a better way to make the camera mount more robust and find a way so the tach can be read easily and accurately. I am doing this mostly for Meis so he can tape out the sleeper pipe mod.

also, the bike runs good at the altitude I am at so results can vary wildly.

also I am getting some overheating after the end of the power pulls. I need to get that Webco head modded and put it on badly. the engine starts to loose quite a bit of power when it gets hot and it starts borderline piston slapping. the noise it has gets louder when hot.

I need to install the temp gauge as well.

Well I"v had running probs with the DT400, plug was black, even after dropping jets sizes, and pilots, it splutterd in midrange, was ok below 4000rpm, so I bought a Keyster, refurb kit, ,rmoved the jet setter [ imulsion tube.] and no O ring, so installed new tube and needle, will se how it goes, . if rain stops,

I've never seen an o-ring installed on the top of the emulsion tube like that.

The o-ring that gives issues goes on the "jet setter" adapter that threads into the bottom of the emulsion tube and seals into a well in the float bowl...

Neither have I mark, is there a diagram , . it was on the kit ,

just seen manual, and your right no O ring on needle jet nozzle. [ emulsion tube] .
Hers a good video ,

I did another run today but this time I rolled the throttle on and the tach behaved a little better. the roll on for 3rd begins at the 2:08 spot in the video and the 4th gear roll on begins at 3:33 into the video.


I did some number crunching with the gear/speed calculator online.
www.gearingcommander.com/

according to the calculator is should be hitting 54.2 mph in 3rd gear @8000 rpm and 70.7 mph in 4th @8000 rpm.


the speeds indicated by the speedo is very close. the 3rd gear run is lower than calculated at about 52 or 53 mph.

the 4th gear run, the speedo was indicating about 70.5 to 71 mph. at least I am getting peak rpm doing the math. all this was tested with the Hooker pipe. if this is not good enough I will try another tach. I got the feeling the other tachs may not be much better.

if you watch the video full screen at 1080P the speedo and tach should be read easily.

Meis, this should be a little better, let me know if this is ok or I will need to swap out a tach and try again.

while I was at it I calculated 8000 rpm in 5th gear. with the current 13/40 gearing the bike should top out at 92.2 MPH.

with stock 14/40 gearing it works out to 99.3 mph and with 15/40 gearing it should run up to 106.4 MPH. I did not bother doing it with 16/40 gearing.

if this is ok, I will install the stock DT400 pipe I plan to send out and retest.

That video looks great..... I have a real good idea how the Hooker pulls.

Next install the DT400 pipe and do a similar test run

I installed the stock pipe and since I lost the FMF silencer, I used a stock DT400 silencer that has the baffle missing. I was surprised how well it ran and it even how it sounded was very good. it has very noticeably more torque than the Hooker pipe at lower rpms and it even revved out really well. it was not tugging me as hard as the hooker at 8000 but it did a better job than expected.

Its interesting if you compare both videos from about 3:40 in.....

You can see how much faster the Hooker pulls thru the powerband.....
12 seconds for the Hooker versus approximately 18 secs for the stock pipe.

You can also try playing both videos from simultaneously from about 3:35 in and hear the diiference
on how quickly the Hooker pulls and the stock pipe is languishing !

Have you tested with the baffle in ?

I don't have the stock baffles for these silencers. I do have 1 hand made one that the core has perforated tubing and you can wrap it with silencer packing. not too restrictive but not as quiet as a stock baffle or the FMF Turbine Core ll.

I found out the 438 baffle is still available from Yamaha but the 500 or 501 is not.

you are right about the videos. the Hooker makes the stock pipe look super lazy in comparison from the 3:40 point and on!

the Hooker pulls a lot harder! both runs are right at between 1/2 and 3/4 throttle. wot and it goes really nuts with the Hooker on it.
I did not try a WOT run with the stock stuff.

Bigdog....we received your stock DT400 pipe and have opened it up



Your pipe looks to be in good shape with no major issues !



We are now designing a special sleeper cone designed to work with your MX400B top-end.
As you are looking to have your new Sleeper Pipe make power up at 8000 rpm !