Autralian Restricted model MT07. The hidden restrictor. Removal


gregjet

New member
I have the Australian restricted model MT07. I reflashed the ECU and have Akra snail pipe and DNA filter and the throttle rotation restrictor was removed, but the dyno run revealed sill only 54rear wheel HP.
Now the reflash was to Euro spec so the only difference should be the 655ccrelarive to 688cc and the resulting .5 integer decrease in compression ratio. As far as i can make out the has been no cam or valve changes.
Getting hold of the dyno run graph of hp/revs and AFR/revs and comparing them to the published curves for various products on the net I discovered that up to 5000rpm they are all pretty much the same as mine BUT after that the AFR gets richer and richer and the power starts to flatten out.
First thought was gas flow restricton. Either exhaust ( used a fair bit in the 70's and 80's) or an airbox restriction. Crude but reasonably effective in cutting the balls off the power.
SOOOOO... I first went and watched alll the videos on the introduction of the Aussie model and in one , and one only, the reviewer mentioned an airbox restrictor. Time for some mining.

WARNING!!!! Do not do this if you any in any way inexperienced. There are a whole heap of connections that are brittle and easily broken and MUCH finesse is needed to accomplish the following.

Taking off the airbox on the MT is a complete pain in the butt.
First remove the tank. Remove the filter cover and filter.
You actually have to remove all of the connections to the throttle bodies both mechanical and electronic and air tubes and the fuel line. Undo the rubber manifold allen bolts on both sides of each of the throttle bodies. Undo the airbox hoses and airbox bolts. Undo the anti knock sensor connector ( I think that is what it is) . The throttle bodies have to move down to get them out and the wires are in the way.
THEN lever the throttle bodies towards the back of the bike and slip out the front manifolds between the engine and the throttle bodies . The bolts have to be very loose.to come off the throttle bodies and the engine.
Move the throttle bodies towards the front of the bike and downwards past the knock sensor. You have to turn them a bit.
The airbox will come out without forcing with very careful alignment as you move it forward and down.

OK the revelation. The airbox internal stacks have a very crude double right angled ledge completely around the inside of the entrance to the throttle bodies butting against them. the throttle body inlet is 41mm. The restrictor is 30mm. That restricts the flow to about 53% ( actually less because of the shape of the restriction..
The Stacks are that rubber usually used for motorcycle stacks and is easily worked on. I used a dremel and a grit cylinder bit. and opened the hole out to match the throttle body.
BTW the manifold matching at the engine/throttle body is a little rough as well so I matched it at the same time . On this area the aluminium of the head actually has to be matched not the rubber.

DSCN0966.jpgFront of throttle bodies and restrictor ledges removed - Copy.jpg
 
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gregjet

New member
Just rode it . I also made a new proto type airbox cover and made some panels to help keep the engine hot air away from the inlet.
The bike is totally different. So much more responsive. power appears to be substantially more. Will have to get dyno run to confirm arsedyno results.
Pic of proto air inlet and hot air diversion panels. I also cut the pointy bits off the airbox that don't do anything to make air box removal and replacement easier.
DSCN0974.jpgDSCN0977.jpg

Please do not do this if you are a beginner. The bike MUST have the throttle jerkiness fixed and the weight bias problems fixed before you do this mod. If you have a loaded tourer that mod would be worth it even without the reflash, pipe and filter to allow the greater airflow needed for the extra weight and wind resistance.
 

dfl05

New member
Hi gregjet,

What do you mean by "throttle jerkiness"? Is this a known issue? I have noticed this jerkiness but kept thinking it was just my inexperience and that I should try harder to be smoother.
 

gregjet

New member
dfl05,
Part of the wheelie happy manners of the MT07 is the roughish fuelling ( the other is the undersprung rear shock). Not as bad as the MT09 but still there. Part of the reason I do not believe this bike to be a suitable beginner bike.

OK the important bit.
Got the bike on the local dyno this afternoon. WAHOOOOOOOOO! My seat of the pants dyno was pretty well right. The results are as much as I reckon you can hope for from the LAMS bike. HP max rear wheel in now about 64HP @9000 rpm and max torque is almost exactly the same at 43, again which doesn't surprise me from the engine config and the camming. With reflash, Akra snail pipe, DNA filter previous before intake restrictor removal max was 54hp @ about 84000rpm. So an increase of 10hp and an extra 600rpm useable at the top. The really big thing is the AFR is now pretty well right for a road bike.


MUCH LATER EDIT: RE: AFR and PUTTING ANY MOD THAT INCREASES AIRFLOW> I have been all over posts and external web sites that have Dyno graphs with AFR's on them. ALL show the MT is rich from about 9000-9500 and increasingly so as you get to limiter...NOT LEAN. Some show AFR's of 10:1 which is just about not actually firing. That means that almost any airflow increase mod will NOT damage anything as that is where any detonation or Hitemp problems would occur. I ain't gonna run lean at all.

dyno graph pre and post restrictor removal (5).jpgdyno graph pre and post restrictor removal (6).jpgdyno graph pre and post restrictor removal (7).jpg
 
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Chillipom

New member
Gregjet. This sound like the breakthrough we have all been waiting for. Do you think that the reprogrammed ecu is important? Did you buy the unlimited throttle stop or modify the original
 

Chillipom

New member
Tw586. Can you explain you comment about TPS in the other derestriction thread? No problem now? Could your previous limp home problem have been due to air/ fuel ratios because of the retracted internal stacks as mentioned here?
 

tw586

New member
Tps issue was traced to a fault in my Digital multi meter, To low internal impedance while monitoring tps voltage. ecu was thinking its and internal short in the switch. I have removed the throttle plate limiter and the bike is running all good now. I was surprised how little difference it made, but now understand there is more to be done.
 

Noggie

New member
Hi gregjet,

What do you mean by "throttle jerkiness"? Is this a known issue? I have noticed this jerkiness but kept thinking it was just my inexperience and that I should try harder to be smoother.
Is your bike brand new and not run in yet?
My throttle was a bit jerky when I first got it, but after the first service it was a lot smoother, think the injection synchronization helped a lot on my bike.
 

dfl05

New member
Noggie. It is new but now run in. Had first service last week. Still jerky. Only way I found not to be jerky is to try and ride like I stole it.
 

Noggie

New member
Noggie. It is new but now run in. Had first service last week. Still jerky. Only way I found not to be jerky is to try and ride like I stole it.
maybe they did not do the injection synch at your service, also you might check your chain tension.
Mine came back much smoother after the first service.
 

Damosil

New member
how much was the reflash and dyno time? Or could i do the DNA filter, airbox mod and throttle restriction without the reflash and be safe? Also i see you have a new rear shock, what is it and where in AUS did you get it from and have you played around with the front forks yet?? So many questions sorry, but you seem to be the right guy to ask :D.
 

gregjet

New member
Chillipom : read the article. Yes I removed the throttle bodies. I don't know if it can without removing them but did it to ensure delicate things didn't get broken.

The bike is run in just over 2000km

The throttle jerkiness I refer to is the stuttering and dip caused by the euro lean mix AFR.

Reflash was about $500 ( had to send to ECUWest in WA, but I believe there is someone in Sydney that does it.If you do the stack resize without the ECU reflash I probably wouldn't do the throttle plate change unless you do loaded touring. May run way too lean up top with the stacks open and no load. If you are a genuine LAMS rider probably not a good idea to open them up anyway .

Most bikes chasing HP for road riding is a waste of money ( almost completely) BUT on this bike much can be achieved for a modest expense. I almost never do much to my ride on the road bikes' engines, except full exhaust and that is for weight loss not HP ( I am a weight weenie as the cyclists call them). Nearly always do my suspension first, then exhaust and any easy cheap weight loss.

Rear shock, as far as I am concerned, should be THE FIRST thing done to this bike...FULL STOP. My opinion is that this bike with the stock shock is very poor handling and hard to ride unless you are a dirt rider. It should not be a LAMS bike, in my opinion, as it is with the lack of front end feel and no ABS. The stock shock is THE worst spring/shock combination I have had to contend with in years. Only the pseudo shock/spring combo I was racing on a Sachs150 was worse. Don't laugh, Jack Miller rode one at our club at the time to help learn his road racing skills. That's why he carries so much corner speed. Learned to race on a bike with pretty much no power.
If at all possible get a Ohlins shock. By far the best. I have a Nitron, but only because the Ohlins were unavailable at the time and for a while after. Then the front end needs fixing. I used gold valve emulators and did it myself , but I have the equipment and have been doing it for years. Matris make cartridge fork inserts that are getting good reviews and I may still even go down that route now I have got the HP extra. Then , and only then, go chasing some HP. I got my suspension locally. If you are in Melbourne there are some of the best motorcycle suspension places in Australia. Check them out. And if you get work done tell them what you are actually going to do with the bike. Don't tell them you are going to track it if you are going to ride it on the road for most of the time or go loaded touring. A good suspension place will set you up for the bike to work properly at what you do.

Then tyres ( my pick is Michelin pilot road 4's (not 3's)). I find the std tyre OK but harsh and I think they contribute to the front end vagueness.
 

Ralph

New member
"The throttle jerkiness I refer to is the stuttering and dip caused by the euro lean mix AFR"

Just for info,
Euro full power bikes don't do it at least the two I have ridden don't, not ridden a restricted bike.
They are very weak at tick over and some can cut out just as you touch the throttle to set off
but on the ones I rode there were no stuttering or flat spots as soon as you move off.
 

gregjet

New member
Ralph.
The super lean mix is pretty much responsible ( along with the soft rear end ) for the overwhelming desire of the bike to wheelstand without provocation. looks and feels spectacular but is seriously undesireable.THAT IS jerkiness of the worst kind. Noticed as soon as the reflash was done. The bike didn't want to fling the front end up unless you actually opened the throttle quickly and that takes some doing with a throttle cam as slow as the mt's. The bike is considerably MORE controllable. Makes a huge difference when you accellerate out of corners from before the apex. The front isn't as vague.
 

gregjet

New member
Chillipom , personally I wouldn't recommend the stack opening on a no afr fixed ( ecu reflash or power commander) as the mix is very lean std ( 14.2-14.7) and more airflow would possibly just make it worse. Certainly not WITH the throttle stop removal until better AFR's established. EXCEPT for loaded tourers with the throttle stops in place as they need low speed airflow and the fuel flow max would be still relatively low. The ECU/O2 sensor MAY be able to increase fuel flow enough but it is a big gamble and would take time to reset itself even if it can. Remember that the stack restrictions decrease the air flow to less than 53%.
The ECU is actually a different one from overseas and the HO. The part number is actually different ( of course I don't know exactly WHAT the internal differences are). Still I like a person that is willing to take a risk to experiment. Just look out for the signs as too lean can mean death for a motor and would be hard to UNDO opening up the flow.
 


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