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Discussion Starter · #1 ·
So here's the situation everyone, I bought a 2007 DRZ 400 SM and It has had a lot of butchery done to it and a lot of good engine work too. The engine work that has been done is : Bored and stroked to 462cc, has a full Akrapovic exhaust, a keihin 39mm fcr carb, the guy put as many holes in the airbox as humanly possible (Hell there are 6x1.5" holes in one side of the airbox, stupid I know, and that only the one side) and it has hot cams installed, not sure if it is jetted but who knows.

I have fixed most of the electrical and general butchery and now I'm working on the fuel system. I have an MRD SSW full system on the way, a used airbox with only the 3x3 hole cut into it on the way, and a james dean jet kit with fuel adjustment screw on the way.

I plan on starting from scratch essentially and am wondering what is the best set up for the bike and mods I have. I plan on following the instructions that come with the jet kit unless you guys have a better setup idea for me.
 

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Discussion Starter · #3 ·
It ran but wasn't running properly. exhaust popping , bogged a little. Ran poorly for the first few kms driven. Lacked power for the upgrades it has.
 

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make sure the new cams are degreed in properly... have you done a compression check and leak down test...do that first then check the cams. rm
 

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if you talk to eddie at SSW or post in the fuel section of thumpertalk there are tons of threads with the exact jetting you should run for your elevation. There isnt anything wrong with all the holes in the airbox. Lots of guys do it. With the bigbore, cams and carb its possible you actually needed more air than a 3x3. I would guess that bike would benefit more from a 41fcr than the 39 at this point. I believe the 39 pretty much reaches its peak with the E cams, mrd/ssw and a 3x3. If you look at drz's that actually race supermoto(not many of them) you might even see no airbox and a filter seen from the rear of the bike.

Here is an example for you. The old yosh drz.




if your bike is still together i would start by just putting tape over the holes and riding it to see if its any better. With an fcr carb you cant just go WOT in the low revs or it will bog. There is an accel pump that squirt fuel to help avoid this but there is no vac operated slide in the carb or butterfly. If you turn the throttle you raise the slide. If the revs are too low it will bog cause the motor cant rev up fast enough and it floods. If you crack into it at higher rpms how does it feel?
 

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I read this thread just to see what the Post Office could have possibly done to your bike


To be clear in this, you bought this tricked DR but it was running poorly and you never rode it to where you thought it was right?
 

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With an fcr carb you cant just go WOT in the low revs or it will bog. There is an accel pump that squirt fuel to help avoid this but there is no vac operated slide in the carb or butterfly.
Whatchu talkin bout man.

i got WOT from idle and my FCR rips my arms off with no BOG. if you get it jetted and tuned right, and then time the AP pump (see Eddie mod). the FCR will give you killer throttle response. and I rock the old FCR39 slant style (E model) which is apparently light years behind the newer FCR39MX.
 

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Whatchu talkin bout man.

i got WOT from idle and my FCR rips my arms off with no BOG. if you get it jetted and tuned right, and then time the AP pump (see Eddie mod). the FCR will give you killer throttle response. and I rock the old FCR39 slant style (E model) which is apparently light years behind the newer FCR39MX.
You can do so with the engine under load, but not sitting in neutral though.
 

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Well He got the Bike running almost perfect and than sold it.

Head was sent to Eddie for Proper valves, and head work, (Hot cams don't work with a 462 Bored and stroked engine)
Replaced the FCR 39 MX with an FCR 41 (I Scored the Cams and FCR so Woo Hoo :bannana:) And I can tell you just like the rest of the work done on this bike the Carb wasn't Jetted anywhere close to correct by the PO (150 main Jet, 42 Pilot Jet, Air Jet still installed, no O-Ring Mod) Hell that setup would barley work on a Stock Engine.
Exhaust replaced with an MRD SSW

After the bike was put back together, it Ripped. I mean tore your arms off fast (for a DRZ) I couldn't keep up to it, (Where before he couldn't keep up with me) We did get a chance to take both our bikes to the SuperMoto Track in Drumbo Ontario before he sold it.


I guess their where so many things butchered on this bike that the OP decided it would never be reliable, and hence the reason he sold it.

Sad to see it go, but it was fun to help him tear the thing apart.

Moral of the Story, Buy your Bikes BONE STOCK. or make sure the PO new what the frack he was doing!
 

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Whatchu talkin bout man.

i got WOT from idle and my FCR rips my arms off with no BOG. if you get it jetted and tuned right, and then time the AP pump (see Eddie mod). the FCR will give you killer throttle response. and I rock the old FCR39 slant style (E model) which is apparently light years behind the newer FCR39MX.
I got my fcr from Eddie:). Simple physics if you crack the throttle wot at low rpm with little to no load it will bog. That's why my idle is at 2k. Also the accel pump timing does affect this but the engine will stumble. On an bsr carb the slide would only raise with the appropriate engine vac. The drz rotating assembly is too heavy to rev up fast enough for the fcr. With a light flywheel its a little different.
 
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