A little writeup on the first couple of mods for the DRZ. I came across a German website called ABP Racing, who supplied various tuning parts for different offroad and supermoto bikes. First off, I wanted to change the extremely lousy CV carburettor to a REAL carburettor. So a new Mikuni TM36 was definitely on my list. I went with the Mikuni carb instead of a Keihin FCR, because I was very familiarized with the Mikuni as it is almost the exact same design as the RS34 carbs I use on my Honda, and because the Mikuni in some cases are up to 50% cheaper.

Along with the new carburettor, I bought a K&N filter to make the engine breath a little better than with the stock closed air box and foam filter. Filter was a direct 2 minute swap deal.

The original DR-Z 400 E model was a bit more aggressive engine-wise, compared to the newer DR-Z SM and S model which comes with lower engine compression ratio, milder cam shafts and CV carb and therefore also a smaller ID exhaust pipe compared to the E model. Therefore it was also a must to change the original DRZ SM scrapmetal exhaust. The original exhaust was so quiet that you could only hear the engine when it was running in idle. With the wind against your helmet, the road beneath you, and no tachometer, it was impossible to determine what RPM you were running. With no motor sound indicating stress of the engine.

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New bike calls for a new category. I’ve gotten my DRZ400 last year, just before the end of the season, and have only had the chance to put around 6,000 km on it. At first when I picked it up at the dealer, and drove off, I found it a little disappointing. Although it seemed very light, and handled and braked very good, the engine power and lack of throttle response was really just a disappointment.

After getting used the the stock CV carburettor and how hard you had to twist the throttle to make anything happen, it suddenly seemed somewhat decent. Barely after hitting the first 1,000 km, I bought an Akrapovic Evolution Line Titanium exhaust system, that for knowing the high quality and good reputation of the Akrapovics, and of course for the sweet looks of it! Of course a new REAL carburettor went with it, a Mikuni TM36, with accellerator pump and manual choke, and a slot in K&N filter. All that along with the so-called famous 3×3 airbox mod (cutting a 3×3 inch hole in the airbox, instead of the standard snorkel) really made a day/night difference.
The throttle response was now razor sharp, and the bike can now easily do throttle wheelies in 1st and 2nd gear. You have to be careful on the throttle in the lower gears, not to do them. It would be a huge shame not to post a picture of my Hondas new stable-mate.

A few mods has been made since the picture. A new SDG black “gripper” seat, a Manual Cam Chain Tensioner, new LED blinkers and Zeta hand guards.
   
Later a couple of extra mods came up. It never quite stops. As with the Honda CB-F which is currently under a huge make-over, more info will come on that later.

I feel like I’m writing this every time I post here, and if I take a look back and check, it’s probably the case! But anyways, it has been a very long time since my last post, and a lot of things happened since then.

First of all, I broke the Mikuni RS carburettors which I had some problems with. I had to be a smart-ass and turn the pilot screws with a screw-driver when I had the carbs off the bike, and that way had no feeling whatsoever with the amount of torque given to the pilot screw nozzle in the carburettor housing. So, the tip of the pilot screws got penetrated into the carburettor housing and broke off from the screws. The hole in the housing are even larger now, so there are no way to make these run perfect.

So, I decided to buy a new set of Mikuni RS34’s, and so I did. Just $ 1000 out the window, sometimes getting experience turn out rather expensive, when you have to learn the hard way.

Anyways, I got the new set of carburettors, and a new set of jet needles. The bike runs much stronger in midrange and low-end now, with the engine sounding much more satisfied with fuel. For the record, the needles I am using are 9DZH04 (measures Ø 2.48mm). I will make a diagram with the jetting parts some time.

I have gotten a new stainless 4-1 Cobra exhaust system (the one with upswept middle pipe) with stainless cannister. I was really amazed by this system, and I think that this is by far the best looking exhaust system you can find for reasonable money for these bikes. I have no idea about the performance yet. This exhaust system came with a db-killer/silencer that are good for long road trips, I had a lot of trouble getting this thing out of
the cannister. It seemed that the trick was to unmount the cannister and press a waterpipe through the exhaust from the middle-pipe side, and BAM it was out the very instant, with no force needed.

I have discovered that my front light and instruments are making a lot of ratchet noises, not as much as the flatslide carburettors, but this is really annoying. This is nothing that new rubbermounts will be able to fix.

So, last night, I decided to buy a new set of instruments for my bike. I have chosen a set of Koso RX1N with white backlight, because of the posibilities, the looks and the low price compared to other instruments around.

It has been a long time since last update, again. The project has been standing still for about a month now, wether I can blame lack of motivation or lack of funds, I don’t know. Probably both.

I have a major issue with the bike, that I have to sort out before I can “ride” it for real.
This is for all of you Mikuni geeks out there! my knowledge is very limited when it comes to carburettors,
which also scared me a bit when I were thinking about purchasing the Mikuni RS34 carbs. Team d’Or told me that it was pre jetted to a Honda CB900F with the 985cc Wiseco big bore kit, but it would most probably require some fine tuning to my specific application.
The problem is, that the fuel mixture is too lean in the midrange, 1/4 -> 3/4 throttle. First off I thought I could adjust my way out of it, by moving the needle clip a couple of positions downwards, trying with one at a time of course.
Now the needle clip is in the lowest position, and I’ve still got a lean running engine. I had my bike dyno’ed some weeks ago, and the guy told me that I would have to get a 20 percent thinner needle, (huh? I thought they went in smaller steps?).
I have tried to figure out the Sudco online catalogue to find out which needle I would need for replacement, but it seems that I’m already running the thinnest needle made for my carbs.

So, perhaps I can resolve this problem by changing the needle jet, by getting a set of needle jets with larger inner diameters. Any thoughts?

My carb setup are as follows:

It has been a long time since my last post, my server has been down and I have not been able to recieve e-mails at the address stated on this site. I have been up to a lot with my bike since my last post in January, basicly the engine is put together and running now.

I bought a set a Wiseco 985cc 10,25:1 compression, forged piston kit and had the cylinders rebored by 3mm Ø. The motor has been put together with the new main and big-end bearings. As goes for the top end, I have regrinded the valves against the valve seats with some “valve paste” to make them seal properly, all of the exhaust valves were covered in carbon.

I recieved a set of Mikuni RS34 Flatslides from Team d’Or, and bought four K&N Pod filters (RC-0981).

Last week I finally recieved my new Dynatek Dyna 2000 ignition with Dynatek 2.2 Ohm coils and 8mm suppression core ignition wires, I bought it from Z1 Enterprises in the U.S., best price I could find on a new Dyna ignition with coils, and impressive fast shipping.

The Bronson archive is currently not available and has not been, for the whole day. It seems that I forgot to pay for the renewal of the domain bronson.dk, which caused it getting suspended. It will be up within the next 24 hours.

Okay, finally picked the engine up from glass blasting. So finally I can get started on the slow boring process of unwrapping duct tape from the casing and cleaning up the horrible mess, I’d rather spend too much time cleaning up the casing than too little - this is where it pays to be patient and do your best, if not the glass/aluminum grit will kill the engine, once started.

Okay, I usually don’t shoot pictuers without flash, but I just couldn’t bring out the details on this picture without it. So bear with me. I have taken the liberty of removing some of the duct tape already, to see wether the gasket surfaces were hurt or not. No problems found yet, so it all looks good.

Hurray! I called the company that was supposed to glass bead my engine casing and it seemed that it has been ready for a while, although they never called me? - Hmm no big deal, I’m going to pick it up in the morning, as soon as I find someone that can help me with the transportation, the alternative could be a taxi.
I’ll post some pictures of the result as soon as I get home. I can’t wait to get started on this.

Hey, I’ve got some good news this time. I have been wondering a lot on how to figure out the connecting rod bearing color codes, because I really couldn’t make up the indications on the crank shaft. Anyways, I opened the rods to look at the bearing conditions, the half shell bearings for connecting rod #1 and #4 looked OK, with no scratches whatsoever. But number #2 and #3 both had some minor scratches, they didn’t look as bad as the main bearings but I’m glad I took them apart to check them anyways.

I tried measuring the current con rod bearings with plastigauge to find out if the oil clearence was out of spec, just as I did with the crank shaft main bearings. To my luck, all of the bearings were still into spec, dispite the wear on #2 and #3. When reading the original workshop manual, just one more time. I noticed a little picture that indicated the bearing color codes on the bearing itself. Those color codes were gone on the main bearings, but I gave it a shot on the big end bearings. And thankfully, there was still a thin layer of brown color, on the side of each bearing.

So, I hurried in to my computer and placed an order on 8 big end bearings at David Silver Spares. Delivery time was 7-14 days, gees. The thing I’ve come to know about David Silver Spares, is that they always tend to exadurate delivery times, so, I might be lucky having the new bearings next week.

No updates on the project, I’m still waiting for the engine block to return from the glass blasting process. I thought it was something you just delivered and they’d prepare it to the next day or something.

I guess I was wrong.