DRZ 400 bottom end full rebuild thread

Not sure if too many of you are interested, but I thought this may be useful for other home mechanics attempting the same sort of thing, a full bottom end rebuild of a DRZ 400S, including installing a +4mm Hot Rods stroker crank and ACT wide ratio gear set, the balance of the bike will be as my signature states below.

With the bike running embarrassingly rich right the way through with an E header and a 35mm muffler outlet pipe it pulled 36hp at the wheel at 8500 rpm and 26 ft pounds of torque at 6000 rpm, the changes made just before it locked up were a 43mm muffler outlet and a re-jet, it felt heaps fitter and may have been touching 40 hp, the 155 (indicated) top end on 15-41 gearing and trail rims with knobblies would possibly attest to that (I'm 115kgs and a big guy, not fat though ha ha).

I hope some of you may get something out of it, my bits are a least 2 weeks away and I'm in the middle of exams but I hope to have it back together by mid to late nov, and I will be adding my newly acquired big bore header from NZ manufacturer Cycleworks, cheers for the interest in advance and note the attached dyno spreadsheet.

I will dyno it again once its run in, and again once the CW 4mm big bore kit is installed winter next year with the same setup, I will be running the standard bore initially. Once money is available again I will attack the head with RHC 1mmo/s valves and head job (by NZ firm Kelford camtech), RHC 208 and 187 cams, RHC springs, SSW pipe and a 41mm FCR and do a 4th dyno run, just the analyse the progression, pretty sure nobody in NZ has done this. Cheers

Cycleworks Header 2.JPG

Full Dyno.JPG

Highly interested and appreciate going the extra mile of posting it up

Just ordered the ACT gears, be about a $1000NZ landed here in NZ once duties and taxes are paid, bloody dear but worth it? full 4mm stroker crank kit is about $780NZ landed, good thing the kiwi dollar is quite strong, wont be selling the bike so the money I put into it will be for my use only, wont be doing the lightweight flywheel at all, I still need the bike to retain its tractoring ability when trail riding, 1hp on the dyno is not worth $300nz, so the bits are on their way, will strip the motor down over the weekend, just hope the rest of its ok, cheers.

Sorry to hear about the lock up bro....sucks! Keep us posted with the install and the dyno results...I'll be posting my dyno runs up shortly and following up with further runs once I install the big bore early next year...might make an interesting comparison.

Cool, the timing of the rest of the mods will be linked to how much spare money I can find (wife 2 kids, bills etc), was tossing up between Cylinder Works and Athena, the latter is really good but so bloody dear, Namura are cheap but surely they cant sell them through reputable retailers if they are complete shite, surely the problems only occur when people race or flogg the living shite out of their bikes, Tudors and Ice cube are too dear and Im not convinced of the benefits of a 96mm bore for an everyday ride, the limit is the cylinder header water jackets, everybody does the 94mm big bore and they are reliable as a stone, having 2-4 more horsepower is no good when the thing keeps sqeezing gaskets out, Im not convinced, especially as ES has said 94mm should be the limit for most DRZ owners, I trust the expert in this regard.

What part of NZ do you live in?

 

I honeymooned in NZ for two weeks in 2008. I drove both islands. We loved the country. We had some really good food just about everywhere we went. There is a Thai restaurant in Auckland and an Indian restaurant in Christchurch which we felt were the best we've ever had compared to California. We thought some of the mountain lakes between Christchurch and Queenstown were stunning. The only part we didn't see is the bay of islands in the north.

 

Take lots of pictures. I'm sure we'd all like to follow the rebuild progress, especially on a bottom end rebuild.

Good luck!

ill be watching this, ill be rebuildng mine around that same time

Yep the south island is very stunning especially the Alps, Christchurch as you know was hammered from three major quakes and thousands of aftershocks, its a very changed place, I will probably spend a lot of time working up there next year, bay of islands is nice so it the coromandle peninsula (North Island) but the south is awesome, I have decided to get the CW BB kit earlier, order it early next month, I will leave my E model exhaust cams (both inlet and exhaust are the same E model B exhaust cam) as they are close to the old hotcams stage 2 which you cant get anymore, I will have a play with the inlet timing while I'm at it, the existing valves (new 4 play valves, probably shite, bought from a local dealer), springs (might replace the collets to be safe), head, slant FCR and exhaust will remain as is. Will get o/s valves, good springs, head job, 187 cams (208 inlet is too much for an everyday bike I want to trail ride on), MRD SSW and 41mm FCR later next year, I'm selling my Fireblade to fund the rebuild, want to have it all done for the Burt Munro races in Invercargill next year, I will do the beach racing on my trail rims and the motard race on my CBR rims, that's the plan anyway.

What part of NZ do you live in?

 

I honeymooned in NZ for two weeks in 2008. I drove both islands. We loved the country. We had some really good food just about everywhere we went. There is a Thai restaurant in Auckland and an Indian restaurant in Christchurch which we felt were the best we've ever had compared to California. We thought some of the mountain lakes between Christchurch and Queenstown were stunning. The only part we didn't see is the bay of islands in the north.

 

Take lots of pictures. I'm sure we'd all like to follow the rebuild progress, especially on a bottom end rebuild.

Good luck!

Otago in the South Island, Dunedin, Queenstown and Wanaka are within the Otago Region

Otago in the South Island, Dunedin, Queenstown and Wanaka are within the Otago Region

 

Man, I'd love a case of Monteiths Black! I saw a lot of riders for a Burt Munro memorial ride around Lake Wanaka. The roads are pristine, but the speed limit is too slow! I liked the South Island the most as it reminds me of California in many ways, only more dramatic. Amazing place to live!

QueeensTown1.jpg

My parents have got a holiday home on the Kelvin peninsula which is the big bit that sticks out with the golf course in that picture, taking the wife and kids there in early Dec for a break, hope to trailer the DRZ up to do the Skippers canyon and a few other rides, if I get it together in time, anyway a 462cc DRZ with a wide ratio box will be better than a 399cc one that's for sure. Some of the roads in Otago and South Canterbury are not busy and have FA cops on them, the west coast of the South Island is spectacular, when I get my HD Dyna Sport next year I will head up for a blast again, been ten years since I've done that ride, too bloody long.

I've never been anywhere like the west coast of the south island of NZ. We took a helicopter flight over Fox Glacier because the road was closed due to a storm and we couldn't hike it. Two weeks later it opened and a guy and his brother were hiking the glacier with a group. They walked 50yrds away from the group and one of them got crushed to death by a caving piece of ice.

 

What was stunning about the coastline there is beach, then low grasslands with herds of cows grazing, then tropical vegetation, then BAM a 12,000 ft. mountain range with glaciers not 20 miles from the beach. Unreal!

 

Punakaiki was also interesting with the pancake rock. We were told you can not find this type of rock formation anywhere else in the world.

 

 

 

Punakaiki7.jpg

I've never been anywhere like the west coast of the south island of NZ. We took a helicopter flight over Fox Glacier because the road was closed due to a storm and we couldn't hike it. Two weeks later it opened and a guy and his brother were hiking the glacier with a group. They walked 50yrds away from the group and one of them got crushed to death by a caving piece of ice.

 

What was stunning about the coastline there is beach, then low grasslands with herds of cows grazing, then tropical vegetation, then BAM a 12,000 ft. mountain range with glaciers not 20 miles from the beach. Unreal!

 

Punakaiki was also interesting with the pancake rock. We were told you can not find this type of rock formation anywhere else in the world.

Fantastic you had a great experience in NZ, I remember that incident, but they took no notice of the guides and wham, nature bits you back, looking forward to getting back over there soon.

Second exam done, another in 10 days, tomorrow arvo the engines coming out of the frame and getting stripped, hope I don't find a mess inside, crank and bearings are going to be new, the 2nd to fifth gears are new, anything else I should replace while its out, what bearings are typically a good idea to replace while the things in bits, output sprocket side, input clutch side (I only did those when I replaced the fireblade's gearbox), balancer shaft, do people typically replace the plastic oil pump gear while its in bits, don't want to go nuts but I have never had a DRZ to bits so Im not sure what is and isn't good practice with them, is it all right to use good aftermarket bearings or do you always seek oem, cheers for the help in advance.

Took, why in gods name is my DRZ the only one in the world without grease nipples on the swing arm and linkage, anyway the bottom end it getting split as I tying, the have the proper tools to do it, I don't and its money well spent, I think my oil pumps sucked in some s**t methinks, more money

I've just read some of my old posts, plenty of typos doh, yep I'm getting a bike shop to split the cases, should have it all good to go in a couple of days, picked up some new Suzuki valve collets just to replace the old ones I reused for the new valves from the last rebuild, just to be safe, fitted my CBR 250 rims today, looks like a boss especially with the new motard front guard, bought them off a guy who made up an entire package to fit a DR 650, with a couple of minor tweaks and adjustments they fit great, trailtech speedo is next, hopefully I will receive notification from customs that my bits have arrived from the US, the duty kills it price wise but still cheaper than buying locally from importers ($1000 for a CW big bore kit and $1000 for the crank only, rip off), anyway I will be a pig in s**t when it arrives. Cheers

The beast slowly awakens again, I love my workshop, and my bike lift, getting seriously barred up about this build

DRZ Motard.JPG

Just got given a factory workshop manual, truly stoked, still waiting on bits to come from the states and my last ever university exam to be over with (a few beers will be downed that night), the cases are split and it all looks pretty good internally, even the crank is salvageable, no damage to the cases or gearbox, the oil pump feels a bit crunchy which is strange and may be the only casualty of the bearing failure, do you think it may be prudent to replace the output shaft while its in bits, at $260 NZ its a bit dear but it may be good insurance for the 50 odd hp it may eventually make, especially in light of the threaded piece coming off in various failures listed in TT, Im replacing all the bearings and the plastic oil pump drive gear as well, your thoughts experts on the output shaft?

So which bearing actually failed and caused the lock up?

F***ing stator side crank bearing, I suspect whatever failure happens on the stator side the locktite fix is supposed to fix happened, then the dodgy PO had it all bodgied up to get it running, I suspect something got into the bearing and it slowly disintegrated finally failing completely when I was riding it, bugger, trying to do a full rebuild with zero money is trying to say the least, it could be worse

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now