The drz400s rebuild, stronger...faster...somthinger!

[955616846]

Originally Posted by focallength

so here is the score so , far. Im waiting for a puller for the fly wheel then Ill split the case. Initial inspection shows some slight play in the rod, which means shes shot. I ordered a complete hot rods lower parts kit, to rebuild the bottom end. The gears arent blue, but I wont know until I can split the case. So far no definitive causes, the cylinder does show signs of previous wear and oil could have slipped passed the rings. The cylinder is nice and flat, but the head is pretty well warped.

Ill have the case honed just in case, so that both parts fit together perfectly.

Now the cylinder is salvagable, Ill prob. send it off to cylinder works or millenium and have them hone and replate it. Still not sure if I wabt to go with a BB or not.

The head is just a big paper weight, however there are signs of dirt being sucked into the valves, which is not that uncommon with a dirt bike. Just means Ill have to really check my air intake when I re install it. Most likely it happened over time, however I did notice that the FCR-MX carb dosent fit quite so well, so Im going to have to do something about that. Maybe find a airboot from another bike thats a little bit longer.

So lower parts kit should be here tomorrow as well as the puller, in addition Ill replace the countershaft bearings. Heres hoping the gears are good. Stay tuned, sorry no pics, nothing new to show...

I may pick up a kick starter kit though, should be easy to install with the engine in pieces...

In case you haven't worked this one out... If you want the kick starter and you're buying a new head then be sure to buy one for an E which already has the holes for the compression release machined.
I assume that you already have a case splitter and crank puller. If not, the latter is important and the Tusk brand gear is reasonably priced.

[focallength]

Ok, one thing I wanted to fix was the fcr-mx airboot issue. Anyone who has one knows it barely fits and is prone to air gaps.
so I bought a 2 inch rubber coupler, trimmed the inside of one side so the air boot fits. I also trimmed the tab and one row of the rubber rings. The carb fits in with a little gap, which is no biggie as the ring tightens it down nice. I cut the coupling to about an inch, you only need about an extra 1/2 inch to make it fit.

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Oh, never look into a pumper carb and turn the throttle wheel

[955616846]

I'd still be concerned about air leaks between the adaptor and the section to the air box with the lack of support for the clamp. A short length (~40mm or so) of exhaust tube inside the adaptor and butted against the bell mouth will give the hose clamp some purchase without crushing the plastic underneath. Exhaust tube can be split, pulled up with hose clamps and re-welded to get the correct outside diameter.

[Starchamp]

Why not just get an E boot? MacGyvering is best left for trailside repairs.

[955616846]

I've done mine "properly", but perhaps the reason for these sorts of mods is that not everyone has the money to spend. IIRC, that bit of plastic is about $60. Add that to the cost of all of the other little bits and it adds up very quickly especially when there are more pressing concerns. My suggestion of "Macgyvering" as you put is in line with with whatever FL had in mind, whatever that was, when he went down this path. Methods such as this have often used where suitable "proper" parts are not available and stand the test when done properly.

It is his bike, he can do as he pleases.

[Starchamp]

Agreed, mostly, and I wasn't referring to your exhaust tubing suggestion in particular, but rather the entire approach. I just think that with all the money being put into the engine, if it were my bike I'd not skimp on a $50 rubber boot (about how much they're going for on ebay, complete with entire airbox) and risk sucking unfiltered air into the works. To each his own, I guess.

[focallength]

Is the E boot longer? I just assumed the s and e boots were the same.
ive never heard anyone suggest the E boot, if its longer and makes the.carb fit properlly ill get one.

[Starchamp]

Yes. 4strokes.com offers the below as the complete list of parts needed for the FCR conversion, but you can probably get away with just the outlet boot:

Suzuki Part Numbers:
FCR Carb: 13200-29F10
Velocity Stack: 13670-29F00 (plus gasket and 2 screws)
Intake: 13111-29F00
Outlet: 13881-29F00
Clamp: 09402-58208
Clamp: 09402-60208
Throttle Cables: 58301-29F00

But again, I'd just grab one off of ebay rather than go through Suzuki.

[focallength]

Ok, so I finally got the cs bearings in, going to split the case, soon. But I was thinking, the head got real hot and may have damaged the head bolt threads on the case. So...ill send the case halves ofg and get some timeserts installed. This will prevent any strippage of the head bolts when putting the engine together, plus if I go BB itll strengthen the case so the head dosent pull itself apart. $100 will make the engine stronger and give some peace of mind.

[focallength]

So, I think I finally have a solid number for a rebuild

Bottom end $575 w/cs bearings
cylinder, bored (434) plated with piston, clips/bearings etc... $450 (millenium, will ship a bored stock cylinder with a JE piston)
head $575
cams (hot cams) valves, springs etc...$625
rebuild clutch $400
timing chain,timeserts $175

$2800, not including parts for carb.

Will get a drz w/13.5 compression, 434 BB, stg 1hot cams, kibblewhite valves, hot rod bottom end, complete new clutch, strengthend head bolts.

[KLXmcrider]

I'm feeling a little envious of your rebuild. I want something similar so I'll be watching
this thread , day dreaming as always........

[955616846]

I don't think that the case inserts will be necessary and you still don't know the state of the crank or transmission...

[focallength]

Originally Posted by 955616846

I don't think that the case inserts will be necessary and you still don't know the state of the crank or transmission...

Crank is being replaced, whole new hotrods bottom end, the onlything that may remain are the gears, (if their good, which they look ok from what I can see, ill know by friday )and countershaft, everything else is new (bearings/seals). The timeserts are just insurace, dont want to break a headbolt, it is possible, so better safe than sorry. Especialy since I wont know until it happens then id have to tear the engine apart again, $80 to be safe is money well spent. Plus those threads will never break with titanium inserts. Ive had a bad experience with a head seperating on a bigbore and ive heard enough war stories...not dealing with that crap again. Ill most likely even order some better head bolts, if im building this thing I might as well make it unkillable.


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[focallength]

Sorry for the delay, got the cases back yesterday, bottom end is together and in the frame.

I had the timeserts put in, they were drilled a little deeper so I can put in longer head bolts. Maybe overkill but better safe than sorry.
Replaced all of the seals, bearings, the bottom end is brand new aside from the gears, they were in good shape. New hot rods crank.

Next is a 434 bb kit, just send the sleeve and for $419 I get a bored out sleeve, piston and rings.

The big hurt is the head, itll all be brand new, a blank head is 575

I need to replace the clutch and basket another $400

And ill get new bigger radiators to support the bigbore and increased compression as well as the hot cams.

Pics soon...

[focallength]

Im going to try out mylers for the radiators. They sell oversized radiators for 135 so i ordered one to make sure it fits ok, ordered the millenium 434 bb kit.

They said it should fit ok with a clarke 3.9 tank. They look great and the added cooling should help with the 434 kit , increased compression and hot cams. I should have the radiator thursday and the bb kit some time next week.

Ill get lots of pics as the parts roll in.