Jump to content

DRZ400 Big Bore Kit Question

By CruiseControl,
in DRZ400/E/S/SM

 Share

Recommended Posts

Proficient

CruiseControl

Posted
Posted

I have an 05 400sm. I am considering getting an Athena 440 big bore kit for it. I already have the Yoshi exhaust, air box mod, and re-jet. If I go for the kit I will also swap to the better carb set up that so many on this site talk about . Has anyone made these modifications and can they give me some idea of how it turned out? How will it affect dependability? and last, should I spend some more cash and change out the camshafts if I make the changes or leave the stock camshafts. I like everything about the bike but am wanting more punch.

Thanks.

Link to comment
Share on other sites
Collaborator

krod

Posted
Posted

MT 94mm piston, fcr carb, yosh full system, yoshcams, yosh cdi box, and crank. ****in bike rips, . Stock gearing bike will pull the front up in 2nd gear. Has same power as my 04rmz, just needs to lose some weight.

Link to comment
Share on other sites
Rising Star

mrquick68

Posted
Posted

K-rod, i hope with all of that work done you can pull the front wheel up in 2nd gear!

I would think with all that work you should be making around 43hp as the Yosh cams aren't that lumpy. Still, I bet it rips. No 4th gear wheelies?

Link to comment
Share on other sites
Rising Star

Grantmac

Posted
Posted

You want cams, carb, 94mm AND NEW VALVES!!!!!!

Seach if you want but it's just the truth, you will need new ones. Especially with a healthier set of cams and a $500 brand new piston right below them!

That said, you will also be making somewhere north of the 50HP mark at the wheel with thos mods, about 60% more than a stock S model:)

Grant

Link to comment
Share on other sites
Collaborator

krod

Posted
Posted
K-rod, i hope with all of that work done you can pull the front wheel up in 2nd gear!

I would think with all that work you should be making around 43hp as the Yosh cams aren't that lumpy. Still, I bet it rips. No 4th gear wheelies?

To high of altitude here steels alot of the power. At see level I am sure it will pull up in 3rd maybe 4th.

Link to comment
Share on other sites
Collaborator

krod

Posted
Posted
Can't afford the crank but can probably pull off the cam's, carb and 94mm. What bore kit did you use or did you send it off?

Eddie sent it out for me. Millenium 94mm. Without the crank with the other mods bike will still rip. Did not want all low end torque so I went with the yosh cams but the hot cams are a lot cheaper.

Link to comment
Share on other sites
Rising Star

Grantmac

Posted
Posted

If your gonna invest over $400 in a big bore, why run the risk of stock valves? Go with the RHC valves and your good to go for whatever you want in the future. I was thinking of just doing the valves and then doing everything else later.

So no, you don't NEED to, but you should.

Grant

Link to comment
Share on other sites
Grand Master

10guy

Posted
Posted

Anytime you need to go into the engine for the first time then I'd replace the stock valves. Even though there are thousands of stock two piece valves out there in bikes and doing just fine, I've seen/experienced enough of the drz/klx ones failing to feel good about the recommendation. To me it's not a waste of money, rather cheap insurance against

PICT0045.jpg

PICT0036.jpg

PICT0035.jpg

Engine looks really clean doesn't it? It should, it had less than 7 miles on a fresh rebuild. (Not my engine but I was there for it).

Link to comment
Share on other sites
  • 3 years later...
Experienced

bin

Posted
Posted

Wondering the same thing I have an 09 sm with 39mm carb, JD jet kit 165 main, both hot-cams, and running a 15-47. Picking up soon my big bore. I have done some reading and it's rather mixed in places. Books say no valve work is needed but riders are saying do it, wile it's apart and you should be doing it sooner then later. Has anyone not changed them n gotten away clean so far?

Link to comment
Share on other sites
Grand Master

Erik Marquez

Posted
Posted
Wondering the same thing I have an 09 sm with 39mm carb, JD jet kit 165 main, both hot-cams, and running a 15-47. Picking up soon my big bore. I have done some reading and it's rather mixed in places. Books say no valve work is needed but riders are saying do it, wile it's apart and you should be doing it sooner then later. Has anyone not changed them n gotten away clean so far?

Seeing as that is my motor in the pictures above.. I vote yes.. replace the OEM valves with at least a new set, plus springs and cotters and a good install. Better yet, send the head to SSW and have RHC valves and springs installed.

BTW, that motor above, was a less then two year old, low mileage motor, with a brand new 434 BB kit. I had 10 miles on the new motor when the OEM valve failed. No real sign of a previous issue. No leakage, it had never hot the piston. Old piston showed no signs of detonation, nor had i hydro-locked the motor previously.

  • Like 1
Link to comment
Share on other sites
Grand Master

Erik Marquez

Posted
Posted

It was used like most any DRZ,, it was run in the middle to upper RPM range, proper gear selected for the obstacle or terrain ridden on. Had it hit the rev limiter? Yes, absolutely did it live there bouncing off the top. no.. It's a mechanically welded two piece part that failed,, stuff happens.

My fault.. I had enough hours on that head that I should have at least replaced the valves and springs with new OEM.. I chose to finish the season with this head and then send it to SSW for RHC valves...... Did not make it that far.. So a brand new part was bought and sent for the same treatment.. End result my 450 BB kit cost me a 434 big bore kit, new head casting in addition to the 450 cylinder from MT, new piston and rings, and the valves, springs, tops from RHC and install by SSW.

Link to comment
Share on other sites

Create an account or sign in to comment

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

Reply with:

ThumperTalk

Register a new account Sign In Now
 Share
Go to topic listing
×
×
  • Create New...
Terms of Use
Copyright
Privacy Policy