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Recommendations on rebuild parts/configuration please


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Hey guys, long time reader, first post. Have a 2006 DRZ 400 sm. Only ever ride on the street and want to maintain max reliability, but get the best out of her. Love her, but low on compression and done nearly 25k miles. Need a rebuild. Currently 3x3, rejet, and full Yosh RS-2. Other than that, engine wise, stock. Over last six months or so, have bought myself a BB KIT with JE piston, FCR 39 and a set of HotCams (stage 1 in and ex). Thinking of buying the MRD Z-pro,

so essentially items for a 50hp build.

Questions:

1 Should I consider full rebuild including bottom end? Will mentioned mods put too much stress on my tiring crank? If so, a +4mm HotRod crank if I'm to split the case? Or just standard?

2 if I were to go a BB and stroker, should I consider the 41mm FCR? Not spending heaps of time in high RPM, prefer lower down torque

3 Valve suggestions? Ron Hamp valves available? If so, where to buy?

Ferrea next best option? And is +1 oversize advisable?

4 MRD worth it? Kinda don't mind my RS-2. But if I'm spending all this money on other parts Should I 'unlock' their potential by allowing them to breathe and perform?

I'd really appreciate your opinions guys! Thanks in advance :-)

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My bike has about the same mileage , I was burning oil so I'm in the middle of doing my top end ( my using oil was due to a bad vale seal ) so I'm interested in this to , I have my top end off waiting to get my head back I put new rings in about 5k back , my cylinder looks to be in great shape the cross hatch marks are still there but I'm putting in a cylinder works bb , my con rod has no play up & down & very very little side to side

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RE #3 have you seen this in William1 signature line?  You might contact him to see what's up with it.

 

Selling a Ron Hamp Built DRZ400SM Ported, Big valve head - The Real Deal

 

I'm no expert but I think you want the 41 mm only if you have the full meal deal on the motor (stroker, BB, worked head) and then only if you want to take advantage of the high rpm performance, think street not dirt.  

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If your bike has had regular oil changes say every 1,000 k I would assume your crank would be fine take the top end off & check the rod for play in saying that there are many people on here who know far more than me if you don't get an answer start a new post

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Wow, a little bit more expensive than what I expected. Thanks npm.

Any other advice on the build config?

 

Unfortunately that's the draw back with building full on performance motors.  

 

If you don't want to go all the way with your build I'd suggest checking to see if the crank is good, if it is, just put the BB, FCR, and cams in and call it a day.  If you want the absolute most power for your kit a pipe like the MRD PRO is required (with the down side of more noise).  At 25 K you should also re-do the head and probably a new cam chain.  

 

You asked about Ron Hamp you can contact him via TT https://thumpertalk.com/user/22057-ron-hamp/ 

Or his website http://www.ronhamp.com/

 

He seems to be a pretty busy guy so you might have to be patient. 

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  • 2 weeks later...

As recommended, pulled the engine down, unfortunately enough play to warrant crank replacement. Whilst having the case apart, thought I may as well pop a +4 mm stroker in rather than standard.

Two questions:

1 Will my hotcams stage 1 be appropriate for the BB stroker?

2 Hotrods cranks the way to go? Will it all simply bolt together? Spacer required with my setup?

Thanks guys, Dave

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i'd inspect the rod play and go with the "i've done oil changes regularly, it should be fine" assuming there isn't any weird cam journal markings, or any excessive rod play.

 

25,000 isn't much on a properly maintained drz bottom end. i'd expect some kind of top end failure/wear long before the bottom end having an issue. it's bathed in oil all day long after all. 

 

if you're determined to split the cases, i'd skip the big bore/power stuff and instead do the WR transmission upgrade. seems like that's really what the bike needs, from my perspective. 

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As recommended, pulled the engine down, unfortunately enough play to warrant crank replacement. Whilst having the case apart, thought I may as well pop a +4 mm stroker in rather than standard.

Two questions:

1 Will my hotcams stage 1 be appropriate for the BB stroker?

2 Hotrods cranks the way to go? Will it all simply bolt together? Spacer required with my setup?

Thanks guys, Dave

 

Davo , if you get the stroker it will cost you more than you think . The hotcams will be no good and if they are the newer stage 1 , you dont have anything different to whats in the bike now . The bike will need a lot of work done on it for a stroker package , head work , rhc or web cams , 4!mm FCR , splitting the cases , but no spacer as the newer 4mm doesnt need it . You can build a mild stroker engine without all of the go fast bits , but I hear it is a bit of a compromise . Cylinder works is a tried and trusted product and if installed properly , you should have no worries about longevity or reliability . Basically it all comes down to cost , just double it for the stroker , greg

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