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The 2-Stroke Garage => Turning Wrenches => Topic started by: old-too-smoker on December 21, 2019, 08:08:54 AM

Title: New RZ350 project bike, thinking of going big bore
Post by: old-too-smoker on December 21, 2019, 08:08:54 AM
Happy holidays fellow smokers.  While waiting for my RD250 project bike seller , to find the title, I crossed paths with a good deal on a RZ350, it runs good but has crack case. I have a good set of cases in my treasure chest I will swap out. while its apart thinking about a big bore kit. Looking at these Cheetah SUPER CUB Cylinder 611cc with 78mm bore for 10mm stroker cranks. I guess you have to machine the cases for the crank, somehow modify the RZ pipes to fit the banshee exhaust manifolds. Has anyone done this? Seems like it would be a lot stress on the RZ cases and trans parts. Any advice?
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: rodneya on December 21, 2019, 02:47:13 PM
First off, dont ever buy from BP Racing unless you want to get garbage Chinese rubbish parts.
Yes, 10mil requires case trenching and machining for the transfers to fit. You will also need CR500 reeds, huge carbs and possibly modify the trans and clutch.
Cheetas are a drag cylinder, so it may not really be that great to ride  on the street.
You also need bog bore, big flange pipes to hope to make any power out of that setup. Snipes or LED custom pipes will be well over $1000

If you add up machining and parts and decide if it is worth 5K plus
4mil 421cc Driveline of Serval is a better way to go in my opinion

Title: Re: New RZ350 project bike, thinking of going big bore
Post by: motodreams on December 23, 2019, 10:35:30 AM
Like said above, this is not a plug and play setup.  You need to modify everything from intake to exhaust.  Definitely need custom chambers.  Essentially all of the big bore cylinders need to go direct to a porting shop before use.  Off the shelf they are not great.  Very few people go that big and if they do those are $10K plus setups.  You are still looking at a few grand for the 421s when done correctly.
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: old-too-smoker on December 30, 2019, 08:47:21 AM
That is what I figured, i dont want a race bike just a good street rider. Thanks for the input!
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: motodreams on December 30, 2019, 09:20:44 AM
When you go that big it will be never ending upgrading.  carbs, then rad, water pump, clutch, potentially primaries, custom pipes, ignition.  Once you've spent that money you may as well improve the poor suspension and brakes.  Next thing you know you've got a fortune sunk into a bike worth no more than a clean stock one.
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: paul1478 on December 30, 2019, 10:08:00 AM
Quote from: motodreams on December 30, 2019, 09:20:44 AM
When you go that big it will be never ending upgrading.  carbs, then rad, water pump, clutch, potentially primaries, custom pipes, ignition.  Once you've spent that money you may as well improve the poor suspension and brakes.  Next thing you know you've got a fortune sunk into a bike worth no more than a clean stock one.
true but wow, what a bike it would be....
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: m in sc on December 30, 2019, 10:13:29 AM
I never mod with the intent of resale value.  Depends what you want out of it over all, but the 421 setup is a solid choice.  def address the forks, brakes and rear shock, best things i did to my rz was suspension & brake upgrades.
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: SUPERTUNE on December 30, 2019, 11:40:26 AM
Call  my friend Tony Doukas to help with case machining. He the go to guy to talk on a engine setup with using these kits.

https://shop.bansheedepot.com/ (https://shop.bansheedepot.com/)

Chuck
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: pdxjim on December 30, 2019, 04:12:40 PM
Read this:

http://rdlccrazy.proboards.com/thread/48809/421cc-pros-cons

... and this:

http://www.2smoked.com/Yamaha_RD_%26_RZ_upgrades_-_RZ350_RD350_Big_Bore_Primer.html



Title: Re: New RZ350 project bike, thinking of going big bore
Post by: Halmic on December 30, 2019, 10:08:32 PM
I've got a 421cc Banshee-engined RD that puts out 86rwhp (with top end pipes and 36mm Lectrons), I can't imagine an RD (or RZ) chassis and brakes can handle much more than this.
Title: Re: New RZ350 project bike, thinking of going big bore
Post by: motodreams on December 31, 2019, 09:19:17 AM
The RD is ancient tech compared to the RZ (which obv is a long way from today's geometry).  The start on an actual perimeter frame and 2 iterations of major development later.

Frame was a giant improvement and the spindles + forks were better as well.  Plus mono vs. twin shock.