'86 RD350+'89FZR400=awesomeness in the making

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motoholic71
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'86 RD350+'89FZR400=awesomeness in the making

#1 Post by motoholic71 » Thu Aug 27, 2020 8:03 am

Hey everyone its been a while everything ground to a halt for a long time but lately slowly but surely I picked up the slack and have been putting to good use my 2-hour-long lunch break lo and behold I actually have something to show for it.

So a little background this is a project born from my disappointment regarding the handling of the RD which was grossly outdated when it came out.

Then I noticed the FZR400 just beside it with much better stuff and being just one generation younger, bikes of the same ballpark and stable and were at one point simultaneously in production in the homeland.

These conditions are very important to me as I deslike mixing makes and abrupt time leaps. they even share the same master cylinders so I now have spares.

The plan is to keep RD frame and engine and adapt FZR wheels, brakes and suspension.

Luckily I got a hold of a first generation FZR still with a 18' rear wheel but featuring a deltabox swingarm, floating discs with 4 pot calipers and 38 mm front suspension.
This bike came out like so for just the 1989 year and then they introduced the RR model with a wider and heavier swingarm, wider 17' rear wheel and last but not least much beefier front, unnecessary weight because the RD frame wont handle the extra stiffness.
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The later model FZR is useless to this project as it's not possible to use the parts without major frame surgery.

Unfortunately the FZR was in a appalling condition as you can tell by the looks of some parts, adding to the work and expense but they're rare and in my view ideal for the project.

Got the wheels ready with nice sticky bridgestone radials
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The rear wheel is a 18' x 4' and the front is a 17' x 3' which I'm thrilled to have because the RD frame was meant for 18' wheels and I think it would look awkward with smaller rear.

As long as I can get nice tyres, I'll still enjoy the agility of a 17' front which is where it matters. Can't wait to feel the massive improvement.

BTW I have a 140 rear tyre, anyone knows if the chain will rub the tyre forcing me to use offset sprockets? I'd really hate to have to be limited by those dam offset sprockets, but I'm still working on fitting the swingarm to test all the alignments etc., so if anybody has a similar size rear wheel can give me a hint?

Now the swingarm fitment is just possible by a hair, the pivot anchors had to be ground down to a flush height and then this happened
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So I had to go ahead and embrace the dam trench Mr. Yamaha San left hidden and dig a little more just when the swingarm finally cleared the pivot.

This was all done by hand with an angle grinder and a couple of files and it's dam hard to keep it straight and level it was a bitch but when it was just about to sing victory this :smt013 :smt011 Yeah some ill probably say why not machine the swingarm instead?? well because it's not the right way, the swingarm is a replaceable factory part which it should fit as is and besides the wider the pivot points are, the better the rigidity and handling will be.

So I forged ahead and dug out the ol Dremel and went to town on it
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And here comes the TIG
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Have I ignored this soon there would be cracking around the bolt bushes/anchor points, hopefully a last grinding to recover straightness of the surfaces and it will be the end of it.

Next on to the suspension link which is a much better improved light strong alloy part with needle bearings when compared to that unreliable RD system with the ill designed super heavy cast iron pieces with nylon bushings; Thank god that be gone for good.
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The FZR shock has the exact same anchoring point to the frame as the RD so that is solved (advantages of using same make and generation bikes) so left is adapting the lower link pivot point and then the rods length will adjust the ride height, changing the least possible to preserve suspension geometry but there's still ways to go.

Inside the engine there is straight cut primaries from Nova racing, TZ mains on the crank and many other mods that will hopefully unveil here;

Don't forget please if somebody knows about the wider tyre possible without chain contact please tell us about it, hopeful I am since I had a 130 on the stock bones and the stock chain guard intact so it should be at leas close :smt047
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Darrell
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Re: '86 RD350+'89FZR400=awesomeness in the making

#2 Post by Darrell » Thu Aug 27, 2020 8:38 am

Wow! Thanks for the post, and please keep it current as you progress. I'd have been tempted to restore the 400, which was a pretty cool bike, but one of the best things about bikes is that we can take them in individual directions, assuming that we have the talent.
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Re: '86 RD350+'89FZR400=awesomeness in the making

#3 Post by tacky1 » Thu Aug 27, 2020 11:58 am

Looking really good. Keep up the good work, Keep the progress pics posted, :)
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Re: '86 RD350+'89FZR400=awesomeness in the making

#4 Post by kpke » Thu Aug 27, 2020 12:04 pm

I ran a 150x18 tire on an 18" FZR wheel with an FZ alu swingarm for years with no offset CS sprocket. Had the rear sprocket carrier machined to align the chain. This one has since been converted to SV 17" rear wheel. It now has an offset CS sprocket. I have another bike with the same FZ alu swingarm and FZR 18" wheel configuration with a 140x18. No offset CS sprocket. Both had the swingarms machined to fit the frame. BTW both have FZR forks with the narrow 17" wheel. Hopefully you put a 110 on the front. 120 does not work as well. It slows the steering a bit.

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Re: '86 RD350+'89FZR400=awesomeness in the making

#5 Post by Questo vecchio rz » Thu Aug 27, 2020 6:27 pm

Nice, I've had the aluminum FZRr swingarm conversion on my bike. since I bought the conversion from a forum member here approx 15+ years ago....I've since altered the assembly but basically it's uses a Honda 4.5" NSR Magtek wheel and a 150 wide tie , The profile will be changed now due to ride height ...it will be awhile before she sees the asphalt again. The conversion worked quite well when I 1st got it...was quite an improvement vs stock it had a Works performance shock
. My front is a combination of machined Billet GSXR upper and lower triple clamps from Attack racing. combined with Honda RC51 USD forks. I ran all my numbers and tried to get the offset/rake and wheelbase as close to a TZ 250 as possible, it's not perfect but as close as I could get.. without major frame modifications
I'm confident she will deliver exactly what I want from her, albeit she will (require ) a steering stabilizer....My frame is gusseted in various locations, nothing crazy, just head shock area, shock mount and a X brace on the top ...same as many of the race bikes and many used in the old days in Japan on 250/350 race bike's. IMO nothing major is required...The frame for what it is, is more than adequate for my power level and skill set....people I know with far more skills and racing pedegriee have delivered national championships on the same basic original RZ frame...it's just fine...for what it is.. I'll never be able to see the limits of this frame.....only in my dreams...where I'm a RZ racing hero..lol 😄
A couple years ago I sent all the parts to RGV Steve and he perfected all the poor machining done by the original builder whom assembled it with alot of very very poor tolerances. I also had him create a captive rear brake caliper instead of using a torque arm. Forks have been revalved buy a race shop California. It will be awhile before shes back together .
I've tried to cut weight in the basic areas , with the magnesium rims, lightweight floating rotors, titanium buttons . Last year I had custom machined titanium axles.. that cost me $320 a piece... I know that's cheap but it was expensive to me I don't have a big budget.

There's a guy whom works for a custom bike shop here in So Calif whom had had a 17" deltabox FZRRr conversion on his RZ for about a decade or so ..he set his up if I remember correctly utilizing Adj length GSXR links? Totally different from mine, I'm not sure exactly what..his specs were..it's been years since I talked to the guy. But that bike hauled ass, and performed quite well when raced, he said it was exceptionally stable at speed, but his bike couldn't complete for podiums as it was underpowered, stock engine.
Mine should be far better, also be will utilize a fully Adj Penske Rear shock.
Some of the best handling RZ conversions I've ever viewed have been a combination of FZ or FZR components.
There's no reason you shouldn't have good success and be extremely satisfied with your conversion.
Obviously these components are based off bikes built almost 20-30 years ago now... Originally I was utilizing Honda MC 18 and 21 parts which are much, much lighter... But I'm willing to give up some weight for the incusion of upside down forks and the beefy swing arm.. although the swing arm is pretty stout and looks heavy it's only weighed in fractionally higher as a whole assembly then a stock setup with 18... And by the time I'm done I should down on weight... due to the lightweight hardware,axle and magnesium wheel, I will also be using the lightest weight (slick) tire I can find in a150 equivalent, I should be able to squeeze a 160 with the right profile.. but if I don't need it I won't bother.
If I was to do it again obviously ... It's 20 years down the road and the new R6 components work fantastic with substantially less weight, a lot of people are utilizing those not necessarily with the RZ frame but all things being equal it's all fun and good for the hobby.
Good Luck keep posting your results
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Re: '86 RD350+'89FZR400=awesomeness in the making

#6 Post by evan_calgary » Sun Aug 30, 2020 8:44 pm

Nice work! Why not ditch the super old tech RZ frame and use the new tech aluminum FZR400 frame with the RZ engine? Seems like a much better end product to keep the great engine and use the better chassis. I've owned both and the FZR even with 600cc FZR motor in it still seems relatively nimble. Regardless, you've done some nice work there.

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Re: '86 RD350+'89FZR400=awesomeness in the making

#7 Post by JonW » Sun Aug 30, 2020 10:39 pm

evan_calgary wrote: Sun Aug 30, 2020 8:44 pm Nice work! Why not ditch the super old tech RZ frame and use the new tech aluminum FZR400 frame with the RZ engine? Seems like a much better end product to keep the great engine and use the better chassis. I've owned both and the FZR even with 600cc FZR motor in it still seems relatively nimble. Regardless, you've done some nice work there.
A guy here did an FZR250 frame with an LC engine a few years ago, its still knocking about on the Fb forums i think
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Re: '86 RD350+'89FZR400=awesomeness in the making

#8 Post by motoholic71 » Tue Sep 01, 2020 4:34 am

Thank you guys for your replies and encouragement.

Very glad to hear that is possible to run standard sprockets with this set up. I've seen the FZ swing arm conv. I almost did it myself if had not lost a bid on the swingarm a few years back but was not thrilled about it although it sure must be a lot easier than what I have now.
my aim is indeed to improve the bike but also to try and keep the donor byke simple (same brand, era...) and also to modify parts as little as possible so if it happens to need replacing parts it could be done with the least hassle as possible.
Hope to have further developments soon, I'm now struggling with o ringing the cylinders, the dimensions of the channel, whether or not to use TZ o rings....Hope to get it right.
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Re: '86 RD350+'89FZR400=awesomeness in the making

#9 Post by JanBros » Tue Sep 01, 2020 4:03 pm

O-rings : stay at least 3mm clear of the combustion chamber
make the groove as wide as the ring (or just slightly wider for easier removal)
make the groove 80% of ring deep.
the rubber is not pressed together, only deformed.
cross-sectional surface of for example 2mm ring = 3.1415 x (2/2)² = 3.1415mm²
cross section of the groove = 2 x (2/100x80) = 2x 1.6 = 3.2mm²

so the ring almost completly fill's the groove. stil better to make it slightly wider while keeping the 80%
if it runs, you can race it !

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