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The 2-Stroke Garage => Haus of Projects => Topic started by: abbott10r on September 05, 2019, 02:30:27 PM

Title: 1975 RD350 Race bike build
Post by: abbott10r on September 05, 2019, 02:30:27 PM
Hey All. Pretty new to the RD world but not new to motorcycles and wrenching on them. Grew up on 2 stroke dirt bikes. Made the switch to 4 stroke street bikes almost 15 years ago. Got pretty heavy into track days with my Ducati 748. Now I'd like to get into some vintage road racing with this RD350.

So, I am looking to you guys for advice on how to set this thing up for road racing. Motor is coming completely apart. It's stuck and it's going to need a lot of work. It'll get all new seals and bearings. Crank will get a full inspection along with the top end.

Mostly interested in what people recommend for pipes (market seems small for selection), port timing, head work, reed set ups, recommended carbs, battery-less electronics, wheels, etc.

Appreciate any input you guys can throw at me. I am going to catalogue everything and make this a very nice build that is hopefully competitive. Will post pictures of the donor soon.

-Joe
Title: Re: 1975 RD350 Race bike build
Post by: 2 Stroke Jamoke on September 05, 2019, 02:44:51 PM
I got three words for you , Chuck SUPERTUNE Quenzler! There are a ton of good mods for the rd and Chuck is the man when it comes to power! I'm sure he will chime in
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 05, 2019, 06:52:51 PM
I have seen some of his posts and information to others as i creep around the forum. Sounds like a wealth of knowledge
Title: Re: 1975 RD350 Race bike build
Post by: Organicjedi on September 05, 2019, 08:01:58 PM
Are you planning on racing in a club or just a track bike? Club racing rules would limit what you can all do in some areas such as carb choice.
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 06, 2019, 07:23:04 AM
Quote from: Organicjedi on September 05, 2019, 08:01:58 PM
Are you planning on racing in a club or just a track bike? Club racing rules would limit what you can all do in some areas such as carb choice.

Would like to get into some club racing. Haven't researched a lot yet as to which one yet. Any recommendations?

I live in the North East (Finger Lakes region of NY). We don't have any local tracks except for NYST but they don't race there. Pineview run is also starting to open up to bikes, but track days only and is a 1.1 mile road course. I would have to travel to Ohio, PA, NJ or NH as my closest race tracks. I also heard from a friend that there is a circuit up in Canada on the other side of Ontario lake that races.
Title: Re: 1975 RD350 Race bike build
Post by: Organicjedi on September 06, 2019, 11:12:36 AM
There's always AHRMA Northeast. I don't know what else there is by you.

Sent from my SM-G955U1 using Tapatalk

Title: Re: 1975 RD350 Race bike build
Post by: teazer on September 06, 2019, 12:00:06 PM
For Sure Chuck is very knowledgable, but you could spend some time reading the Rules Book for AHRMA and WERA to get your head around what's allowable.

There are also a few articles around on what to do and how to build a road racer.  One magazine even published a booklet on step by step changes.

Old bikes do not go, stop or handle like modern bikes, so it is even more important with an old bike to spend most dollars on the chassis.  Upgrade forks and brakes and rear shocks first and set the bike up really well. Getting the chassis right has a bigger ROI than motor changes.

Stock carbs are fine up to 60 or more HP but a decent ignition helps and good pipes are a must. You have a few choices there from Swarbrick to Millenium to Lomas to SPEC11 etc.

Heads need to be modified to get squish perfect (and the same on both sides) and run decent race gas. Ignitions are available from PVL or get an ex TZ Hitachi or FEMSA or Motoplat or go modern and get an HPI system and skip a few decades of development.


Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 09, 2019, 06:38:25 AM
Quote from: teazer on September 06, 2019, 12:00:06 PM
For Sure Chuck is very knowledgable, but you could spend some time reading the Rules Book for AHRMA and WERA to get your head around what's allowable.

There are also a few articles around on what to do and how to build a road racer.  One magazine even published a booklet on step by step changes.

Old bikes do not go, stop or handle like modern bikes, so it is even more important with an old bike to spend most dollars on the chassis.  Upgrade forks and brakes and rear shocks first and set the bike up really well. Getting the chassis right has a bigger ROI than motor changes.

Stock carbs are fine up to 60 or more HP but a decent ignition helps and good pipes are a must. You have a few choices there from Swarbrick to Millenium to Lomas to SPEC11 etc.

Heads need to be modified to get squish perfect (and the same on both sides) and run decent race gas. Ignitions are available from PVL or get an ex TZ Hitachi or FEMSA or Motoplat or go modern and get an HPI system and skip a few decades of development.

Thanks for the insight Teazer. Suspension and chassis are all things being targeted as well. I've been reading the rule book for VRRA which is an outfit in Canada. they have 3 tracks they race on and 2 of them are only 3.5hrs from me and the last 1 being 4.5hrs so that is pretty reasonable.

Still going to look into AHRMA and WERA as well.
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 09, 2019, 06:44:39 AM
So, speaking of suspension...What do you guys recommend for rear shocks that aren't outrageously over priced?

I will be going thru the forks on this bike as well. the tubes are rusted to shit so they will need to be replaced as well but I see a couple online stores that offer them.
Title: Re: 1975 RD350 Race bike build
Post by: pdxjim on September 09, 2019, 10:30:36 AM
Quote from: abbott10r on September 09, 2019, 06:44:39 AM
So, speaking of suspension...What do you guys recommend for rear shocks that aren't outrageously over priced?

I will be going thru the forks on this bike as well. the tubes are rusted to shit so they will need to be replaced as well but I see a couple online stores that offer them.

Hagon.
Title: Re: 1975 RD350 Race bike build
Post by: sav0r on September 09, 2019, 12:34:41 PM
Quote from: abbott10r on September 06, 2019, 07:23:04 AM
Quote from: Organicjedi on September 05, 2019, 08:01:58 PM
Are you planning on racing in a club or just a track bike? Club racing rules would limit what you can all do in some areas such as carb choice.

Would like to get into some club racing. Haven't researched a lot yet as to which one yet. Any recommendations?

I live in the North East (Finger Lakes region of NY). We don't have any local tracks except for NYST but they don't race there. Pineview run is also starting to open up to bikes, but track days only and is a 1.1 mile road course. I would have to travel to Ohio, PA, NJ or NH as my closest race tracks. I also heard from a friend that there is a circuit up in Canada on the other side of Ontario lake that races.

Watkins Glen doesn't do any club racing?
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 09, 2019, 12:39:26 PM
Quote from: sav0r on September 09, 2019, 12:34:41 PM
Quote from: abbott10r on September 06, 2019, 07:23:04 AM
Quote from: Organicjedi on September 05, 2019, 08:01:58 PM
Are you planning on racing in a club or just a track bike? Club racing rules would limit what you can all do in some areas such as carb choice.

Would like to get into some club racing. Haven't researched a lot yet as to which one yet. Any recommendations?

I live in the North East (Finger Lakes region of NY). We don't have any local tracks except for NYST but they don't race there. Pineview run is also starting to open up to bikes, but track days only and is a 1.1 mile road course. I would have to travel to Ohio, PA, NJ or NH as my closest race tracks. I also heard from a friend that there is a circuit up in Canada on the other side of Ontario lake that races.

Watkins Glen doesn't do any club racing?

No they won't allow motorcycle racing. There isn't enough run off for them and there are too many walls. Liabilities I suppose. It's too bad because that's only an hour from me!
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 10, 2019, 06:17:31 AM
Brought the RD home last night! It's crusty...but a good base to start with. Can't wait to dive into it this winter.

I'll be selling a lot of stuff off of the bike since I won't be using it on the street if anyone is interested in anything.
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 10, 2019, 06:17:58 AM
another picture
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 10, 2019, 06:18:17 AM
and 1 more
Title: Re: 1975 RD350 Race bike build
Post by: bitzz on September 10, 2019, 10:30:59 AM
If you plan on racing with the VRRA, and want to be competitive; get an RD400.
The class structure puts your RD350 up against TZ350s.
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 10, 2019, 11:49:11 AM
Quote from: bitzz on September 10, 2019, 10:30:59 AM
If you plan on racing with the VRRA, and want to be competitive; get an RD400.
The class structure puts your RD350 up against TZ350s.

That's weird they would do that. I was looking for an RD400 but wasn't having any luck in my financial bracket. Maybe if I come across a basket case I'll snatch one up while I work on this one. could make the 350 a street/track bike and grab a 400 to race. We'll see what happens as time allows but I look forward to the knowledge you guys have here. pretty impressive stuff.
Title: Re: 1975 RD350 Race bike build
Post by: sav0r on September 10, 2019, 06:50:45 PM
No Glen, that is a bummer.

I've hit a few of those walls in cars, they aren't any fun, even with a car around you. It makes a lot of sense when I think about it.

Title: Re: 1975 RD350 Race bike build
Post by: pdxjim on September 10, 2019, 10:44:41 PM
Speaking of rear shocks, Chris ^ does a few mods on RFY shocks to make them perform well.
Title: Re: 1975 RD350 Race bike build
Post by: abbott10r on September 11, 2019, 06:45:47 AM
Are these swingarms legal in vintage racing? sounds like from what I've read online, the stock RD swingers are a bit weak and flex too much. by the sounds of this VRRA rule, it needs to be of "original style". but the last sentence "Replicas of period swingarms are permitted" and that swingarm on Oilypipes website is a DG replica from the times.

http://www.oilypipes.com/yamaha-products.html
Title: Re: 1975 RD350 Race bike build
Post by: bitzz on September 11, 2019, 08:37:21 AM
If you plan on running VRRA middleweight production, the only class an RD has a chance in, the swingarm has to be steel... and no reservoirs on shocks.