[DSstroker]

Ok I'm using as Ds7 (RD yamnaha) frame from 72. The rear passenger pegs are in a perfect place already for my feet with a set of clip-ons or clubmans, but what about shifting and braking?

Should I have the shifter cut and an extension welded in, or does someone make rd shifters made for rearsets? And the brake lever; again someone make them short or do I have to have that cut down and welded??

Also, looking at the shop manuals for these bikes they show a diagram of piston that were cut and grooved so as to let the intake stay open longer. Does someone sell these pistons already milled or do I have to give 2 pistons to a machine shop with the diagram? Any other hints or tips for the RD, R5, or Ds7 (all are the same except the LC models and engine size or gears) I would greatly appreciate it. Trying to make this happen with the focus and zeal of a cult member. LOL.

Sounds like 2 lawnmowers screaming in tandem.

 

[krapfever]

Shifter: Some folks just re-mount the shift lever 180 degrees from stock and use the passenger peg mount. This cheap and easy way gives you a "GP" shift pattern (1 up, 4 down). A little weird getting used to it, but it works.

Brake: Yeah, you're going to have to fab something. Some modern sportbike pegs have the setup you are looking for (mid 90s gsxr/katana, and fz 600's -- somebody on here can verify this as I'm sure there are even more). What you want is a peg-through-lever design where the lever rotates on the peg mounting shaft and the brake/shifter linkage mounts to the lever using a heim (swivel) joint. Aftermarket rearsets all operate with this basic design. If you can find a set, the good news is you can mount both sides and eliminate the need to rely on the GP shift pattern mentioned above.

By the way, regardless of what setup you use, you will have to bend up some steel rod to make the brake linkage. (The DS7 is not a cable rear brake is it?) Also, making a functional rear brake light switch is probably more trouble than its worth.

Milled pistons? Not sure exactly what you are talking about.



Honda go sideways!

 

[LiLBull]

Not every one is familiar with your particular frame so pictures of what you have help for further discussions.To answre your particular question I would have to search the web find your frame and then find a picture that has it in close up so I can see what your up against.rear sets are another of those weekly or bi-monthly newbie questions.
A very important question but one everyone has answered more then once so responce will be spuratic depending on mood.
Easiest way to accoplish rear sets is to get some at a salvage yard or used bike shop where they have a bid full to sift thru .
because mpdern bikes use them they are plentiful.How ever getting a pair that does what you need to work on your bike,thats made in aluminum and not the older heavey steel.And that they will sell you reasonably will be your barganing skills.
Ask what they want for a set before you start rifling thru their bins so they dont scatch there head and give you some high priceafter you have done all the leg work.
After you have the pieces you still have to make them work.I agree that the grandprix shift is sometimes the easiest arrangement.
you ussually can adapt the brake rod you have but may have to rethread the end with a die.
Once you have gon ethru this once you will see its just a thing you have to make and come up with .
The othe idea is to find bikes like yours with rear sets on them and copy what the did.a club would be usefull for a particular make.

as far as pistons Im assuming you mean carbs and as Ill say time and time again...you just cant mod on thing without sacrificing another for street leave engine as stock as possible except for exhaust and filters,and good oil.
get the best shocks and springs ,seat and tank and bars you can get set up your rear sets so you can use them in comfort,get good tires and wheels .HAVE A GREAT CHASSIS and a stock motor will give you a full streetable motor that you can actually use all of with your new chassis.


Im so far behind ,that I think Im in first.

 

[kenessex]

I believe what you are talking about with the pistons is relieving the skirt and lowering the dome in the area of the ports. In short, don't do it. Run stock pistons until you know what you are doing and what you want. Cutting pistons without having good expansion chambers, carbs and cylinder porting is simply an exercise in futility. It won't work and the pistons are fragile enough in a stock engine that you will end up cracking skirts and sticking rings. If you want a good easy to ride bike for the street or beginning track rider then leave the engine alone!!!! I really mean it. Don't port it or polish it or match the transfers or anything. If you want to fool around with that stuff then get your engine, exhaust, carbs and chassis perfect first. Then get a spare motor, DS7,r5b or c, RD250 or 350,(think they all will pretty much bolt into your frame) and work on it. That way when it seizes (it will), blows crank seals( it will), breaks a piston(it will) or lunches a crank( it will) you will have a good reliable motor to throw back in and keep riding or racing. If you are going to race it take a spare motor with you. Ever buy a spare RD350 at the track so you can spend all Saturday night in the back of a Dodge van, tearing down two motors so you can replace the transmission so you can race on Sunday? I have and it sucks. You can do a motor swap in under an hour on a race bike. High performance modified 2 strokes make great power and are a blast to ride. They lose reliability and have a huge learning curve before you can claim that they are going to stay together.

Good luck,
Ken

AHRMA 412
Vintage racing - old guys on old bikes

 

[champ]

ken, by jesus, where have you been????

JS

 

[kenessex]

Champ,
School has started. I had to be back at our district office for meetings on July 31. Then I went to my school for a week to get it in shape. Then I had to go to Anchorage for a week to get my 9 new teachers tuned up and have an inservice for the returning teachers. Plus do some major shopping for the first part of the year and then fly back to Hooper Bay(find it on the map) for three more days of getting ready for school. Kids started on Thursday. Another successful start to another wonderful year of education.
I have barely had an opportunity to check in here and see what is happening. Plus you guys are suck a vulgar bunch of fucktards that our network censors about half the threads here for excessive profanity. Then if I really want to read it I have to use my personal laptop and sign on through AOL so it isn't filtered.

Ken

Tex, still looking for a teaching job in wonderful rural AK.

AHRMA 412
Vintage racing - old guys on old bikes

 

[xander450]

Bull... it's a 2-stroke.

For all the talk of chassis upgrades, I wouldn't mind having a conversation about what ought to be done to an engine, should someone decide not to follow the orthodox progression (clips/rearsets, steering/swingarm bushings, shocks, tires, then top end, boring/crank shaving, external oil cooling, and finally selling for a quarter of what you put in it). Otherwise we're going to keep having conversations about how to install clubmans.

I wasn't always so ornery.

A

 

[kenessex]

Xander,
I'll give it a go for you. First off it depends on your intended use. I would not run a race motor on the street much, but I would run a well built street motor on the track. For instance when I was racing Honda 500 singles I used the Wiseco 12.5:1 piston and it would detonate like crazy unless race gas was used. I never ran that set-up on the street.

So for a good place to start with HP performance mods; 4 stroke
1. Good exhaust - better gas flow and less weight
2. Bigger more easily adjusted carbs - EG VM- series Mikunis
Trade off- usually loss of bottom end torque
3. Ported head and good valve job
possible trade off - loss of bottom end - might not notice on the street
4. Cam and valve springs - depending on cam can add HP wherever you want within reason.
5. Higher compression bigger bore pistons - power gain everywhere in the rev range. Guaranteed loss of engine life. Places additional strain on crankshafts, rods, bearings, seals, clutches, some primary drives, etc.
A 2 stroke is a little different.
1. Match the cylinder ports to the liner and the cases to smooth the flow. This should level out the torque curve everywhere. A basic blueprinting operation.
2. On a multi, cc the heads to balance the power pulses.- should make for a smoother revving engine.
3. with a reed valve engine, replace the reeds with more flexible, stronger reeds. Better bottom end smoother transitions.
4. Good exhaust expansion chambers - will narrow up the power band. Depends on the pipes where it will be.
5. Bigger carbs - will narrow up the power band but you will be able to compensate for the pipes creating rich and lean spots. You may need to go with power jet Mikunis to avoid excessive lean spots on acceleration.
6. Porting the cylinder, raising and lowering ports, cutting piston skirts and crowns, changing squish bands in the heads, opening piston windows in the skirts. Vary dramatically from engine to engine and need to be done by an expert!!!! Will dramatically decrease engine component life. Crank life may become measured in tens of hours. Piston and ring life in increments of single hours under race conditions.

2 strokes are much more sensitive and failure can be much more catastrophic. From my personal experience, I generally don't care for the 2 strokes as much, although I have raced them and probably will do so again and I really want a big air cooled 2 stroke cafe racer for the street. In either case, I will have a stock engine with cleaned up and matched ports, a bottom end expansion chamber and stock carb. Since I know a little bit about racing 2- strokes I will take a look at the piston crown to get an idea about flame fronts and such and if need be send the head out to an expert to get reshaped for better gas flow not more HP. I don't like lean and rich spots during the combustion process.
My good CB350 has stock(K0)cam, mildly ported head, stock pistons, 2-1 exhaust and stock carbs. It needs bigger better carbs cause it runs out of breath on top end. It is a good streetable engine and competative on the track. I believe Tex's is about the same. I have built stronger CB350 race motors in the past. High compression big bore pistons - eventually cracked rings after 2 seasons, lots of races. Webcam, lightened valves, light retainers, heavy duty springs - got leaking cam seals, broken retainers, scuffed cam bearings, worn rockers and seized valve guides. Normal wear for that set-up. I ran 30mm Lectron carbs that would stick open in the rain but made great HP. I won 5 or 6 WERA regional championships with that bike and missed more practice time and sleep than I am willing to put up with anymore. If it isn't reliable on the street or the track I am not interested.

So my suggestion is if you are not experienced in building engines, I would not go beyond basic blueprinting or what is known to be a basic improvement proven to work or not work on your particular bike. For instance, on a Yamaha 2-stroke twin do not use individual air cleaners with a hard back end because it causes wave issues in the intake and makes the carbs difficult if not impossible to tune. For the RD series and presumably the DS7/R5( but who knows for sure since they ar piston port not reed valve engines) the best solution is to use the stock RD intake rubbers with a K&N filter.

Sorry about the long post, but there is no easy answer and we haven't even gotten into the peculiarities of individual differences of various makes and models.

Ken

AHRMA 412
Vintage racing - old guys on old bikes

 

[Geeto67]

the biggest advantage you have with a 2 stroke is that you are not lugging around the added weight of a valve train. (weigh a cb750 head and then subtract the weight of 4 h2 heads and you will be astonished at how much a valvetrain weighs - hell the cb750 cam alone is around 15 lbs).

Since 2 strokes suffer reliability issues when you hot rod them much more than the 4 strokes the best way to make any kind of power (outside the initial blueprinting which I think is almost manditory as well as reed valves) with them is to lighten the bike as much as possible.

Scrambler73 on the kawi triples board showed that you can get low 300lbs wet weights out of the heavy h2 750 motors and heavy kh500 frames. With chambers and a decent set of carbs you are looking at 70-80 crank hp or as much hp as a 78 cb750f but 200lbs less. There are two stroke bikes out there that can get the weight down enough to get into the magic sportbike power to weight ratios of 5 lbs per hp without making over 60hp. I remember seeing some racing RD350s that were in the 250lbs range. That is pretty light.


Ken, it is funny that you mention the individual K and N filters. presumably they work really well with the RD motors because they are reed valve. One thing the kawasaki triples guys were complaing about with pod filters and piston port engines is that the pod filter end cap actually works to send reverberation back toward the pipes (like a reverse chamber) thus making it harder to tune. On a piston port engine I would recommend a foam Uni filter if you want an individual filter or a pod filter with a plastic endcap (as they tend to absorb the sonic waves and not send them back).

If you can convert a DS/R5 to reed valves do it - it makes tuning much more consistent and easier.


Edited by - geeto67 on Aug 26 2007 10:06:45 PM

 

[LiLBull]

its good to have chats about engines when may thats exactly what is left to do, to your bike after you have a well to do potent chassis.
The reason so much talk for the NEWBIES is just thats what everyone thinks will make them go fast...the engine.
You have to be able to use the power it generates.You have to be able to run and stop this energy once you increase the power.
Most beginners in cars and bikes have no clue that any engin emod over stock is a major compromise somewhere else in the power band.
Most dont understand race engines ,not that they dont belong on the street.Its the very fact race engines are fine tuned in a narrow power band .Hence not made for the street where an over all WIDE powerband is needed...sometimes to get out of trouble,from unattentive motorists.

The reason the majority of racers tell you chassis first is they are completely familiar with the intent a race engine has for making power...SPECIFICLY for a Specific purpose.

So engine mods are fun to talk about and expensive to trial and error one for the street will make less patient people beat it with a hammer and never want a bike again.
So talk about engines LAST...you can not go directly ahead and do any engine mod first.
That said go at it have fun ,Ill enjoy all my stock engine has to offer,nestled in side my light upgraded chassis, for many a performance mile...passing house upon house of guys that play with their engine first,fustrated and alone as I actually ride my bike day after day.

Im so far behind ,that I think Im in first.

 

[DSstroker]

Thanks for all the help guys. I think I'm gonna just put a stock rd350 engine in the bike (now that I know it will in fact bolt up) and a set of ported heads I can pick up for a relatively cheap price. I don't wanna race this little guy, just be able to get out of the way of the tailgaiters or other un-forseen road hazards as the 250 and its gearing is a little lacking once you're up to 70mph on the highways. It actually tops out at about 85.
The bike is in pieces right now and I'm stripping the frame for a backyard repaint...lol.
Geeto, if you read this: any salvage yards here in NY? I really can't find any online or in my upstate phone book.
Thanks again everyone.

Sounds like 2 lawnmowers screaming in tandem.

 

[Geeto67]

In the city area....no, but upstate there are a few I have heard of but never been. There used to be a real good one in rochester but I haven't been there since the 1990s.

There are a few in joisey, and one I heard abotu recently in philly. Gimmie a few days to wrestle up some names and addresses.

 

[DSstroker]

Thanks Geeto. Depending on where in joisey, I may know how to get to the town. I'm from the Monmouth shore area originally. I'm living up in Albany now, so I'd of course be willing to drive quite a ways to get what I need. Now to go add to the how to be a dummy post in techincal forums.

Sounds like 2 lawnmowers screaming in tandem.