RE- suscitation

[peaktopeak]

Thought maybe I would write about my journey with the BOF (Bike of the Future) so far. Seems that modern bikes work so well
at most everything, that they are a bit sterile when compared to vintage bikes. There is gratification in working on a bike and
actually making it run better. The plug adapter was my first modification and was supremely effective in improving engine performance.
It idles better and runs smoother. Hopefully once I get to the carb adjust, there will be equally beneficial results.
I had moments of doubt at first. I wasn't sure I had made a good decision with my $8600.00. I even asked the seller if he would consider
letting me return the bike for another in his collection. Looking back, I am glad he said no. My final reason for keeping it was, they are
not making any more Suzuki RE5s. The more I ride it, the more I appreciate some of the unique features. The bike handles really well.
It is significantly better than the GT750K I restored five years ago. Perhaps the rotor has an affect on the way it corners. It truly is a
ride like no other. Maybe , God willing and the creeks don't rise, I can ride it into my dotage.

 

Attachments:

[wayne]

Please continue to update as you work on the bike. It's valuable information. I found little difference from the plug adapter but that's a feature I've found with RE5's. They're very individual.

And you're absolutely right re the handling. Way superior to the GT750K and also to the later GT's (I also owned an M GT). I think it was Cycle magazine that ran an eight bike test which included GT, Z, Norton, BMW, Goldwing and others. Although they weren't that impressed with the RE, they named it the best handling bike and that was reflected by several magazines back in the day. It's not a bad bike, quirky, different but the overall package is a decent ride. However, with everyone jumping on the wagon to bag the bike as the years rolled on, the good stuff was forgotten.

[h2e Al In Aus]

hi I am with Wayne on the handling thing , I am more than happy with both my RE s , ,ground clearance is very good as well , and general performance on the road is very good for a bike of its age and engine size , they are a pleasure to ride when everything is right !!!!, its a pity Suzuki didnt spend a bit more time getting them set up right before they released them , but it was the wrong time ,wrong bike , wrong yr , wrong everything !!!!, thank god they did it !!!, it is a one of a kind , that most would not aprieciate

[peaktopeak]

When I first got the bike it had old hard tires. I bought a set of Dunlop 204s at the shop and had the guys sthingy them on. The new rubber was transformational. Loads of grip, quick and easy to transition left and right and ground clearance galore. I noticed that it is more of a tug to get it on the center stand now. The aspect ratio must be lower with the Dunlops. I now roll the back wheel on to a piece of wood to make the center stand easier to deploy.
The RE has a nice combo of light steering and stability that rivals some RD350s that I have owned. It has none of the head shake of those old Yamahas. I wonder if the Norton rotarys raced at the Isle of Mann also had clockwise rotating rotors.

Of course vintage means there is always something to fix. Right now I am fettling the leaky petcock. parts are ordered. We have 10% ethanol in our fuel here which is not good for anything rubber. After that, I am going to see if I can improve the fueling. I ride at an elevation of 5000 to 9000 feet, and sometimes higher, so I would love to flow more air. I did tidy up the stock air filter but I would like to get one of the Jess filters to see it it makes a difference. 30% more flow would be very helpful. My bike came from Minnesota and is most likely jetted for lower elevation. I have not found much on jetting here on the board. Are REs sensitive to jetting?

[wayne]

Yes, they are sensitive to jetting. The reason there's so little about jetting is people are scared by that carb. Very little successful fiddling has been done. I had a very experienced engine tuner and dyno shop owner who was dumbfounded by the readings as I changed jets during dyno runs. They're not an ordinary motorycle carb. I do know of one meticulous experiment going on which involves rejetting several parameters in the bike. Hopefully it'll work.

Meanwhile, the PMJ (primary main jet) is accessible under the brass bolt on the side of the carby where the air horn bolts on. At sea level, increasing this jet's size is the quickest way to significantly improve a hesitating bike. At elevation, you could try changing it out with maybe a leaner jet. For your info, stock was 90 and later reduced to 87.5 when some other changes were introduced. You can change it in a few minutes. Once unscrewed, stick a toothpick down the hole to stab the jet and remove it. Under the carb very close to that PMJ is the SMJ (Secondary Main jet) also behind a bolt. Stock is 180. You may consider trying some other sizes given your extreme elevations.

Buy a handful either side of those sizes and have a play. Try some brief runs without your air filter and note the effect. Fastest way to increase airflow although not the way you'd want to run it long term.

[peaktopeak]

I have turned up the idle. Lower idle is common with a carbureted bike at altitude. It is now right at 1225 rpm. The bike liked this. I also moved the air mixture screw out a 1/4 turn. I did not notice any difference so I put it back at 1/2 turn out from soft shut. I have tons of jets from my two stroke road racing days. I will see if jetting makes a difference. One change at a time, of course.

[timpa136]

Lower idle and immediate choke off from a cold start is what I noticed from different vacations at altitude as well.

Idle mixture sounds bout right at specs. The air screen/filter on the float bowl cover benefits from frequent attention.

[wayne]

Jul 16, 2021 9:04:34 GMT -5 peaktopeak said:

I also moved the air mixture screw out a 1/4 turn. I did not notice any difference so I put it back at 1/2 turn out from soft shut.

If the "air mixture screw" that you are referring to is the brass screw with spring that comes out at 45 degrees on the carby top, that's actually a fuel mixture screw. It meters aerated fuel so opening it allows more fuel downstream of the primary butterfly.

But generally, very hard to pick the difference with that screw. When you get closer to getting the bike running well, the procedure for adjustment is HERE under RE5 SERVICE BULLETINS. Open and go to page 8 (one of the last procedures of Bulletin #9).

[peaktopeak]

A quick correction I’m running Dunlop 404s not 204s
I am very appreciative of the advice and feed back from the board.
My bond with the bike is growing. I enjoy having my curiosity
piqued and learning about this machine. Sure, my Z H2
Is a wonderment of modern technology, and ungodly fast
but in a way, also uninteresting. Don’t get me wrong,
I adore it, just in a different way than the RE5. I guess
that is why having to few motorcycles is not possible.

[peaktopeak]

I went for a ride after fixing my leaky fuel petcock. It was an interesting ride. It was a hot day last Monday and as I left the front range and began the climb to my favorite mountain route a new thing happened with the RE5. As the temperature went down and the altitude increased, my temp gauge went all the way to C. I thought, oh it must be broken, but the motor was indeed running very cool. I downshifted and brought the revs to 4200 rpm and the needle began to rise. Hmmm. So at the top of the route, I realized that the bike was running better. Not as much hesitation and much smoother acceleration. The temp gauge was indeed working and indicated that the bike was running a bit cooler. Overheating has not been an issue for me so far.

The day before my ride I made note of the PMJ and the SMJ. They are a 100 and a 180. Thanks to Wayne about the toothpick extraction method, worked like a charm. I will try a 102.5 on my
next ride and see if that makes a difference. I am thinking that the bike is lean because it ran better as I climbed to 8000 ft. I will also have a look at the plug and see if it can tell me anything.

I am having a great time riding this bike.

[charles]

Jul 21, 2021 15:39:39 GMT -5 peaktopeak said:

I am having a great time riding this bike.

So say we all.

Congratulations.

Charlie

[timpa136]

Jul 15, 2021 21:57:35 GMT -5 peaktopeak said:

When I first got the bike it had old hard tires. I bought a set of Dunlop 204s at the shop and had the guys sthingy them on. The new rubber was transformational. Loads of grip, quick and easy to transition left and right and ground clearance galore. I noticed that it is more of a tug to get it on the center stand now. The aspect ratio must be lower with the Dunlops. I now roll the back wheel on to a piece of wood to make the center stand easier to deploy.
The RE has a nice combo of light steering and stability that rivals some RD350s that I have owned. It has none of the head shake of those old Yamahas. I wonder if the Norton rotarys raced at the Isle of Mann also had clockwise rotating rotors.

Of course vintage means there is always something to fix. Right now I am fettling the leaky petcock. parts are ordered. We have 10% ethanol in our fuel here which is not good for anything rubber. After that, I am going to see if I can improve the fueling. I ride at an elevation of 5000 to 9000 feet, and sometimes higher, so I would love to flow more air. I did tidy up the stock air filter but I would like to get one of the Jess filters to see it it makes a difference. 30% more flow would be very helpful. My bike came from Minnesota and is most likely jetted for lower elevation. I have not found much on jetting here on the board. Are REs sensitive to jetting?

Yes they are sensitive.  Also the humidity and temperature, air filter and subject to the last tank of gas . Sometimes the slightest nudge of the idle mixture is what really settles the bikes performance.  Keep us posted. Tim

[peaktopeak]

So I have been Mr fettle here lately. I am finding that I can make it run better. I tried going way lean on the 
primary jet. I tried an 85. It said "no way Jose-san" ,bad idea. I didn't even try to ride it. Eventually settled on the 
100 primary that was in it when I got it, and down one step on the secondary to 175. Now it has better pull on top
from 4 to six RPM. The stumble is hardly noticeable as long as I am very smooth with the throttle.  Gas mileage
dropped to an unacceptable level. 80 miles to reserve from a full tank. The manual states that the primary jet is mostly responsible
for fuel efficiency. I believe it. So next, I picked up a 97.5 and a 95 to see how they do. The 90 I tried really did not
work. It just falls on its face at 3750 and won't get on with it until 4100. I know the cable sync is the answer but
I wanted to get as close as possible on the jetting before I get into that. Next up is 97.5 PMJ and 175 smj.  
I did another cleaning on the air filter and this time no oil. That seemed to be a good step. When I tried simply removing 
the air filter, it would not even rev. This one keeps me busy at the trial and error but it is interesting. 

 

[wayne]

Thanks for the feedback. I've not tried the 175 SMJ in combination with a larger PMJ. Hmmm......

Get stuck into that cabling. It's pretty straight forward and should be done before you go too far with jets. Just make sure you follow Bulletin 9 and get all the cables loosened off not forgetting the grub screw and locknut under the throttle grip. Undo and back right off.

Make sure when you set "Zero" on your angle gauge, primary butterfly is fully closed (it tends to hang open a fraction due weight of cabling so will give you a false starting point). Push it closed with a shish-kebab stick and check that's when you're showing Zero on the gauge.

[peaktopeak]

Yep bulletin 9 is next up after the jetting is as good as I can get it. I do need to buy an angle gauge if anyone knows where there is one available.