Post by wayne on Jul 5, 2024 0:41:59 GMT -5
Thank you for sending us this article Franky, member FHERFERT.
See below an article from Wankel News No. 41. I believe it may be the newsletter of the Hercules Wankel Interest group and has been translated from the original German.
Occasionally there's an "EDIT SRE5MB" and it's my attempt to interpret something that may have been lost in translation.
Otherwise I've retyped the article exactly as received including its minor translation quirks.
As an aside, it's the tidiest carby conversion I've seen particularly as it uses a stock style of air horn.
Wankel News No. 41
Carburetor conversion Suzuki RE-5
2007-04
By Klaus Sauer
We recently received an email from Klaus Sauer in which he describes the conversion of this Suzuki RE-5 to a Bing constant pressure carburetor (32mm) (EDIT Suzuki RE5 Message Board SRE5MB: as this is translated from its original German, I think Klaus would be referring to what we call a constant velocity, CV, carburetor).
Before the conversion, Klaus had complained about the power gaps when accelerating his Suzuki (shaking between 3000 and 4000 rpm) (EDIT SRE5MB: I believe Klaus has to be describing the hesitation or flat spot which is the common and principle issue with the RE5 carb. This interpretation of his problem is backed up by comments made by the author after the conversion. The “shaking” would have to be the common “grinding vibration” and is not a carburetor fault).
Suzuki Wankel specialists such as Hans Reuser had recommended that he replace the original register carburetor with another model, e.g. from Stromberg. Klaus then carried out a number of tests with other carburetors, including a 40 mm Keihin constant pressure (EDIT SRE5MB: CV) carburetor. With this carburetor, the power output in the lower speed range did not improve at all: instead, fuel consumption rose to utopian heights of more than 12 litres/100 km!
Picture 1: Well-maintained Suzuki RE-5 from Klaus Sauer
Klaus’s next series of tests was based on the good old Bing Constant Pressure carburetor, as used in the BMW R65 or R80. These carburetors have the great advantage that they can be obtained as used parts in good condition for little money.
Technically, the Bing 32 mm with the flat carburetor top (cover) is best suited for the RE-5, as there is very little free space above the carburetor. These carburetors were only used by BMW for a few years. The more common version with the nose-shaped cover (R 75/5 to R 80 Monolever, but also W 2000) does not fit well here.
Why 32 mm Bing carburetor?
Mathematically, the passage cross-section of the 32 mm throttle valve matches the maximum passage of the original register carburetor quite well (EDIT SRE5MB: ie the large secondary throat). The original carburetor of the RE-5 has a passage of 18 mm (EDIT SRE5MB: the primary throat) (Venturi funnel = 15 mm) in the partial load flap, and 32 mm (Venturi funnel = 27 mm ) for the full load range (from 3,500 rpm). The 32 Bing now has a slightly smaller passage overall, which in turn improves the torque in the lower speed range – assuming the correct nozzle design. If the larger counterpart with 40 mm (Bing Series 94) were used instead of the 32 carburetor, the peak power would only be increased slightly, although the acceleration in the partial load range would be significantly worse.
After the conversion and adjustment of the jets, the engine characteristics of the Suzuki have improved significantly: The engine pulls absolutely cleanly from low revs to top speed without jerking (EDIT SRE5MB: hesitating is meant, I’m sure). There are no more power gaps! This positive change can be probably attributed to the Bing constant pressure principle, which according to the Bing data sheet offers decisive advantages for mixture formation in the lower rev range, especially in small-volume four-stroke engines!
At the same time, fuel consumption decreased: with the original carburetor, depending on driving style, between 9 and 10 liters were consumed, but after the conversion, it is only between 6.5 and 8.5 liters per 100 km! With this carburetor, the engine responds well to the gas and the motorcycle is overall more lively to drive.
The converted engine was successfully tested by Klaus over a longer period of time. There were no overheating problems at full load! The light color of the exhaust ends, typical for the Suzuki Wankel, remains unchanged. At partial load, the original carburetor tended to over-enrich, which also explained its higher consumption. The spark plugs also had to be cleaned frequently. After the carburetor conversion, these problems are also a thing of the past!
Here is the nozzle configuration used:
The carburetor is an original BMW R 80/7 carburetor. The needle jet and the carburetor needle are from the BMW R 100/S carburetor. The main jet size is 170 (R 100/S) and the idle jet is a 45 jet. Klaus has also installed a spring in the vacuum piston. This improves the engine’s pulling power a little, but is not absolutely necessary.
To connect the carburetor to the engine, a special flange was required, which Klaus turned from a piece of aluminum. The connection to the carburetor is made via a screw-on rubber sleeve that comes from a Suzuki GS 550.
*Picture 2: Detail photo – the carburetor fits harmoniously into the overall picture of the engine!
*Picture 3: Here you can see the rubber flange for the carburetor connection!
Independently of the carburetor conversion, the engine-side part-load control flap was modified (EDIT SRE5MB: I’m sure they’re talking about the Port Valve (PV)). This flap (PV) is normally controlled by 2 cables. Klaus has modified the mechanism so that the control is now connected via the carburetor cable. The flap (PV) was adjusted so that it opens shortly after the throttle valve begins to open.
Overall, this carburetor conversion also seems to be of interest to many other Suzuki RE-5 drivers, although it must be taken into account that an individual approval of the conversion by the TUV is required if the vehicle is not only to be driven on race tracks (EDIT SRE5MB: the “TUV” is presumably Germany’s Roads and Traffic authority).
Please note:
The Hercules Wankel Interest Group publishes conversion tips from its members for general information purposes only. They are always to be understood as well-intentioned advice – without any claim to actual suitability! In particular, the Hercules Wankel Interest Group has not checked the proper functioning of conversion suggestions and their legal consequences!
Klaus Sauer expressly points out that he does not accept any guarantees or liability for his conversion proposal! Liability claims of any kind cannot be derived from this publication – not even against other members of the Hercules Wankel Interest group!
See below an article from Wankel News No. 41. I believe it may be the newsletter of the Hercules Wankel Interest group and has been translated from the original German.
Occasionally there's an "EDIT SRE5MB" and it's my attempt to interpret something that may have been lost in translation.
Otherwise I've retyped the article exactly as received including its minor translation quirks.
As an aside, it's the tidiest carby conversion I've seen particularly as it uses a stock style of air horn.
Wankel News No. 41
Carburetor conversion Suzuki RE-5
2007-04
By Klaus Sauer
We recently received an email from Klaus Sauer in which he describes the conversion of this Suzuki RE-5 to a Bing constant pressure carburetor (32mm) (EDIT Suzuki RE5 Message Board SRE5MB: as this is translated from its original German, I think Klaus would be referring to what we call a constant velocity, CV, carburetor).
Before the conversion, Klaus had complained about the power gaps when accelerating his Suzuki (shaking between 3000 and 4000 rpm) (EDIT SRE5MB: I believe Klaus has to be describing the hesitation or flat spot which is the common and principle issue with the RE5 carb. This interpretation of his problem is backed up by comments made by the author after the conversion. The “shaking” would have to be the common “grinding vibration” and is not a carburetor fault).
Suzuki Wankel specialists such as Hans Reuser had recommended that he replace the original register carburetor with another model, e.g. from Stromberg. Klaus then carried out a number of tests with other carburetors, including a 40 mm Keihin constant pressure (EDIT SRE5MB: CV) carburetor. With this carburetor, the power output in the lower speed range did not improve at all: instead, fuel consumption rose to utopian heights of more than 12 litres/100 km!
Picture 1: Well-maintained Suzuki RE-5 from Klaus Sauer
Klaus’s next series of tests was based on the good old Bing Constant Pressure carburetor, as used in the BMW R65 or R80. These carburetors have the great advantage that they can be obtained as used parts in good condition for little money.
Technically, the Bing 32 mm with the flat carburetor top (cover) is best suited for the RE-5, as there is very little free space above the carburetor. These carburetors were only used by BMW for a few years. The more common version with the nose-shaped cover (R 75/5 to R 80 Monolever, but also W 2000) does not fit well here.
Why 32 mm Bing carburetor?
Mathematically, the passage cross-section of the 32 mm throttle valve matches the maximum passage of the original register carburetor quite well (EDIT SRE5MB: ie the large secondary throat). The original carburetor of the RE-5 has a passage of 18 mm (EDIT SRE5MB: the primary throat) (Venturi funnel = 15 mm) in the partial load flap, and 32 mm (Venturi funnel = 27 mm ) for the full load range (from 3,500 rpm). The 32 Bing now has a slightly smaller passage overall, which in turn improves the torque in the lower speed range – assuming the correct nozzle design. If the larger counterpart with 40 mm (Bing Series 94) were used instead of the 32 carburetor, the peak power would only be increased slightly, although the acceleration in the partial load range would be significantly worse.
After the conversion and adjustment of the jets, the engine characteristics of the Suzuki have improved significantly: The engine pulls absolutely cleanly from low revs to top speed without jerking (EDIT SRE5MB: hesitating is meant, I’m sure). There are no more power gaps! This positive change can be probably attributed to the Bing constant pressure principle, which according to the Bing data sheet offers decisive advantages for mixture formation in the lower rev range, especially in small-volume four-stroke engines!
At the same time, fuel consumption decreased: with the original carburetor, depending on driving style, between 9 and 10 liters were consumed, but after the conversion, it is only between 6.5 and 8.5 liters per 100 km! With this carburetor, the engine responds well to the gas and the motorcycle is overall more lively to drive.
The converted engine was successfully tested by Klaus over a longer period of time. There were no overheating problems at full load! The light color of the exhaust ends, typical for the Suzuki Wankel, remains unchanged. At partial load, the original carburetor tended to over-enrich, which also explained its higher consumption. The spark plugs also had to be cleaned frequently. After the carburetor conversion, these problems are also a thing of the past!
Here is the nozzle configuration used:
The carburetor is an original BMW R 80/7 carburetor. The needle jet and the carburetor needle are from the BMW R 100/S carburetor. The main jet size is 170 (R 100/S) and the idle jet is a 45 jet. Klaus has also installed a spring in the vacuum piston. This improves the engine’s pulling power a little, but is not absolutely necessary.
To connect the carburetor to the engine, a special flange was required, which Klaus turned from a piece of aluminum. The connection to the carburetor is made via a screw-on rubber sleeve that comes from a Suzuki GS 550.
*Picture 2: Detail photo – the carburetor fits harmoniously into the overall picture of the engine!
*Picture 3: Here you can see the rubber flange for the carburetor connection!
Independently of the carburetor conversion, the engine-side part-load control flap was modified (EDIT SRE5MB: I’m sure they’re talking about the Port Valve (PV)). This flap (PV) is normally controlled by 2 cables. Klaus has modified the mechanism so that the control is now connected via the carburetor cable. The flap (PV) was adjusted so that it opens shortly after the throttle valve begins to open.
Overall, this carburetor conversion also seems to be of interest to many other Suzuki RE-5 drivers, although it must be taken into account that an individual approval of the conversion by the TUV is required if the vehicle is not only to be driven on race tracks (EDIT SRE5MB: the “TUV” is presumably Germany’s Roads and Traffic authority).
Please note:
The Hercules Wankel Interest Group publishes conversion tips from its members for general information purposes only. They are always to be understood as well-intentioned advice – without any claim to actual suitability! In particular, the Hercules Wankel Interest Group has not checked the proper functioning of conversion suggestions and their legal consequences!
Klaus Sauer expressly points out that he does not accept any guarantees or liability for his conversion proposal! Liability claims of any kind cannot be derived from this publication – not even against other members of the Hercules Wankel Interest group!
