Post by wayne on Nov 21, 2022 22:42:29 GMT -5
Another essay from Sam. It clarifies the correct plug gap setting (as there were several Suzuki errors) and, as Sam does, tells a good story:
In reply to the spark plug gap controversy, I can fully understand the confusion in the Rotary Community. With the mixed gap settings and incorrect information supplied by Suzuki, this certainly would lead to some in-depth discussion.
To help clear this up, on page 148 of the RE5 Service Manual, it states that the early NGK A9EFV spark plug should be set at 0.55mm (0.06”). The manual is semi correct. The 0.55 mm is right but the 0.06” in is wrong. An update service bulletin No. RE-3, dated March 15, 1975, tries to correct the 0.06” with a new value of 0.165” (which is also wrong). It should read 0.0216”, or 0.022”. Thus, we now have 0.55 mm and a 0.022” for a correct A9EFV gap setting. These figures are confirmed on page 40 of the 1975M Owner’s Manual.
The A9EFV spark plug was later replaced by the improved platinum tipped version A9EFP, which also had a new gap setting of 0.032” (0.813 mm). This is correct. However, on page 40 of the new 1976A Owner’s Manual, it lists the A9EFP setting at 0.031” (0.8 mm). This should be corrected to read 0.032” (0.813 mm). This is the setting that I use.
Remember, the Rotary engine is not as regimented as the standard piston type. It is flexible and forgiving with allowances. Thus, the gap setting could run from 0.030” (0.762 mm) to 0.032” (0.813 mm) without any difference in performance. As an added note, the official NGK master spark plug chart lists the A9EFP at 0.032”.
Also, to answer your questions regarding other RE5- spark plugs, remember that the big 18 mm plug was designed specifically for the RE-5 only. It will not be found in any trucks, tanks, planes or rockets. Suzuki R&D engineers worked closely with NGK to develop this special plug. NGK produced the A9EFV model plug that was used successfully on the RX and RP models prior to production of the RE-5.
At that time Suzuki was looking for a second source supplier as a back up, just in case something happened to NGK. They went over to ND/Nippondenso, who manufactured the MA31ept plug that looked almost identical to the NGK. Suzuki used both the ND and NGK plugs in the first 500 mfg (50-50). However, the ND plug was prone to burn out and foul up in less than 600 miles. Needless to say, the MA31ept plug was recalled and destroyed and was immediately replaced with the NGK A9EFV.
For your information, below is a list of spark plugs used throughout the life span of the RE-5 Rotary:
1. MA31ept (Nippondenso) – Recalled
2. A9EFV (NGK)
3. A9EFVP (NGK)
4. A9EFP (NGK)
5. A9EFP (NGK – Racing)
6. AU10EFP (NGK)
7. AU10EFP (NGK – Racing)
8. BF-78G (Champion)
9. BF-78GS (Champion – Racing)
Note: The Champion spark plug was manufactured specifically for the RE-5 Rotary market, and was exactly like the NGK A9EFP, at half the price. It looked and worked every bit as well – if not better. Due to being an exact clone, reports of litigation on the horizon by NGK caused production of this plug to cease in less than one year. The BF-78G and the MA31ept plugs are much sought after by RE-5 collectors and museums for display. -- Sam
Further trivia, the "A" denotes thread size 18 mm. V denotes a Gold Palladium centre electrode. P for a platinum electrode. U denotes a surface or semi surface discharge plug.
For interest, on the left are the three basic NGK's. The A9EFV (gold palladium), A9EFP (platinum tip) and the later AU10EFP (slightly colder). For interest, two additional plugs that fit and work, the BOSCH MAG310T2SP and MAG340T2SP. I think the 310 is the hotter, correct me if you know better. If anyone has a picture of the Champion please contribute.
Amazing the resources that live behind this Board. TIMPA136 sent me the following pics. Here is the extremely rare Nippon Denso MA31
The fairly rare NGK A9EFVP (#3 on Sam's list)
And not mentioned by Sam but indeed made for the RE5, TIMPA136 sent me these pictures as well. The NGK E8103 and E8095. He says the 8095 is possibly a mid heat range between the 9 and cooler 10. TIMPA136 also tested the Champion BF-78G but as per conditions of the test, it had to be returned to Champion.
In reply to the spark plug gap controversy, I can fully understand the confusion in the Rotary Community. With the mixed gap settings and incorrect information supplied by Suzuki, this certainly would lead to some in-depth discussion.
To help clear this up, on page 148 of the RE5 Service Manual, it states that the early NGK A9EFV spark plug should be set at 0.55mm (0.06”). The manual is semi correct. The 0.55 mm is right but the 0.06” in is wrong. An update service bulletin No. RE-3, dated March 15, 1975, tries to correct the 0.06” with a new value of 0.165” (which is also wrong). It should read 0.0216”, or 0.022”. Thus, we now have 0.55 mm and a 0.022” for a correct A9EFV gap setting. These figures are confirmed on page 40 of the 1975M Owner’s Manual.
The A9EFV spark plug was later replaced by the improved platinum tipped version A9EFP, which also had a new gap setting of 0.032” (0.813 mm). This is correct. However, on page 40 of the new 1976A Owner’s Manual, it lists the A9EFP setting at 0.031” (0.8 mm). This should be corrected to read 0.032” (0.813 mm). This is the setting that I use.
Remember, the Rotary engine is not as regimented as the standard piston type. It is flexible and forgiving with allowances. Thus, the gap setting could run from 0.030” (0.762 mm) to 0.032” (0.813 mm) without any difference in performance. As an added note, the official NGK master spark plug chart lists the A9EFP at 0.032”.
Also, to answer your questions regarding other RE5- spark plugs, remember that the big 18 mm plug was designed specifically for the RE-5 only. It will not be found in any trucks, tanks, planes or rockets. Suzuki R&D engineers worked closely with NGK to develop this special plug. NGK produced the A9EFV model plug that was used successfully on the RX and RP models prior to production of the RE-5.
At that time Suzuki was looking for a second source supplier as a back up, just in case something happened to NGK. They went over to ND/Nippondenso, who manufactured the MA31ept plug that looked almost identical to the NGK. Suzuki used both the ND and NGK plugs in the first 500 mfg (50-50). However, the ND plug was prone to burn out and foul up in less than 600 miles. Needless to say, the MA31ept plug was recalled and destroyed and was immediately replaced with the NGK A9EFV.
For your information, below is a list of spark plugs used throughout the life span of the RE-5 Rotary:
1. MA31ept (Nippondenso) – Recalled
2. A9EFV (NGK)
3. A9EFVP (NGK)
4. A9EFP (NGK)
5. A9EFP (NGK – Racing)
6. AU10EFP (NGK)
7. AU10EFP (NGK – Racing)
8. BF-78G (Champion)
9. BF-78GS (Champion – Racing)
Note: The Champion spark plug was manufactured specifically for the RE-5 Rotary market, and was exactly like the NGK A9EFP, at half the price. It looked and worked every bit as well – if not better. Due to being an exact clone, reports of litigation on the horizon by NGK caused production of this plug to cease in less than one year. The BF-78G and the MA31ept plugs are much sought after by RE-5 collectors and museums for display. -- Sam
Further trivia, the "A" denotes thread size 18 mm. V denotes a Gold Palladium centre electrode. P for a platinum electrode. U denotes a surface or semi surface discharge plug.
For interest, on the left are the three basic NGK's. The A9EFV (gold palladium), A9EFP (platinum tip) and the later AU10EFP (slightly colder). For interest, two additional plugs that fit and work, the BOSCH MAG310T2SP and MAG340T2SP. I think the 310 is the hotter, correct me if you know better. If anyone has a picture of the Champion please contribute.
Amazing the resources that live behind this Board. TIMPA136 sent me the following pics. Here is the extremely rare Nippon Denso MA31
The fairly rare NGK A9EFVP (#3 on Sam's list)
And not mentioned by Sam but indeed made for the RE5, TIMPA136 sent me these pictures as well. The NGK E8103 and E8095. He says the 8095 is possibly a mid heat range between the 9 and cooler 10. TIMPA136 also tested the Champion BF-78G but as per conditions of the test, it had to be returned to Champion.
