- Location
- Ontario, Canada
G'day fellers and fellerettes. I have just bought an older head pipe to complete my B pipe setup, but for some reason I always come up these weird questions that I seem to have a hard time locating the answers to lol.
So the question is, for the SuperJet version of the B-pipe head pipe, does it perform to the same level across all versions, or are there differences between the older head pipes known as the "A" pipe, vs. what we have seen for the last who knows how long "B" version?
I did a lot of digging around and here is what I have found, if anything needs to be corrected please mention it, but the initial question remains. Along with the assistance of a few of our best here on the X
this is what I have found about the headpipe from its early days through to current.
Keeping in mind, I believe what I bought to be the "A" version of the head pipe but maybe it is an early "B" that just never received the "B" designation on the tag. It has nothing more than Factory Pipe engraved on the tag. So anyway, after much research on this thing, I think I finally found some reference to them to help identify which one is which...hopefully this will serve as a useful reference for someone else and save some search time.
The earliest "A" version: The earliest "A" versions had only 2 water screws, the 2 screw version was used across the board on all Factory Pipes from the Kawi 650sx, 750sx/sxi, and SJ 650. They all have the same thicker flange of about 1/2 inch difference from the current "B" version, but the bores might be different. The Yami variant came with a 43 or 44mm bore by default.
The next generation "A" version: It still has a thicker bolt flange than the "B" version by about 1/2" which is essentially the only difference between the two other than also not being tagged on the engraving plate as a "B" pipe. This next gen version is the 3 screw version which I believe is when they started to separate them from each other making one more for Kawi and one more for Yami. When the "B" tag arrived? I do not know.
The "B" version: The current and only version that we are most familiar with having a flange thickness of about 1/2" thinner than the "A" version. It has been noted that on occasion the flanges have cracked at the bolt locations due to the thinner flange thickness. The only other change is that earlier "B" versions which were probably meant for the 650's? had a bore of 43-44mm, as did the manifolds of that time. This was found to be problematic on the 701 as it contributed to melting pistons. GroupK states on one of their "resto" write-ups that they made this observation and reported it to Factory. If I read this correctly, it was not long after that, that Factory began making both manifold and head pipe bores at 46mm? as standard issue. The current normal gasket (at least from Blowsion) measures at 46.5mm I.D. This bore diameter change cured the piston melting issues that some may have seen on the 701 engine.
The newer "A" version: Further along the line the SXR variant was made, the standard bore diameter from Factory on this variant I do not know. The SXR head pipe will work on the Yamaha but the Yamaha head pipe will not work on the Kawi ( <---according to Blowsion on their website) and due to the number of degrees the pipe twists inward on the Yamaha version ( <--- according to posts and photos found from the past). The SXR version is in more of a straight line toward the front of the hull whereas the Yamaha variant is twisted and tucked closer into the engine to follow the narrowing round nose hull design. The thicker flange is still there but there have been occasional reports of clearance issues with this head pipe on the Yamaha manifold. It seems that due to how the Yamaha manifold contours inward on the PTO side to clear the Yamaha oriented "B" version head pipe, the contour is only so tall, the thicker flange raises up the large end of the head pipe (as we would expect it to ) and can sometimes be a fitment issue in regards to both the chamber-to-head pipe mating as well as coupler thickness and installation.
What I also do not know is:
- if there have been any changes to the inside diameter from the older "A" pipes to the current "B"
- if there have been any length changes made to accommodate the different sonic wave of the 701 from the 650
- if the water screws and hole sizes have been increased or decreased <---probably doesn't matter but might as well mention it anyway
- if one variant performs better than another <---probably not if there have been no dimensional changes aside from the degree of twist between the current Yamaha and Kawi versions
So how about peeps...is there anything missed? Is there any known performance improvements from one to the other under original Factory Pipe specs other than the changed bore sizes to accommodate the 701 needs?
So the question is, for the SuperJet version of the B-pipe head pipe, does it perform to the same level across all versions, or are there differences between the older head pipes known as the "A" pipe, vs. what we have seen for the last who knows how long "B" version?
I did a lot of digging around and here is what I have found, if anything needs to be corrected please mention it, but the initial question remains. Along with the assistance of a few of our best here on the X
this is what I have found about the headpipe from its early days through to current.Keeping in mind, I believe what I bought to be the "A" version of the head pipe but maybe it is an early "B" that just never received the "B" designation on the tag. It has nothing more than Factory Pipe engraved on the tag. So anyway, after much research on this thing, I think I finally found some reference to them to help identify which one is which...hopefully this will serve as a useful reference for someone else and save some search time.
The earliest "A" version: The earliest "A" versions had only 2 water screws, the 2 screw version was used across the board on all Factory Pipes from the Kawi 650sx, 750sx/sxi, and SJ 650. They all have the same thicker flange of about 1/2 inch difference from the current "B" version, but the bores might be different. The Yami variant came with a 43 or 44mm bore by default.
The next generation "A" version: It still has a thicker bolt flange than the "B" version by about 1/2" which is essentially the only difference between the two other than also not being tagged on the engraving plate as a "B" pipe. This next gen version is the 3 screw version which I believe is when they started to separate them from each other making one more for Kawi and one more for Yami. When the "B" tag arrived? I do not know.
The "B" version: The current and only version that we are most familiar with having a flange thickness of about 1/2" thinner than the "A" version. It has been noted that on occasion the flanges have cracked at the bolt locations due to the thinner flange thickness. The only other change is that earlier "B" versions which were probably meant for the 650's? had a bore of 43-44mm, as did the manifolds of that time. This was found to be problematic on the 701 as it contributed to melting pistons. GroupK states on one of their "resto" write-ups that they made this observation and reported it to Factory. If I read this correctly, it was not long after that, that Factory began making both manifold and head pipe bores at 46mm? as standard issue. The current normal gasket (at least from Blowsion) measures at 46.5mm I.D. This bore diameter change cured the piston melting issues that some may have seen on the 701 engine.
The newer "A" version: Further along the line the SXR variant was made, the standard bore diameter from Factory on this variant I do not know. The SXR head pipe will work on the Yamaha but the Yamaha head pipe will not work on the Kawi ( <---according to Blowsion on their website) and due to the number of degrees the pipe twists inward on the Yamaha version ( <--- according to posts and photos found from the past). The SXR version is in more of a straight line toward the front of the hull whereas the Yamaha variant is twisted and tucked closer into the engine to follow the narrowing round nose hull design. The thicker flange is still there but there have been occasional reports of clearance issues with this head pipe on the Yamaha manifold. It seems that due to how the Yamaha manifold contours inward on the PTO side to clear the Yamaha oriented "B" version head pipe, the contour is only so tall, the thicker flange raises up the large end of the head pipe (as we would expect it to
) and can sometimes be a fitment issue in regards to both the chamber-to-head pipe mating as well as coupler thickness and installation.What I also do not know is:
- if there have been any changes to the inside diameter from the older "A" pipes to the current "B"
- if there have been any length changes made to accommodate the different sonic wave of the 701 from the 650
- if the water screws and hole sizes have been increased or decreased <---probably doesn't matter but might as well mention it anyway
- if one variant performs better than another <---probably not if there have been no dimensional changes aside from the degree of twist between the current Yamaha and Kawi versions
So how about peeps...is there anything missed? Is there any known performance improvements from one to the other under original Factory Pipe specs other than the changed bore sizes to accommodate the 701 needs?
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