What other O.E. pistons work in a Honda CB350 for a swap ?
- Thread starter grcamna5
- Start date
rockcitycafe
I make things.
Nebr_Rex said:
what year qualifies as "late" I looked at some and got a little giddy for building an 850something with the stock 750 motor that's being replaced by the fran-kz-stein 900
Nebr_Rex
Coast to Coast
Roc City Cafe said:
"80 to "82 can be coincidered early and "83 on late with some mix in "82 and "83.
Late engines have squared off fins on the head and block. Early are rounded. H (LTDs) and E (standard)
models received Keihin carbs with early engines. GPzs got Mikunis. Later GPzs got bigger cams.
Spectres have late engines, standard cams and Keihins.
.
rockcitycafe
I make things.
and those are 66mm od with a 15mm wristpin?
surprised no one's used them in a cb750 yet
surprised no one's used them in a cb750 yet
rockcitycafe
I make things.
Nebr_Rex said:
that and/or the intake, they're not inline anyway, a good way to pocket the pistons is to take a scrap valve and grind it to a point, then put the piston at tdc and mark it through the guide with the valve, then line it up in the mill on the punch mark
Hi xb33bsa,
I appreciate that link man.I hope to be able to save that much over time but for now,I'm on a small limited income and every penny counts.I Love Wiseco especially those forged pistons
,them are Beauties !
Thank You for finding that for me as a Great option,
Bill
I appreciate that link man.I hope to be able to save that much over time but for now,I'm on a small limited income and every penny counts.I Love Wiseco especially those forged pistons
,them are Beauties !Thank You for finding that for me as a Great option,
Bill
grcamna5 said:Yes, I will do that Rex & list the dimensions here..,after the Holidays.
Thanks
I'll get over to storage and get a hold of those pistons;I only have a US inch calipers for now and hope that'll be OK to use.I'll be back w/ those dimensions after a while..
Ok,I Finally got those specs,I'm sorry it took SO long to get a piston to measure.
I measured the side of the piston from the top(shoulder)edge down to the bottom of the skirt inline w/ the valve pocket cut into the crown and it measures 2.339 in.
I then measured the piston from the shoulder-top edge of the crown down to the upper edge of the wrist pin hole and it measured .644 in.
This is a Std. size 64mm OE CB350K4 piston..,I hope to find another pr. of used pistons that are 66-67mm w/ a 15mm wrist pin size. I really don't want to go higher than 10.25:1 Compression Ratio.... sometimes all I can get is basic regular 87 oct. fuel
I can measure the height of the dome of the piston crown if needed, Thanks
I measured the side of the piston from the top(shoulder)edge down to the bottom of the skirt inline w/ the valve pocket cut into the crown and it measures 2.339 in.
I then measured the piston from the shoulder-top edge of the crown down to the upper edge of the wrist pin hole and it measured .644 in.
This is a Std. size 64mm OE CB350K4 piston..,I hope to find another pr. of used pistons that are 66-67mm w/ a 15mm wrist pin size. I really don't want to go higher than 10.25:1 Compression Ratio.... sometimes all I can get is basic regular 87 oct. fuel
I can measure the height of the dome of the piston crown if needed, Thanks
Nebr_Rex
Coast to Coast
Rex,
The 2) piston pics(thanks for those) that you have here;is the one on the right the KZ440 ? and the one on the left the newer(82' or 83' ?)KZ750 4 cyl. ?
I want to know which one of these pistons you mentioned will be almost the same as my CB350 stock measurement of .644 in. ? I don't (ideally) want to have too high of a C.R.)
I like those 3 piece oil control rings.
Thanks,
Bill
The 2) piston pics(thanks for those
) that you have here;is the one on the right the KZ440 ? and the one on the left the newer(82' or 83' ?)KZ750 4 cyl. ?I want to know which one of these pistons you mentioned will be almost the same as my CB350 stock measurement of .644 in. ? I don't (ideally) want to have too high of a C.R.
)I like those 3 piece oil control rings.
Thanks,
Bill
Nebr_Rex
Coast to Coast
The one on the left is the 440 piston. The one on the right is the early 750 piston.
All KZ 400/440/650/750s have the same pin height of .665 . The late 750 piston
is the same as the early version with 2 valve pockets. The differences are the ring
thickness and dome height, being the the late version is about 1/8 in. taller. The
440 has a tall dome and a small intake valve relief because it has a 37 cc combustion
chamber and 9.2/1 compression ratio. The early 750 has 9/1 and the late has 9.5/1
with their 26 cc chamber. The early piston has a dome volume of roughly 3 cc. The
late piston has a dome volume of about 4 cc. Add the difference in pin height of
.665 minus .644 equals .021. That is how much higher the KZ pistons will be vs. the CBs.
You will have to calculate if a KZ piston will fit your application.
.
.
.
All KZ 400/440/650/750s have the same pin height of .665 . The late 750 piston
is the same as the early version with 2 valve pockets. The differences are the ring
thickness and dome height, being the the late version is about 1/8 in. taller. The
440 has a tall dome and a small intake valve relief because it has a 37 cc combustion
chamber and 9.2/1 compression ratio. The early 750 has 9/1 and the late has 9.5/1
with their 26 cc chamber. The early piston has a dome volume of roughly 3 cc. The
late piston has a dome volume of about 4 cc. Add the difference in pin height of
.665 minus .644 equals .021. That is how much higher the KZ pistons will be vs. the CBs.
You will have to calculate if a KZ piston will fit your application.
.
.
.
I remember early in this thread how a member here told me to "do the Math"...basically.
I Never was very good at math(algebra),etc. I need a course to get me closer to the correct size piston for my correct 'squish area'.
I've also been told by a few others that they installed the KZ750 pistons and it worked out good... ? I'll need to do a bit of learning now.
Thanks Rex for good measurements that you posted,it gives me something to use for later when I figure out my next step. ??? :
I now see why the other member posted the 66mm Wiseco's and told me it'd be a lot easier to just get these forged pistons. I wonder if it would be possible to run these 10.5:1 pistons on regular 87 oct. ? That's a goal of mine for this piston swap also.
Are there any of you who have raced CB350 twins and done what I'm hoping to accomplish some day ? ?
I Never was very good at math(algebra),etc. I need a course to get me closer to the correct size piston for my correct 'squish area'.
I've also been told by a few others that they installed the KZ750 pistons and it worked out good... ? I'll need to do a bit of learning now.
Thanks Rex for good measurements that you posted,it gives me something to use for later when I figure out my next step. ??? :
I now see why the other member posted the 66mm Wiseco's and told me it'd be a lot easier to just get these forged pistons. I wonder if it would be possible to run these 10.5:1 pistons on regular 87 oct. ? That's a goal of mine for this piston swap also.
Are there any of you who have raced CB350 twins and done what I'm hoping to accomplish some day ? ?
no you are just not dealing with reality
10.5-1 with 87 would probably need to be ignition too retarded and lose power
the math involves careful measurements using liquids and clay, making measurement in a dummied together motor, there is no other way to do it
and really each chamber should be done with a matching piston
as well you need to get the squish clearance very precise in a 10.5-1 , patience and knowledge a lathe and experience using one
good luck with it there is plenty of info available online about cc'ing, squish bands and CR"s ..the math part is very easy a 7th grader could do it the measurements are pretty easy as well just need to be carefully done
all this when you can buy them for under 300
10.5-1 with 87 would probably need to be ignition too retarded and lose power
the math involves careful measurements using liquids and clay, making measurement in a dummied together motor, there is no other way to do it
and really each chamber should be done with a matching piston
as well you need to get the squish clearance very precise in a 10.5-1 , patience and knowledge a lathe and experience using one
good luck with it there is plenty of info available online about cc'ing, squish bands and CR"s ..the math part is very easy a 7th grader could do it the measurements are pretty easy as well just need to be carefully done
all this when you can buy them for under 300
