C-200 cafe'....My project bike..... - Page 4

MICRider · 12-22-2012, 05:39 PM

+1 on DRATV, I've ordered a bunch of stuff from them as well and it was all good and I thought the prices were reasonable. I've got a Lifan powered CT about 75 percent done, then I ran out of steam on it.

66Sprint · 12-29-2012, 12:11 AM

Well, One more step closer....I just ordered a 24mm Mikuni carb (measured at the gasket/port, so I suspect it's actually a 21 or 22mm venturi equavalent), and manifold to replace the Sheng Wey that came with the engine....Interestingly enough, the Sheng looks to be a better match for a CT 90 as it has the petcock built into the float bowl and appears it would face forward properly mounted on the manifold provided...........However, the port sizing on the engine and manifold DID NOT match well....(engine port 26mm, manifold port 20.5mm)...This MAY be a common problem and can cause some tuning frustrations....There should be long, smooth, tapered transitions from size to size, NOT abrupt steps (up or down in size)....Those of you having "carburation hiccups" at specific throttle openings/speeds may want to check into this......
The replacement manifold is supposedly 24mm at the carb end and 26mm at the engine side, so it should work out well....We'll see.....

Weldangrind · 12-30-2012, 11:30 AM

I'm guessing that you'll port match the new manifold to optimize it as well.

I bought a 24mm Mikuni for my project as well, and it has the petcock and a sediment bowl. Got lucky with that one, but in retrospect, it might be too much to feed a 110. I was considering a 45 degree intake tube to keep the pod filter out of the rear tire stream.

66Sprint · 12-30-2012, 02:59 PM

Weld, I found that about a 28 to 30 degree angle was sufficient for the adaptation I was working on (pushrod C200 engine into a CT 90), and made up a "quicky" adaptor plate....Works great!....

Nice part is that because it is made from 1/4" aluminum, it can easily be tapered to use for port matching......

I also noticed that most suppliers are "sizing" the carbs they sell by the port size where they attach to a manifold, rather than the calculated venturi size...So unless I buy a "known" Kei-Hin carb (as originally used on a Honda), I'm somewhat at a loss as to application based on engine displacement...For instance, the stock CB 125 Honda had a 22mm carb, ( calculated venturi sizing) but a 23.7mm port size (IIRC)....So those specs were what I went by to choose the "24mm" Mikuni......

Weldangrind · 12-31-2012, 11:02 AM

When you say "calculated venturi size", does that mean the effective area of the venturi? I always thought that the venturi horizontal diameter was the measuring point.

BTW, I've noticed the same thing. The very popular (around here) 30mm Mikuni is actually measured at the intake tube side.

Nice looking adapter. My "quicky" stuff is much less refined, yet delightfully tacky.

66Sprint · 12-31-2012, 05:22 PM

The APPROXIMATE area of even an "out of round" oval is (diameter+ height) divided by 4, the result squared, and multiplied by PI.... This means the effective venturi diameter is half the sum of the height and width .......For width, I simply measure the apeture across slide diameter, (as several size carbs use identical slides) then stick a thin rule down the passage and "eyeball" judge the height.....Not exact, but close enough for comparisons.....
The differences in apeture width seem to be the factor between Kei-Hin 18 (CB200), 20 (CB/CL 175), and 22mm (some CL 175) carbs which otherwise look identical...

**cheesy** · 12-31-2012, 08:22 PM

Too nice of an adaptor to be a 'quicky'. Some thought and patience went into the design and finish.

Quote:

Originally Posted by Weldangrind

My "quicky" stuff is much less refined, yet delightfully tacky.

That defines a certain luggage rack I know of.

66Sprint · 12-31-2012, 08:41 PM

You are giving credit where none is due..... drilled a/the large hole in the plate, used my finger through it from underneath to center manifold to mark the bolt holes.... bolted it on the engine, and turned the manifold and carb until I had clearance,...Marked the second set of holes...then "quicky"countersunk holes with a larger drill bit for clearance, (nothing fancy) ..... Perimeter shape is simply cut to support the manifold shape with a sabre-saw......
Logical yes, but not really a mental effort for looks, just for functionality....Figured I could re-make and "dress" one out if it worked properly, even considered fabrication from plastic to provide additional thermal insulation to the carb.... but never got around to it....LOL....

66Sprint · 01-04-2013, 05:03 PM

Update:
I got the supposed 24mm Mikuni today....Port size at attachment flange is right at 25.72mm ...SO 26mm... HOWEVER, it matches the bore of the manifold VERY well and the manifold matches the engines intake flange as well....No problems to this point.... My problem with this carb is the VENTURI looks too small to be a 24....Here's my calculations and method:
First, I picture the actual opening at the venturi as two half circles (one top, one bottom) with a rectangle in between..... This means the area of the venturi is the sum of the rectangle and one full circle....
Width of opening is 16mm....length of opening is 25mm....This gives me an r= 8mm circle, plus a 16 x 9 rectangle.....
Area of the circle is Pi x R squared, so 3.14159 x 64 = 201.06 sq mm
The rectangle adds 16 x 9 = 144 sq mm.....= 345 sq mm total......
Divide by PI and take the square root will give the equivalent circular radius....=10.479... the equivalent diameter is twice that, or 20.958 (approximately 21mm).... Not close enough to 24mm in my books...
Even allowing for measurement error and rounding during calculation, that means it is at best a 22mm venturi equivalent carb..... Certainly NOT what I ordered/purchased, but actually perfect for my needs.....

LOL.... looking closer, it has 22 , (and several other numbers) stamped into the flange (including 230, s3, and 3847)......

Anyhow,...To the point of this post, ....Anyone have jet sizing that works on a 125 engine with a "24" mm Mikuni???....Currently has a #15 pilot and a .95mm main (seems about right on the main...Or maybe a 105?).... Might save me some time and $.......

Thanks, Steve

Weldangrind · 01-05-2013, 01:19 AM

It sounds like that will be the ideal carb. No idea if the jetting is correct, but I'm looking forward to your testing.

66Sprint · 01-08-2013, 01:03 AM

Update continued.....
For anyone "ftting" a larger diameter manifold, and bigger carb, Here are some possible time-savers.....Of course, I will have some additional modifications (adaptor plate) to make as the original carb was "aimed" straight back at the center of the frame, and the new manifold has the "to the left side 45 degree twist"... As you can see, the original manifold was longer and higher anyway, so I believe these mods will bring it back to somewhat the original positioning....

1...
The insulator plastic block from a 150cc Chinese "scooter" has a 24mm main bore.... Its attachment bolt spacing is correct for the "24mm" manifold to cylinder head joint on the 125cc Lifan horizontal engine... Slight work with a half-round mill file made port matching easy and fairly quick......

2...
I'll be using a second insulator block at the manifold to carb joint for the two reasons given above (longer/further back, and higher)....While the original block that came with the 125 Lifan probably COULD be enlarged to match the manifold, a "24mm" one is already available for a couple dollars, and it will be easier to port match without risking losing the inner lip that retains the O-ring.....

Hopefully, I'll get to mount the engine this week and tweak the mounting....

Steve

Weldangrind · 01-08-2013, 09:54 AM

Are you planning on connecting to the original airbox? Do you have a link for the 24mm insulator?

66Sprint · 01-08-2013, 03:49 PM

Weld, I grabbed a used one off a 150 scooter at my shop, (for the manifold to engine) but I BELIEVE (not 100% sure) this link is the same item:
http://www.lifanenginepartswholesale...ke-p-9965.html

IF you mean the 24mm carb to manifold gasket, I'm told it's part number GS01 @ PCCMotoparts (on ebay) or @ 909-980-8806.....about $5 shipped.....

I've ordered the latter, but won't get it until Saturday....I'll let you know how well it fits....

And YES, original airbox..... :wink:

Steve

Weldangrind · 01-09-2013, 12:38 AM

I'm guessing that 150 scoot is a GY6. Good to know.

Something about that old bike is really compelling. 8)

66Sprint · 01-09-2013, 06:57 PM

Weld,
I was surprised today to find the insulator (carb to manifold) in my mailbox.... (Very prompt service) and am happy to report it is a perfect fit to the carb and manifold..... The "GS 01" number is correct for this application......

...Now I just have to figure out how to alter the angle of the manifold twice.... If you look at the pic of the original, you can see it has nearly a 45 degree rise as well as being straight back along the engine....The manifold I have has NO rise (flange "flats" are at 90 degrees to each other) and it does have the 45 outward (left) rotation that I don't want.....
SO....
...It's kindergarten time! (time for cutting and pasting)...
Hack-sawing, filing, and eventually aluminum welding if you MUST be technical....
However, in the mean-time, I'll cut and "fit" the sections and test run it by joining them temporarily with a short rubber hose and a couple of band clamps......LOL....

However I'm NOT set-up to do the aluminum welds....Know anyone who is and would be willing to try?......Steve

.

12-30-2012, 11:30 AM	#48
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I'm guessing that you'll port match the new manifold to optimize it as well. I bought a 24mm Mikuni for my project as well, and it has the petcock and a sediment bowl. Got lucky with that one, but in retrospect, it might be too much to feed a 110. I was considering a 45 degree intake tube to keep the pod filter out of the rear tire stream. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

12-31-2012, 11:02 AM	#50
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	When you say "calculated venturi size", does that mean the effective area of the venturi? I always thought that the venturi horizontal diameter was the measuring point. BTW, I've noticed the same thing. The very popular (around here) 30mm Mikuni is actually measured at the intake tube side. Nice looking adapter. My "quicky" stuff is much less refined, yet delightfully tacky. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

01-05-2013, 01:19 AM	#55
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	It sounds like that will be the ideal carb. No idea if the jetting is correct, but I'm looking forward to your testing. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

01-08-2013, 09:54 AM	#57
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Are you planning on connecting to the original airbox? Do you have a link for the 24mm insulator? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

01-09-2013, 12:38 AM	#59
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I'm guessing that 150 scoot is a GY6. Good to know. Something about that old bike is really compelling. 8) __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

12-22-2012, 05:39 PM	#46
MICRider Join Date: Oct 2009 Location: Alberta, Canada Posts: 3,274	+1 on DRATV, I've ordered a bunch of stuff from them as well and it was all good and I thought the prices were reasonable. I've got a Lifan powered CT about 75 percent done, then I ran out of steam on it.
	0

12-29-2012, 12:11 AM	#47
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	Well, One more step closer....I just ordered a 24mm Mikuni carb (measured at the gasket/port, so I suspect it's actually a 21 or 22mm venturi equavalent), and manifold to replace the Sheng Wey that came with the engine....Interestingly enough, the Sheng looks to be a better match for a CT 90 as it has the petcock built into the float bowl and appears it would face forward properly mounted on the manifold provided...........However, the port sizing on the engine and manifold DID NOT match well....(engine port 26mm, manifold port 20.5mm)...This MAY be a common problem and can cause some tuning frustrations....There should be long, smooth, tapered transitions from size to size, NOT abrupt steps (up or down in size)....Those of you having "carburation hiccups" at specific throttle openings/speeds may want to check into this...... The replacement manifold is supposedly 24mm at the carb end and 26mm at the engine side, so it should work out well....We'll see.....
	0

12-30-2012, 02:59 PM	#49
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	Weld, I found that about a 28 to 30 degree angle was sufficient for the adaptation I was working on (pushrod C200 engine into a CT 90), and made up a "quicky" adaptor plate....Works great!.... Nice part is that because it is made from 1/4" aluminum, it can easily be tapered to use for port matching...... I also noticed that most suppliers are "sizing" the carbs they sell by the port size where they attach to a manifold, rather than the calculated venturi size...So unless I buy a "known" Kei-Hin carb (as originally used on a Honda), I'm somewhat at a loss as to application based on engine displacement...For instance, the stock CB 125 Honda had a 22mm carb, ( calculated venturi sizing) but a 23.7mm port size (IIRC)....So those specs were what I went by to choose the "24mm" Mikuni......
	0

12-31-2012, 05:22 PM	#51
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	The APPROXIMATE area of even an "out of round" oval is (diameter+ height) divided by 4, the result squared, and multiplied by PI.... This means the effective venturi diameter is half the sum of the height and width .......For width, I simply measure the apeture across slide diameter, (as several size carbs use identical slides) then stick a thin rule down the passage and "eyeball" judge the height.....Not exact, but close enough for comparisons..... The differences in apeture width seem to be the factor between Kei-Hin 18 (CB200), 20 (CB/CL 175), and 22mm (some CL 175) carbs which otherwise look identical...
	0

12-31-2012, 08:41 PM	#53
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	You are giving credit where none is due..... drilled a/the large hole in the plate, used my finger through it from underneath to center manifold to mark the bolt holes.... bolted it on the engine, and turned the manifold and carb until I had clearance,...Marked the second set of holes...then "quicky"countersunk holes with a larger drill bit for clearance, (nothing fancy) ..... Perimeter shape is simply cut to support the manifold shape with a sabre-saw...... Logical yes, but not really a mental effort for looks, just for functionality....Figured I could re-make and "dress" one out if it worked properly, even considered fabrication from plastic to provide additional thermal insulation to the carb.... but never got around to it....LOL....
	0

01-04-2013, 05:03 PM	#54
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	Update: I got the supposed 24mm Mikuni today....Port size at attachment flange is right at 25.72mm ...SO 26mm... HOWEVER, it matches the bore of the manifold VERY well and the manifold matches the engines intake flange as well....No problems to this point.... My problem with this carb is the VENTURI looks too small to be a 24....Here's my calculations and method: First, I picture the actual opening at the venturi as two half circles (one top, one bottom) with a rectangle in between..... This means the area of the venturi is the sum of the rectangle and one full circle.... Width of opening is 16mm....length of opening is 25mm....This gives me an r= 8mm circle, plus a 16 x 9 rectangle..... Area of the circle is Pi x R squared, so 3.14159 x 64 = 201.06 sq mm The rectangle adds 16 x 9 = 144 sq mm.....= 345 sq mm total...... Divide by PI and take the square root will give the equivalent circular radius....=10.479... the equivalent diameter is twice that, or 20.958 (approximately 21mm).... Not close enough to 24mm in my books... Even allowing for measurement error and rounding during calculation, that means it is at best a 22mm venturi equivalent carb..... Certainly NOT what I ordered/purchased, but actually perfect for my needs..... LOL.... looking closer, it has 22 , (and several other numbers) stamped into the flange (including 230, s3, and 3847)...... Anyhow,...To the point of this post, ....Anyone have jet sizing that works on a 125 engine with a "24" mm Mikuni???....Currently has a #15 pilot and a .95mm main (seems about right on the main...Or maybe a 105?).... Might save me some time and $....... Thanks, Steve
	0

01-08-2013, 01:03 AM	#56
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	Update continued..... For anyone "ftting" a larger diameter manifold, and bigger carb, Here are some possible time-savers.....Of course, I will have some additional modifications (adaptor plate) to make as the original carb was "aimed" straight back at the center of the frame, and the new manifold has the "to the left side 45 degree twist"... As you can see, the original manifold was longer and higher anyway, so I believe these mods will bring it back to somewhat the original positioning.... 1... The insulator plastic block from a 150cc Chinese "scooter" has a 24mm main bore.... Its attachment bolt spacing is correct for the "24mm" manifold to cylinder head joint on the 125cc Lifan horizontal engine... Slight work with a half-round mill file made port matching easy and fairly quick...... 2... I'll be using a second insulator block at the manifold to carb joint for the two reasons given above (longer/further back, and higher)....While the original block that came with the 125 Lifan probably COULD be enlarged to match the manifold, a "24mm" one is already available for a couple dollars, and it will be easier to port match without risking losing the inner lip that retains the O-ring..... Hopefully, I'll get to mount the engine this week and tweak the mounting.... Steve
	0

01-08-2013, 03:49 PM	#58
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	Weld, I grabbed a used one off a 150 scooter at my shop, (for the manifold to engine) but I BELIEVE (not 100% sure) this link is the same item: http://www.lifanenginepartswholesale...ke-p-9965.html IF you mean the 24mm carb to manifold gasket, I'm told it's part number GS01 @ PCCMotoparts (on ebay) or @ 909-980-8806.....about $5 shipped..... I've ordered the latter, but won't get it until Saturday....I'll let you know how well it fits.... And YES, original airbox..... :wink: Steve
	0

01-09-2013, 06:57 PM	#60
66Sprint Join Date: Nov 2012 Location: Roanoke, Virginia Posts: 76	Weld, I was surprised today to find the insulator (carb to manifold) in my mailbox.... (Very prompt service) and am happy to report it is a perfect fit to the carb and manifold..... The "GS 01" number is correct for this application...... ...Now I just have to figure out how to alter the angle of the manifold twice.... If you look at the pic of the original, you can see it has nearly a 45 degree rise as well as being straight back along the engine....The manifold I have has NO rise (flange "flats" are at 90 degrees to each other) and it does have the 45 outward (left) rotation that I don't want..... SO.... ...It's kindergarten time! (time for cutting and pasting)... Hack-sawing, filing, and eventually aluminum welding if you MUST be technical.... However, in the mean-time, I'll cut and "fit" the sections and test run it by joining them temporarily with a short rubber hose and a couple of band clamps......LOL.... However I'm NOT set-up to do the aluminum welds....Know anyone who is and would be willing to try?......Steve .
	0