Spent a couple of hours today doing flanges and stubs to mount the Mikunis. Looks good so far. Maybe I'll be able to fire it this weekend.
Mikunis are mounted on X-flow
- Thread starter MustangSix
- Start date
A
Anonymous
Guest
Holly Weapon Systems Batman!!!!!!!
What size are they?
Need to have an article just on the Carbs!
Jack, that's a Jaw Dropper!
John
What size are they?
Need to have an article just on the Carbs!
Jack, that's a Jaw Dropper!
John
A
Anonymous
Guest
Lookin Good!!!!!!!! :checks: 
:checks:
:checks:
....as the small six world holds it's breath....
I really hope this works out for all of us as it will be a great option available for those who want it. mainly I am waiting to see how it is in the long term as far as reliability. we are all crossing our fingers for you Jack!!
nick
I really hope this works out for all of us as it will be a great option available for those who want it. mainly I am waiting to see how it is in the long term as far as reliability. we are all crossing our fingers for you Jack!!
nick
Ok, I couldn't wait. I primed the carbs with a squirt bottle and hit the ignition. It roared to life on the second spin and settled into a fast idle. 
Then it ran out of gas about 15 seconds later as the float chambers went dry. Not enough time to check throttle response or do any tuning, but it seems like this just might work. Gotta hook up the fuel tank.
Holy cow! Open headers sure are loud! The cat hates me again!
Then it ran out of gas about 15 seconds later as the float chambers went dry. Not enough time to check throttle response or do any tuning, but it seems like this just might work. Gotta hook up the fuel tank.
Holy cow! Open headers sure are loud!
The cat hates me again!
A
Anonymous
Guest
What are those from?
Have you done this before?
Have you done this before?
Those are 36mm Mikunis CV's. What you see is actually two sets from 1100 GSXR motorcycles. I removed one carb from each end, fabbed a linkage to mate the two sets, and modified the bracketry to hook them all back together.
I have never tried this before, but there are many accounts of this being done on Triumph Spitfire engines with success. It's a poor man's Weber DCOE. You can find these carbs for $20-30 a set. the neat part is that they only require a 1.5" diameter stub to mount with a short rubber hose.
The carbs are constant velocity, so they tend to be somewhat self correcting. In an individual runner setup like this, they may be too small for extremely high rpm use. They have to feed a cylinder twice as large, but at only half the speed (for the most part), so perhaps they will be ok. A 200 at idle is tasking the carbs to draw as much air as an 1100 bike at 1500 rpm. But the GSXR can run up to over 9000 rpm on these carbs. This engine is limited to about 5500. We'll just try it and see.
If this doesn't work, I have a lot of 175CD Strombergs on the shelf. I'll use three of them instead.
I have never tried this before, but there are many accounts of this being done on Triumph Spitfire engines with success. It's a poor man's Weber DCOE. You can find these carbs for $20-30 a set. the neat part is that they only require a 1.5" diameter stub to mount with a short rubber hose.
The carbs are constant velocity, so they tend to be somewhat self correcting. In an individual runner setup like this, they may be too small for extremely high rpm use. They have to feed a cylinder twice as large, but at only half the speed (for the most part), so perhaps they will be ok. A 200 at idle is tasking the carbs to draw as much air as an 1100 bike at 1500 rpm. But the GSXR can run up to over 9000 rpm on these carbs. This engine is limited to about 5500. We'll just try it and see.
If this doesn't work, I have a lot of 175CD Strombergs on the shelf. I'll use three of them instead.
xafalcongs
Well-known member
Hey Jack,
WOW! BTW, if 38's don't work, you can get Mikunis in sizes well up to 48. In fact, you could look into the HSR 48 series that are used on Harleys. These have a much larger fuel bowl and an adjustable accelerator pump. One 48 feeds 80ci on the Harley whereas your 200 is only 33.33ci per cylinder. There are also HSR Series carbs in the 42 and 44 mm range.
Oh, your car is the greatest. I have been looking at building something really light with a 200 and Crossflow head. Funny thing was, I was considering 3 webers or 6 Mikunis. Looks like you beat me too the punch by many months! I'm not as handy so mine will not be a Lotus but may be a TR6....I did find a few Track-T's for sale.....hum....
--J
WOW! BTW, if 38's don't work, you can get Mikunis in sizes well up to 48. In fact, you could look into the HSR 48 series that are used on Harleys. These have a much larger fuel bowl and an adjustable accelerator pump. One 48 feeds 80ci on the Harley whereas your 200 is only 33.33ci per cylinder. There are also HSR Series carbs in the 42 and 44 mm range.
Oh, your car is the greatest. I have been looking at building something really light with a 200 and Crossflow head. Funny thing was, I was considering 3 webers or 6 Mikunis. Looks like you beat me too the punch by many months! I'm not as handy so mine will not be a Lotus but may be a TR6....I did find a few Track-T's for sale.....hum....
--J
A
Anonymous
Guest
Only a suggestion, but the needle and seat assembly in those is probably 3.0 or so for gravity feed, and if you put pump pressure through them the needle won't seal. Mikuni makes 1.5 needle assemblies for snowmobile use that probably fit.
I thought of that. I'm going to try turning the fuel pressure way down first. I have a regulator that will drop the pressure to 1 psi. I looked at the needle/seat assemblies and they should hold that. If not, I'll replace them.
some bike motor cart people make a gravity tank that they pump fuel into then the overflow from it returns to the gas tank and gravity feed the carbs that way...might be a simple solution for now.
nick
nick
A
Anonymous
Guest
I think 1 psi may do it, you may just have to lower the float a bit if still too much.
Not that many needle profiles available for the CV Mikunis (compared to the VM type (fixed slide GP).
Do you know your needle jet type?
See stuff listing for VM I have:
http://www.victorylibrary.com/mikuniparts.htm
http://www.victorylibrary.com/tech/mikuni-2.htm
http://www.victorylibrary.com/tech/mikuni-3.htm
Not that many needle profiles available for the CV Mikunis (compared to the VM type (fixed slide GP).
Do you know your needle jet type?
See stuff listing for VM I have:
http://www.victorylibrary.com/mikuniparts.htm
http://www.victorylibrary.com/tech/mikuni-2.htm
http://www.victorylibrary.com/tech/mikuni-3.htm
That is great. I understand that, desipite the lower head presure, the CV carbs operate just like SU's and Strombergs. So the relationship I found for SU/Strombergs may hold true for CV carbs as long as the tip of the needle is exposed at wide open throttle.
Twentyover posted a link to the SU site after I did a mathematical search on needle profiles verses net Hp. He noted is use of the old Haystack program. It is based on the siple premise that annular discharge is proportional to net hp at wide open throtte if the constant depression carb sprung to open fully at wide open throttle, just like what I found. (Although its better than mine).
See http://fordsix.com/forum/viewtopic.php?t=8483
panic, that resource you have there is simply mighty. People would flock in droves to use it. If you'd like to cross-check my findings and posibly add them to your work, you'll find that cracking jetting is not a big deal.
The cost of bunch of six carbs lookes great to me,and is lookes to be backed up by impecable information.
Twentyover posted a link to the SU site after I did a mathematical search on needle profiles verses net Hp. He noted is use of the old Haystack program. It is based on the siple premise that annular discharge is proportional to net hp at wide open throtte if the constant depression carb sprung to open fully at wide open throttle, just like what I found. (Although its better than mine).
See http://fordsix.com/forum/viewtopic.php?t=8483
panic, that resource you have there is simply mighty. People would flock in droves to use it. If you'd like to cross-check my findings and posibly add them to your work, you'll find that cracking jetting is not a big deal.
The cost of bunch of six carbs lookes great to me,and is lookes to be backed up by impecable information.
twentyover
Well-known member
Actualy, the link for haystack should have been http://www.jetlink.net/~okayfine/su/sutech.html - lets you compare variuos needles needles, .090 jets to .100 jets.
Thanks for the resource, but these are very different from the round slides in those pages. The slides are flat and made from a black composite material. The needles look like teflon (or something similar) coated aluminum.
Also, the slides are not pulled by the cables. They are vacuum operated according to air flow like an SU or Stromberg. They react according to butterfly opening.
There are a lot of needles and jets available from the Hayabusa tuners, but for now, I think I'll see how the stock ones work, just to establish a baseline. I asked a Suzuki cycle tuner about the regulator set at 1.5 psi and he thought it would work fine. In fact, he recommended I go to 3.5 psi instead to improve the flow.
If this works, for about $90 I have some killer carbs. If not, oh well. Back to automotive carbs.
Also, the slides are not pulled by the cables. They are vacuum operated according to air flow like an SU or Stromberg. They react according to butterfly opening.
There are a lot of needles and jets available from the Hayabusa tuners, but for now, I think I'll see how the stock ones work, just to establish a baseline. I asked a Suzuki cycle tuner about the regulator set at 1.5 psi and he thought it would work fine. In fact, he recommended I go to 3.5 psi instead to improve the flow.
If this works, for about $90 I have some killer carbs. If not, oh well. Back to automotive carbs.
A
Anonymous
Guest
More needle stuff:
http://www.teglerizer.com/suneedledb/index.html
http://www.teglerizer.com/suneedledb/index.html
A
Anonymous
Guest
Jack: you need a parts breakdown of your CV to determine whether some of the small parts I have interchange. A lot of Mikuni stuff is used in more than one "platform".
BTW: you may have a sized, replaceable air correction jet, or just a drilled orifice, but this is a nice "over-ride" on needle tip area.
Harley used Keihin CV in 34-40mm sizes for the last 10 years or more, may wind up in the trash when their owner puts on open pipes and the shop sells him a $350 S&S instead of a tune up. I've bought these in perfect shape for as little as $10. Very similar design and body shape. Try a search in eBay:
.
IMHO Vizard's "Mini" book has the most useful info on the SU.
BTW: you may have a sized, replaceable air correction jet, or just a drilled orifice, but this is a nice "over-ride" on needle tip area.
Harley used Keihin CV in 34-40mm sizes for the last 10 years or more, may wind up in the trash when their owner puts on open pipes and the shop sells him a $350 S&S instead of a tune up. I've bought these in perfect shape for as little as $10. Very similar design and body shape. Try a search in eBay:
IMHO Vizard's "Mini" book has the most useful info on the SU.
A
Anonymous
Guest
Here's a current search.Note there are some NEW ones listed.
I'm sure you're correct that there's a lot of interchageability. Here's a shot of one of the carbs I took off. The guys at the cycle shop had some detailed drawings and parts lists, but I didn't get a copy yet.
They also had some ideas for air correction jets, needles, etc., but all agreed that since this was unknown territory that I should start with what I have and go from there.
They also had some ideas for air correction jets, needles, etc., but all agreed that since this was unknown territory that I should start with what I have and go from there.
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