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Carbs
#1
jonbouy Avatar
jonbouy John McCoy
San Jose, Costa Rica   CRI
My 1966 TR4A currently has stock SZ carbs and I just plain don't like the way they react and I am thinking of switching out. I have read comparisons between Wevers and Mikunis and see both pro and con. Has anyone used both of these and have a stong opinion on which to consider more? Any suggestions will be gladly accepted.

Thanks!

John

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t.lay Avatar
t.lay Tom Lay
Grayslake, IL, USA   USA
My take: Webers are complicated - not so much in design, but because there are so many tuning options/variables available. You can drive yourself nuts with the options. ZS can work just fine - but need to be in top condition. Not nearly the number of tuning options like webers or SUs for that matter. Mikunis are simple, reliable, flow well, but don't have the history/knowledge base for TRs. For now I'm staying with my ZS, but mainly because webers or mikunis bump me into a different run group. If I were switching on a street driven car, I would looking very hard at mikunis or thinking of rigging up an injection system.

jonbouy Avatar
jonbouy John McCoy
San Jose, Costa Rica   CRI
Tom,

Thank you so much for your reply and insight. I've always heard that Webers were tuning nightmares and I hear good things about the Mikunis. My mechanic tells me that the current carbs do not need rebuilt but they tend to load up a lot when the car is warm and then it runs roughly and is extremely hard to start after a short stop. I use the car strictly for street use with the exception of a couple of rallys each year and speed isn't a function of our kind of rallys. I usually run the car at an elevation of between 750 and 1000 meters but our rallys in Panama are at sea level - I understand that elevation changes can effect the carbs but they continue to load up at any elevation. Thanks again for your insight.

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JimG Avatar
JimG Jim G
Aurora, CO, USA   USA
The Mikuni HSR 45's are fantastic. They flow the same as the Weber DCOE 45's, have accelerator pumps and you can buy parts at any Harley shop. They were designed
as a direct replacement for SU's ot ZS's.
I picked up significant horsepower and they give a real kick in the pants coming off corners. Super easy to jet too.
Last I checked Pierce Manifolds had them for about $ 245.00 each and then you need the
rubber boot adapters and phonolic spacers. Mine bolted right on.
One of the single best things I've done for my car.


Attachments:
Motor.JPG    45.1 KB
Motor.JPG

jonbouy Avatar
jonbouy John McCoy
San Jose, Costa Rica   CRI
Jim,

Thanks for sharing your experience. I think I am going to go that way for mine also.

Regards,

John

cintitr4 Avatar
cintitr4 Dave Connitt
cincinnati, OH, USA   USA
Hi Jim,
While I was working through my overheating TR$A problem, I noticed on your response that you are running the Mikuni carburetors. I currently have SU's which seem OK but I really am impressed by the good reports from all that have switched to the Mikuni HSR45's. Can you give me a little more detail on your installation? I noticed you have a pressure regulator, are you running the standard fuel pump? Where did you buy all the pieces? I noticed there are a couple of places that sell kits but they want about $1K. Just trying to see what my options are.
Thanks,
Dave Connitt

tinks-dad Avatar
tinks-dad Silver Member Bob C
Newburgh, NY, USA   USA
John,

My neighbor has a TR4 with the same issue-driveability problems that he blames on the carbs. It's so bad he wants to sell the car, which by the way is a beautiful fire engine red like yours. I spent about 30 seconds inspecting the throttle shafts and it's pretty obvious the rear carb has excessive clearance, to the point where you can hear the shaft knocking around in the body. Encourage you to check yours before you swap carbs.

Bob

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JimG Avatar
JimG Jim G
Aurora, CO, USA   USA
Dave,
The Mikuni's are one of the best things I've done for the car. Once they are jetted for a certain altitude your done, no more carb issues. Pierce Manifold has them right now for 275.00 ea. Sudco is about 380.00. Ebay prices are anywhere from 300 - 400+
The rubber boots are about 25.00ea. and linkage parts about 25.00. You can get the boots and linkage parts through Sudco.
I used a throttle cable kit from Ratco only to find out they supplied me with a Lokar cable which can be purchased at the local Auto Zone for a lot less. I bought mine from Vintage Performance Developements but they were shipped direct from Sudco and supposedly gave me a break on the price since I was the Triumph guinea pig. If I need to I can completely remove a carb in under 1 minute. Jetting changes are done with the carbs on the car. I use the Holley red ( electric ) pump regulated to 4psi.
I eliminated the chokes all together, I've never needed it
If you decide to go that way I can send you some pretty detailed photo's of the set up and get you some jetting info to get you started.
jim g

cintitr4 Avatar
cintitr4 Dave Connitt
cincinnati, OH, USA   USA
Jim,
Thanks for the information. The SU's I have are OK but this is something I will do next spring for sure.
Will be in touch,
Dave Connitt

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Re: Carbs
#10
cintitr4 Avatar
cintitr4 Dave Connitt
cincinnati, OH, USA   USA
Hi Bob,
My SU's are OK, I just rebuilt them as part of the whole car restoration. I just like the added performance and fuel economy.
Dave Connitt

Re: Carbs
#11
ceecpa Avatar
ceecpa Silver Member Charles Edwards
Richmond, Virginia, USA   USA
In reply to # 924205 by JimG Dave,
The Mikuni's are one of the best things I've done for the car. Once they are jetted for a certain altitude your done, no more carb issues. Pierce Manifold has them right now for 275.00 ea. Sudco is about 380.00. Ebay prices are anywhere from 300 - 400+
The rubber boots are about 25.00ea. and linkage parts about 25.00. You can get the boots and linkage parts through Sudco.
I used a throttle cable kit from Ratco only to find out they supplied me with a Lokar cable which can be purchased at the local Auto Zone for a lot less. I bought mine from Vintage Performance Developements but they were shipped direct from Sudco and supposedly gave me a break on the price since I was the Triumph guinea pig. If I need to I can completely remove a carb in under 1 minute. Jetting changes are done with the carbs on the car. I use the Holley red ( electric ) pump regulated to 4psi.
I eliminated the chokes all together, I've never needed it
If you decide to go that way I can send you some pretty detailed photo's of the set up and get you some jetting info to get you started.
jim g

Jim, I can't find a tab on Pierce's site for Mikunis. I'm interested in this conversion so I'm greatly interested in your pictures and the jetting information.

Thanks,
Chuck

Re: Carbs
#12
JimG Avatar
JimG Jim G
Aurora, CO, USA   USA
Chuck,
They don't advertise them on the site, you have to ask for them. Tonight I'll look for some photo's and see what I have in detail.
The car is in storage for the winter so on Saturday I'll go take a few more to point out some doo's & don'ts for Mikuni's.
jim

Re: Carbs
#13
cintitr4 Avatar
cintitr4 Dave Connitt
cincinnati, OH, USA   USA
Hi Jim,
I am not sure if my last post went through so if you get two of these, my apologies..
I would like a copy of any pictures and comments you come up with on this conversion.
Thanks,
Dave Connitt

Re: Carbs
#14
JimG Avatar
JimG Jim G
Aurora, CO, USA   USA
This should get things started. I'll try to get some better pictures of the cable bracket over the weekend.
jim


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Carb 3.png

carb 4.png    234.1 KB
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Re: Carbs
#15
cintitr4 Avatar
cintitr4 Dave Connitt
cincinnati, OH, USA   USA
Thanks for posting the pictures Jim
Dave Connitt

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