View Full Version : Zenith 175 CD's

03-31-2012, 11:36 AM
Anybody have just the basic adjustment settings for these? im new to carb tuning ( although my father has all the special tuning tools for these) . Everthings all cleaned up with new seals and o-rings but somethings still not right. Front carb seems to be dry and the rear carb is pouring fuel all over the place ( out the air filter). this is all on a non-starting TR7. any basic help would be apprectated

03-31-2012, 12:03 PM
Both those conditions likely have root cause in the float chambers.
If fuel is overflowing, then the fuel supply is not being cut off when the proper level is attained. A problem with the needle valve which when the floats rise with the fuel level should cut off the fuel until the level drops a bit, would be my guess. Possible too that the floats have lost buoyancy due to a leak, but not as likely as a sticky needle valve.
Same for the other dry carb, only that needle valve stuck in the closed rather than partially open position.
Just a guess but that what it sounds like to me.

You'll want this. Basic adjustments after refurbishing are within:

03-31-2012, 12:37 PM
Thank you very much i guess itll all come apart again to check everything. as for your link, seems to be beyond helpful, printing it right now and heading back out to the garage!

03-31-2012, 06:30 PM
Sounds all too similar, My first wedge had both clips for the float hinge rusted off completly. Lots of water in the tank as well. Hope yours is in better shape.

04-01-2012, 09:22 AM
yea they're all fine so i dont know wwhat the problem seems to be, just had them all apart again last night and nothing seems out of the norm

04-01-2012, 09:39 AM
Is the fuel on the rear carb coming out of the line that goes to the charcol cannister? If so it HAS to be the float/needle valve.

04-01-2012, 09:53 AM
How did you go about checking the needle valves? You can't tell much by just looking at them.

04-01-2012, 07:36 PM
I'll take a shot in the dark here. Did you use grose needle and seats??? If you did take them out and wash them in lacquer thinner, they have a coating on them that gives all kind of trouble, if you don't wash them.


04-01-2012, 08:43 PM
Anticipating a response
Grose jet on the far right

04-02-2012, 09:27 PM
the far right is what i have. everything seems clean. floats seems alright so i dont know how to tell where the problem is. . seems like a float issue but ive check them and they seem to be sitting correctly

04-02-2012, 09:29 PM
checked everything in accordance to that buckeyes triumph guide that you sent me to

04-02-2012, 09:43 PM
Myself and lots of others have reported problems with the Grose Jet; at least the version that is used in the 175 ZS carbs.
One of mine flooded the carbs the very first day I installed them. Removed the carbs cleaned the Grose jet, rolled around the ball bearing, ball point pen fashion quite a bit, reinstalled them only to have them start flooding again a few weeks later, diluting my motor oil
Out they came, only to be used again in pictures to illustrate what to avoid.
If your carbs are flooding and you have Grose jets it doesn't take too much deduction in my mind to expose the culprit

04-02-2012, 11:46 PM

Near as I can tell, the Grose Jets have a larger bore, which means it takes more force from the float to hold them closed. Sometimes that is no problem, but if your fuel pressure happens to be just a bit on the high side; or the fuel a bit less dense than usual; or a float just a bit on the heavy side; then you might have a problem.

And in spite of the hype, the original valves work just fine. There is no need to "improve" them.

04-03-2012, 05:16 PM
yea thanks everyone. i dont know if they were changed to these jets, theyve been in these carbs and rane fine for the last four years, so i dont know why they are a problem now. Ill continue sifting through the carbs later on, for now its nice and warm here so its bodywork time for today

04-03-2012, 05:41 PM
Oh, you can be sure someone replaced the original plunger type needle valves with those Grose jets.

04-03-2012, 06:50 PM
theyve been in these carbs and rane fine for the last four years, so i dont know why they are a problem now.

One possibility is that the floats have absorbed a bit of ethanol from the fuel and become heavier than they were. Someone, I forget who offhand, has started selling "unsinkable" floats to address that problem.

04-03-2012, 09:17 PM
Someone, I forget who offhand, has started selling "unsinkable" floats to address that problem.

Joe Curto is selling them now.

04-03-2012, 09:18 PM
thats possible i suppose but unfortunately i have no awesome way of telling whether thats happening or not. yesterday i have the bowls apart again and the floats i didnt notice any fluid in them but the yellow color of them makes it difficult

04-05-2012, 09:34 PM
I don't like the Grose jets.
I would change them out for the other kind.
If you have fuel coming out all over the place I would certainly suspect the jets or a holed/stuck float

04-06-2012, 11:39 AM
There's been enough flooding problems cured by removing the Grose jets and replacing them with the the original type to make this a 'no brainer'
If, by some stretch of the imagination that proves not to be the solution, take consolation that in the end you ultimately do have a more reliable product and have eliminated 1/3 of the suspects