Triumphrat

CharlestonRider · 06-02-2005

Hello All,
I currently have my carbs off my 1998 Trophy 900 and I want to set the float and fuel level height. I have the Haynes manual, but I am a little suspicious of the values that are listed (it lists the float height at 14.5mm and fuel level height at 1.5mm) because it lists a single value for the 900 and 1200s (even though different carbs were used on different models...Keihin or Mikuni). So, if anybody has the Official Triumph Service Manual for the 1998 Trophy 900, would you be so kind as to reply to this message and let me know what Triumph lists as the float height and fuel level height for the 900 Trophy with Keihin CVK carbs. Thank you in advance!

Cheers.

John

trophyrider00 · 06-02-2005

I checked both of my factory manuals, an old one I bought in 1997 and my newer one I purchased in 2001. The old manual list the float height and fuel level for the Mikuni carbs, but the new one doesn't list them for either carb, just idle speed.

Now, in the text of the newer manual under fuel system and exhaust, it says to set the fuel level at 1.5 +/- 1 mm above the joint face so I am assuming it is the same for both carbs. It mentions nothing about setting the float height except for how to do it. No mention about the measurement. Sorry I couldn't help you more. Hopefully someone can enlighten us both about it.

CharlestonRider · 06-02-2005

Scott,
Thanks for taking the time to look for me. I really appreciate it. The spec you listed is the same as the Haynes manual (so maybe it is correct after all :wink: ).

Cheers.

John

j98sprint · 06-03-2005

I never noticed before but the factory manual doesn't list a float height measurement. It does list a fuel level height as Scott mentioned.

According to the manual you check the fuel height with tool #3880125 connected to a short length of fuel hose that is connected to the float bowl drain screw. If it's not 1.5mm +/- 1mm above measured at the joint face of the float bowl and carb body then you're supposed to pull the carbs, adjust the float(s) up or down (and guess how much) by bending the float tab, put everything back together and remeasure the fuel height, hoping you bent the float tabs the right amount. If it's off, do everything again.

That's crazy. I would go with the Haynes manual measurement of 14.5mm.

j98sprint

trophyrider00 · 06-03-2005

Thanks for comfirming to me I wasn't blind or stupid J98. I went back and forth in that new manual looking for that info. I can't believe they don't put that stuff in there.

CharlestonRider · 06-03-2005

Thanks to everyone who took the time to look up the information for me in the Triumph service manual. Now that I am certain that the Haynes manual is correct, I will set my fuel level this evening at 1.5mm above the float bowl mating surface.

In defense of going through the trouble of setting the fuel level (rather than just setting float height) is that the fuel level in my 3 carbs is variable even though my float heights are all pretty close. So, very minor differences in float height can result in pretty significant changes in fuel level (which is very important in terms of mid-rpm performance). Ultimately, it is the height of the fuel in the bowls (and not the height of the floats) that determines performance.

Currently, I have my carbs in a vise on my benchtop and my gas tank on top of a milk crate (on my benchtop). This allows me to attach the fuel lines to my carbs and check the fuel level without having to reinstall them in the bike. So, I can be absolutely sure that the fuel level is correct when I put the carbs back in the bike.

Thanks again everyone for your help.

John
aka "CharlestonRider"

j98sprint · 06-04-2005

The tank and carb set-up you have on the bench sounds like a pretty good idea. I'm assuming you have tool #3880125 to check the fuel height? Did you buy it from the dealer? How much? Or are you measuring using another method?

j98sprint

CharlestonRider · 06-04-2005

J98Sprint,
I am using a piece of clear tubing rather than opting for the official Triumph tool. The clear tubing does the same job at 1/50th the cost! The trick is to make sure you don't move the tubing around once you open the float bowl drain. Works like a charm!

John

trophyrider00 · 06-04-2005

If I remember right, the Mikunis are what you are supposed to use the tool with. I think the manual just mentioned using a piece of clear tubing for the Keihns.