105 Main Jets in UK

[t4tiger]

Hi,

I have been reading the excellent articles on carbs here and notice that Mustang talks about changing the main jet on Keihins to 105.  I explained my plans to do this to the local Triumph dealership and they said that this was the wrong thing to do in the UK as we are at a different height above sea level to you good folks in the US.  You're knowledgeable opinions are most appreciated. Thanks

[Mustang]

105 mains run fine in my 98 steamer from. sea level to 14,000 ft in the rocky mtns .

I live at 400 feet above sea level.........

do you have severe throttle hesitation/ bog (like almost quits running) when you twist it WFO and it will actually pick up engine speed when you start closing the throttle . If so 105's are for you

[t4tiger]

Hi Mustang,  Thanks for the prompt reply.  I can't really say that it does have that characteristic, I've never tried it.  There is hesitation when you rev it hard from idle and It seems to idle quite poorly.  I've stripped the carbs down and they are getting a sonic bath as we speak, I'm going to balance the carbs and thinking of doing the valve check before it goes back together.  This the first time I've ever done any mechanicing and I'm doing what I've picked up here.  I wanted to check on the 105 thing whilst it's all in pieces.  I presume that if I do the change it won't cause any harm?  Thanks

[Mustang]

If it runs rich it won't be by much'......you would not even notice.

Mikunis' came standard with 105 mains btw .......

[GavD]

When I was getting mine back on the road my Keihins had 38 pilots and 98 mains in. I junked the rotten cans for Motad exhausts which are a bit more free flowing, changed the pilots to 40's and mains to 105's as recommended by Mustang. Runs a treat, pulls well across the rev range.

[qbto]

When I was getting mine back on the road my Keihins had 38 pilots and 98 mains in. I junked the rotten cans for Motad exhausts which are a bit more free flowing, changed the pilots to 40's and mains to 105's as recommended by Mustang. Runs a treat, pulls well across the rev range.

Gav, What sort of mpg are you getting with this set up ?

[GavD]

About 45-50 I think, never worked it out. I generally get about 180 miles until the fuel light comes on if thats a guide. At that point I'm still running on main tank. Never pushed it much further to see when I go onto reserve, but that would be irrelevant anyway as I've fitted a different fuel tap and I think the main tank pipe is a bit shorter than a standard one.