Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: Steffan on January 23, 2008, 10:13:37 AM
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I am thinking of fitting a larger Mikuni to my 500 bullet currently it has the HMC 50 silencer virtually unbaffled and a replaced airbox for free-er breathing and the Micarb had been rejetted. I was thinking of a 30mm but there is a 32 in the offering. I was wondering if anyone had tried any of these options and if they could share the benefit of their experience? BTW the head, barrel and piston remain untouched.
Thanks
Stephen
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Hi
The problem when fitting a larger carb is the velocity of the air flow through it slow and. you may find your low speed running suffers. When you think about it if the inlet opening to the valve is say 28 mm you wont gain much but fitting a 32mm carb. A variable venturi carb may be a little better than a butterfly or slide type. Maybe you would gain more by having perfect jetting or a modern cab of the same bore.
My thoughts anyway
Ken
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on my 350 i replaced the mikarb with a amal concentric, and the bike seemed to run a lot better.
there was very little difference in power, but the engine lost the strangled feeling and became a different beast.
mpg plummeted to an ice-cap melting 70mpg- although i did tend to give it a fair bit of welly (you have to when it sounds that good!).
throttle response was greatly improved, and could now be measured on a clock rather than a calender.
my 350 with a free flowing exhaust, no air filter and a concentric was considerably quicker accelerating than a standard 500. however if i was using it every day i'd put a filter on it to save carb wear.
don't expect it to be much quicker, just alot 'happier' and much more plesant to ride.
the biggest difference is felt when ditching the original silencer and putting on a british pipe.
bullet350
-bulleteer for three years!
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Standard Engine...go for the 30mm.
With the freer flowing Air box and exhaust then a 30mm carb it will be noticeably quicker at the top end.
And you wont notice loosing a little at the bottom end.
Mine runs a Goldie pipe,30mm MK1 Concentric and one up on the G/box sprocket.
Will cruise at and indicated 80,but bits fall off !
Jethro
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you wont notice loosing a little at the bottom end.
Will cruise at and indicated 80,but bits fall off !
SORRY ! 70mph....a little optimistic then. ::)
Jethro
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Go on 120 off the Gower cliffs..
R
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Go on 120 off the Gower cliffs..
R
The first one I hab in '92 would do an indicated Ton....!
If I did that too often it didnt last very long between rebuilds ::)
Was Gas flowed by The Cylinder Head Shop....
Jethro
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I can verify high 90's and bleeding ears from following Jethro's Enfield, and he's lying if he calls the chromed pipe bolted to the side of it a silencer, it's a bl**dy amplifier I'd say :o :D