Mikuni Carbs

[excess11]

I saw a set of mikuni round slide carbs for sale. These were the non Constant Velosity type. What would be the advantage or disadvantage of non Constant Velosity carbs on an XS1100!!!

[skids]

Re: Mikuni Carbs

Well, your handle is "MacGyver" so I'll bet you can get them to work with a paper clip, a book of matches, and some tape!
=:-)

Originally posted by excess11
I saw a set of mikuni round slide carbs for sale. These were the non Constant Velosity type. What would be the advantage or disadvantage of non Constant Velosity carbs on an XS1100!!!

[Dennyz]

I ran a set of "Smooth Bore" Mikunis on my "F" for a short period of time. What I learned is that Yamaha has a good reason for using constant velocity carbs. You know all that torque an XS motor has from around 1500 rpm up in to the 5K range? Well, CV carbs allow a smooth transition through that power band. With smooth bores, it is an all or nothing kind of thing. Great for racing where the engine is up in the higher RPM most of the time, bad for street riding where control at the lower RPM is desirable.

The smooth bores really shinned at the top end. I could easily go 140mph with lots of pull left over, where with CVs, 140 is about max.

With the smooth bores, off idle performance was terrible. It was possible to stall the motor on launch. If I had a passenger on the back it was even worse. If the motor did not die, all of a sudden (passing through 2000 rpm) the giant would wake up and it was off to the races (wheelie time).

The smooth bores also require a pull/pull throttle cable setup (two cables). This means loosing the stock throttle assembly and running a separate kill button and starter button.

It was an interesting experiment, but not very practical for street driving.

[wildbill]

Has anybody tried the carbs off of a CB 750 or a Z-1 on one of these bikes? Might be interesting.

[sksxs1100]

I still have not heard an update on the fuel injection setup that was being done... anyone else hear more about it?

[Dennyz]

I have a FI solution in progress for the XS. The real unfortunate aspect to FI is the cost. I have not been able to get the cost down to under $1000 for a one off solution. It is very possible to build your own or use one off another bike if you have the know-how. But a plug-n-play solution is spendy. Not many XS folks are interested in putting that kind of $$ into their bikes and most XSs are working fine with the stock carbs. If 100 people wanted FI for their vintage bikes, it drops down in the $600-700 range. If 1000 people where interested, well you get the picture.