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Discussion Starter · #1 ·
Has anyone experimented with alternative carbs? I know about the edelbrock single carb conversion, which "seems" like it would be a good idea, but the reviews are really bad. I think the edelbrock is only a 40mm? I'm toying with the idea of a single carb conversion, but I don't want the edelbrock. I'm thinking about an S&S Super E. They use them on 883 sportsters. Why wouldn't they work on a thumper? Esp if the thumper was bumped up to the 762cc mark? The Super E is a 47mm carb with an enrichment lever, instead of a choke, thus less restriction in the venturi. I had a 96" stroker shovel head with an S&S ... I think it was a G, and we all know how difficult older Harleys are to start in cold weather, but with the S&S it was ZERO problem. The other major diff is the S&S has a butterfly instead of a slide. Does anyone know how that affects performance? Also, I understand the fact that 883 is way larger than 762, but the 883 only turns about 5000 rpm, maybe 6 if your lucky, what could a modded Rappy motor turn?...maybe 9000 rpm? Would that make up the difference in required CFM to feed the motor? I do know they use the S&S on hillclimbers, and being on a HD vtwin, vibration and incline shouldn't effect the performance of the carb either. Any ideas suggestions knowledge?
 

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He stated he wanted a single carb conversion
 

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I think you will have to look far & hard to find something that works better than the dual FCR setup.

There are now some larger sizes of single carbs, take a look what the big-bore KTM's run, 54mm single FCR I think............
Some drag racers use Lectrons, both single & dual setups have been used I believe, good for straight-line work, but not so good for an all-purpose type quad, or so I have been told.

Problem with street-bike carbs is they don't much like the sideways/reverse lean G-forces created by the cornering action of a quad, tends to upset the operation of the float bowl leading to either flooding or starving.
I am having to work through this on a hybrid I am slowly building.............

The other problem you may find is getting jetting to work.
Modding Stock, or the dual 35/39 FCR route is well known, & there is plenty of help available.
I tried a few things, looked at a few different options, then went for a set of FCR's.
They come up 2nd hand from time to time, got mine for $500, which is about the going rate.
 

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Discussion Starter · #5 ·
I think you will have to look far & hard to find something that works better than the dual FCR setup.

There are now some larger sizes of single carbs, take a look what the big-bore KTM's run, 54mm single FCR I think............
Some drag racers use Lectrons, both single & dual setups have been used I believe, good for straight-line work, but not so good for an all-purpose type quad, or so I have been told.

Problem with street-bike carbs is they don't much like the sideways/reverse lean G-forces created by the cornering action of a quad, tends to upset the operation of the float bowl leading to either flooding or starving.
I am having to work through this on a hybrid I am slowly building.............

The other problem you may find is getting jetting to work.
Modding Stock, or the dual 35/39 FCR route is well known, & there is plenty of help available.
I tried a few things, looked at a few different options, then went for a set of FCR's.
They come up 2nd hand from time to time, got mine for $500, which is about the going rate.
How do normal atv carbs compensate for the G forces in their float bowls?

I've heard of these FCRs...I've looked at their site etc..but it seems foreign or something and I can't find any dealers/suppliers. If they work better and are easier to tune/maintain, I'm down with sticking to the duals. I just can't stand the pilot screw placemnt on stockers. Theoreticly a single should be easier to maintain since there isnt another to be synchronized with.
 

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Discussion Starter · #9 ·
Why do the easel rock carbs get bad reviews what makes them no good
Well, no one has really said what exactly is wrong with them, just that there are more people that say they wasted their money than say they are pleased with results.
 

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How do normal atv carbs compensate for the G forces in their float bowls?

I've heard of these FCRs...I've looked at their site etc..but it seems foreign or something and I can't find any dealers/suppliers. If they work better and are easier to tune/maintain, I'm down with sticking to the duals. I just can't stand the pilot screw placemnt on stockers. Theoreticly a single should be easier to maintain since there isnt another to be synchronized with.
Dual carbs do not need to be synchronized for the Raptor since they are feeding one cylinder only............
As long as they are pretty close to be equal at idle is good..............
 
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