Just ordered Mikuni HSR42 Carb
#11
05-30-2012, 03:24 PM
Join Date: Apr 2012
Location: Loveland, CO
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#12
05-30-2012, 04:58 PM
Seasoned HDF Member
Uncle G, the CV I was running had all of the tricks done with 48 & 205. dumped fuel at roll on but cleared out quickly and ran great, also was insurance with roll on detonation so I left it alone.
You might try a experiament and turn that screw out 1/16 of a turn as I mentioned that the Mikuni runs at cruise off the low speed jet by a digitial AFR reader and see if the mileage increases. Have a 20 low with a healthy engine, can get 14.2 cruise with a very very little exhaust pop off the 20 low speed adjusted off the air mixture screw. 1/16 of a turn can change .6 AFR at cruise which adds up on a trip, don't know if you can hit 50 mpg but anything helps.
You might try a experiament and turn that screw out 1/16 of a turn as I mentioned that the Mikuni runs at cruise off the low speed jet by a digitial AFR reader and see if the mileage increases. Have a 20 low with a healthy engine, can get 14.2 cruise with a very very little exhaust pop off the 20 low speed adjusted off the air mixture screw. 1/16 of a turn can change .6 AFR at cruise which adds up on a trip, don't know if you can hit 50 mpg but anything helps.
Says a lot for how good the CV carb really is in terms of efficiency. Then again, back then, we had real gasoline, not this E10 stuff we have to burn today, so...
#13
05-30-2012, 09:44 PM
Grand HDF Member
UncleG, reads air fuel ratio by a 02 sensor made by Daytona sensors, a smaller version of what dyno's use to sample AFR's and can also tune EFI systems that use a Power Commander, nice tool.
#15
05-31-2012, 03:11 PM
Tourer
We've built turbo'd 4 strokes for 4 years now.
Because we run over 15 psi with a starter of 11:1 we run leaded 115 octane.
If you want to see a wide band screw up ,,throw lead at the o2 sensor .
We use the rapid bike unit , which allows us to use the base map and a our own map for boosted runs (depending on starting voltage from map sensor)
Rapid bike allows us to make changes to timing as well as fuel.
Because we run over 15 psi with a starter of 11:1 we run leaded 115 octane.
If you want to see a wide band screw up ,,throw lead at the o2 sensor .
We use the rapid bike unit , which allows us to use the base map and a our own map for boosted runs (depending on starting voltage from map sensor)
Rapid bike allows us to make changes to timing as well as fuel.
#16
06-09-2012, 12:08 PM
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Update
Got the mikuni and ness intake installed. Havent got a chance to ride it yet but it started right up. I did not change any of the carb settings before i installed it. It was too lean at idle, only liked to run with the choke on so I have some tuning to do. It did seem to improve throttle response with a few quick revs. Ill update again when I get a chance to ride/ tune it.
#18
06-09-2012, 06:37 PM
Check the air screw and make sure it is 2 turns out. To richen the idle mixture turn it in, to lean the mixture turn it out. If the final adjustment is less than one turn out put in a larger pilot jet. If it is more than 2 1/2-3 turns out then it is too rich , so put in a smaller pilot jet. Also there is a vacuum fitting just under the choke fiting on the rear of the carb make sure eihter your VOES/ETC is hooked up to this or it is plugged, it is fairly common for the hose/plug to fall off of this, Hope this helps.
John
John
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