Flat slide carbs anyone?
#1
Senior Member
Back Marker
Thread Starter
Join Date: May 2005
Location: Thousand Oaks, CA.
Posts: 120
Flat slide carbs anyone?
Does anyone have any info on using flat slide carbs.... I think Mikuni was the brand of choice..... I also heard that these, though may not necessarily give you more power, however the response is way better....
#2
Yes, response is better, but only if you have a very smooth throttle hand. If you whack it open it'll bog hard because the fuel won't catch up with the airflow for several seconds. Great for a race bike and a seasoned racer. Bad for a streetbike. Want more power? Get high comp pistons. It'll be more forgiving on the street.
#3
Keihin actually does the hot setup. Had them on the Ducati, have one on the Duke. Razor sharp throttle response. Lots of backfiring. Rotten gas mileage. I don't believe they're made as big as the stock carbs on the Hawk.
#5
Originally Posted by Kendrick
Maybe I'm just cofused, but the honda specs already list flat slide carbs as used on the superhawk.
Kendrick
Kendrick
#6
The VTR's carbs are indeed flat-slides but of the CV (constant velocity) variety. In essence they have flat slides but have a secondary slide that helps to control airflow (reacts to intake vacuum) so as to overcome the stumbling problems typically encountered in carbureted fours-strokes (when you crack opne the throttle, vacuum drops and so does the aux slide, tehrery keeping intake velocity decently high, once the engine vacuum builds up again, teh slide open allowing the engien to ingest more air).
Also, the unusually large diameter of the carb venturi on the VTR's carbs results in relatively low velocity airflow which makes the carb/engine combo all the more sensitive to hesitation and bogging. (note: non-CV flatslides work very well on two-strokes however). I don't think that replacing the VTR's carbs with non-CV units would be desirable unless you want to deal with all of the bogging issues (you would need a very smooth throttle hand to say the least). Accelerator pumps do help to overcome this bogging to some extent, however (squirt raw fuel into air stream to compensate for loss of vacuum and hence decrease in fuel draw from jets) .
Not sure if this is possible but I know that in some instances (snowmobile carbs) people do machine the venturis to increase the diameter and generate more airflow (perhaps an oval or offset bore would work best as it wouldn't alter the low-end too much but still generate more airflow on top-end)
cheers
Mikstr
Also, the unusually large diameter of the carb venturi on the VTR's carbs results in relatively low velocity airflow which makes the carb/engine combo all the more sensitive to hesitation and bogging. (note: non-CV flatslides work very well on two-strokes however). I don't think that replacing the VTR's carbs with non-CV units would be desirable unless you want to deal with all of the bogging issues (you would need a very smooth throttle hand to say the least). Accelerator pumps do help to overcome this bogging to some extent, however (squirt raw fuel into air stream to compensate for loss of vacuum and hence decrease in fuel draw from jets) .
Not sure if this is possible but I know that in some instances (snowmobile carbs) people do machine the venturis to increase the diameter and generate more airflow (perhaps an oval or offset bore would work best as it wouldn't alter the low-end too much but still generate more airflow on top-end)
cheers
Mikstr
#8
Hi guys, I don't get on here much any more as I just don't have time nowadays.
The Keihin FCR carbs that are commonly used for the VTR are 41mm, no doubt due to some of the reason listed by you guys. Pretty common mod in Japan. Have a look on Japanese ebay.
Personally I think the throttle rsponse would be too savage.
Keep your eyes on "ozfirestorm.com.au", we have a member who is doing this mod at the moment, and no doubt there will be astory on there when he is done with it.
The Keihin FCR carbs that are commonly used for the VTR are 41mm, no doubt due to some of the reason listed by you guys. Pretty common mod in Japan. Have a look on Japanese ebay.
Personally I think the throttle rsponse would be too savage.
Keep your eyes on "ozfirestorm.com.au", we have a member who is doing this mod at the moment, and no doubt there will be astory on there when he is done with it.
Thread
Thread Starter
Forum
Replies
Last Post
andy9743
General Discussion
21
07-03-2007 05:03 PM