M8 Engine modified to Carburated. CAN-Bus Removed
#52
03-20-2019, 12:56 PM
Tourer
#53
03-21-2019, 06:04 AM
#54
03-21-2019, 06:18 AM
Also kudos to the guy who did the conversion!
I converted a 2007 Street Glide to carb using a DTT ignition with my own wiring harness and used a Mikuni HSR48. I couldn't get the Mikuni to deliver enough fuel without an electric pump so I ultimately went back to EFI. The engine was a 120".
I will say this, that carb was extremely responsive to throttle input, moreso than many EFI systems.
As for pro drag racing, I have yet to see an EFI bike or car outdo a carb. When NHRA mandated the switch in Pro Stock to EFI, the cars all went slower and have still yet to perform as well as carb to this day, and its been several years now.
I converted a 2007 Street Glide to carb using a DTT ignition with my own wiring harness and used a Mikuni HSR48. I couldn't get the Mikuni to deliver enough fuel without an electric pump so I ultimately went back to EFI. The engine was a 120".
I will say this, that carb was extremely responsive to throttle input, moreso than many EFI systems.
As for pro drag racing, I have yet to see an EFI bike or car outdo a carb. When NHRA mandated the switch in Pro Stock to EFI, the cars all went slower and have still yet to perform as well as carb to this day, and its been several years now.
Maybe you had a flow issue out of your tank? Which would make sense since you say you needed an electric fuel pump on a carbed bike, which is commonly gravity fed.
#55
03-21-2019, 08:09 AM
Tourer
yes it is. probably the only one on the planet left.
Although I am planning a stage one this spring.
*edit* I guess I have to take that back. The previous owner changed the wheels for chrome ones and I've been told the front forks have extra chrome on them as well. but engine/power wise. it's the same as the day I bought it.
Although I am planning a stage one this spring.
*edit* I guess I have to take that back. The previous owner changed the wheels for chrome ones and I've been told the front forks have extra chrome on them as well. but engine/power wise. it's the same as the day I bought it.
Last edited by anothernewb; 03-21-2019 at 08:11 AM.
#56
03-21-2019, 12:28 PM
Road Warrior
I have to ask, what specifically was wrong with the HSR48 where you had to convert back to FI? S&S themselves puts their Super G on the 124" engines so carbs are fully capable of performing with engines that large.
Maybe you had a flow issue out of your tank? Which would make sense since you say you needed an electric fuel pump on a carbed bike, which is commonly gravity fed.
Maybe you had a flow issue out of your tank? Which would make sense since you say you needed an electric fuel pump on a carbed bike, which is commonly gravity fed.
The major issue I found was at WOT it would indeed starve for fuel. This engine made 146/144 on a dyno not known for happy numbers. The HSR fuel bowls are relatively small and it is possible for it not to keep up fuel wise. So much so that Mikuni was aware of it and the instruction manual reads as follows for the HSR48:
"Engines producing more than 120 horsepower should supply fuel from an electric fuel pump to the HSR48. Do not exceed 4 psi and use the smaller Mikuni Needle Valve Assembly (p/n: 786-27001-2.3)"
http://www.mikuni.com/pdf/hsr48x-viewdata.pdf
There were a few other problems. I love Mikuni's for their tune-ability and immediacy in throttle response, that said here are my findings in general with them
- Can be tricky at starting depending on temp/altitude
- Since starting was a bit murky, ring gear took a beating
- Idle can be a bit tricky and find I fiddled with the idle adjustment constantly (they idle faster when hot, even with nothing touched)
I was noticing significant fuel standoff also when around 3/4 throttle; you could smell it.
So off it went. Really didn't want to dig in to electric pumps and all that so back to EFI I went and just tuned it as best I could.
#57
03-27-2019, 10:42 PM
Seasoned HDF Member
#60
02-14-2020, 05:31 AM
