V-Twin Forum banner

1 - 3 of 3 Posts

·
Punch It!
Joined
·
356 Posts
Discussion Starter #1
I need some help on my build. It is a GMR component build put together by a local Indy. GMR stg III heads, 98” high comp (10.5:1) pistons, R&R 615/585 cam, 1.67 roller rockers, SE 51 mm TB, PC III, ST Supermeg exhaust open end cap, 15 discs, SE AC with K&N filter. Here’s the problem I have about 150 miles on it, it has not been dyno tuned. It has a stumble from 2,500rpm to 3,500rpm when trying to maintain a steady rpm. It feels like the fuel is surging or the ignition is skipping. It is noticeable both in the bikes feel and in the exhaust note. If you get on it will accelerate through those rev bands without a problem, above 4,000 is not a problem (in fact it’s very quick) it is just while maintaining those rpm’s that is hesitates. Does anyone have any ideas which way I should go with the tune, increase fuel, decrease fuel, timing? I tried the MAP GMR sent me and it would hesitate worse that the one I have in it from the DJ website. I plan on a Dyno tune but was hoping to get 500 miles on it before. Recently I read about bigger TB’s causing problems, does anyone have experience with the SE 51mm and think that might be my problem? I haven’t gotten any first hand information about tuners in the Houston TX area, does anyone have any recommendations? Thanks.
 

·
Average Dude
Joined
·
6,263 Posts
bigblock455 said:
I need some help on my build. It is a GMR component build put together by a local Indy. GMR stg III heads, 98” high comp (10.5:1) pistons, R&R 615/585 cam, 1.67 roller rockers, SE 51 mm TB, PC III, ST Supermeg exhaust open end cap, 15 discs, SE AC with K&N filter. Here’s the problem I have about 150 miles on it, it has not been dyno tuned. It has a stumble from 2,500rpm to 3,500rpm when trying to maintain a steady rpm. It feels like the fuel is surging or the ignition is skipping. It is noticeable both in the bikes feel and in the exhaust note. If you get on it will accelerate through those rev bands without a problem, above 4,000 is not a problem (in fact it’s very quick) it is just while maintaining those rpm’s that is hesitates. Does anyone have any ideas which way I should go with the tune, increase fuel, decrease fuel, timing? I tried the MAP GMR sent me and it would hesitate worse that the one I have in it from the DJ website. I plan on a Dyno tune but was hoping to get 500 miles on it before. Recently I read about bigger TB’s causing problems, does anyone have experience with the SE 51mm and think that might be my problem? I haven’t gotten any first hand information about tuners in the Houston TX area, does anyone have any recommendations? Thanks.
I have a similar build, only with mildly hand ported heads and stock TB. My bike has a similar stumble, only at most "no load" speeds. As soon as I put a load on it, it smoothes right out. My bike has been properly tuned and is running the best it ever has. I can only attribute the stumble to the cam/exhaust doing its "own thing". I think it is inherent in the cam. I could also be full of sh!t.
 

·
Let er rip!
Joined
·
2,876 Posts
With those actually being R&R heads, and their cams. Maybe give Reggie at R&R a call.
 
1 - 3 of 3 Posts
Top