[SCCTrim]

I have had the chance to spend a little time with the bike now, and also was able to get it back on the dyno today. Suprisingly the A/F really wasnt that far off...even with the accel pumps enabled.


For comparison the 1st sheet is the bike prior to having the exhaust cam advanced 1 tooth, and with the stock cvk carbs.

75.36 hp
59.93 lbft of torque

The sheet below is from today, this is the same dyno as the sheet above.

82.30 hp
61.06 lbft of torque

The carbs still need some work regarding tune...the bike is lean at idle...and rich around cruising speeds of 65/70 mph. We dropped the main's from 145's to 142.5 to bring the bike closer to 13 at cruising. I have the needles setup on notch #5...they are raised all the way up. I backed out of doing anymore tuning on the dyno and bought another pair of needles. After I get those in I'll get the bike back to the shop for another run...and maybe swap out the pilot's.

While the peak torque is nearly the same, the curve is much flatter....the bike pull's great and is a thrill to ride.


Comparing these carb's to the stock cvk's is difficult regarding drivability...rather like comparing say...a Sport bike to a Harley. Two totally different piece's of equipment...I don't believe...( I may be wrong )...that either the mikuni's or the fcr's will ever hold the level of drivability of the cvk's. These carbs..( mikuni's/fcr's )...simply are not constant velocity carbs.

The power come's on rather abruptly, not to the point where it's undriveable by any means...I do find myself now having to be much more self aware of how smooth I am with the throttle however. Learning smooth throttle control is a good thing.

I'd recommend these carbs to anyone serious about building hp.

No telling at this point whether or not advancing the exhaust
cam made any difference on paper...as I had said before...I doubt it made any real difference on paper. The real benefit however is by the seat of the pant's feel of the bike.

 

[pabonne]

I was wondering when we'd see this. That's some serious power... Impressive that you've managed to get this from the Bonne's powerplant. Definitely shows the rest of us what can be done. Great work. :upthumb:

 

[HiVel]

Looks like the bike is all done at about 6,500. This would bother me as I am an inveterate revver of engines=twist em till they cry uncle! Do you think some other cams ( I do not know who or where to get some)would move the HP curve and also increase it to around 85 HP. My bike has the Procom module to increase red line -do you see the need for that yet? Seems like the driveability situation you describe wpould make th ebike harder to go fast on a curvy road. Perhaps it would be best for just racing in a straight line?
Love the carbs and would like to get some anyhow!

 

[SCCTrim]

The bottom scale is not properly scaled to show the correct rpms. The dyno operator took the bike to 8000 on this run.

 

[HiVel]

Now we are cooking!!

 

[sweatmachine]

Very impressive, 80+ well documented horses at the wheel. Really, that puts you next to any stock bike claiming 100 hp, and probably above any 100 horse bike in the torque department.

Nice stuff. I can't quit thinking about the stroker kit. I think I may have to finish up my XS and sell it for some stroker money...seriously. A stroker with those carbs should be good for at least 90hp and 75 ft lbs...mmm

color me jealous.

 

[SCCTrim]

Just back in from adjusting the carbs abit...managed to finally properly disable the accelerator pumps and the bike love's it. Snappy acceleration, pull's like a frieght train.

Don't let anyone tell you these carbs dont work...they are awesome.

Final settings:
97 needles on #5 position
20 pilots
142.5 mains
7/8 turn out on air screw


Machine...don't talk yourself out of the 904 kit due to the small gain in displacement...the added torque / hp from the increased compression ratio is where it's at.


Based upon what I've done to my bike, you should expect roughly 20 horses more or less from a 904 kit and carbs.

 

[Brooksie]

SCC-do you think you can get comparable gains with 35mm Kehins?

 

[SCCTrim]

I've never ran the cr carbs, so my thought's on this are speculation. My answer would be no, while I'm sure the cr carbs do boost performance, seeing how they are the same size as the stock carb's I do not believe they would give the same performance advantage as the mikuni's. I would also assume the mikuni's flow alot more air than the cr's due to the difference in size...ie: 35mm versus 42mm.


Again this is only speculation....just make's sense to me...more air, more fuel, more power.

BTW...I was informed that the reason the rpm's are not correctly scaled in the 2nd dyno sheet is due to the fact that the Gately's had their race bike on the dyno just prior to mine. Rob neglected to reset the rpm's for a 8000 limit..( the race bike redline's at 10000 )..Hence the improperly calculated readings.

 

[TBAbob]

SCCTrim,

Very interesting! Not on the forums much anymore and today is my first visit to this new segment after the split. I live just north a Allentown and it appears that we have some things in common. I have had the 42mm HSRs on my '02 America for well over three years now and I'm just finishing a ground up resto of a '69 BSA Rocket 3!

Initially, I really didn't see much of a power gain with the Mukunis although they looked a heck of lot better and they allowed me to lose the stock air box and aquire a very useful "trunk" under the seat!

I always had a problem with the bike running too rich. I can't even count the number of times that I've had these on/off of the bike and the number of jet combinations that I tried. Even custom ordered leaner than normally available jets from Mikuni! Still the bike had plenty of power and "Harley hunting" was real easy! LOL! Always thought (and still do) that these carbs are just too big for the bike.

Two winters ago, I dropped in the Weisco 904 big bore. The lean problem got a little better and power got better. Big surprise, huh? Last winter I dropped in a set of British Custom street cams. Without touching the ultra lean carb settings this combo finally got the bike to stop blowing black soot out of my Sceptre pipes but only after I also disabled the accel pumps!

I dynoed the bike a few months ago and got almost the exact reverse results that you did. 65 HP and 83 lb/ft of torque!! Weird, huh? We ran the bike twice to be certain and we also had run my '05 Rocket 3 just before this with the expected results so I don't think there was a problem with the dyno. This bike drips torque!! Seat of the pants confirms the results as well. It's actually difficult to shift into any gear including fifth without having the front end jump! I love it!!

Perhaps this spring we ought to meet up somewhere and swap rides. Might be interesting! I'm still thinking that the Mikunis are really too big.

BYW, I put a Hyde 850 big bore and a set of MAP street cams in the Beezer "while I was there". I just can't help myself. Sigh!

Cogito ergo equito

Bob

 

[SCCTrim]

Welcome back to the forum's Bob...don't know that I've ever gotten to swap story's with another original rocket3 owner, great bikes!

The mikuni carbs are large, no denying that, but I dont believe they are so large that they cannot be properly setup to increase performance. I'm curious to know how you have your's setup regarding needle size, position, pilots and mains.

Always looking for another riding buddy, we do several ride's at Capitol Area Triumph in the spring/summer/fall...maybe we can meet up for one of them next season.

Pulling the plunger's and springs from the carbs made all the difference in my carb setup...it wasnt enough to simply remove the plunger accuator rod.

Seem's odd your only getting 65 horse's out of the America...I'm sure it's strong with the 904 kit and the mikuni's however...I bet that beezer is smokin with the 850 kit in it :-D

 

[keef]

Good info SCCTrim - the cam mod and the carbs get more interesting the more I see your results.

 

[TBAbob]

SCCTrim,

Checked your pics. Very nice 750 Bonnie!

Hanover's an easy day ride. I rarely put less than 100-150 miles on any time that I ride. If nothing else, we can meet at Triumph Come Home next summer. You're close enough to PUSH a bloody bike there! LOL! Or we could meet at the H-D plant in York and see what we're "missing". Or not! Ahahahahahaha! We'll trade an e-mail or two next year and see what develops.

BTW, I did remove the plunger and springs to disable the accel pumps. I left the operating rod in. If nothing else it helps keep dirt out of the float bowl.

Cogito ergo equito

Bob

 

[SCCTrim]

On 2006-11-13 09:51, TBAbob wrote:
SCCTrim,

Checked your pics. Very nice 750 Bonnie!

Hanover's an easy day ride. I rarely put less than 100-150 miles on any time that I ride. If nothing else, we can meet at Triumph Come Home next summer. You're close enough to PUSH a bloody bike there! LOL! Or we could meet at the H-D plant in York and see what we're "missing". Or not! Ahahahahahaha! We'll trade an e-mail or two next year and see what develops.

BTW, I did remove the plunger and springs to disable the accel pumps. I left the operating rod in. If nothing else it helps keep dirt out of the float bowl.

Cogito ergo equito

Bob

Thanks for the compliment Bob...

Did you make the come home rally this year? I was there off and on, and had just gotten my bike prior to that rally.

I only live maybe 10 minutes from there max

Looking forward to meeting you for a ride.

 

[Brooksie]

SCC-great stuff on the Mikuni carbs. Bonnie Performance site is a little confusing as to what is needed to go with those bad boys, but the gains shown are worth a phone call. It's either that or the BC carbs (39MM) Thanks again for the info!

 

[HiVel]

On 2006-11-11 15:56, Brooksie wrote:
SCC-do you think you can get comparable gains with 35mm Kehins?

I have afriend who Knows about this stuff and he says the Mikunis are AWESOME when they are dialed in correctly as these seem to be. As good as or better than a real sharp tune on Fuel Injection. Good stuff. Gotta do that!!

Mill the head!

[ This message was edited by: HiVel on 2006-11-14 16:31 ]

 

[jojje1963]

On 2006-11-12 10:01, TBAbob wrote:
SCCTrim,

65 HP and 83 lb/ft of torque!!
Bob

My guess is that it was the other way around. Was that 83lb/ft at or above 6000rpm? If it was, you are looking at the HP line. The lines will cross at 5200rpm and after that the HP will always be the upper line, no exceptions.