| Author | Message | ||
     Harold |
I posted this in the more power section also. My S1W has an Millenium 88ci with 12:1 CP pistons and N6 cams. The heads are stock and it has a 42 Mikuni. I just had it dynoed, and don't have the chart yet but the dealer said it did 88hp and 97 ft/lbs. I suspected something like that from riding it, as it has great low-end power, but didn't seem to have much more top end that a stock S1W. I think it must be restricted at upper RPM's to have the torque drop off. Does anyone have any ideas on what is going to make the biggest difference? I am thinking a 45 carb, and of course porting the existing heads or getting ported XB heads, but would rather not have to replace the cams too. Upping the carb to a 45 I assume would mean a new intake manifold also. The new carb would be the easiest and cheapest thing. Any ideas on how much that would add? | ||
| Guell |
Heads... the power is in the heads. | ||
| Phelan |
I agree with Matt, but ideally you should go with ported heads w/ sunk valves, N9 cams for more overlap and a 45 mikuni. At work now will post more later. | ||
| Phelan |
Okay, I said what I did because from your numbers, it looks that the motor is starving in the top end as you said. I recommended the N9s because they have more duration/cam overlap. The exhaust valve being open for a portion of the intake valve's openning time is essential as it actually creates a vaccum to pull the intake charge into the motor, which is essential on a big bore motor as yours. The heads also need porting to allow enough air to come into the motor to power the charge. The valves need to be sunk in most cases to maintain valve to valve clearance when using a long duration cam as the N9s. The carb also needs to be larger so that the motor gets enough fuel to burn without becoming too lean. | ||
| Rick_a |
There should be more power to be had through tuning. The Mikuni 42 has been proven to be able to feed 125hp motors, so a 45 isn't necessary...though it should add a few hp. Use it with the big bore manifold. Head work would definitely be good, as suggested, and a SE 575 (needs an updated pinion gear), 536, Red Shift 585 or the N9 (less expensive through S&S as the 555) are all popular streetable cams. None of those cams are a bolt-in proposition, and each has it's own nuances, so careful assembly, set-up, and clearancing is critical. | ||
| Harold |
Thanks for the input. What would I need to change the N6 cams. Is that just to get a little more power? There are some x1 heads on ebay, that have Nallins stage 2 done to them. I believe they fit right on a S1 don't they. When they dynoed it, they were tuning it too also. I will pick it up today, and post the chart this afternoon. I was hoping for torque in the 100+ column, but no cigar. | ||
| Phelan |
If your bike is an S1W, then you already have thunderstorm heads. You can upgrade to XB heads but you will need a new front mount (available from American Sport Bike). With ported heads, the cams will give you a significant power boost because of the overlap. | ||
| Limitedx1 |
Those numbers seem low to me. my bolt on x1 put 90hp to the wheel. | ||
| Phelan |
Ron, they are low. That's what we're discussing is how to fix the situation. The motor is starving for air up top. It won't make more power until it gets more air. To summarize, I'd say get ported heads with larger valves (or have this done to your stock heads), then get the cams later, followed by the carb. With some merchant skills, you can recoup some of your costs with the old stuff. And I picked up a set of N9 cams on eBay two weeks ago for $100. I'd offer them to ya but I'm trading them for some SE .551s because I don't want to sink my valves. | ||
| Harold |
Here is the dyno chart, and you can see the power drop like a rock after 4,000. I am going to get the heads done, and am thinking about just staying with my carb and cams at first to see if it makes enough of a difference that I am happy. I like to wheelie, so ultimate power is not as important to me as torque at around 4K.  | ||
| Limitedx1 |
i thought an 88" motor even with stock heads would touch 100 horsepower? before i went to ported heads i would change fueling now | ||
| Maru |
I am in the process of a 90 cubic inch project. Everything I have been told refers to how hard it is to feed an 88. They make tons of power early but it takes a lot of work to get them to continue to breathe past 5000. You need cams first. You have really mild cams for an 88 and as a result the bikes runs like it should. Yes headwork would be nice but without more cam you are wasting your money. | ||
| Harold |
The dealer said my air/fuel mix, and hence the jetting, was right on, although I didn't get the graph of it. Since it will need heads anyway no matter what, I figure on doing them first and see how much it improves. Right now 60-80 roll ons are immediate, since its right in the middle of the power band. 80 to 100 is only a bit slower, and so far I haven't taken it faster than that. | ||
| Kalali |
Sorry may be I am missing something but to me it looks like th HP climbs up to 6K-6.5K RPM before it drops off. The Torque does drop after 4K which I think is somewhat normal. | ||
| Harold |
Having the torque numbers higher than the HP is normal on a big twin that doesn't rev very high, but not our motors. If the torque had stayed at 80 until 6,500, it would be putting out over 100 hp, but it had dropped to 70 which only gives the 85 you see in the graph at that rpm. The high horsepower graphs you see have to have the torque stay up there past 5,250 to get hp higher than torque. That is going to be the goal with this motor, without going to cams and exhaust that don't start making good power until 4,000. | ||
| 186bigtwin |
It's all in the heads I have a 88" XL and it makes 116 HP @ 7100 rpm.............. | ||
| Maru |
Hi Steve. I think we would both agree it is not al in the heads or the cams but it is in the total package including cams, head, exhaust and on and on. Having said that, you will not get decent cylinder fill at the rpm necessary to produce 100 plus horsepower with those cams no matter what you use for heads. The big Xl's rarely make much more outright power than a good 1250 they just make it sooner. A SE .575 cam is a pretty mild cam for an 88 and when coupled with the right exhaust will make plenty of power below 4000. | ||
| 186bigtwin |
Maru, you are right and my bad, it is the total package, I forgot to mention I use .625 redshift cams and a S&S "G" manifold with a 44/47mm Mikuni VM and a custom made exhaust with the STD heads, it does take it all; adding one wrong ingredient can make the recipie come out bad.......... | ||
| Harold |
So the N6 cams are considered mild? Do the more radical cams need adjustable pushrods? There are some Redshift 585 v2 on Ebay right now. How would they do, or is it better to spend a little more and get something else? | ||
| Maru |
I think you should call Dan at NRHS. He is very helpful and his shop has done a ton of 88's. | ||
| Jimidan |
If you are already set up to go to Pammy and Co., they can instruct you on how to get the performance you desire...probably much better than anyone on here. They will have the engine right there in front of them. They have a dyno on site and know how to use it. They have vast experience in building these motors and you should follow their advice to the letter. There is more to building these 88 inch motors to be durable than just bolting on parts. I know, as I have two long term engines and I have learned a lot in the process. The engines really need to be blueprinted too. One of my engines has STD heads, Mikuni 45 with S&S manifold, S&S rods, Red Shift 585 cams, Nallin's HD springs and roller rockers, Crane pushrods, Jims Hydrosolids, Zippers oil pump, JE pistons with Axtell cylinders. It has 35,000 hard miles on it. I would get on it tomorrow and ride it across country. It has done several track days as well. The other engine is similar, but with Nallin's Stage 3 Thunderstorms. there is not much difference in performance. Both have a flat torque curve that starts out over 100 ft/lbs at 2500 RPMs. They both red line at 7,000 RPMs...so there is very usable power from 2500 to 7000 RPMS. But, they cost a lot of money (thanks Mom, for the inheritance!). Who bored out your cases? | ||
| Harold |
I bought it with the 88's, so I don't know about the cases. 3rd gear power wheelies should be easy, but will yours pull it up in 4th also? | ||
| Oldog |
+2 Jimidan CycleRama for the work,.. | ||
| The4ork |
been reading alot about buel engines lately and ive come to the conclusion that best bang for the buck seems to be headwork, not increasing engine size... but which heads? p&p XB heads or p&p Tstorm heads? | ||
| Preybird1 |
I have the XL1200 heads with 7mm stainless valves and single beehive xb springs p&p stage 2 light from NRHS And my motor is the 80" and 1250 big bore kit with new jugs. My bike puts down 112 rwhp EDIT: my motor is the 80" Phelan your right, I had to think about that for a minute. Wow i don't know how i got that wrong. (Message edited by preybird1 on September 23, 2009) | ||
| Phelan |
Russ, your bike is 76" with the 1250 kit. 80" is 1340cc. XB heads are a better piece for p&p, but you need a new front mount. The other nice thing is that the XB heads have larger fins so they cool better. | ||
| 186bigtwin |
There's alot more power to be had with a 88" motor, just look at either NRHS or Cyclerama's dyno sites, these things are capable of between 115 and 130 HP with the right parts and tuning. | ||
| Buellsrule |
It is the total package. I recommend Cyclerama or NRHS for headwork, at least Redshift .585 or higher(do your homework on cams). Race header with D&D slip on or Force big bore pipe. Good intake: Force, race filter set up, etc...This should be good for 120+. You'll need a good clutch i.e. Evolution, Barnett, Energy One, etc... Hope this helps. Frank. | ||
| Harold |
The bike is at Cycle Rama right now, getting the heads, .600 cams, 45 Mikuni, adjustable ignition, and Wes's magic. Hoping for at least 120 hp, and that the stock clutch lasts a little while. | ||
| Preybird1 |
My stock clutch started slipping on the dyno after the motor build and it only had 8900 miles on it. Now i have a Barnett race clutch and it is sweet! |
