| Author | Message | ||
     Ezblast |
4.175" cyl/pis. @ 10.5 comp. - as used in the XBRR, with the 12 stroke - 809cc of thumping goodness - and Brian of Revolution Performance said he'd be more than willing to help build such a Motor and if I had the money I'd be on his door step right now - lol - Through all the debate Blake has been right about what the Nikasil is about - showing that impartial research will always get at the truth. EZ | ||
| Ezblast |
LOL - easy answer - because no one made them in the size he needed! At least he could modify the iron to the size he did want. EZ | ||
| Ezblast |
Yes - the single classes here at various tracks in Cali allow the Blast to race, and I'm told that it is similar in other states as well. Thumper racing is alive and well! EZ | ||
| Buelliedan |
EZ, Please explain how you can fit a a 4.175" bore cylinder into Blast cases? The biggest bore that will fit is 3.875 unless you know some miracle way of getting more? You also are wrong with your calculations. A 4.175 bore with the 12 crank (3.813 stroke) gives you 855cc. Your answer as to why FMJ does not run Nikasils contradicts what you just said about Millenium making you 4.175 bore cylinders for a Blast. I believe FMJs cylinders are 4" bores so obviously Millenium could have made some Nikasils to fit right? (Message edited by buelliedan on May 20, 2008) (Message edited by buelliedan on May 20, 2008) | ||
| Ezblast |
Actually you are wrong - if you weld the old holes and offset the jug a bit - and redrill and face the case to accept the jug you can go larger - Brian and I discussed that very thing when I asked him about the XBRR - and since I don't have to worry about a second cylinder - I don't have to worry about crowding, and the lower cc # came in using the stock Blast stroke - which would be more beneficial for a jug that size. Actually - I think he's running oval pistons. EZ (Message edited by ezblast on May 20, 2008) | ||
| Buelliedan |
Sorry I lived in Missouri for many years so you would have to show me how that can be done for me to believe it. Not saying it can't just its never been done and I don't see how it could be. Your calculations are still wrong. A blast stroke is 3.125 which gives you 701cc with a 4.175 bore | ||
| Ezblast |
There is a crazy Flattracker running a 4.0 - had to do this - thats where the idea first got thrown out, Brian picked the Stroke - less than the 12's hmm - suposedly the same stroke as terry's new 720, keeping the jugg size of his older 650? That conversation was a bit down the road - lol - I know I posted it here, but it will take searching to find the details. EZ http://www.badweatherbikers.com/buell/messages/201 64/11471.html?1156548480 | ||
| Fast1075 |
Reuel, I think the big limiting factor would be the OHV/Pushrod design as far as LOTS of rpm go, but as you said the more oversquare the better for rpm...but you are on the right track with the exotic fuel idea as far as making power goes anyway... Ultimately its all about cylinder pressure (within a given bore/stroke/rod lenght package), the more cylinder pressure you build the more torque you make at the crank....the combination of torque and rpm allows the CALCULATION of horsepower...this broad statement does not take into account factors like thermal efficiency, frictional or pumping losses.. Anybody ever nitrous a P-3? Can the crank handle it? (with a GOOD tuneup)...I am told the trans should be up to the challenge...Best head?? Modified stocker? Aftermarket?...one of those dual plug sportster jobs??? How would the above along with a good cam package work with (to stay strictly on topic) a 515 bore kit? | ||
| Ezblast |
I'm more conservative - your burning the candle at both ends - The bigger the bore, if you want any kind of rpms, means your stroke has to stay short - realistically - keeping the Blast stroke and going for a custom maximum bore of 4.175 - ala the XBRR - 11.0 comp, Head matched to fit - would have to be stage 2 at least to really enjoy the power, crank would be fine - perhaps have it lightened a tad, but since your splitting cases anyway - a baker shift drum kit and fresh bearings and gears are in order as well. Upgrade the bearings. ETC EZ (Message edited by ezblast on May 20, 2008) | ||
| Ezblast |
To be on topic - when I redo the dailly driver engine - it will be with a 515cc kit, stage 2 head, baker drum, se550 cam and 1.75 rockers, fresh gears and bearings, wheel bearings as well - lol - same carb - cv40, Terry P exhaust system, my stack - lol - that will put my errand runner into a really fun focus and stay reliable for a long while - hell - I'm looking forward to rebuild time - lol - the XBBlast engine - I would love to have at over 800cc - lol;0) EZ | ||
| Buelliedan |
EZ, My wifes blast basicaly has that same 515 engine kit you are describing but without the altered rockers and it has a Jardine exhaust. It makes 40 hp at the rear wheel and has been more reliable than stock. It has no problem reaching 75 mph by the time we enter the freeway from the on-ramps. | ||
| Reuel |
If one could get a better air/fuel mix that is possible with standard carburetors or fuel injection, could one go to 13.5:1 or more? My Blast always has been able to easily get up to 75 on a freeway onramp. From 75 to 90 takes much longer than from 0 to 75. | ||
| Ezblast |
Yeah - I have the same thing minus the ratio rockers and substitute the B70 cam instead - similar lift profile but a bit more aggressive ramping - if you copy the Terry P. exhaust (his custom LSR mated to a 4" supertrapp) I gave dimensions for in the exhaust section, you'll think you have a new bike all over again - its that good. That motor combo has over 15000 on it now and is still going stronger than ever. I think the SE 550 cam has a gentler profile that would even better support long top end engine life, you can feel the B70 kick in, the SE is much smoother - Yuppers that group of engine mods really is worth it, and though you are still down on hp compared to a lot of singles, you are actually over them on torque to the rear. Since torque is the source for all that is fun in a Buell - this is a good thing! EZ | ||
| Fast1075 |
Comparing the blast engine to say....a Rotax is definately not apples to apples...lets just say it will be a stout blast engine...my stocker runs "OK"...with an extra 10hp or so it will run better... I'm just waiting for an excuse to mod it up...i do want to select a head to use and get it built up before i buy the cylinder kit...i dont want to tear it apart and have it sit a long time waiting for parts...get everything in order...tear down on a saturday .... riding on sunday. | ||
| Buelliedan |
Fast, The 515 kits with some headwork and cams is the way to go. It will boost you up about 25% which is 10hp or so. | ||
| Ezblast |
Nope, however, they are raced against, and you would still have more torque to the rear wheel than say their 550 - lol - do not look at crank numbers, look at rear wheel dyno numbers - a stock Blast has the same to the rear wheel torque as a KLR stock. EZ | ||
| Fast1075 |
My previous "thumper" was Honda XL based...with a 10mm Poweroll stroker crank, full on portwork,max bore w/12-1 compression, cam and a 38mm Mikuni MV...it ran like a scalded ape...IF you could kick it over (it broke several sets of kickstart gears)... It WAS CONSIDERABLY lighter than a P-3, with a wet weight of only 235 pounds. | ||
| Ezblast |
LOL - very nice - however, if you replace parts with lighter parts you can trim down a lot of weight -  both of these bikes are a lot lighter than stock! EZ | ||
| Ezblast |
The dyno reported torque is crankshaft torque. Otherwise it'd change wildly for different gear runs. - True, however, either all factories have wildly optimistic dynos or they are not selling people the bike they are dynoing - meaning that almost all independent dynos get similar numbers that are usually almost 10% lower than the factory quoted numbers. That is what I meant by that comment. EZ | ||
| Reuel |
Correct me if I'm wrong. The dyno measures engine RPM change and tire speed, so it calculates what the engine is putting to the road and adjusts for RPM differences so it can get the true RPM and torque, thereby calculating what the engine is putting on the road. | ||
| Ezblast |
As was given to me by the expert;0) - To clarify: Rear wheel dynos report torque at the crankshaft that is indexed to the rear wheel, meaning the losses between cranshaft and rear wheel are accounted for. In effect, the torque at the rear wheel is ratio'd down by the overall drive ratio to get the torque at the crank. The numbers reported by the factories are actually measured right at the crank and indexed to the crank, no drivetrain losses are involved. Thus they are higher and are so just as much as dyno test RWHP is higher than the HP at the crank. My point was that if you measure torque at the rear wheel say for first gear, the number will be something like 1000 FT-LBs versus the 70 FT-LBs for the crankshaft. It is incorrect to say that the torque is at the rear wheel. It isn't. Me: My point is that independent dynos seem to concur in their numbers or are at least a lot closer than factory numbers are, making them more trust worthy than factory numbers - of any brand. Torque is the measure of all that is good, and is measured at the crank. EZ | ||
| Buelliedan |
Torque from a dyno run is really an "educated guess" is the best way to describe it. | ||
| Fast1075 |
We tried a chassis dyno run once with the small tire Top Gas bike (1428cc with 2 stage nitrous)...all we accomplished was to tear up the tire LOL!!! /and that was with the progressive stage limited to 50% !! | ||
| Ezblast |
True Dan, however, their guesses are a lot closer together than the factory quotes - and I'm talking about all motorcycles in general - not just Buell. EZ | ||
| Blake |
"Torque from a dyno run is really an "educated guess" is the best way to describe it." The reported torque is just as accurate as the reported HP. There is no guessing involved. It's a very simple calculation. (Message edited by Blake on May 23, 2008) | ||
| Reuel |
Yup. Measure actual torque and RPMs at tire, measure RPM at engine, do the math. Result=power from engine minus power lost between engine and tire. | ||
| Blake |
Actually, the dynojet and other inertial danamometers measure the drum's angular rate of rotation (time interval per rotation) and from that directly calculate the acceleration from one rotation to the next and then the power required to do so. From that powerand given the sensed engine rpm, the calculation for torque follows. (Message edited by blake on May 23, 2008) | ||
| Blake |
To be fair, I think what was speaking to was the Dynojet fudge factor. However, that does apply equally to RWHP as well as torque. | ||
| Berkshire |
There was some talk of big-bore kits being on sale in this forum a few weeks ago, and Myrtleblast just posted about a $315 price on an NRHS kit ("diagnosing problems" thread, May 27 & 28). I just looked, and the NRHS website shows $395 for the Iron-lined 515 Blast kit, $595-$645 the Iron-lined 600 Blast kit, and $645-$695 for Nicom in either size. Shipping was another $24. I didn't see any big-bore kits there for $315, and nothing for the Blast was listed on their "specials" page. Either I was looking at the wrong thing somehow, or the special JUST ended! ...looks like I'm back to my original plan: new piston + .030" over stock jug. | ||
| Gearheaderiko |
10.5:1 piston I hope? |
