| Author | Message | |||
     Ezblast |
Depends on the exhaust - my Bub needed the needle shimmed .03 and then was perfect on the Black, on the red didn't need it, and my WB was almost flat with no needle shimming - go figure - but the 45/175 will put you between 13 and 14(and a tad above withe the 45 keeping you in the 14 area) on your AF. GT - JBOTDS! EZ  | |||
| Ezblast |
Dynos 
   GT - JBOTDS! EZ (Message edited by ezblast on January 02, 2006) | |||
| Gearheaderiko |
Splitfire plug # SF 416D | |||
| Gearheaderiko |
I have an M2 needle but it is non-adjustable and seemed to kill the top end somewhat when I used it. Havent shimmed or done any modifications other than jetting and a different spring, because a)I needed a place to start from. b) without fully understanding the consequence of each modification, I'm like a blind man with a Rubics cube. c) Since I dont ride it everyday, I wont have the luxury of day by day tuning and the chance of running it lean and blowing the motor during a race would defeat the present goal (racing-not necessarily winning). The XB head is using stock XB size valves with heavy springs. It might have had some porting. sidenote: I planned to use this head completely stock and it would have worked just fine with the cams and rpm limit I'm using, but I got talked into going with the heavy valves and springs so I could run any cam I wished, they then seemed unwilling to sell me anything but the B50's!!!! | |||
| Ezblast |
Then perhaps the N9 or RED SHIFT 630/585 would be better suited to those springs, or go back to the XB stock springs for more lift - if you do then step the guides for extending head longevity - no sucking due to high comp or oil weapage/penatration, or wear. GT - JBOTDS! EZ | |||
| Bobbyhead |
Gearhead, about your spark plug choice. Do you realize what heat range you're running there ? I used this sites NGK equivilent to our stock plug, then used an cross ref chart I have, and find that the Splitfire #SF 416D is the hottest of the 3 heat ranges they make in our size. The number 416C is cooler, and the 416B is the coolest, and equal to what comes in the Blast stock. I'm guessing you didn't realize this? And for racing, you really don't want to run that high a heat range plug. You better swap it out before you start racing. Remember, running fast- use cold plug, running slow- use hot plug. The heat range is the temp the plug stays at to ward off carbon build up, and has nothing to do with spark ignition. FYI, I'm a factory Ford Service Tech, and part time SCCA racer. Bobby | |||
| Ezblast |
Concur! | |||
| Gearheaderiko |
Bbyhd:I dont remember where & how I got the plug #, but I'm sure some research went into it. I have found that when using cross reference charts to cross reference charts, it doesnt always come back to the same original number (spark plugs or otherwise). I will check into it though.Thanks. As far as racing with it-too late! I'll get a full report tomorrow at the track about the engine performance. All I know is Matty finished first in his class with it!!!  | |||
| Gearheaderiko |
EZ & cams: The dark side whispers.......!!! Perhaps cams & additional headwork after a few more races and the next SLO ride. Actually the original intent was to build a reliable, streetable, hi-po Blast engine with off the shelf parts. Meaning all the parts were available at the local Buell/HD dealer, so if out on the road (or track), it wouldnt be a big deal to find replacements and they should last as long as the stockers.It wasnt intended then to be a committed race bike. When I started this project a year+ ago it was also intended to be an open book so others could learn, have input, see any mistakes made (like the unnecessary headwork) and that everything would literally be 'bolt on' and it would be accessible to the average Blast enthusiast. So as I learn, others may also.(at another forum this approach led to ridicule and demeaning) Thanks for the input. | |||
| Gearheaderiko |
"or go back to the XB stock springs for more lift" EZ, how would that give me more lift? | |||
| Bobbyhead |
Hey Gearhead, so you didn't blow up the motor today  Ya know, I researched that SF plug too,and there are only three plugs in our size, and the one you mentioned WAS the hottest of the three. Whaaaaaaaa, why can't you write up a race report now ? whats this about- (at another forum this approach led to ridicule and demeaning) ? And I was going to ask that same thing about going back to stock Xb springs myself, how would they give more lift? Bobby | |||
| Ezblast |
"or go back to the XB stock springs for more lift?" With heavier springs more tension - on a high lift cam this would be good because you still don't want them open too long in the event - the tenser springs would prevent that, but with a lesser cam perhaps the event is closing too soon robing power - a thought - GT - JBOTDS! EZ | |||
| Gearheaderiko |
The mechanical relationship wouldnt change. If the valves stayed open longer because of weak springs, it would be valve float! } | |||
| Gearheaderiko |
I am glad the motor didnt blow up! I will check the plug situation. I wasn't at the race today, James or Matty will tell that story! As far as the other forum(not Badweb)-we wont go there-suffice to say that some peoples egos are built up by putting others down-not uncommon on the internet. (Message edited by gearheadErikO on October 16, 2005) | |||
| Ezblast |
Yes but the opposite could also be true - or Buell would use heavier springs - the heavier springs may close the valves faster causing a shortened event - robbing you of power - my thought - GT - JBOTDS! EZ | |||
| Swampy |
I think the XB springs need to be used with a higher lift cam because of coil bind. This is the carb section isn't it? LOL I found out yesterday that when you put a Drag Specailties carb kit in, it has a new emulsion tube that uses Mikuni jets which have a different diameter and pitch thread then the stock CV jets. | |||
| Bobbyhead |
EZ, Gearhead is correct. The lifters are always in contact(following) with the cam lobes, if weaker springs don't follow the lobes at high rpm, then it's known as valve float. The only advantage that weaker springs might have, is less wear on the cam lobes, and cam bearings. Then there are some who believe, heavy springs also create more friction. But in general, an OHV motor using pushrods and rockers, will always have more friction and more valve train slop, than and OHC engine with cam lobes working directly on the valve buckets(over the valves/springs). Bobby | |||
| Swampy |
AND.... The higher pressure valve springs will prevent the valves from float, got to keep the valve operations precise. I used to work building Ford motors for racing,(Professionally, I was paid for it) We used to look for witness marks on the top of the pistons after they were run to reassure ourselves that the valve was staying open as long as it could. Darn! This is still the carb section! LOL | |||
| Ezblast |
LOL - yes it is! - However, I'm just stating that if Buell had thought a heavier spring was needed for a stock style cam (Which for an XB it is) then they would have used it, using heavy springs with a stock style cam could/should speed up the closing event due to more spring pressure being applied (the opposite of float)is what I'm talking about - too light a spring will float, too heavy a spring will...nespa? GT - JBOTDS! EZ | |||
| Bobbyhead |
(EZ)No, it ain't so. The whole idea is, that the valves open and close precisely as the cam grind tells it to. Cams are ground to very precise specs, and the idea is, to keep the valves opening and closing in perfect unison to what the cam dictates. There CAN'T BE too quick a valve closing time because of the spring pressure, only too slow with weak springs, which causes valve float at high rpm. BTW, from the specs I've been reading on cams in general for both H-D and Buell. The XB cams (also found in the latest XL1200)are the hottest cams ever used by the factory in a street bike. And to give another example, previously in the XL Sportster line(not including the old XR1000), the pre rubber XL1200s had the hottest cams in an XL model. But the irony is, that exact same cam grind is what comes stock in a P3 Blast. I just read that, and was shocked ! So what I'm trying to say is, even a stock XB cam is pretty racey stuff for a Harley motor, and the stock springs that go with those cams can't be like ones previously used in any other Harley application. So I'd say the springs that Gearhead is now using, can't be too much heavier than a stock XB spring. Does anyone have the spring pressure rates for the two springs we are comparing ? Bobby | |||
| Gearheaderiko |
Buell used 7mm (thinner) valve stems and a gentle ramp grind cam so they could use less stiff springs. That meant less weight and less wear on the valve train.It also meant, like the Blast, it cant tolerate much more aggressive cams. The valves and springs I'm using are larger stemmed and a higher spring rate.I'll try and find the comparative spring rates. | |||
| Ezblast |
OK - so I missed that, however, then I definately would be looking at the more radical cams, and I still can't figure out why your power/torque numbers are so low. GT - JBOTDS! EZ | |||
| Naustin |
Maybe it's that 98 octane race fuel?? I don't know how big of difference it would make though. I read somewhere that the higher the octane rating, the less energy there is per unit in the fuel. The higher octane makes it less prone to pre-ignition which is great for high compression. But 10.5:1 isn't THAT high, and you might get away with lower octane, higher energy content fuel. Otherwise, wouldn't it have to be the exhaust? (Message edited by naustin on October 17, 2005) | |||
| Gearheaderiko |
EZ: I still dont believe the last dyno numbers are accurate. Significant differences in performance seemingly rule out the dyno reading that I have less HP and the same torque as before. Naustin: You are correct. Higher octane-slower burning-less power. You run the lowest octane without preigntion. I talked with the guys at the local experienced VW speed shop and they rec running 50/50 with pump gas (getting about 98 octane).I've also run 104 on the street with great results. Since I had some knock & ping on the street w/91, I figured running 100 mph, in 100 degree heat, at full spark advance was too much to risk on pump gas. 98 isnt that high and better safe than sorry. The exhaust definitely changed the powerband and let it rev faster. | |||
| Humboldtblast |
out of nowhere my bike at startup, started to idle really high and would idle funny, kinda like its huntin' for a spot but cant find it. Also, i have the poppin sickness... Checked the boot and all the exhaust fitting, and still does it. does this sound like a leaky boot problem? | |||
| Naustin |
Yeah. Sometimes you can't see the crack in the boot until you take it all the way off and look through the inside for light coming through. Replace the boot. If it still does it, then go from there. When you replace it, be VERY careful to install it properly and not over tighten the hose clamps, which can damage the new one right off the bat. | |||
| Jprovo |
Also check the exhaust system out for leaks... | |||
| Ezblast |
Yeah - a loose header or cracked header/can can also give you those simptoms. GT - JBOTDS! EZ | |||
| Humboldtblast |
Ill call redwood tomorrow and get a boot... soon as it stops raining ill post some pics!! | |||
| Bueller492 |
I wish I found this site before I started working on my blast. The bike was great with a Vance& Hines exhaust untill I installed the Pro-Air Cleaner and Dyno-Jet Kit. There was a huge loss in power, will not go uphill. Everything looks fine with the intake and carb boot. I used the BJ155 main jet and followed the instruction in the kit perfect. The instructions do not call to change the 42 slow jet to a 45 but you drill the slide lift hole, replace spring and needle. Can anybody help me? Should I get it checked out by a dealer. |
