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Discussion Starter · #1 ·
BB Shearer's made a best of 103 hp (with Lectrons) @ 9000 rpm, with no overrev whatsoever. SBs made 103 (with Lectrons)@9600 rpms with good overrev. BBs had a little better power at lower RPMS, not a good broad curve that I thought the BBs produced.



We ended up getting 109 hp out of the SBs with some different carbs, but never tried the BBs with them.



So, is it better (in 300ft) to have a motor that makes 103hp @9000 or 9700? Or does it even matter as long as its geared accordingly? The motor should (and did) make peak power quicker (i.e. reach 9000 rpms quicker) with the BBs for sure, as the SBs had to rev out to 9600 rpms.



I plan on getting more HP out of this motor, but for now I have to run it for what it is.
 

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BB Shearer's made a best of 103 hp (with Lectrons) @ 9000 rpm, with no overrev whatsoever. SBs made 103 (with Lectrons)@9600 rpms with good overrev. BBs had a little better power at lower RPMS, not a good broad curve that I thought the BBs produced.



We ended up getting 109 hp out of the SBs with some different carbs, but never tried the BBs with them.



So, is it better (in 300ft) to have a motor that makes 103hp @9000 or 9700? Or does it even matter as long as its geared accordingly? The motor should (and did) make peak power quicker (i.e. reach 9000 rpms quicker) with the BBs for sure, as the SBs had to rev out to 9600 rpms.



I plan on getting more HP out of this motor, but for now I have to run it for what it is.
HP is HP, more is good. Personally I have always liked more rpms. The low end on the BB is similar to the SB pipes, so why wouldnt you want to run the pipes that make more power? As long as you gear and clutch it correctly, it will run faster. Your never going to launch a Banshee at anything less than full throttle anyways, so low end isnt as much of an issue. Also remember that a pipe with more overrev will be a little more forgiving if you miss the shift on the high side a bit. The 10mil will have enough ooommmpphhh to pull it out. Just my .02
 

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Did you see if the BB pipes liked more timing or play with timing any? What carbs and what size made more power?
 

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not tryin to high jack... ive been getting my 4mill cub back together for this season, ive actually ended up using the bigbore inframe shearers, ive dyno'd tested countless pipes at this point including small bores oof and 3 sets of custom sets mat has sent over. the bigbores on a 4mill made the most peak 98hp as well as torque 48-50 it did only rev about 9200-9300 but made 6 or 7 more hp on the front side of the curve then the small bores, small bores made 96ish lil less torque but hit 10,000. that motor may end up being a asphalt only motor using the small bores and tryin to peak around 10500 and over rev close to 11000. youd want the pipe that comes on the hardest being the race is only 300ft if the bigbores came on harder then the smalls but didnt make as many rpms,id take the big bores
 

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ive always heard the sb are better on the 4-10mils but alot has to do with timing...but i agree if the bb are showing more hp id run those and maybe get a time and swap out the pipes at the track and see which one has a better time..let us know if u do ive always wondered why the sb pipes always get a better time..
 

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I never know what to think with these dyno testimonials. Matt at Shearer flat out told me that he re-designed the new SB OOF pipes specifically for the 421 - 4 mill cub motors. He said he's getting 5-7 HP more with the new design. He also said that for a 10mill cub he would recomend his SB OOF for draging and his BB OOF for duning. (BB would keep less heat in the motor for long run times) I never hear about guys making changes between parts. I'd want to hear about the timing and jetting changes for each pipe. If you don't find the best overall tune for each part you try...then your only finding out which pipe worked best for the jetting and timing you had for a baseline.

I'm not ripping anybody....I'm just saying....It would be nice to get ALL the notes from the dyno session. A/F ratio for runs, compare torque curves, peak power VS. overall power, etc......

But hey, thanks for sharing the info. It's better to get some real info than just a bunch of opinions.
 

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For a 300 foot race, I'd put on what makes the most HP and Torque the soonest.



J...how much tuning did you do per pipe? Timing, jetting, etc?

Who ported the cub? I'd like to see a cub ported for SB and a cub ported for BB for an all out comparison...but I realize that will never happen.



Kevin @ HJR told me I should be running SB on my 10 cub, I'm just wasting any more money on pipes unless I had a concrete reason to...that'll show up as a number on a slip.
 

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Discussion Starter · #8 ·
HP is HP, more is good. Personally I have always liked more rpms. The low end on the BB is similar to the SB pipes, so why wouldnt you want to run the pipes that make more power? As long as you gear and clutch it correctly, it will run faster. Your never going to launch a Banshee at anything less than full throttle anyways, so low end isnt as much of an issue. Also remember that a pipe with more overrev will be a little more forgiving if you miss the shift on the high side a bit. The 10mil will have enough ooommmpphhh to pull it out. Just my .02


This is kinda what I was thinking.



Did you see if the BB pipes liked more timing or play with timing any? What carbs and what size made more power?


We tried the timing from +11.5 (plate maxed out) and +8 with the BBs. No significant difference at all on peak hp or the curves. We didn't overlay the graphs, but they looked about the same, and peak hp was same and at same rpm. Never tried to change the timing on the SBs - just left at +8.



We started with 41.5 mm (?) Lectrons with the needles (packards) set at 1.88" and pjs wide open and ran them all the way down to 1.5 turns out. Made the best power at about 2.5 turns out. 103 hp.



Next we went with PWKs. PWK 39 mms made the most power. The first set we tried was drilled out to 0.118 and also had a powerjet that accepts a mikuni pilot jet (in addition to the clippard pj.) We drilled out that jet to 0.70" for the second run and it was bout the the same - 105 hp I believe. These carbs were running it lean, even with the pj wide open.



Next we put on some more pwk 39mms that had been drilled to 0.120" with single clippard pjs wide open. First run was 109 hp. Made another run I think and it was 107 or so.





I never know what to think with these dyno testimonials. Matt at Shearer flat out told me that he re-designed the new SB OOF pipes specifically for the 421 - 4 mill cub motors. He said he's getting 5-7 HP more with the new design. He also said that for a 10mill cub he would recomend his SB OOF for draging and his BB OOF for duning. (BB would keep less heat in the motor for long run times) I never hear about guys making changes between parts. I'd want to hear about the timing and jetting changes for each pipe. If you don't find the best overall tune for each part you try...then your only finding out which pipe worked best for the jetting and timing you had for a baseline.

I'm not ripping anybody....I'm just saying....It would be nice to get ALL the notes from the dyno session. A/F ratio for runs, compare torque curves, peak power VS. overall power, etc......

But hey, thanks for sharing the info. It's better to get some real info than just a bunch of opinions.


Overall power was very similar among the different pipes. At least nothing really jumped out on the graphs as being different - again, we didn't overlay them. Don't remember the TQ exactly, but I'm sure the BB made more. We didn't use A/F ratio to tune. Just compared back to back runs to see which way the power and peak went; and tuned accordingly. I DON'T THINK THESE ARE THE NEW SB SHEARERS, BTW. I've had these about 3 years and I don't think those were out yet.



For a 300 foot race, I'd put on what makes the most HP and Torque the soonest.J...how much tuning did you do per pipe? Timing, jetting, etc?

Who ported the cub? I'd like to see a cub ported for SB and a cub ported for BB for an all out comparison...but I realize that will never happen.



Kevin @ HJR told me I should be running SB on my 10 cub, I'm just wasting any more money on pipes unless I had a concrete reason to...that'll show up as a number on a slip.


These cylinders were ordered from the builder knowing I intended to run the BB pipes. Your saying run the BBs? I guess I'll have to try both at the track and see which is better, but I'll have to calculate gearing for the 600 rpm peak difference. I won't name the builder; I think there is more in this motor. The domes were kinda jacked up. I had 200 psi and 180 psi in the left/right cylinders, respectively. The one with 200 had pitting when I took the head off, even though I never saw it on the plugs. The plugs are hard to read on the dyno, compared to the track. I have some new domes coming, I'll keep ya posted when I run it or dyno it again.
 

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Stop talking smack about the Lectrons already J...LOL.

J/K.



Good research, like you said...the track numbers don't lie.

I hate relying on a dyno to be honest...it's cool to F around on, but too many a man left a dyno session with his head down thinking that number meant much...you know what I'm saying.

I think the new SB pipes have only been out a year or two at most.
 

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Discussion Starter · #10 ·
Stop talking smack about the Lectrons already J...LOL.

J/K.



Good research, like you said...the track numbers don't lie.

I hate relying on a dyno to be honest...it's cool to F around on, but too many a man left a dyno session with his head down thinking that number meant much...you know what I'm saying.

I think the new SB pipes have only been out a year or two at most.




Yeah I know its just a number, but my unported (cleaned up by F.A.S.T.)421 Cub made 98 hp with the pjs all the way out, then 100 hp on the next pull with 'em 1 turn in (We didn't do much more tuning on it after that). So for a drag ported 10 mil Cub to make only 109 (and tuned to lean to run at the track when it made that HP) is dissapointing.



There have been several smaller motors than mine make more power on this particular dyno.
 

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Discussion Starter · #11 ·
Oh and I am gonna run the Lectrons on it for now. My friend and dyno owner/tuner said they would be much safer on it. They give it plenty of fuel across the board. The PWKS seemed to be a little lean everywhere - and if we did richen them up, the hp would probably go down to about the same as the Lectrons.



So to be fair to the Lectrons, had we got them in the same state of tune as the PWKS (ragged edge lean) they probably would have made similar HP.
 

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wow the truth comes out. motor is questionable, carbs wern't in the similar state of tune.>.. now this post will start a war on which carbs are better and which pipes are better..



last 421 i did about 3-4 years ago had average domes from fast for a cub. and BB shear's and 41mm lectrons it did 105+ and pulled VERY hard also the carbs were having problems suppling enough fuel. james was going to get bigger bowls or possibly pump it. but ended up seling the motor due to funding issues'



so if your lec's are suppling more than enough fuel and you have the stock small bowls i;d say there is a LOT more left inthe engine. get the correct alky domes for it and try again.. the domes will make a big change in the motor..



motors that rev high are fun to ride BUT i always have found that to get my fat butt around i need the bottom end and aceleration capacity.





either way should be a fast engine!!
 

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Discussion Starter · #14 ·
Squish came up different everytime I checked it. I finally decided it was around 0.055". I got measurements as low as 0.49" in one cylinder a couple of times; but I got 0.055" several times. Piston rocking, I guess.



I have the domes and calipers in front of me. Squish band is 8.26 mm (0.325") if I'm measuring it right. It's the surface from the outside until it meets the inner combustion chamber right? Need any other measurements let me know.
 

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Discussion Starter · #16 ·
wow the truth comes out. motor is questionable, carbs wern't in the similar state of tune.>.. now this post will start a war on which carbs are better and which pipes are better..



last 421 i did about 3-4 years ago had average domes from fast for a cub. and BB shear's and 41mm lectrons it did 105+ and pulled VERY hard also the carbs were having problems suppling enough fuel. james was going to get bigger bowls or possibly pump it. but ended up seling the motor due to funding issues'



so if your lec's are suppling more than enough fuel and you have the stock small bowls i;d say there is a LOT more left inthe engine. get the correct alky domes for it and try again.. the domes will make a big change in the motor..



motors that rev high are fun to ride BUT i always have found that to get my fat butt around i need the bottom end and aceleration capacity.





either way should be a fast engine!!




We got the Lectrons as lean as we comofortable with, it just happened that the PWKS were (too) lean when we bolted them on. I was already biased toward the PWKs, I admit it. But I didn't intentionally run the Lectrons out of tune to make them look bad.



Ever notice after a hard dyno pull that the plugs are always nearly dry with PWKs and wet with Lectrons? My friend says his motors last longer with Lectrons - we think this may be why. I dunno. Any opinions?
 

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I was just teasing about the Lectrons J, you know that...



Really should measure squish with the domes on the motor.

high .040s to mid .050s is fine. I run mid to high 50s. I'm gonna cut that down a little and get low 50s for this year.

I need it to come out of the hole a little harder for my fat arse.



My plugs are normally a little wet when I come back off a run...I'm fine with that. I run a pump and big bowls, too. Overkill, but why fix what ain't broke!



It takes a couple passes to get heat on the plugs...



I run 20cc alky cut domes on mine J. I have a set from HJR and a set from Dan Wade @ Patriot.
 

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We got the Lectrons as lean as we comofortable with, it just happened that the PWKS were (too) lean when we bolted them on. I was already biased toward the PWKs, I admit it. But I didn't intentionally run the Lectrons out of tune to make them look bad.



Ever notice after a hard dyno pull that the plugs are always nearly dry with PWKs and wet with Lectrons? My friend says his motors last longer with Lectrons - we think this may be why. I dunno. Any opinions?




pwks best carbs in the world hands down..also id say the plugs was dry after the run with them being lean maybe jet them correct and get us a # then so we can compare them to the lectrons..but it really dont matter what #s they pull the sb pipes are gonna run better on a 300ft track its proven and the what carb you use is which ever one you can tune better..which i still prefer keihein pwks even though im running lectrons on my bike..lol..
 

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Discussion Starter · #19 ·
I was just teasing about the Lectrons J, you know that...



Really should measure squish with the domes on the motor.

high .040s to mid .050s is fine. I run mid to high 50s. I'm gonna cut that down a little and get low 50s for this year.

I need it to come out of the hole a little harder for my fat arse.



My plugs are normally a little wet when I come back off a run...I'm fine with that. I run a pump and big bowls, too. Overkill, but why fix what ain't broke!



It takes a couple passes to get heat on the plugs...



I run 20cc alky cut domes on mine J. I have a set from HJR and a set from Dan Wade @ Patriot.




Squish was measured with solder with head torqued down. My new domes will be 20 cc. These were 19 cc. And yeah, I know you were just kidding about the Lectrons. It was really toward cam - he's rubbing it in my face a little
. I've been hating on Lectrons for a long time, and he's seen that in posts here and on HQ. I have to admit I was wrong (and he is right) about some aspects of them
; but there is room for improvement in their design, I think.
 
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