| Author | Message | ||
     Lakes |
Well, have read a few posts on fitting XB rocker box, to the older Buell's, also saw someone say how there bike feels like it goes better after the XB rockers fitted. but no one has a before & after test. well i've been around Harleys a long time have done a few crank breathing changes to big twins in the past & seen how the harley motors have improved there crank breathing & oil pumps over the years. i also have used dyne's, & drag raced my bikes ( all Harleys & this Buell i have now. the drag strip for me is a great test, tell's me a lot too. so was interesting this past week talking to an old Friend who has spent more than half his life working on Harley motors & Buell motors & drag racing. he was saying he was helping at the track, new rider & who had never drag raced b4. young guy has a tube frame carb Buell 1200 74 inch. he went to the track one day & first time out the young guy ran 12.1 104mph with slow 1.9 sixty foot time , the motor had a non stock crank vent from rear rocker box to exhaust pipe, so my friend just disconnected the vent from rocker to exhaust & put a $20 one way valve he picked up on the hose going from the non stock vent in rear rocker, so just had hose with one way valve going to nothing. went back to track with young guy, the bike ran 11.7 115mph still with slow 1.9 sixty foot. so a really good gain from just a cheap mod. the XB heads have the valves that work like one way valves , built in. just thought i'd mention this. Happy New Year all, good riding weather here where i am on the Australian coast. | ||
| Rocket_in_uk |
I have TS heads with breather pipes from both heads T'd into one line running to the rear. Without harping on, I've never managed to stop the puking entirely, which lead me to try a crank vent. Main reason being, I had it in my head once it started to puke even just a little it was then getting sucked out. Can't say it's stopped puking for sure but I haven't ridden it so hard the last two years, but I'm fairly certain there's no power gain. When these crank vents became available I remember a certain BadWeB person back then dyno testing them and no gains were seen ever!  Just saying in case I get accused of pissing on someone's bonfire  Rocket in England | ||
| Lakes |
puking oil out, is common with Harleys , a crack in a piston, or broken ring can cause it to do it worse . do a leak test, see how well rings are sealing. that filter at end of breather hose, not needed & just fills with oil then turns into like a spray gun. catch can with a drain plug is about the best. but i just have my breather hose exiting at the rear of bike. does not seem to puke oil. | ||
| Hootowl |
A long hose, running uphill from the breather bolts, will rarely drip oil. The oil, once it passes through the umbrella valves, runs down hill to the breather bolts, and if the passage from there isn't down hill all the way to the catch can, oil simply builds up un the passage in the head and in hose, making the breather system ineffective. IMHO the breather hose under the tail section is a waste of time, and is ineffective. The hose should run down (down hill all the way) to a catch can. | ||
| Hootowl |
Unless the hose is full  | ||
| Lakes |
hootowl you are right, but i don't think my 2000 model TS heads have umbrella valves? think the XB heads do. the Dyna Twin cam i had used umbrella valves. the reason i put the breather out the back is, if i ran it straight down, there would be the risk of oil under rear tire. i ran a catch can on the dyna as i drag raced it a lot, but it used to get water in it from riding in the rain. i think it must be breathing as no oil leaks & it made good power on dyno with hose like it is. but i'll look into it. thanks | ||
| Hootowl |
Actually, the XB's don't, the XL's do. The XBs breathe through PCV valves (check valves) in the top of the valve cover. The XL engines breathe through umbrella check valves that are internal to the head. The other side of that one-way (theoretically) valve is a passage that leads to the breather bolt. Once oil goes through the umbrella valve, it can not reenter the head, and must be allowed to drain out. Having the hose run up hill from the breather bolt prevents that from happening. | ||
| Foximus |
Build a breather into the exhaust header and you'll see real gains. | ||
| Airbozo |
I recently did the XB rocker mod and so far the only difference I notice is no more oil dripping from my air cleaner onto my header pipes. I almost miss the smell of burning oil when warming my bike up in the morning. Or the plume of smoke coming off the bike in the afternoon. So far nothing is dripping from the hose yet (but it's only been a hundred miles or so). | ||
| S1owner |
Lakes Talk to Lafeyette (buellistic) he has some good info on breathers and crank venting has it all laid out for you pm him it will be worth it. | ||
| Buellistic |
The BEST HEAD BREATHER SYSTEM is the BLAST(XB) SYSTEM which like all BREATHER SYSTEMS, for SAFETY should be run to a CATCH CONTAINER SYSTEM ... When the BLAST came out in 2000 "i" put the PCV's in my OEM ROCKER ARM COVERS which allowed me to put them where "i" thought best ... ALSO installed a TIMING PLUG PCV SET UP ... My only intent was to LOWER the internal pumping action of the engine to a better controlled state ... PM me if you want a copy of the TIMING PLUG INFO ... (Message edited by buellistic on December 30, 2013) | ||
| Rocket_in_uk |
Lafayette, I'd like to see that thanks. You have my mail Rocket in England | ||
| Lakes |
Just an update, as my. Friend came to visit. The bike he got 11mph higher trap speed from at that drags. Was fitted with a non stock breather from rear rocker cover connected to the exhaust pipe, he remover the connection to exhaust put a one way valve he got from s&s just routed hose to a catch can saw trap speed go from 104 mph consistent to 115mph consistent & ET drop from 12's to 11. 7 quarter mile no other change. He will be back at track this week again | ||
| Hootowl |
"Was fitted with a non stock breather from rear rocker cover connected to the exhaust pipe" Huhwhat? The breather was connected to the exhaust? | ||
| Cyclonecharlie |
What kind of oil is he running in that motor?.....Wouldn't be snake oil would it?  | ||
| Yo_barry |
A couple of things... 2001 S3T... Always puked into the stock airbox. Oil would leak out the bottom and coat my right leg on long riding days. Installed a catch can and routed the two breathers to it, no longer dumping into the airbox. I also replaced the butterfly valves, opened up the return holes to 1/8" and champhered the holes for the butterfly valves so they didn't stick, all per current HD lore. It still puked and the filter on the catch can would get saturated with oil and make a mess. Note, I had the catch can mounted on the battery strap between the engine and battery. Later I did the XB rocker box conversion. This seems to work really well, but I did a couple of other things at the same time. The first change I did was to shorten the body of the PCV for the rear cylinder. This was to provide clearance between the valve and the bottom of the fuel tank. Guess what is inside the valve....are you ready? yeah butterfly valves exactly like the ones that were mounted down in the rocker box before the XB conversion. Ok, the other thing I did was take off the catch can with the breather filter. I routed the hoses to a tee, the single line is routed to a Red Bull can attached behind the license plate, no filter on this one. I also placed a tee in this line with the single line dropping straight down to a spot close to the oil drain hose. In this line I screwed in a 3/8" bolt to plug the line. Spooge collects in this line. As it's clear, I can see when I need to drain it. This has worked really good. I've currently got the front head off to sort out a broken front engine mount/broken bolt. I'm planning on re-installing the XB rocker covers, front on rear cylinder and rear on front cylinder. This takes care of the clearance between the fuel tank and PCV. Can anybody see any problem with doing this? I know some posters have used two front XB covers. Barry Hollister, CA | ||
| Buellistic |
CycloneCharlie: Surely you remember Smokey Yunick ... He used EXHAUST SCAVENGING on his RACE ENGINES ... Nothing new about this, just GOOGLE EXHAUST SCAVENGING !!! This is OLD, OLD SCHOOL !!! | ||
| Hootowl |
Exhaust scavenging works, with a properly designed header, for assisting with the breathing of the other cylinder, but there will be pressure in the pipe during part of the combustion cycle, and it can't be a good thing to pressurize the engine by blowing exhaust back into it through the breathers. What am I missing? | ||
| Buellistic |
The point that the exhaust wave sucks and how far it occurs from the exhaust valve ... | ||
| Hootowl |
Only for part of the engine's rotation. I get how that can help with the other cylinder, but not for maintaining vacuum on the breather. There will be pressure there part of the time. I think most of the time. | ||
| Buellistic |
You must remember that with a 2 cylinder engine, you in fact have two engines tied together ... So you must also have an exhaust scavenging in the second cylinder header at the right spot from the exhaust valve ... | ||
| Hootowl |
What does that have to do with attaching the breather to the exhaust pipe? There's PRESSURE in the exhaust pipe MOST of the time. The breather should be under vacuum or atmosphere, never pressure. I want to understand. I just don't. | ||
| Buellistic |
Would you like to discuss this over the phone ??? | ||
| Cyclonecharlie |
LaFayette, The way I'm reading it. He disconnected the line to the exhaust and installed a oneway valve.And never had both cylinders tied in to the exhaust. And yes I loved Smokey's Garage. | ||
| Lakes |
Well about year & half back, my friend picked up a carb tube frame Buell 74 inch had n4 cams 2 1/2" collector no baffle in muff. & this fitting the guy he bought it off had fitted to rear rocker box. the bike is to teach his son to drag race on a MC. he was just saying how well his son is going for someone thats never ridden a MC & he is just teaching him. low 12's 104mph first time at track is good, if you don't think so go & try for yourself. then as he was not sure about the breather hose into the pipe he removed it from the exhaust bought a plastic one way valve S&S make for the job put that onto the hose, as it is at a Drag strip they require a catch can. you empty them out after the day at track could have been a plastic tied drink can. but with that simple change next time at track & his son still learning he ran 11.7 consistent & 115mph. & at a drag strip an increase of 11mph is a good gain in HP. if you think 11.7 115mph from a learner not good try for yourself, the boy ran consistent times not trying to shift fast just trying to be consistent. | ||
| Cyclonecharlie |
Lakes, I like and believe your story about this young ladd. He obviously has talent at his new task.And I do appreciate the degree of difficulty you express. I would believe the increase in speed and better trap times were more his learning curve than some mystic engine modification.  | ||
| Lakes |
Cyclonecharlie , i've spent a lot of time drag racing street bikes at the track, like every week unless it rained 12 month of the year at one time. i found if you don't miss a shift the trap speed will be the same on the day. like if i see a harley or Buell doing 120mph trap speed & runing twelves i look at the 60 ft time that will always be slow, so that just tell's me the bike is a 10 second bike but the rider not good enough to ride it out the hole hard enough. i used my trap speed to tell me if my power was up or if it was loosing power. the trap speed on my 2001 Dyna twin cam 95 inch would be between 118mph & 121mph but i was only doing 11.2's my 60 ft's were only 1.8 , if i went hard out the hole could have got 60ft down to 1.6 then if no missed shift would have been in the 10's we had the air quality on the day printed on time ticket as well as a lot of other data i used. i never changed tune at all & the only time the trap speed would change is if air quality on day was better or if i missed a shift, but my trap speed no tuning changes at all only changed 3mph in a whole year going just about every week & racing once a month for twelve month straight. that's why i know 11mph increase in his trap speed tell's me that the crank breather change his father did worked. i'm 66 years old & retired now live over 300k from the track now so have not raced for 6 months i'm not about to do that crank breather change but will do what Buelistic did but use the s&s one way valve as can get one easy cheers  | ||
| S1owner |
I think some are confusing things or I am. He stated that his freind removed the vodoo crank valve to the exhaust and put in a one way to a can thus the one tied to the exhaust was hindering the bike. Did I read it wrong? | ||
| Hootowl |
That's the way I read it. Blowing exhaust into your engine cases can't help. | ||
| Cyclonecharlie |
Lakes, love your story. I was never a drag race guy.My love was dirt track,turning left.For almost 60yrs.I've been going to dirt tracks,either on the track or in the pits. So I can appreciate your passion for your sport.Will be interested in your assessment of the oneway valve on your bike. |
