Topic: CB750A Street ET bracket drag bike. A year to build it.

[jweeks]

Dragracer,
     Does this fuel have evaporation problems in the summer heat? We all run a lot at tracks on 90 degree + days.
I'd still be looking at a couple of notches higher on the needles. The fuel is an overall boost, not just a mid-range fix.
     How would you know what you've gained - dyno run without the exhaust sensor? The problem would be not knowing if there was anything more left?
     We're running the #1 Dyna curve; we started with the #5. We got quicker advance but less overall advance. I tried a little more overall advance at Rockingham. Too many variables to be shore, but it seemed to not like it. Opinions?

                                                                                       JW

[Sam Green Racing]

Rip van Green here not sure if the poor conection was down to you or me.
I spoke to Jimmy about an hour ago and it was fine.
Give him a phone call and he will tell you what I couldn't.
Alls well with me though.
I'm going to see if I can find someone in your area with a stock auto with a view to putting it on the same dyno to find out what the loss is from the crank (47bhp) to the rear wheel. (?)

Sam.

[ivanhoew]

im totally confused !! . sam , do you live in england then fly to america just to ride your 750 ?

[dragracer]

Dragracer,
     Does this fuel have evaporation problems in the summer heat? We all run a lot at tracks on 90 degree + days.
I'd still be looking at a couple of notches higher on the needles. The fuel is an overall boost, not just a mid-range fix.
     How would you know what you've gained - dyno run without the exhaust sensor? The problem would be not knowing if there was anything more left?
     We're running the #1 Dyna curve; we started with the #5. We got quicker advance but less overall advance. I tried a little more overall advance at Rockingham. Too many variables to be shore, but it seemed to not like it. Opinions?

                                                                                       JW

VP does have some criteria for the U4.4 to prevent vapor lock due to expansion from heat but they mainly address supressing engine heat. I know of no one who has had an issue with evaporation from the MRX01. We live in the deep south so its been tested time after time as far as high ambient temperatures go. It would be great if the ATL crew could find someone to buy a gallon or so of the MRX01 from for testing so they won't have to spend big $$ on a full 5 gallon pail. I do feel this fuel is what the bike will like. The reasons i don't run it in anything i race is due to the cost and the fact i'm not trying to maximize horsepower from fuel.  As  you know, we run at least 3 bikes and it can get costly supplying that fuel for all of the bikes. We bracket race 2 of the bikes and the other 2 are set up specifically to run an index. We dial the ET bikes for whatever ET they run that particular day under the  conditions at that moment. I also have a problem with getting the VP fuel in my immediate area so i stick with Renegade brand fuel from my local motorcycle dealer. You may also want to look into the Renegade fuel brands. They have several octanes  for bikes and some are oxygenated like the VP. VP is tried and proven so if cost is not overweighed by the need for an extra tenth or a hundredth and a few mph's more then its worth it.

[Sam Green Racing]

Bill,
     What gas are you looking to get another 4-5 horses from? Oxygenated race gas? Overlapping posts here. Just left my track's rules meeting today. VP c10 gas this season $9.75/gallon.(110 octane) And that's the cheap stuff....?

     No, street ET doesn't require pump gas. I'd rather see Sam's happy face at Valdosta.(11's) If you see mine there, probably I'll be racing something...

                                                                                        JW

Although I would love for it to run in the 11s, it's looking very unlikley.
As it's an ET bike, I'll be satisfied if it can just run very consistent numbers irespective of what fuel is in it.
You can get the same pump fuel anywhere but you can't always get the race fuel and it will be a lot of messing changing jets if you can't find the fuel you want. Is it not better to stick to just pump gas.
You worry about the cost of race fuel, I just filled up at $10.75 a gallon for cheap pump gas.

Sam.

[Sam Green Racing]

im totally confused !! . sam , do you live in england then fly to america just to ride your 750 ?

It's an 836 and yes It's not just to ride the bike though, it's to see all my mates and it's well worth it.

Sam.

[Sam Green Racing]

im totally confused !! . sam , do you live in england then fly to america just to ride your 750 ?

That's correct. Sam can't stay here to long secondary to the out of wedlock children and broken hearts from previous visits.
[/quote

Murphy, please read the post above (reply #1092) I did say it was to see all my good mates.
I'm having second thoughts about the one in Boston.

Sam.

[Tintop]

Guys, i got a call from Keith this afternoon. He was distraught. It seems between the time he left for sork this morning and around noon, some azzhole thief came along and stole his trailer with his bike and tool box. This wiped him out as far as race stuff.  I think there were some pictures of his bike posted on this site by Jim or Sam. Please take a look back through this thread to familiarize yoursleves with the way the bike looks. Its a CR500 Honda 2 stroke- very unique.

Contact Voodooracer through this site if you ever see this bike.

All i can say is i can't stand a damn thief!!!!!!!!!!!

The bike has been recovered as of this morning- great news for Voodoo.

Great news, any luck on the rest?

[Bill/BentON Racing]

Bill,
     What gas are you looking to get another 4-5 horses from? Oxygenated race gas? Overlapping posts here. Just left my track's rules meeting today. VP c10 gas this season $9.75/gallon.(110 octane) And that's the cheap stuff....?

     No, street ET doesn't require pump gas. I'd rather see Sam's happy face at Valdosta.(11's) If you see mine there, probably I'll be racing something...

                                                                                        JW

Although I would love for it to run in the 11s, it's looking very unlikley.
As it's an ET bike, I'll be satisfied if it can just run very consistent numbers irespective of what fuel is in it.
You can get the same pump fuel anywhere but you can't always get the race fuel and it will be a lot of messing changing jets if you can't find the fuel you want. Is it not better to stick to just pump gas.
You worry about the cost of race fuel, I just filled up at $10.75 a gallon for cheap pump gas.

Sam.

We going in the 11's,but will continue to improve bike as long as it's making sense.I know we have an ET bike,CONSISTENCY first! Brian carries the fuel,VP dealer and hell of a guy. Sam, you'll see the 11's just like you saw the 12's!
More pics:

Finally,sync time.

Not what we wanted!

Better!!!!

Ready to go back to dyno,almost.Bill

[scottly]

     We're running the #1 Dyna curve; we started with the #5. We got quicker advance but less overall advance. I tried a little more overall advance at Rockingham. Too many variables to be shore, but it seemed to not like it. Opinions?

                                                                                       JW

The #1 curve is fully advanced at 2500 RPM, while the #5 curve is fully advanced at 5500 RPM. 5500 is awfully late for full advance, IMHO. I would run the #1 curve, maybe the #4, and play with the crank trigger settings. You have a built-in dyno with an auto, at least for the bottom end; the higher the stall speed, the greater the torque.
Also, if the ignition is late, the motor will appear rich with a tailpipe sensor, as the fuel will not have enough time to burn, and pass into the pipe.

[Bill/BentON Racing]

Scottly,it appears # 1 best choice @ this time.
Mike,the VP rep should be shot,I always try to buy 5 gallon,those light aromatics get gone quick!
Brian can/will/is set up to test the fuels on his dyno.
Bike idles and runs much better
Life is good! Chainsaw back in the hunt. ,Bill

[scottly]

Scottly,it appears # 1 best choice @ this time.

That is my thinking. Try advancing the static timing bit by bit, and see if the stall speed increases.

[Sam Green Racing]

Scott, see Jons post #1084. He did try a few degrees static advance with #1 but not as good.

Sam.

[jweeks]

Scott,
     I didn't check for any launch rpm improvement when I tried my experiment. The time slip was my measure of success. I believe that it was the last pass on Friday night at Rockingham. The mph was also down some, but there could have been other factors involved. We waited a while before we ran that last pass. I still believe that it's worth checking out on the dyno. Torque curve vs rpm will tell us quickly. My Hondamatic twin drag bike loves advance on the starting line. I've picked up a lot in 60', but lost more on the top end. That's where I'm building my own advance curve via MSD to retard the timing as the rpm's climb, (which is what you were suggesting.) My twin runs 85 mm pistons, so it needs more advance with the big pistons than the 836 will require. Getting the most out of a bike motor is always a unique recipe!

                                                                                                    JW

[Bill/BentON Racing]

Jon,that last pass was @ 10:00,one before 7:45.We waited an hour or more in staging lanes. 60 ft time was a little slower,2.6,was 2.5.I agree we'll be checking timing @ 40 and possibly up to 45.Needle will be in 2nd position from top.Mains probably on the money,esp w/better fuel.Massaging/micropolishing bores and slides will help,plus 2 more return springs,I don't need to tell you what carb sync did(idles,feels better down low,smoother etc.).I got idle @ 1800 rpm to avoid stalling engine and to help keep a little creep.Guessing solid mid 12's next time out.RF kept us from getting true rpm readout,calling Brian tomorrow to check,we need rpm vs torque,esp @ 2500-3500rpm's.
Mains still not in or chain,slower than a stock automatic! ;)I believe we're on the way too much better 60 ft times! Honda shop said they would replace oil temp gauge( I like ability to go C. to farenheit)and then clock will also work. Also getting digital voltmeter.Mike,once again,one strong motor and getting stronger! No Sam,we're not building LSR or quickest auto(we'll leave that to Jon),but we are building a solid high 11's low 12's CONSISTENT ET bracket racer! I wanna see only .000-.009 times when you come back,you got plenty of time to practice! ,Bill

[scottly]

Scott, see Jons post #1084. He did try a few degrees static advance with #1 but not as good.

Sam.

Sorry if I seem a bit thick, but it's a bit hard to tell what changes happened when, and with what results. Who has the timing tickets? How about a scan, with notes on setup for each run? You guys did take notes, right??

[dragracer]

Scott, see Jons post #1084. He did try a few degrees static advance with #1 but not as good.

Sam.

Sorry if I seem a bit thick, but it's a bit hard to tell what changes happened when, and with what results. Who has the timing tickets? How about a scan, with notes on setup for each run? You guys did take notes, right??

They did have a log book and made entries after each run. I would hope they made note of the changes as well. I saw Bill jotting down notes at one point. I don't think JW would have had it any other way-lol.

[jweeks]

Is "too much better 60 ft times" even possible? 

                                               JW

[Bill/BentON Racing]

Jon,see what Larry's (Spiderman)60 ft times are this weekend.We'll take those!!! ,
Mike,hopefully we'll improve this weekend(on the dyno),hell,we'd run quicker rt now. ,Bill

[Bill/BentON Racing]

Sam the man,Stig1!,Hell,he even beat Boo Brown! lol!  .Breathes in oxy expels nitrous! Titanium fingers,lightning fast reflexes,mxr-1 for blood,micro polished head...how can I compete? ,Bill

[Sam Green Racing]

Micro polished head,  nothing to stop you having the same Billy  but then again, we don't want to many good lookers in the team of old men. It's bad enough having Frank musceling in with his super duper sun tan.

Sam.

[Sam Green Racing]

Scott, see Jons post #1084. He did try a few degrees static advance with #1 but not as good.

Sam.

Sorry if I seem a bit thick, but it's a bit hard to tell what changes happened when, and with what results. Who has the timing tickets? How about a scan, with notes on setup for each run? You guys did take notes, right??

Scott, everything was recorded and every increment of every run also.
When at Union raceway, the bike was traveling about 40 yards before the mid range kicked in.
That was when we changed the ignition from #5 to #1. the bike then started to kick in about 15 to 20 yards out the hole. Before going to Rockingham, we fitted bigger mains and put in smaller slow running air jets to try to clean up the bottom end. At the Rock, the bottom end didn't seem any better so we went smaller still but to no avail. We tried more static advance on the Friday night but the Bike went slower.
It was difficult trying to figure how much some of these mods made as the bike was getting quicker and faster with almost every run as the motor loosened up.
If we can just find out what's causeing the revs not to come up higher on the line we'll be fine.

Sam.

[ivanhoew]

perhaps a yet looser converter , 4500?

[dragracer]

perhaps a yet looser converter , 4500?

Ummm, you might have to take that up with the converter guy.  I mentioned something about the stall speed on the existing converter once and almost got my head bitten off-lol.

[azuredesign]

perhaps a yet looser converter , 4500?

Ummm, you might have to take that up with the converter guy.  I mentioned something about the stall speed on the existing converter once and almost got my head bitten off-lol.

After reading this thread from the beginning, I was wondering the same thing. It seems a pity to have to pull off the line at 2500 rpm, making what, 30hp maybe, and trying to spool up more quickly by compensating with carb response. What would be the down side of configuring the converter to slip a bit to raise the stall speed? I know nothing about automatics, so I apologize in advance for being naive, but I have been thinking the same thing for a while.