Topic: Samauto II RC1080cc, RC crank and Golden rods, 327 cam etc, CB750 Automatic

[Bill/BentON Racing]

Yeh, me too, but I knew it was a possibility. Now the chassis is 90/95% done. Fix the engine and go after the 10's for next year with it. Everything I did needed doing so it's cool. Thanks for the compliments , Bill

[POPS 911]

BILL: What locked the engine up the first time and cause the almost fatal crash that took the owner down on the track and a life flight

[dragracer]

Pops, I've got a jetting question. The weather is going to be a little bit cooler than when we raced in the summer. My bike slows down under those conditions indicating a lean condition. I haven't got a Wego to determine exactly where the AFR actually falls.  I took a shot in the dark and upped my pilots from 17.5 to 22.5 but left the mains alone. I only replaced the low speed jets because the bike seems to suffer more in the 60' range which affects my 1/8th mile times and conversely the overall run. Give me some feedback please.

Sorry Bill for posting on your thread but I figure Pops would check back here first.

[754]

Dragracer...are you ever under 5K rpms in the 60 feet?.. Cant see being any lower than that..unless you are bogging.

[joe p]

Dragracer...are you ever under 5K rpms in the 60 feet?.. Cant see being any lower than that..unless you are bogging.

What he said!

[dragracer]

Dragracer...are you ever under 5K rpms in the 60 feet?.. Cant see being any lower than that..unless you are bogging.

Frank, I'm launching well above 5 grand and understand why you're asking. I'm just trying to insure that the bike is getting adequate fuel at all rpm ranges when the weather is cool. 90% of the run will be full throttle so the pilots have no real impact

I failed to mention this but, I did order some larger mains yesterday when I picked up the bigger pilots. The dealer didn't have anything large enough in stock I could use, so he sourced the mains from an out of state distributor. I did up the main jet size at the beginning of the year based on problems I had from the last race of 2104 from the cooler temps. To be honest, it really didn't seem to cure my problems. Perhaps I could have gone even bigger then on the jetting but the weather had turned by the next race and the bike ran fine. We're back to cooler weather now so I felt I needed to address the problem. I'll start it up and read the plugs at idle. If they don't turn smooty black, I'll leave the pilots in place. I won't get the new mains until Thursday afternoon and won't have time to install them until I get to the track on Friday morning. We're faced with temps below 55 degrees each morning for time runs and it goes up to no higher than 69- a recipe for lean mixture unless I make proper changes. I have to dial the bike in based on the lower temps so I'm hoping going up on the overall jetting will solve the problem. I'll post a time slip if I can of my first few time trials.

Keep the comments and suggestions coming fellas. I'll be the very first to admit that I'm not the best at conventional carb tuning as most of my time racing this bike, I've never really noticed changes in ET from hot to cold weather. On my other dragbikes, I run Lectron carbs that have no jets at all. You simply tune the mixture by adjusting the slide needle in or out as the are venture type carbs. The Lectron carbs only do 2 things, idle or full throttle. With Lectron carbs on 4 bikes, you learn quickly how to adjust for various weather conditions which is done with the twist of a needle- not jets.

[Medyo Bastos]

i never noticed, are you running pods, or stacks? maybe try pulling pods off during cold temps, and put them back on when it warms up... that is something you can try early morning to see how things feel before having to load up for the track

[dragracer]

No pods. No stacks. They are 36mm Mikuni Flatslides. Open pipe, 112 octane, non- oxygenated fuel.

[POPS 911]

FRANK IN THE 10'S :Last time I was there in the spring with my OHIO WINTER COAT AND GLOVES ON THAT DAY at SGMP my weather station read 245' at that race track = best numbers to add fuel.... as I race at a track DA 2100'- DA 2800' most weekend events. That low jet not in the game after you wack that throttle open, two bad you can't run a two step = throttle slides all the way up. You can buy 10 bikes and have no clue in ET BRACKET racing but a weather station is a must for these carb engines. CV's AND FUEL INJECTION W/BRAIN BOX makes a easy day for the wrench spinner. Watched two racer at a $10,000 PAUL GAST ET race at NORWALK with CV carbs on SUZUKI'S go down to the final 6 = they changed nothing.  Rich jets can slow you down [ head wind also ] use your eyes for the wind but use that weather station for the carb tune. You wonder why a PRO-STOCK SUZUKI runs a RACEPACK that you turn on after the burn out !!!!!  Information on those giant FBG W/POWER JETS to be added or lowered.
PS: I walk over to the BIG BIG JEGS YELLOW TRANSPORTER AND TRAILER [ for  HIS SONS JR.DRAGSTER ] and ask can I check my station against their best JEGS buys and sales to the many bracket racer at our track. A DYNO PULL is NOT a time run but a 60'  330' 1/8 mile  1000'  ET  MPH are the numbers you need and yes IN 1st gear and NO RED LIGHTS!!!!!

[scottly]

I don't know about the flat-slides, but with the VM round-slides, the idle jets contribute to the total amount of fuel over the entire range of throttle opening...

[dragracer]

I don't know about the flat-slides, but with the VM round-slides, the idle jets contribute to the total amount of fuel over the entire range of throttle opening..

I don't know about the flat-slides, but with the VM round-slides, the idle jets contribute to the total amount of fuel over the entire range of throttle opening...

Right on que Scottly. I'll look up info on the flatslides. I'd imagine the concept/ design is similar. I started the bike up with the bigger pilots this evening with the shop door open and the fan blowing in cool air. Obviously I had to tweek the idle more due to a fatter mixture but the bike seemed to rev easier for some reason. Maybe I'm on to something, or maybe not. Lol. I'm going to make the first time trial Friday night without putting in the bigger mains to see how it affects the entire run. If I see no improvement over my data from the cooler temps at the first race of the season, I'll install the next size up mains for the one time run we get on Saturday morning when it'll be much cooler. Pops, I'll hunt someone down with a weather station and note the conditions throughout the weekend. Thanks.

[scottly]

I doubt that a 10-15 degree difference would require a main jet change, unless it was border-line lean at the higher temps?

[dragracer]

I doubt that a 10-15 degree difference would require a main jet change, unless it was border-line lean at the higher temps?

The bike ran best in the heat of the summer, even at the higher elevation in Memphis, but has slowed down some as the temps have dropped. Like you said, border line lean to begin with. Keeping my fingers crossed that little bit extra fuel i might get from the pilots makes a difference on the first time run. If not, i'll install the 135 mains. I'll then go to the 137.5's if need be.

Bottom line, we're bracket racing so i can adjust my dial in to whatever the bike runs. The problem is, if i don't address this issue, as the cooler morning temps turn into warmer midday/afternoon temps, the bike will get quicker making dialing in more difficult. Consistency wins in bracket racing, not setting personal bests.  I also don't want to hurt the engine.


I'm installing a Wego next season so i can data log/monitor my AFR. on the fly.

[POPS 911]

FRANK in the 10's : I will send you to use my small hand held DIAL IN BOX  with instructions on how to use for you to try out. After your first pass =  Simple turn on, set turn button to that ET number, next run push fan button to draw in air to the secret parts, WAIT !!!! and it gives you a plus or minus number for you dial in after your first pass at that track, turn off and the next round do it all over again, Only push down fan button and watch the screen for the plus or minus number do nothing [ all day long ] with the original first pass  ET setting knob......

[Jerry Rxman Griffin aka MuthaF'er]

Pops thats just too slick!

[jweeks]

Pops,
     No, it won't go 10's next season unless the cam is changed and a bigger rear brake setup is made. A four into two into one header wouldn't hurt either.

Frank,
     Just my opinion, but I think that it will take more than one jet size to get it fat enough for the cool mornings. My 'matic motors like being a little lean for best ET's, but needs a jet size per thousand foot density altitude drop. If you want it to live without the tweaking, it needs to be about 2 sizes rich for normal summer passes. It will slow down a little but won't overheat the valvetrain on the cooler mornings.

     Good luck everyone racing this weekend. Be safe!

[POPS 911]

Looks like FRANK got the bracket bike = 10.53 ET on this Saturday morning first time trial .......... leave that SOHC 750 ALONE, tree and sandbag those faster bikes!!!! BILL RC COBRA ran 11.53 needs to get FRANKS tune up if he wants a time ticket with a 10 anything..... all he needs is one second.

[gschuld]

I wonder if Billy got those RS34s dialed in yet or swapped my bored carbs back on that he ran low 11s with on Cobra girl at the last event.  I know he was running short on time to get them tuned properly.  They should allow him to run stronger at the top end I'd think with their extra airflow potential compared to the smaller bored carbs, but they need to be dialed in to make it happen.  Or perhaps it was something totally unrelated that has him off the pace a bit on that 11.53 run.  That bike certainly has 10s in it if tuned up right and a reasonable 60ft.  Go get em Billy...

George

[POPS 911]

GEORGE : Tune carbs ?? it is just a jet change you can do on them carbs = about a 5 minute job, either bigger or smaller. Simple fix = ask FRANK what size jet he has in his flat slides on a tired old motor that ran 10:53 on the time trial. With those good conditions I would guess bigger jets, you do not tuned at a race with one or two time trials, you go every week end or any day your track is open and let's bike run down the 1320'...... bet that !!!!!!  DYNO PULLS ARE NOT A time run.

[gschuld]

I agree Pops.  Benton has never run RS34 carbs before on any motor as far as I know, and he came to the track with a best guess jetting.  I believe he is still running the MR12 oxygenated fuel, which generally wants fatter jetting I hear compared to non oxygenated race fuel(like Frankie is using).  He intended to go the the dyno to get the jetting figured out on his 915 motor, but that didn't work out.  That's why I sent my bored carbs back down to him last minute, the ones he ran on Cobra Girl since last fall, including the 101 rear wheel hp dyno tuning session mid summer.

His plan was to try to get the RS34 carbs jetted OK yesterday, and swap out to the "safe bet" bored carbs if he didn't have luck with the RS34s. 

The find points of carb tuning is clearly not my area of expertise, so I can't add any more than that.  I have NO idea what is affected ting Billy's performance this weekend so far, carburetion may or may not have anything to do with it.

George

[dragracer]

George, unfortunately our friend elected not to change back to your tried and tested bored carbs. Thanks for the extra effort you went through to them returned to Bill. I've been fighting a bad migraine headache all day so my performance was lacking all day. In fact I sat out my last Crazy 8 qualifying pass and never went back up for my street ET buyback round. Tomorrow will be a new day.

[Sam Green Racing]

Hope you are well tomorrow Frankie.

[gschuld]

Sorry to hear about your migraine.  I know well how that can screw up your whole day.  Hopefully all will be good tomorrow.  How did your better half do with her new ride?

Sending you a pm in a minute.

George

[Bill/BentON Racing]

Faulty air shifter button killed round one a rd 3. Checking it now, wouldn't do anything in round 3, started with 140 psi, back in pits with 140 still. Just damn, had my best 60 ft on that pass, 1.637, as Frank said ,tomorrow's another day! 
Wilbur's done well! K. Bill

[POPS 911]

FRANK IN THE 10'S :  Have that headache checked out = could be a CLUSTER HEADACHE a problem I have been tuning on for the past  5 years........... another name for these sever pains is SUICIDE HEADACHES, thanks to THE OHIO STATE UNIVERSITY HOSPITAL STAFF like their Football Team got them handled. Get that win ticket and remember your in my will on those KZ PARTS...... bring a big trailer.