Topic: Keihin CR, Dyna 2000, 836, ported head- Tuning

[scondon]

   OK, so the ride home was more telling. Had just a hint of "rattle" in 5th and the bike accelerated through it quickly. However, when I got of the freeway and hit the first stoplight I got a lot of "rattle" while pulling away(just off idle). #1 setting has idle too advanced for normal operating temps, so unless I retard the timing even further it's back to #4 setting, which works fine at idle when the engine's warm. I may have been too hasty this morning when I set to #1 simply because the bike didn't roar to life on the first swipe at the starter button.

[MRieck]

   OK, so the ride home was more telling. Had just a hint of "rattle" in 5th and the bike accelerated through it quickly. However, when I got of the freeway and hit the first stoplight I got a lot of "rattle" while pulling away(just off idle). #1 setting has idle too advanced for normal operating temps, so unless I retard the timing even further it's back to #4 setting, which works fine at idle when the engine's warm. I may have been too hasty this morning when I set to #1 simply because the bike didn't roar to life on the first swipe at the starter button.

Yes...the advance comes in to early. If only decent fuel existed all the time.

[s3d1t0r]

I can't help but wonder about the use of store bought Octane boosters.  Because here in WA all I ever see is 92 oct premium at the pumps.

[scondon]

I can't help but wonder about the use of store bought Octane boosters.  Because here in WA all I ever see is 91 oct premium at the pumps.

   I've tried that route with no success. The stuff is silly expensive for what it is and a whole bottle added to my 4 gallon tank only raises the octane by 1 or 2. Toluene is a much less expensive route(I think it's 100 octane) but I don't like the thought of getting it around my tank every fill-up since it's used as a paint thinner/stripper.

[MRieck]

I can't help but wonder about the use of store bought Octane boosters.  Because here in WA all I ever see is 91 oct premium at the pumps.

   I've tried that route with no success. The stuff is silly expensive for what it is and a whole bottle added to my 4 gallon tank only raises the octane by 1 or 2. Toluene is a much less expensive route(I think it's 100 octane) but I don't like the thought of getting it around my tank every fill-up since it's used as a paint thinner/stripper

Sean...put it on the Dyno and see. I know what will happen (in regard to when power stops) but do it and see. Try different curves.

[Joel]

I can't help but wonder about the use of store bought Octane boosters.  Because here in WA all I ever see is 91 oct premium at the pumps.

E85 is between 100-105 octane.  You could try mixing in a percentage of it.

[paulages]

sean-- what is your compression ratio?

[scondon]

I can't help but wonder about the use of store bought Octane boosters.  Because here in WA all I ever see is 91 oct premium at the pumps.

   I've tried that route with no success. The stuff is silly expensive for what it is and a whole bottle added to my 4 gallon tank only raises the octane by 1 or 2. Toluene is a much less expensive route(I think it's 100 octane) but I don't like the thought of getting it around my tank every fill-up since it's used as a paint thinner/stripper

Sean...put it on the Dyno and see. I know what will happen (in regard to when power stops) but do it and see. Try different curves.

    I don't intend to run this bike on anything but pump gas. It's already been to Yosemite, the Lost Coast, and all over Bodega and Tomales Bay. It would be a shame to have to turn towards home after only 80 miles

    At the moment I only get a hint of rattle in 5th gear going uphill on one section of my commute home. All other riding is fantastic and I believe that I am close to tuning it away completely. With the stock carbs I had the needles all the way up and it still pinged, but these CR's are somethin' else and I am pretty surprised at how far I can retard the ignition with no ill effects or power loss. I will continue playing with tuning and stop at my best guess before taking it to dyno next month.

   I reread my dyno sheet from the first bike and it peaked at 8700rpm. Torque peaked and fell away after 7300rpm. If I recall correctly, the Million Dollar was still making power after 9500

sean-- what is your compression ratio?

   I'm using Wiseco 836 pistons, 10:25/1 ratio, with a slightly decked head. Pump gas here is 91 octane. I've had to chase pinging around the throttle range on both bikes. Usually, ridding one range of pinging means having other ranges over-rich or ignition overly retarded. With the CR's and Dyna 2000 I am confident that I'll be able to end up with a satisfactory tune for all ranges( with some help from the dyno operator ).

[Steve F]

Which DYNA system do you have?  I tried to find one for our 750's, but wasn't able to figure out which part no. for the DYNA 2000 is the right one.  According to Dennis Kirk catalog, they don't exist. 

[scondon]

 Part # is DDK1-2. Suppression wires are needed when using the Dyna 2000.  Dynoman has a pretty good price on them and service is excellent.

http://dynoman.net/ignition/dyna2000.html#cb750

[paulages]

I'm using Wiseco 836 pistons, 10:25/1 ratio, with a slightly decked head.

do you know how much you decked it, and therefore how much that would have increased the compression ratio? i'm very curious, because several people on here have mentioned running compression ratios in this range, and my project is currently at 10.53/1. i'm assuming you're pinging with this C.R. because you're trying to get as close as possible to a perfect mixture (and richening it up a little would reduce the pinging, but rob a little power)?

sam says they're running 10.5/1 on the cr750, and mike recommended this same range. i trust mike for sure--but am watching your thread wondering if i might end up fighting pre-detonation also.

[scondon]

  You're spot on, Paul   I am trying to reach the "perfect" mixture and am resisting the temptation to just richen everything up and lose a bit of power, and MPG, in the process. Our 91 octane seems to be right on the edge of what would run comfortably in this engine. I think that all 91 pump gas is not the same from station to station as I have had full tanks worth of little to no pinging and full tanks worth of trouble, even though they all said 91 on the pump.

    I think the head was only decked .3mm and that the comp ratio would fall in the 10.5/1 range that you and Sam have.

[750essess]

Raised the needles all the way up on mine, pos 5 on dyna 2000 total advance 35 deg. 94 amoco in the tank. Lugged it around in 5th, no pinging so far. haven't got a chance to get it good and hot and run up a mountain yet though. Need to find a place that sells turbo blue or VP and try that.

[paulages]

  You're spot on, Paul   I am trying to reach the "perfect" mixture and am resisting the temptation to just richen everything up and lose a bit of power, and MPG, in the process. Our 91 octane seems to be right on the edge of what would run comfortably in this engine. I think that all 91 pump gas is not the same from station to station as I have had full tanks worth of little to no pinging and full tanks worth of trouble, even though they all said 91 on the pump.

    I think the head was only decked .3mm and that the comp ratio would fall in the 10.5/1 range that you and Sam have.

when i was in auto mechanics school in the mid-90's, i had an engine teacher who told me that almost all pump gas is the same. they almost all come from the same refineries/ distributors, and there are few regulations on filtration during the transport process. he said that exxon is the only company that moves their own gas, and have filtration at every point of transfer. shell v-tech also filters at the pump. what this means for octane consistency, i don't know (nor did i ever confirm his information). but, if true the filtration issue could explain the differences i've also noticed between 91 octane gas from different companies.

[scondon]

  You're spot on, Paul   I am trying to reach the "perfect" mixture and am resisting the temptation to just richen everything up and lose a bit of power, and MPG, in the process. Our 91 octane seems to be right on the edge of what would run comfortably in this engine. I think that all 91 pump gas is not the same from station to station as I have had full tanks worth of little to no pinging and full tanks worth of trouble, even though they all said 91 on the pump.

    I think the head was only decked .3mm and that the comp ratio would fall in the 10.5/1 range that you and Sam have.

when i was in auto mechanics school in the mid-90's, i had an engine teacher who told me that almost all pump gas is the same. they almost all come from the same refineries/ distributors, and there are few regulations on filtration during the transport process. he said that exxon is the only company that moves their own gas, and have filtration at every point of transfer. shell v-tech also filters at the pump. what this means for octane consistency, i don't know (nor did i ever confirm his information). but, if true the filtration issue could explain the differences i've also noticed between 91 octane gas from different companies.

   Not sure what the different companies would be adding to make the same 91 octane fuel behave so differently but it does seem to be that Chevron, 76, and Shell are my best bets. I'm also under the impression that some shady independents just aren't dispensing 91 from the premium pump.

Raised the needles all the way up on mine, pos 5 on dyna 2000 total advance 35 deg. 94 amoco in the tank. Lugged it around in 5th, no pinging so far. haven't got a chance to get it good and hot and run up a mountain yet though. Need to find a place that sells turbo blue or VP and try that.

   One part of the equation that I've failed to mention so far is the total weight of bike + rider and final drive gearing choices. I'm about 245lbs all geared up and have been running 18/48 sprockets or 2.64 ratio for break-in of engine. I will be switching to 17/48 or 2.82 ratio shortly and expect that it will improve the lugging rattle of a hot bike going uphill in 5th gear.

   I did try the #5 position for a short bit but felt the advance was coming on too slowly. Let me know how it works for you when you reach those mountain roads

[MRieck]

 The 17/48 will certainly help. For now I'd downshift to get the RPM's up Sean.

[scondon]

The 17/48 will certainly help. For now I'd downshift to get the RPM's up Sean.

    If I want to use my superpowered CB750 racebike to lug my fat ass home, uphill in 5th gear without pinging, and with the gearing I choose, then I believe it is my constitutional right as a god-fearing, tax-paying American to do so. There is definitely something wrong with this bike

     As usual, Mike, I appreciate that you let me flounder around a bit before giving up the answers By changing my throttle control and downshifting when appropriate I am currently able to ride in any condition without having to hear that "rattle"

     I ordered up one more set of main jets from Buzz (115's). This would be the third set I've ordered so he sent an email requesting my phone # to see if he could help. I felt like I was being called into the principal's office   Anyway, after 20 minutes of talking cams, displacement, airflow at given rpms related to cam choice, etc.... and comparing that info to our conversation last Friday along with my recent tuning experiences I am confident that I am damn close to calling it good.

     Ya know Mike, I actually understood 80% of what Buzz was telling me and was able to hold up my end of the conversation quite well. I'd have made ya proud indeed, Headmaster

[MRieck]

The 17/48 will certainly help. For now I'd downshift to get the RPM's up Sean.

    If I want to use my superpowered CB750 racebike to lug my fat ass home, uphill in 5th gear without pinging, and with the gearing I choose, then I believe it is my constitutional right as a god-fearing, tax-paying American to do so. There is definitely something wrong with this bike

     As usual, Mike, I appreciate that you let me flounder around a bit before giving up the answers By changing my throttle control and downshifting when appropriate I am currently able to ride in any condition without having to hear that "rattle"

     I ordered up one more set of main jets from Buzz (115's). This would be the third set I've ordered so he sent an email requesting my phone # to see if he could help. I felt like I was being called into the principal's office   Anyway, after 20 minutes of talking cams, displacement, airflow at given rpms related to cam choice, etc.... and comparing that info to our conversation last Friday along with my recent tuning experiences I am confident that I am damn close to calling it good.

     Ya know Mike, I actually understood 80% of what Buzz was telling me and was able to hold up my end of the conversation quite well. I'd have made ya proud indeed, Headmaster

Congratulations son...now go collect your sheepskin and get on with it.

[MRieck]

PS.....Buzz is a great guy to talk too. I had to cut him off the last time I spoke to him and it was on his nickel. A great dude.

[scondon]

 Bike is now tuned as well as I'm going to get it before taking it to dyno. I've managed to tune out any rich "blubbering" and lean "rattling" at all throttle ranges, though I can still experience lean "rattle" if I lug the engine when it is really hot. Really nice to be able to experience the full throttle range without having to baby it through certain transitions

 Keihin CR 29mm-

115 main

needle clip- 2nd from top(lean)

62 pilot- 3/4 turns out

 Dyna 2000-

#4 advance curve

33.5 degrees total advance

[bwaller]

Good job Sean,

With that kind of patience and know-how you should hire yourself out!