Topic: Phaedrus: CB750 RestoMod - Update: 09/23/21 w/ new video

[Jerry Rxman Griffin aka MuthaF'er]

Ron,

Sounding good. Do you have a dyno close by that you can use?

[MCRider]

Ron,

Sounding good. Do you have a dyno close by that you can use?

Yes. Dreyer's Honda has one, about 15 miles from me. Rick uses them for his LSR bike. Haven't looked into the cost, Rick said he'd get me a deal, but I'm ready to pay my way.

That wilil be the first step after breakin is complete. Before Christmas is my goal. So it can uncover any tuning soft spots that need addressing.

[seanbarney41]

Rick reports: "the Webcam 41 comes in at 6000 rpm, and carries past 8500, not a kick in the pants, but definitely noticeable."

I doubt those 1.5mm OS intake valves had anything to do with it.   

so basically...a stock cb750?

[Stev-o]

Like reading your test results.  What was the front wheel issue? Balance??

[MCRider]

Rick reports: "the Webcam 41 comes in at 6000 rpm, and carries past 8500, not a kick in the pants, but definitely noticeable."

I doubt those 1.5mm OS intake valves had anything to do with it.   

so basically...a stock cb750?

Don't know if you're joking with me or don't know. So here's a recap: Originally I was going to tour with this engine as I had with a prior 888cc engine. It went so well, I was just upgrading it. Planned to use a mild cam.

Touring is out of the question now due to a disability. I had Mike (JMR) re do the top end:  888cc, Arias forged pistons, kept the mild cam, went with 1.5mm OS intake valves at Mike's suggestion, Mike JRieck ported and valve job, guides, valves, 29mm Smoothbores, APE bottom end. So we'll just be racing against the clock, nothing serious just fun.

[MCRider]

Like reading your test results.  What was the front wheel issue? Balance??

We checked the bead seating real close and it seems OK. So balance is the next check. I balanced it to begin with. Will try again (I have a stand) Could be partial fork oil issue. We'll see.

[grcamna2]

Like reading your test results.  What was the front wheel issue? Balance??

We checked the bead seating real close and it seems OK. So balance is the next check. I balanced it to begin with. Will try again (I have a stand) Could be partial fork oil issue. We'll see.

Ron has the front wheel been made true side to side & up and down ?

[MCRider]

Like reading your test results.  What was the front wheel issue? Balance??

We checked the bead seating real close and it seems OK. So balance is the next check. I balanced it to begin with. Will try again (I have a stand) Could be partial fork oil issue. We'll see.

Ron has the front wheel been made true side to side & up and down ?

I built it from scratch so I think so. But that's what we'll have to check Sunday shop time.

[MCRider]

There were a few other teething problems we hit first. After a few days sitting there's a mysterious puddle of oil on the floor, off the feet of the centerstand. After much hemming and hawing, we figure its most likely the hose off the breather at the back of the trans. It was there with a clamp on it, at the tank too. But the clamp took a few more turns. While we were at it we just tightened as evenly as possible every bolt underneath whether it had a trace of oil on it or not. Which was mostly the oil pan bolts.

There was a zizzziinng sound when Rick pulled out of the driveway. Only thing that had been changed from a few weeks ago was the add on of the chainguard. It was free of interference while on the centerstand. But upon removal the tale was told. The guard was hitting the chain up near the Drive Sprckt. With weight on the bike it was hitting the chain. So we cut and ground off the offending part of the guard and reinstalled. The real problem was that the big stay towards the rear had a dogleg bent in it, to put the blade of the guard squarely above the chain. But up front they left the stay straight which put the blade of the guard offset to the chain and zizzz.

I'll likely have a new one made as some other details I don't like. But for now and in a pinch, its sturdy and clear.   While we had it off, we removed the sprckt cover to clean the aluminum shavings out, and install the 17t, dwn frm a 18t.

Called Dreyers and Dyno time is $80hr, fair enough. He said an hour or less was plenty of time. So, next is to fix the pitti pat in the front wheel, get some more break in miles, then go to the Dyno. Still a few weeks away.

[Jerry Rxman Griffin aka MuthaF'er]

Ron,

What does Dreyers do for the 80 bucks? Is it just a sniff and print? Single pull/multiple pulls? If a single pull/partial hour maybe they will give you the print out and let you go home, rejet then return for the remainder of your hour?!

There is a scarcity of dynos in this area. Stopped by my Harley shop on my F looking for a crankcase breather filter without luck but I did talk to my old buddies in service. They asked about the Fat Boy and I gave them the RIP story. They said they'd put my Honda on the dyno for $49 for a sniff and print. No jetting work. That was after they saw me ride up on the 750 and went outside to take a look 

[MCRider]

Ron,

What does Dreyers do for the 80 bucks? Is it just a sniff and print? Single pull/multiple pulls? If a single pull/partial hour maybe they will give you the print out and let you go home, rejet then return for the remainder of your hour?!

There is a scarcity of dynos in this area. Stopped by my Harley shop on my F looking for a crankcase breather filter without luck but I did talk to my old buddies in service. They asked about the Fat Boy and I gave them the RIP story. They said they'd put my Honda on the dyno for $49 for a sniff and print. No jetting work. That was after they saw me ride up on the 750 and went outside to take a look 

I didn't know too much what to ask. He said it would take 2 to 4 runs to establish a good reading, then one for real. Also said there was something to be done with the tachometer. I'll ask some more intelligent questions before actually going.

[MRieck]

 I dyno seesion with an FI bike can take a 2 or 3 hours though my buddies 929 took about 4 pulls to get the Power Commander right on. My Hayabusa took over 2 hrs as did my RC-51.
 Ask Brent Waller how long it can take.
 The dyno would be the best thing for the bike Ron as you can get some good break in time and get concrete A/F info. It save a lot of time and you don't have to worry about hurting the engine with to lean or to rich.
 I highly recommend you use the dyno with a skilled operator.....you will be very pleased. Bring all jets and needles. By jets I mean needle jets too. Nothing better than to look at a chart with a fairly straight line across the 13 to 1. The FI bikes get a perfectly straight line if the operator is good.

[MCRider]

I dyno seesion with an FI bike can take a 2 or 3 hours though my buddies 929 took about 4 pulls to get the Power Commander right on. My Hayabusa took over 2 as did my RC-51.
 Ask Brent Waller how long it can take.
 The dyno would be the best thing for the bike Ron as you can get some good break in time and get concrete A/F info. It save a lot of time and you don't have to worry about hurting the engine with to lean or to rich.
 I highly recommend you use the dyno with a skilled operator.....you will be very pleased. Bring all jets and needles. By jets I mean needle jets too. Nothing better than to look at a chart with a fairly straight line across the 13 to 1. The FI bikes get a perfectly straight line if the operator is good.

What does "straight line across the 13 to 1" mean? Dealing with a newbie here. 

[Retro Rocket]

Air fuel ratio....

[MRieck]

Air fuel ratio....

[Jerry Rxman Griffin aka MuthaF'er]

Your dyno session should provide 2 'curves' and an air:fuel ratio line. One 'curve' on the graph is a horsepower 'curve' while the other is a torque 'curve'. ie HP vs rpm and torque vs rpm.

'Straight line across the 13:1' would indicate an air fuel mixture ratio of 13 to 1 across the whole rpm range. While you'll never get a straight line it would be optimal. This not-straight 'line' will tell you what your air to fuel ratio is across the rpm range so that you can make jettring changes to get it closer/as close as possible to that 'theoretical' 13:1 line then you're done as your carbs are jetted and it's making the maximum power for your setup.

Get them sync'ed before going but it depends on whether you're just getting readings or the guy will actually dyno tune your carbs too which might include synch'ing and jetting. Be sure to ask what to expect during your session.

[bwaller]

It's nobody's fault but many dyno operators make their money giving v-twin owners a 3 pull brag sheet to show to their buddies. Around here it's this way. Rarely do these guys work with carbs any more. The operator makes good money without having to think too hard!

Mikes friend and "go to" machine shop owner is an excellent dynamometer operator as well. We were hours dialing my bike in but it's because of Rick's thoroughness. He coaxed every bit of available power out of the thing.

I am no expert Ron but certainly Mike is correct, and if I can offer any advice, ask around about dyno shops for one with a good reputation. It will be worth it to travel further to take advantage of experience.

[grcamna2]

It's nobody's fault but many dyno operators make their money giving v-twin owners a 3 pull brag sheet to show to their buddies. Around here it's this way. Rarely do these guys work with carbs any more. The operator makes good money without having to think too hard!

Mikes friend and "go to" machine shop owner is an excellent dynamometer operator as well. We were hours dialing my bike in but it's because of Rick's thoroughness. He coaxed every bit of available power out of the thing.

I am no expert Ron but certainly Mike is correct, and if I can offer any advice, ask around about dyno shops for one with a good reputation. It will be worth it to travel further to take advantage of experience.

+1  That makes sense 

[MCRider]

A to F ratio: I see now.

I'll see what Dreyers offers by way of help and expertise. I don't have any carb parts, just what they came set up with. So I'll get a baseline. Show it to you guys, get some ideas what to buy, and do it again. 

Lucky for me I'm not under any time constraints. The seat of the pants dyno indicates we are close. No stall spots, flat spots etc. I have no deadline other than I'd like to keep the progress moving along.

I'm checking for other Dynos in the area.

PS: Done with search: Ther are 3 more within 25 miles, 3 more within 60 miles, and 3 more if we include the Harley Shops. Don't know if they would stomach a rice burner or not.

[calj737]

If you hadn't already figured it out, if you do go to a shop and they include carb adjustments/changes as part of their service, I'd be 100% certain they only use factory spec, original jets. If you don't have any already, buy some in advance, take them along, and return (if possible) unused components. Much cheaper and more efficient to do the changes while at the shop already.

My $0.08 (devalued for currency exchange rates ;-) )

[MCRider]

If you hadn't already figured it out, if you do go to a shop and they include carb adjustments/changes as part of their service, I'd be 100% certain they only use factory spec, original jets. If you don't have any already, buy some in advance, take them along, and return (if possible) unused components. Much cheaper and more efficient to do the changes while at the shop already.

My $0.08 (devalued for currency exchange rates ;-) )

I'm running VM29 Mikuni Smoothbores. I don't expect the Dyno operators to have parts for them.  I'll be buying jets from Sudco. I assume they are Mikuni. Also Z1 Enterprises dabbles in the VM line, also assume they get them from Mikuni. But I'll confirm before buying. Thanks.

I expect to go twice. Hopefully that will get it.

[bwaller]

Ron as you know Sudco is expensive but usually has a fair number of parts for the VM29's. Jeff at Z1 is good  for offering better prices. You might also check Carb Parts Warehouse in Ohio. You'll have to call but they have a good supply for these carbs at better pricing then Sudco. They know the carbs well.

Just a story about Mike's friend Rick Stetson. With my bike on the dyno he wanted to try smaller air jets. I had three sizes with me but the smallest size was already in place. I was pretty sure there were only three sizes available and told him so. He disappeared for a few moments and returned with a box of smoothbore parts including several different sizes of airjets I didn't have. My mouth dropped, it really is a one stop shop!! I asked him if he wanted to sell me the box but he only smiled & shook his head no. 

[MCRider]

Ron as you know Sudco is expensive but usually has a fair number of parts for the VM29's. Jeff at Z1 is good  for offering better prices. You might also check Carb Parts Warehouse in Ohio. You'll have to call but they have a good supply for these carbs at better pricing then Sudco. They know the carbs well.

Just a story about Mike's friend Rick Stetson. With my bike on the dyno he wanted to try smaller air jets. I had three sizes with me but the smallest size was already in place. I was pretty sure there were only three sizes available and told him so. He disappeared for a few moments and returned with a box of smoothbore parts including several different sizes of airjets I didn't have. My mouth dropped, it really is a one stop shop!! I asked him if he wanted to sell me the box but he only smiled & shook his head no. 

Good leads thanks!

My plan so far is just to get a prelim from Dreyers and see how I like their service. Then I'll come home and brainstorm the parts I should buy. Install them and either go back to Dreyers or try one of the other locations.

http://delsperformance.com/index.htm

[MCRider]

We rearranged the items in the shop and garage to fit everything in. I'd been leaving my vehicle outside so the trailer was in. But that's not a safe practice. Even in neighborhoods much nicer than ours, leaving a ar out invites mischief. At least you could once bring your garage door opener in. Now the opener is in the visor, and programmed in. So a bad guy can get in your car, open the garage door and have his way.

By putting a bike on the trailer and otherwise wiggling things around we got all the bike stuff in the shop stall, and the cars in the garage stalls. With room to work on the bike, barely.


Of the many things we wanted to do, we first worked on identifying why the speedo was hopping around in the 100mph range. BEst it seems. the inside of the motion-Pro cable is 5mm shorter than the inside of a stock cable. So if it wasn't getting up into the head deep enough, maybe it would skip at higher loads? I trimmed down the  inside cable of a stocker, and put it in the Motion-Pro outer braided cable. Maybe that will fix it. MArcel speculated it was something other than the head itself, otherwise it would skip and bounce at lower speeds.


NExt was the wheel bounce, again at high speed. Had to pull the left side caliper and otherwise fudge around to pull the wheel.


On the stand it appears to be true enough, but slightly out of balance. The "Pit Bull" balance stand comes with a rod to substitute for the axle, which is not long enough to reach the balance bearings on both sides, the axle that is. But this doesn't seem right to me. The rod is smaller diameter than the axle and the wheel "hangs" from this rod. Shouldn't the axle be used, or in this case a rod that's exactly the diameter of, fitting properly in the hub bearing, and then long enough to span the distance between the balance bearings? Anyway that's what I think and I'll have a rod turned down the proper diameter and length to satisfy me. Then we'll get a good balance on it.


Seems that it's stiill wet sumping. So we'll plan on instaling one of Elan's stopper kits this winter.

 

[edwardmorris]

If its cheaper than spinning a new rod, consider the cheap harbor freight balance stand that comes with two tapered adjustable pieces (look like a stepped drill bit, only smooth) and use with the rod you have. The HF stand is passable but its almost certain that the rod they ship with will not be straight.  I cut my own replacement rod and used the rest as is, worked out ok.