Topic: Classic Bonneville Racer

[Old Scrambler]

Finally able to get to this ....................1st run was OK for a trial run as a naked bike. 2nd run was similar..........3rd run was very slow as I knew something was wrong so I backed off and idled into the pits. Found #1 and #2 intake adjuster screws had completely turned out and both lash-caps were off. All parts were found laying around but one partially broken lash-cap was laying on its side in an oil-return bore. With damaged threads and down one lash-cap, we re-worked and switched rockers so that the cap-less unit would be on #1 and could be easily checked after each subsequent run.

Turned a 132 so knew we were down on power. Switched sprockets and ran with the tach at 9,900 but no appreciable gain in speed. I decided my best chance at getting past 150-mph would be to put the fairing on, install the C-12 fuel with smaller jets and give it a try............but I did not do the paperwork until the following AM which was not allowed for a change of class........event though I was planning to run on my own record ........This was a new rule for 2019 to prevent last-day attempts while successful riders were in the impound-area tearing down their motors.

Today I am back in Wisconsin and did a compression test.......#s 1-2 at 165........#s 3-4 at 160. Conclusion: No serious damage to the motor. After one more run I would have moved the timing either way about one degree to try and find the missing power that was there in 2018. Yes, the Canadian Trident took 3 of my records.....but only by 1-4 miles each with the fasted at 148+...........

I will have everything stored in Pocatello, Idaho by December, and will be in Alaska for all of the summer in 2020. Next attempt at 150 will likely be in 2021. Disappointing, yes, but always learning and endured the roughest track. Today I talked with a good friend that crews for a fast SCTA car.......he said the rookies at that event were lead across the courses in their cars and left tracks for all to complain about   To me it felt like riding across a very large railroad yard

[RP]

Thanks for the update.  Bonneville is not an easy as a lot of people think.  "I ran down the Expressway at 150, I can get that record no problem"

Better luck in 2021

[754]

Well Dennis, you went again and rode there, that in itself is worth it..
 Too bad I was not there.
 Hey.. cool news, there is a girl photographer,  puts out a book of pics each year. Leigh is all I remember of the name.
Anyway on the weekend I found out that the awesome pic she took of Roy from here, and myself , last year is in the 2018 book.. now I need to get a copy.l
 Hope you got to do some road riding.. I had a pretty good August, no rides before that.. felt great to get out on the road , and enjoy some miles and scenery..

[RAFster122s]

Dennis, sorry the experience on the salt this year was not as sweet as last time. I hope your return to the salt sees records fall.

Best of luck on the bike teardown and clean up to get rid of all the salt.

David

[Old Scrambler]

Thanks for the encouragement..............Frank, I may be stopping at a Starbucks near you in May......or later...

[Old Scrambler]

Today..............got the bike back together with new welded and lightened rockers, added gas, charged the battery, and it fired on the first try

Now for a few miles on some back-roads in Idaho ..........and then to the local dyno

My wife did a short video and posted it on Facebook under Dennis Weinhold .........

[turboguzzi]

link to video or it didnt happen.... (dont have FB )

[754]

Has it been back together since inspection at Bonneville in 18 , or is this the first time since..
 Fun day on the Salt, that was....

[Old Scrambler]

Together in 2019 with new jugs due to a deep ring-score from sitting between 2016 and 2018.........I guess I need to find someone to turn the motor over while I'm traveling

Replaced the rockers, adjusters, and nuts (Ti) due to thread damage in 2019 on my first run......missed a shift

Also tried an adjustable cam sprocket but found it a no-go so replaced it..........which means I had the cam out a few times while playing around in the garage.......lots of assembly lube now invested

With several other small changes the bike is now 1" lower, 1" more narrow at the outer ends of the bars, and 3-lbs. lighter. In past years Dave Murre and I would tune and used a dyno to tell us what we had...........This year I plan to get input from a proven race-tech tuner with his son doing well on the AMA race circuit...............but first I will run a few miles (hours) on a back-road to be sure the rings are seated.

[PeWe]

It would be nice to hear it
Youtube or Bitslide.....

[MRieck]

Also tried an adjustable cam sprocket but found it a no-go so replaced it..........which means I had the cam out a few times while playing around in the garage.......lots of assembly lube now invested

Can you elaborate on this? I have used adjustable sprockets in many different bikes with no problems. I even have a very custom set up for my CBX engine (which normally has the bolts threading into the cam sprocket as opposed to the cam flange)

[Old Scrambler]

Mike......I was thinking of retarding the cam by a degree but immediately had valve to piston interference............tall and fat lobes at 110-degrees with 1mm longer rods is a pretty tight fit

[scottly]

Sounds like you need to cut some valve clearance pockets in the pistons if it's that close!

[MRieck]

Mike......I was thinking of retarding the cam by a degree but immediately had valve to piston interference............tall and fat lobes at 110-degrees with 1mm longer rods is a pretty tight fit

1 degree is really nominal. Not to pry but what is ex valve to piston @ 10 degrees BTDC? I have had several LSR 750 cams ground with 110 LC (KH hybrid pieces) and had to sink the valves and pull material off the piston reliefs.

[Old Scrambler]

Mike.........no notes on that measurement. Pistons already relieved (eye-browed) by a few thou for minimal clearance at straight-up cam setting............My one-time (one-way) fastest speed is a smidgeon above the record, so will run what I have with other fine-tuning. Relieving pocket material is still an option I (with Dave Murre) don't like to sink valves because you give up compression, change the flow pattern, and unless you shorten the stems, the rocker to valve angle is slightly changed and spring-pressures may have to be adjusted.

[scottly]

Mike.........no notes on that measurement. Pistons already relieved (eye-browed) by a few thou for minimal clearance at straight-up cam setting............My one-time (one-way) fastest speed is a smidgeon above the record, so will run what I have with other fine-tuning. Relieving pocket material is still an option

A few thou isn't enough; should be more like 1mm.  Ask me how I know..

[Old Scrambler]

No indications of valve to piston interaction were observed after removing the few thou.........and 4 records were set The required 'eyebrow' relief was in the upper portion of the already radiused valve-pocket. To prevent detonation, we began with 130 jets (fell on face at high rpms) and moved down by 2.5 increments to as low as 120s.............. 

[MRieck]

Mike.........no notes on that measurement. Pistons already relieved (eye-browed) by a few thou for minimal clearance at straight-up cam setting............My one-time (one-way) fastest speed is a smidgeon above the record, so will run what I have with other fine-tuning. Relieving pocket material is still an option I (with Dave Murre) don't like to sink valves because you give up compression, change the flow pattern, and unless you shorten the stems, the rocker to valve angle is slightly changed and spring-pressures may have to be adjusted.

Sinking the valves on a CB750 is very often necessary with the long duration cams. Lift doesn't matter as much as the duration. I've measure many heads with different amounts of sinking and it hurts the exhaust more the than the intake but the 750 exhaust port flows well so it is a wash. Changing the valve installed height isn't that big a deal and any loss of spring can be made up with a shim. Start with Beehives and you're in a good place already. Compression drop is negligible and if you really want to step up use Ti valves with flat faces.
 Keep in mind the national record ProStock CB back in the day had the valves sunk over .080 and ran a positive deck of .100.
 

[scottly]

Mike......I was thinking of retarding the cam by a degree but immediately had valve to piston interference............

Once again, this is a red flag! I'll shut up now............

[Old Scrambler]

By a degree.......more like 3........You guys will soon make me a better mechanic. I measured the marks on my cam-sprocket and found it to be more aggressive than I thought. My degree wheel may have rotated when I was getting the slack out of the cam-chain.............It sure was easier to do with 3 or more hands

This is an F2 head with old-school J&E pistons standing 27-thou above the deck. Flat SS valve faces with beehives and a 25-thou squish-band at the chamber radius over a 30-thou copper head-gasket at 19 ft-lbs. torque on OEM studs.   

[754]

I would not mess with minimum ckearance from valve to piston, not leaving room for error.... can and often will bite you.l

[Old Scrambler]

Upper 70s and very mild breeze today so trailered the bike to a quiet country road that has no driveways for more than 7 miles and a recent asphalt surface. Just trying to get the rings seated while using 10W40 and changing speeds at rather low rpms. All went well so now  will try to get some dyno time

[Old Scrambler]

Dyno-Jet today................Primary tech was travelling so did cell-assist. I ran the bike...........1-minute pull at 11,000 rpms caused the rear tire to chunk.........new tire was $174

We then did 3-runs with the tech operating the throttle..........#1 showed A/F at 13.3 and steady to 14,000 rpms.......He was not watching the tach .......#2 showed A/F at 13.5 and #3 at 14. I attribute this to hotter oil. Altitude is 4,410-ft so about the same as Bonneville. HP was only 70.98 at 11,500 rpms.................Torque was 31.98 at 11,100 RPMS...............

I have a few things to do..........BUT THE MOTOR SEEMS TO BE READY

Salt conditions are currently the best in many years

[Jerry Rxman Griffin aka MuthaF'er]

14,000! I'd say so.

What wouldn't be a little lean at those R's. Half size larger      Wouldn't I love to see mine spin like that  #$%*, I'd like to see mine at 4,000' instead of 6,900'. And ANOTHER rear tire for you too LOL.

Congrats. 

[scottly]

You're too lean, and hotter temps tend to make a motor run richer than when it's cold; thats why you choke a cold motor. How much HP did it make at 14,000 RPM? Was this on an eddy current dyno? Got a graph??