Topic: CB750 AHRMA Sportsman 750 Racer

[Jerry Rxman Griffin aka MuthaF'er]

Fantastic news Matt. Congratulations. I hope to see you race in person again.

[Old Scrambler]

Apparently the Barber Vintage Motorcycle crowd-event has been cancelled.....BUT....the AHRMA races will be held

[slikwilli420]

Apparently the Barber Vintage Motorcycle crowd-event has been cancelled.....BUT....the AHRMA races will be held

Yes, that's correct. Going to be a really weird event. Im so used to 80K+ people wandering the grounds. It will be very strange to have the whole place to ourselves. Id still expect top-notch racing, too bad no one will be there to enjoy the sights and sounds aside from riders and crew.

[PeWe]

No TV channels that cover it?

[Ramrod_Racing]

Yes, that's correct. Going to be a really weird event. Im so used to 80K+ people wandering the grounds. It will be very strange to have the whole place to ourselves. Id still expect top-notch racing, too bad no one will be there to enjoy the sights and sounds aside from riders and crew.

It'll pretty much look like the WERA race I went to there a few weeks ago.

[chrissprior]

Great work on the oiltank! Lovely to see the detailing. And no do not redo anything for that matter. Follow your own path in this. But mind you there are more roads leading to Rome. Even with the oem oiltank there is no problem with air. The system works, but the reason behind the use of the dry sump is not clear. They, Honda, did not stop making models with it for no reason. And very few had any problems. But..........there are also people who wonder how it would look or work without the tank and lines . Some for looks, some for other reasons. Like me, I ran my 750's all with dry sump, tanks, lines, coolers and what not. Always looking for ways to improve the bike for use on track, with use of time specific parts. No USD forks, no Ohlin shocks, no wide tyres, just like in them ol'days. Build, or altered all my parts by myself and some parts, SMAC wheels, tank are all in my possession from new in '75. Long story, but my main reason for going to run and test the "Sumpthing" is that there is a lot of theoratical discussion without any practical backup. If I wonder about an issue I tend to do something about it, if interesting. And I think this is.
I have made an agreement with BJ, who has this produced and we are both interested to see how it copes with a bike build for the track, though designed for mainly caferacers who dislike the oiltank feature on the bike.

Will keep you updated.

Rob

Hi Rob, sorry just looking into the sumpthing !   Did you do your testing and what results did you have

Chris

[dragracer]

Thanks for the detailed report.  Congratulations on the win and strong finish.  I will check my schedule for Kershaw and try to come up.  I'm about an hour away from the track.

[slikwilli420]

Well, Im still here and right now the bike is in bits with about 3 weeks until I kick off my 2021 race season. I never did make it to the big show at Barber in October, thanks to Hurricane Delta. The guys I talked to got drenched, and to me thats no fun, nor am I a huge fan of riding in the driving rain. Needless to say, the itch to go racing is pretty bad right now.

I had another crushing blow in the form of a destroyed cam chain tensioner (stock Honda this time, not the Cappellini from last time, try to keep up ). I had the head checked over by JMR and got a clean bill of health on springs and guides so its ready for another season, minus a few time serts that need to be installed.

I pulled the cases apart to take a look at my MessnerMoto primary tensioner to see how it was holding up and it looked great, with no discernable wear on the top slider or the bottom tensioner. I did notice some interesting wear on the crank bearings on the alternator side, worn down to the copper. So new green bearings were ordered and coated with Calico CT-1 dry film for some reportedly excellent wear resistance and additional lubricity. I also had the cased line lapped and checked by Kenny at Cycle X just to be sure that part of the equation was all good to go. He gave the cases a clean bill of health and they are headed back now.

The rest of the bike just needed some good old fashioned cleaning and elbow grease to get up to snuff. My front brake rotor performed flawlessly last year, giving as much confidence as the cast iron before it, so that system will simply get a fresh fluid change and be good.

I have also taken to building a swingarm similar to the CMR units, but with my own take on things. Unfortunately, with Denis passing I wasn't able to get in the queue to have mine built. It has been a pretty simple process, though taking a lot of time. The whole unit is 1x2 4130 chromoly with tapered roller bearings for the pivot. All the final welding and fittings (shock mounts, brake torque arm stay, paddock stand bungs and chain slider) are set to be welded up early next week.

The only other major component that needed some love was the bodywork. I finally had a proper seat cover made up (thanks Mom!) and had the bike all painted. Now the seat, tank and front fender are covered in Subaru World Rally Blue, with the appropriate stickers added of course.

A few pictures for your enjoyment!













22 days...

[Ramrod_Racing]

Very nice!

See you at CMP

[slikwilli420]

Very nice!

See you at CMP

Yessir Mr. #1 plate. You racing F Vintage?

[Ramrod_Racing]

Very nice!

See you at CMP

Yessir Mr. #1 plate. You racing F Vintage?

Yes. Though it would be a more fun bump up class than VSBHW because of the grid size and diversity. I may have to reconsider come next year.

[bwaller]

Matt have you ever sent a used oil sample to Blackstone? They make a determination of bearing wear (protection) by suspended metals and viscosity loss among other things.

[Jerry Rxman Griffin aka MuthaF'er]

And do you have an assumption on that bearing wear? Clearance? Oil flow? Etc? I'm curious what the clearance was after the wear. What's the crank journal look like?

[johno]

I find that worn bearing interesting Matt, Ive had an engine that had the crank balanced etc and done a couple of seasons racing when stripped had the same wear on the last main alternator side.   I miked the crank up as new, journals looked good, straight edged the main bearing cases etc all perfect. I assumed it was the rotor out of balance making the end of the crank flex  so had it rebalanced etc but when checking the new bearing clearances during reassembly I had to go from green to brown to tighten the clearance as it was about half thou more than original anyway new bearings worked well and I never had problems again. 

[MRieck]

 What size lines are you running to the oil cooler Matt? -8 ?

[slikwilli420]

Matt have you ever sent a used oil sample to Blackstone? They make a determination of bearing wear (protection) by suspended metals and viscosity loss among other things.

I have not Brent but I know Martin is a fan. Definitely worth doing though with all the cam tensioner business going on I might get off results. Still worth looking into though.

And do you have an assumption on that bearing wear? Clearance? Oil flow? Etc? I'm curious what the clearance was after the wear. What's the crank journal look like?

Clearances were good and that was the only one that looked off. Oil flow was a thought but if it was restricted then the connecting rod would have suffered as well and those bearings looked great. Crank checked out dead straight as well. The only thing that changed from the prior year is the mirko primary tensioner which has a ridiculously heavy spring compared to stock. But if that was the case I would think the bearings closest to the center would have suffered most.

What size lines are you running to the oil cooler Matt? -8 ?

All the lines are -10 since that's what fits over the original fittings on the engine. This is a new problem that hasn't popped up before. Still scratching my head.

[scottly]

Is this the crank that Kenny welded the oil passage closed on the end?

[slikwilli420]

Is this the crank that Kenny welded the oil passage closed on the end?

Yes it is and I wonder if that is keeping enough oil from flowing through everything. I figured with it plugged then oil at that end would just go toward the crank and rods and that end. Also this is the 3rd year with this crank so I can't imagine it's an issue all of a sudden but could be wrong.

[Tintop]

Is this the crank that Kenny welded the oil passage closed on the end?

Yes it is and I wonder if that is keeping enough oil from flowing through everything. I figured with it plugged then oil at that end would just go toward the crank and rods and that end. Also this is the 3rd year with this crank so I can't imagine it's an issue all of a sudden but could be wrong.

Is it possible that after a couple of years use & the sealed end, that crap has built up inside and has started to reduce flow to that bearing?

[johno]

If were talking about the same hole (starter gear lube hole) I used to weld them up, Ive even brazed them, all without problems but one day while I was tapping the cross drill holes I realised how brittle the casting is and so on my last crank I used the Federal Mogul seal savers which tap on and a couple of drops of loctite, jobs done.  In my old age opinion any welding on the brittle cranks is not good and I know lots of people have found that to be true.
Im sure you have already done this Matt but just pop the crank between centres and clock the end bearing trueness just in case,
like the Irish say, to be sure to be sure 

[slikwilli420]

Is this the crank that Kenny welded the oil passage closed on the end?

Yes it is and I wonder if that is keeping enough oil from flowing through everything. I figured with it plugged then oil at that end would just go toward the crank and rods and that end. Also this is the 3rd year with this crank so I can't imagine it's an issue all of a sudden but could be wrong.

Is it possible that after a couple of years use & the sealed end, that crap has built up inside and has started to reduce flow to that bearing?

That was such a good thought I pulled the rods off and gave it a thorough cleaning. Nothing came out, but now I feel better about it.

If were talking about the same hole (starter gear lube hole) I used to weld them up, Ive even brazed them, all without problems but one day while I was tapping the cross drill holes I realised how brittle the casting is and so on my last crank I used the Federal Mogul seal savers which tap on and a couple of drops of loctite, jobs done.  In my old age opinion any welding on the brittle cranks is not good and I know lots of people have found that to be true.
Im sure you have already done this Matt but just pop the crank between centres and clock the end bearing trueness just in case,
like the Irish say, to be sure to be sure 

Ive seen those on other builds to block that hole. Mine was cut off and a plug welded in. That was all done a couple years ago so nothing new there either. I will need a set of those sleeves for my upcoming superbike since Im not cutting the crank. I also found the right pitch set screws for the alternator bolt so I can get that whole end plugged up right.

[slikwilli420]

Another "fun" update is that after I sealed the cases and started putting shifting bits and covers on, I decided to check out my MessnerMoto cam tensioner (can't wait any longer on other solutions and won't go back to OEM) and offered it up to the top case, only to find that it hits the top slider from the primary tensioner system. The only option now is to cut down the primary slider to make room for the cam tensioner system. Since the vast majority of race bikes in the known universe don't run the top slider of any kind, taking some material off the end won't be the end of the world, but does suck to have to split freshly sealed up cases.

[RAZZ]

Another "fun" update is that after I sealed the cases and started putting shifting bits and covers on, I decided to check out my MessnerMoto cam tensioner (can't wait any longer on other solutions and won't go back to OEM) and offered it up to the top case, only to find that it hits the top slider from the primary tensioner system. The only option now is to cut down the primary slider to make room for the cam tensioner system. Since the vast majority of race bikes in the known universe don't run the top slider of any kind, taking some material off the end won't be the end of the world, but does suck to have to split freshly sealed up cases.

Hi Can you take some photos of This? Im going to use the messner cam and primary tensioners aswell thx


Sent from my iPhone using Tapatalk

[slikwilli420]

Another "fun" update is that after I sealed the cases and started putting shifting bits and covers on, I decided to check out my MessnerMoto cam tensioner (can't wait any longer on other solutions and won't go back to OEM) and offered it up to the top case, only to find that it hits the top slider from the primary tensioner system. The only option now is to cut down the primary slider to make room for the cam tensioner system. Since the vast majority of race bikes in the known universe don't run the top slider of any kind, taking some material off the end won't be the end of the world, but does suck to have to split freshly sealed up cases.

Hi Can you take some photos of This? Im going to use the messner cam and primary tensioners aswell thx


Sent from my iPhone using Tapatalk

Cases are already sealed up but I cut 1" from the end of the top primary slider that faces the cam chain. I cut it right before the 2nd rivet in. Cleaned up the end on my mill and reinstalled.

[MessnerMoto]

Another "fun" update is that after I sealed the cases and started putting shifting bits and covers on, I decided to check out my MessnerMoto cam tensioner (can't wait any longer on other solutions and won't go back to OEM) and offered it up to the top case, only to find that it hits the top slider from the primary tensioner system. The only option now is to cut down the primary slider to make room for the cam tensioner system. Since the vast majority of race bikes in the known universe don't run the top slider of any kind, taking some material off the end won't be the end of the world, but does suck to have to split freshly sealed up cases.

Hi Can you take some photos of This? Im going to use the messner cam and primary tensioners aswell thx


Sent from my iPhone using Tapatalk

Cases are already sealed up but I cut 1" from the end of the top primary slider that faces the cam chain. I cut it right before the 2nd rivet in. Cleaned up the end on my mill and reinstalled.

I just saw this. Pinged by a forum member. I am pretty sure I designed cam and primary chain tensioner to miss each other. Especially because primary chains and cam chain are also missing each other.

Maybe there is interference of  top 1mm on sides or something like that because of not perfect alignment. I mean I have both tensioners in my engine and they are not touching.

you shouldn't have cut of 1" of top primary chain slider thats excessive and it probably ruined function of top slider! Probably a touch by sanding tool on side of one tensioner would have solved interference problem.

Please if anybody have similar problem contact me....