Topic: CB750 AHRMA Sportsman 750 Racer

[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....

[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.

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....

Yeah Mirko, Im not sure what was going on but I had to make a call. Given that the bike was designed without any top slider, taking material off didnt concern me at all, and now they can both live happily together without interference.

[slikwilli420]

The bike is done! First startup didnt go quite as planned. I have been in this engine enough and each time the bike fires right up after letting the carbs fill with fuel. Well this time was different. I used the rollers so much that the motor started to get really hot and I drained the battery, which meant it was time to push! So I took to my quiet neighborhood street to get a running start down the small hill up from my house. I ended up pushing it back and forth about a dozen times, and had decided to pull in and pull the plugs to dry them out and start the process again. Well, being the stubborn SOB I am, I decided to try and bump it a couple more times on the way back to the house, and the last try it finally caught and I was able to get it going. I ran it gently up and down the street in 1st gear, varying RPM a few dozen times to try and seat the rings. Not the way I wanted to break it in, but it will have to do. I got back to the garage and with the roller battery charged up a bit and a warm bike, it fired right up to double check the timing one last time.

That leaves me here, Monday before the race weekend, the first of 2021. I will be heading out with the Mrs. on Wednesday afternoon with an overnight in Columbus, OH before getting to CMP in Kershaw, SC in the late afternoon on Thursday. Then its back to business as usual, chasing my uncle in S750 for another run at a championship year, as well as getting deeper into my bump class, Formula Vintage. That class has a number of fast bikes from Vintage Superbike and a couple 2-stroke classes. I will be up against GS1000, KZ900/1000, RZ350, RD400 and a number of other hot rods. I held my own against some of these guys last year, and thanks to me busting my butt in the off season, I am about 2-3hp "lighter" than last year, which should help with acceleration, braking and general handling on the bike.

Here's a shot from right after I got the last things buttoned up. I should be able to get some great outdoor shots at the track soon.

[Jerry Rxman Griffin aka MuthaF'er]

Great news. Bike looks fantastic. Good luck and stay safe.

[bwaller]

Looks great Matt, we'll be following along.

Penny for your thoughts....I bet you were starting to sweat and worry (maybe even curse a bit) the more you had to push. 

[Ramrod_Racing]

I'll do my best to make a nice big draft for you between 9 and 10 in FV on Saturday 

[slikwilli420]

Great news. Bike looks fantastic. Good luck and stay safe.

Thanks Jerry!

Looks great Matt, we'll be following along.

Penny for your thoughts....I bet you were starting to sweat and worry (maybe even curse a bit) the more you had to push. 

Each time I pulled the clutch and started running I hoped it'd by my last. Perseverance wins the day!

I'll do my best to make a nice big draft for you between 9 and 10 in FV on Saturday 

I'll be out front, just follow me... unless I go in the grass. Think this way, if you're chasing me and I'm chasing Jeff that takes everyone else out of the equation! Hopefully not too wishful thinking. See you Thursday.

[PeWe]

Really beautiful bike!
If it should have a reg plate, a really nice cafe racer!
Have a really good running 2021!

[Old Scrambler]

Go fast and be SAFE............

[Sam Green Racing]

It looks to nice to race Willie, it should be in your living room with spot lights on it. Take care and stay safe mate. Good luck.

[RAFster122s]

Safe travels and hope the adventure & racing is trouble free and fun!

[Ramrod_Racing]

I'll be out front, just follow me... unless I go in the grass. Think this way, if you're chasing me and I'm chasing Jeff that takes everyone else out of the equation! Hopefully not too wishful thinking. See you Thursday.

We shall see! #deepfieldbro

Hopefully your drive will be much dryer than ours.

[gschuld]

I can confirm Matt and Ashley are trackside at Kershaw SC, the freshened up engine started right up upon arrival and today is practice day.  New paint looks good👍

Matt is competing in AHRMA Sportsman 750 and formula Vintage.

Good luck Matt,

George

[754]

  Ummmmmm ... stick something on that blockoff dyno plate..in tbe middle ..
 A bottlecap , badge, sticker ...anything.... it really needs it.