Author Topic: CB750 AHRMA Sportsman 750 Racer (Read 175345 times)

scottly · « **Reply #500 on:** January 08, 2018, 10:45:53 AM »

Did the ball that seals off the passage fall out? This would allow the oil to escape, depriving the bearing.
http://forums.sohc4.net/index.php?topic=83495.0

slikwilli420 · « **Reply #501 on:** January 08, 2018, 12:18:59 PM »

I glanced and remember all of them being in there but will check when I get home. The rod is destroyed and the crank might be, but at this point I want to make sure the crank was at fault and not the cases, which are going to be reused. From where in the case does the oil come from to feed #1? If it is from further down the line, like from #2 and so on, it makes sense in my mind that the passages in the crank were at fault because of a blockage. Could assembly have been a factor here? Remember I didn't put it together but it was done by a guy that has a decent reputation for assembling stockers, though I won't ever use him again.

scottly · « **Reply #502 on:** January 08, 2018, 06:19:56 PM »

The oil galley in the case feeds the main bearings, and flows from the mains through the passages in the crank to the rods; the #1 rod gets it's oil from the left-most main journal. If the case was at fault, there would have also been damage to the main.
Did the bearing actually spin? It looks like the alignment tang of the bearing shell in the rod end is still present?

slikwilli420 · « **Reply #503 on:** January 08, 2018, 06:48:09 PM »

Mains look good. Hard to tell what happened to the rod as there was material smeared all over as if one bearing overlapped the other and welded together.

MRieck · « **Reply #504 on:** January 08, 2018, 07:27:23 PM »

The only cases/oil feed I saw that were definitely at fault for rod feed were the Kawasaki ZX-11. That was well established for #3 and no doubt that stock system left a lot to be desired. Cycle magazine experienced it as did Terry Kizer when turbo charging. At first they just changed to Carrillo rods but what the heck would that actually change. Eventually Kizer and Superbike Mike came up with external feeds from a strong pressure galley.
I replaced at least 6 of those cranks (and the transmissions sucked too).

slikwilli420 · « **Reply #505 on:** January 12, 2018, 07:20:27 AM »

So I have the cases totally stripped and have removed the cylinder studs from the top case. I have not done a lot of these but this case was by far the easiest I have had for removing these studs, with each coming out with slight pressure on the double nut and a set of vice grips. Only a couple had that butt-puckering "snap" to them. I am waiting to hear back from Ken at Cycle X to get studs (cylinder and main) and trans bearings ordered. I will send my trans as well and assemble at my shop since I will be doing the cush drive rubbers first, which is especially critical without a rear hub cush drive.

I spent some time working on the head last night, installing time-serts on 8 of 12 cam tower bolts. The ones with the alignment pins are shallow and I was wary of drilling any deeper than the holes were already so I left them. I have however upgraded the bolts as well to ARP 6pt in the correct lengths. The bolts and inserts will insure that there are no issues with pulled threads regardless of cam lift. I was going to use a valve cover with the tower hold downs welded in but realized that it interferes with the additional oiling holes I drilled, per Hondaman's book. Either way, more oil will get where it should and and chance of pulled threads is gone.

I have also started working on my roller starter. These usually cost around $800 which is ridiculous given the components involved. I am "borrowing" a design that I like and modifying it some to suit my vision. All in I will have about $350 into mine. The pic is the first roller shaft on the pillow block bearings with sprocket. The motor will direct drive one roller and sprockets will drive both at the same speed. The side panels will be water jet from 1/4" aluminum.

With this motor, I am eliminating the kick start which I had the convenience of last season. I have cut down the shaft and will hollow it out some as now its only job is supporting the oil pump gear, which is also being relieved of the now unnecessary kick start ratchet (still stock in picture). These two modifications will save 1/2 lb and not affect performance at all.

slikwilli420 · « **Reply #506 on:** January 15, 2018, 05:52:36 PM »

Bounced around to a lot of little things today during the time off for MLK day. My brother came up to do some lightening to his GT750 hub for this Sportsman 500 ride (CB450) which came out killer. It goes out for new pad material and brake arching soon.

I have been thinking on how to cut off the alternator stub from the crank without having to disassemble everything. I took an alternator bolt and cut the head off and turned some threads off, adding a slot in the end for a screwdriver, and it now threads in to the oil hole in the journal on that end. I should be able to grease the shaft of the bolt to catch any shavings and once I cut the stub off I can pull the piece out and be good to go. I will need to figure out how to plug the end so oil doesn't pour out behind the cover and cause oil pressure issues.

I have also been working on cutting the cases down, relieving them of anything not essential for racing such as the starter box and any other little casting things that can be cut. Its looking pretty good but still debating on cutting out the starter hole as well. I still want to run a flat cover on that side for protection from any boo boo's.

The front hub is also mounted and ready to go, perfectly centered in the front forks. The Borrani wheels should be here in the next week or so and then spokes, and my first go at lacing and truing a wheel.

I had to bust out my Cycle X crank just to look upon its beauty and it sure is sweet. Looking forward to getting it cut down and seeing how it all goes together. It needs a little cleanup from sitting the last year or so but should be ready for prime time soon.

The last is the start of my magic windows between 1&2 and 3&4. I am keeping well clear of all edges and the stud bosses, but so far it seems to be going well.

slikwilli420 · « **Reply #507 on:** January 19, 2018, 06:50:31 AM »

Still chugging on a dozen or more items at any time. The magic windows are coming along nicely. The best tool is actually a small Dremel bit which eats aluminum with reckless abandon if you run high RPM and low feed. I have few different shapes of bits coming to get at the angles needed. One is roughed in and I still need to start the other.

A big piece of the puzzle showed up yesterday, WHEELS! Direct from Italy, my Borrani wheels are finally here. Big thanks to Chris Dietz, a fellow AHRMA racer, for hooking me up. They were substantially cheaper than Buchanans and the service was outstanding. I ordered spokes from Buchanans last night and they should be here early the week after next.

On the weight loss front (me), I am down over 8lbs over the last 2 weeks, with an overall goal of 56lbs in 22 weeks, which gets me to the Friday of my first race of the 2018 season at Gingerman in Michigan. Even this little bit has me feeling better. I am ahead of goal right now and with the bike coming the way it is, I am thinking the bike+rider will be down 75lb or more vs last year!!

Racer Jon · « **Reply #508 on:** January 20, 2018, 03:20:03 PM »

I am sure you did but remember to seal the hole at the starter gear if it was removed. I think it is for the starter gear anyway, never had a 750 with a starter. I almost found that about that hard way once.

Jon

slikwilli420 · « **Reply #509 on:** January 21, 2018, 09:38:04 AM »

On my engine this season I only plugged the ins hole with a modified alternator bolt.

This year I will cut the crank stub off but do need to figure out how to seal the end after it's cut off.

slikwilli420 · « **Reply #510 on:** January 23, 2018, 05:54:19 AM »

So I finished rebuilding the primary cush drive last night and it took a while but there isnt any reason someone with a drill press could not do this.

I cut the rivet heads off with a 1/4" endmill and they drove right out after that, allowing me to disassemble the unit. Everything was in pretty good shape except the needle bearings had a good amount of corrosion on them.

The side plates that once held the unit together now get countersunk for grade 10.9 M6 bolts on each side. The center hub had holes perfectly sized for tapping to M6, not oversized at all as I had read about. Each tapped quite easily but made good threads. I tapped half way from each side since my tap wasnt long enough to go all the way through. I did countersink the holes in center hub a bit as well.

I was able to source German made Koyo bearings for the center for $10 each and made a small tool to press them in, making that task a breeze, much easier than removing the old crusty ones.

Thankfully I marked each outer sprocket to orient with one another because the teeth do not line up in every position. Each bolt got a healthy dose of Red Loctite and was torqued to 84in-lb. I will stake each screw today now that everything has set up.

This was a very simple bit of insurance for any high performance engine build and should last a good long while with fresh rubber as opposed to the 40 year old stuff that came out.

bwaller · « **Reply #511 on:** January 23, 2018, 10:04:15 AM »

Sounds good Matt.

For your info, last off-season I had RaceTech hard anodize my forklegs. Eventually I ended up with two really good (read like new) fork sets and had them do a pair. I could see the ID was honed afterward and seemed smooth as glass. The idea was to help reduce wear and keep oil cleaner, longer. I just disassembled and cleaned them and the oil was like new, no aluminum discoloration whatsoever. I don't know how long this will last but so far so good.

RAZZ · « **Reply #512 on:** January 23, 2018, 10:18:20 AM »

https://pin.it/mnkp2prbnah64u

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RAZZ · « **Reply #513 on:** January 23, 2018, 10:21:17 AM »

Hi i found This crankshaft block nice. Can you show me some pictures of the dremel tools you used to make the magic Windows with, thinking of doing the same thing - Thanks Razz

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slikwilli420 · « **Reply #514 on:** January 23, 2018, 11:18:46 AM »

Quote from: bwaller on January 23, 2018, 10:04:15 AM

Sounds good Matt.

For your info, last off-season I had RaceTech hard anodize my forklegs. Eventually I ended up with two really good (read like new) fork sets and had them do a pair. I could see the ID was honed afterward and seemed smooth as glass. The idea was to help reduce wear and keep oil cleaner, longer. I just disassembled and cleaned them and the oil was like new, no aluminum discoloration whatsoever. I don't know how long this will last but so far so good.

Brent, what was the cost? My oil was pretty gross after relatively limited use this past year. I pulled my forks down to change to lighter damping rods and cut the brake caliper lugs off one fork and the inside was disgusting.

slikwilli420 · « **Reply #515 on:** January 23, 2018, 11:22:21 AM »

Quote from: RAZZ on January 23, 2018, 10:21:17 AM

Hi i found This crankshaft block nice. Can you show me some pictures of the dremel tools you used to make the magic Windows with, thinking of doing the same thing - Thanks Razz

Sent from my iPhone using Tapatalk

Razz, I was just looking at that picture of his cases. I don't want to go that far since you lose ALL impact protection on that side. I am still cutting off the starter box and a few other little things.

I just ordered this 90 degree head for my Dremel:
https://www.amazon.com/gp/product/B00005AXI0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

And these cutters:
https://www.amazon.com/gp/product/B000CDORLS/ref=oh_aui_detailpage_o07_s01?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00DCJN27O/ref=oh_aui_detailpage_o07_s01?ie=UTF8&psc=1

I first drilled 4 holes, then just connected the dots. I will finish off with a fine grit sanding drum until smooth. I am making sure to stay well clear of the bosses for the studs. I also left about 0.070" at the top of the window, going that far lower than the bottom of the groove between cylinders. Once my pistons are done and cylinders bored, I will match the sleeves to my windows.

bwaller · « **Reply #516 on:** January 23, 2018, 07:05:19 PM »

I want to say it was $200 for the pair.

Captain · « **Reply #517 on:** January 23, 2018, 07:27:49 PM »

http://forums.sohc4.net/index.php?action=dlattach;topic=158461.0;attach=368702;image The bottom of the perforated tubes must only be sealed between the inner and outer.......... Do not seal or blank off the inner. It must remain open.

Captain

slikwilli420 · « **Reply #518 on:** January 23, 2018, 07:33:27 PM »

Quote from: Captain on January 23, 2018, 07:27:49 PM

http://forums.sohc4.net/index.php?action=dlattach;topic=158461.0;attach=368702;image The bottom of the perforated tubes must only be sealed between the inner and outer.......... Do not seal or blank off the inner. It must remain open.

Captain

Would adding a large hole through the center of the bottom end cap work sufficiently?

simon#42 · « **Reply #519 on:** January 24, 2018, 10:01:24 AM »

Quote from: bwaller on January 23, 2018, 07:05:19 PM

I want to say it was $200 for the pair.

but it wasnt !

bwaller · « **Reply #520 on:** January 24, 2018, 04:06:19 PM »

Simon, you must have a better memory than me.

I checked the invoice and I paid them $250. Finding really good (forty year old) forklegs is very difficult. I bought a lot of "like new condition" forks along the way, that were #$%*!

When you find good parts, helping them last makes sense. This process helped make the best 35mm fork set up I've ever used, which helps greatly on a roadracer.

slikwilli420 · « **Reply #521 on:** January 24, 2018, 07:41:27 PM »

I'll look into that for next season Brent. Good lowers for GL forks aren't hard to find but good tubes are. When I get a new set of tubes I will do the hard anodize as well.

slikwilli420 · « **Reply #522 on:** January 25, 2018, 05:45:45 AM »

Cal, the lowers are easy to find and I have a couple good sets. The issue is the uppers which tend to be rotten under the headlight ears of stock GL bikes. Even mine are peppered with rust spots. When I get a really nice set of uppers, then I can justify pulling my current forks apart to get the lowers anodized. Then when I assemble again, I will use the new uppers and have a really killer set of forks.

bwaller · « **Reply #523 on:** January 25, 2018, 06:31:25 AM »

Forks by Frank?

slikwilli420 · « **Reply #524 on:** January 25, 2018, 07:13:37 AM »

Quote from: bwaller on January 25, 2018, 06:31:25 AM

Forks by Frank?

About my only choice unless I happen on a nice original set. I thought I had a set but they had substantial wear on the lower ends, all the way through the chrome. This is bathed in oil so no rust but I am not running them on a racer, street bike sure.

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Author Topic: CB750 AHRMA Sportsman 750 Racer (Read 175345 times)