Topic: Correct sprocket carrier....K2 with F3 engine....newbie

[jamesw]

I just bought a 72 750K with an F3 engine, and from reading old threads I know I need to have a 77/78 sprocket carrier & axle spacers.

Being a newbie, I'm trying to figure out if the PO already made this change or not. Is there an easy way to tell? Should I see scoring anywhere, and if there isn't any scoring can I assume the switch was done?

[mystic_1]

Take off the chain guard and then look down the length of the chain from behind.  The front and rear sprockets should be lined up perfectly, not offset from one another.  It should be fairly obvious when you look.

mystic_1

[BPellerine]

78 carrier with the inner spacer,and on the brake side your k2 spacer.billp

[jamesw]

78 carrier with the inner spacer,and on the brake side your k2 spacer.billp

Is this the correct piece?
http://m.ebay.ca/itm/1978-HONDA-CB750-INNER-CUSH-DRIVE-AXLE-SLEEVE-SPACER-/171656811020?nav=SEARCH

[seanbarney41]

Go to the CycleX website, sprockets page, all the way down at the bottom there are pictures of the sprocket carriers and their differences.

[BPellerine]

check your pms james,I think I know the bike you bought.billp

[enwri]

http://forums.sohc4.net/index.php/topic,155096.0.html

There's both axles and carriers in there. 77 and earlier. Note the different stepped internal length. Long one in long carrier

[jamesw]

I took off the chain guard, and to me I don't see the 10mm offset. 

I tried posting a pic from my phone, buy it's not attaching .

As it stands, I'll have to get a second opinion before I do anything else.

[Retro Rocket]

James, the rear hubs look completely different, you don't need a second opinion, you need to look at the rear hub. In the pictures below,  the one on the left is the stock early K model hub, the one on the right is a K7/8, the early K had webbing, the later K doesn't, its quite obvious once you know what to look for...

[jamesw]

James, the rear hubs look completely different, you don't need a second opinion, you need to look at the rear hub. In the pictures below,  the one on the left is the stock early K model hub, the one on the right is a K7/8, the early K had webbing, the later K doesn't, its quite obvious once you know what to look for...

That's great Mick....that's exactly what I needed to know. I'll take a look today and see. Thanks so much

[jamesw]

I checked the hub and it's clearly the k2 with the webbing.

Is there anyway the po used the K2 front sprocket on the F3 output shaft so that it aligned with the k2 rear sprocket? *Sorry if that makes no sense. I just thought there would scoring or obvious signs of wear.

[BPellerine]

not very likely,james,f3 engine in early frame always causes chain problems.billp

[Jerry Rxman Griffin aka MuthaF'er]

My build is a F0 with a K8 engine. F0 same as K2 as far as the front/rear alignment. K8 has the same 10mm offset as the F2/3. Same scenario as yours. I'm also using a 530 chain in place of the K8/F3 630 chain. Starting at the front I have a CB650 front sprocket (single shoulder vs double shoulder) that mates to the end of the output shaft (vs slipping up onto the shaft) and a K7/8/F2/3 rear sprocket carrier with the 10mm matching offset. Once you do this that 10mm bites you in the ass. To overcome this you also need a K7/K8/F2/F3 10mm offset swingarm and it's chain guard.   

[Retro Rocket]

My build is a F0 with a K8 engine. F0 same as K2 as far as the front/rear alignment. K8 has the same 10mm offset as the F2/3. Same scenario as yours. I'm also using a 530 chain in place of the K8/F3 630 chain. Starting at the front I have a CB650 front sprocket (single shoulder vs double shoulder) that mates to the end of the output shaft (vs slipping up onto the shaft) and a K7/8/F2/3 rear sprocket carrier with the 10mm matching offset. Once you do this that 10mm bites you in the ass. To overcome this you also need a K7/K8/F2/F3 10mm offset swingarm and it's chain guard.

Is it necessary to use the later swingarm Jerry, I'm sure there are members that just used a spacer combination to suit the wider hub...?

[jamesw]

I'll take the advice given here and buy a 78 carrier and inner cush stepped spacer and then use my k2 sprocket on the 78 carrier so I can use my 530 chain.

I just don't see the chain "damage" currently.

[Jerry Rxman Griffin aka MuthaF'er]

My build is a F0 with a K8 engine. F0 same as K2 as far as the front/rear alignment. K8 has the same 10mm offset as the F2/3. Same scenario as yours. I'm also using a 530 chain in place of the K8/F3 630 chain. Starting at the front I have a CB650 front sprocket (single shoulder vs double shoulder) that mates to the end of the output shaft (vs slipping up onto the shaft) and a K7/8/F2/3 rear sprocket carrier with the 10mm matching offset. Once you do this that 10mm bites you in the ass. To overcome this you also need a K7/K8/F2/F3 10mm offset swingarm and it's chain guard.

Is it necessary to use the later swingarm Jerry, I'm sure there are members that just used a spacer combination to suit the wider hub...?

When I cross referenced the spacers from the different models, unless I missed something, they were the same. The wider hub is designed to push the rear out that 10mm to match the front. My stuff hit the original swingarm, shock, etc.

This is using the late model rear sprocket carrier to align with the 10mm offset front. Notice that the spacer does not fit and the hub is jammed up to the swingarm.



Notice also where the sprocket is in relation to the shock. The chain guard won't work either as the sprocket is pushed outward by the 10mm.

Now with all this perhaps someone has another solution that I didn't see??

[Jerry Rxman Griffin aka MuthaF'er]

As long as you have correct alignment of the chain front to rear and everything spins freely you're good. There are a number of ways these things have been thrown together. I took the hybrid late model route. One offset lead to another 

[seanbarney41]

Jerry, your bike is nicer than most.  Most folks are happy to leave off the sprocket gaurd thingy, and bulky stock chain guard.  This is what I did with with a K8 engine in a k5 frame and swingarm. 

Another option to achieve correct chain alignment is a 10mm offset rear sprocket from Cycle X.  Shock clearance will be tight limiting shock choice to only those that are nearly as narrow as the oem shocks.
 
JamesW, the only chain damage you will be able to see is accelerated wear on the inner face of the chain side plates.

[jamesw]

As long as you have correct alignment of the chain front to rear and everything spins freely you're good. There are a number of ways these things have been thrown together. I took the hybrid late model route. One offset lead to another 

I'm thinking along the lines that you are. If I could attach a similar pic that would explain why I agree, I would. I asked the admin to look into it.

Maybe I'll drive with the current setup for a season and see how it goes, inspecting the chain often. When I have the bike on the center stand and spin the wheel, I don't see any warp/offset that I "should" see.

[Retro Rocket]

As long as you have correct alignment of the chain front to rear and everything spins freely you're good. There are a number of ways these things have been thrown together. I took the hybrid late model route. One offset lead to another 

I'm thinking along the lines that you are. If I could attach a similar pic that would explain why I agree, I would. I asked the admin to look into it.

Maybe I'll drive with the current setup for a season and see how it goes, inspecting the chain often. When I have the bike on the center stand and spin the wheel, I don't see any warp/offset that I "should" see.

If you have an F3 engine in an early K frame as you've stated,  its NOT aligned, its as simple as that, its not debatable. You'd also be doing pretty well to see a 10mm offset by eye,  especially going by your own admission of,  "Being a newbie", what are you actually looking at..?   spinning the wheel won't show a  thing... A laser or string line, done PROPERLY will show the difference, and it will prematurely wear out the chain and sprockets, there is no way I would ride it like that....

[jamesw]

I do agree that my newbie & inexperienced eye cant decipher mm offsets. I was solely going by what mystic1 who replied earlier in the thread saying that it should be fairly obvious. In any case, I'll take off the front covers and use a laser.

However, I'll buy the inner stepped spacer and 78 carrier today.

[Jerry Rxman Griffin aka MuthaF'er]

We don't have much in the way of visuals from you. Does this look like your output shaft with the engine case bump sticking out or is it flush? Pictures REALLY help us help you.




OK, next, from this picture you will notice (barely) the sprocket 'shoulder' inside the washer and bolt. It has a 'shoulder' on ONLY the outside edge and not the inside edge. The stock CB750 530 front sprocket has shoulders on BOTH sides. If you use your stock 530 sprocket you will give it MORE offset than you should have. The 77/78 engines used a 630 sprocket that did NOT have a shoulder on the inside where it bolts to the output shaft end. This is the CB650 sprocket I mentioned. 

At the least run some form of straight edge across your rear sprocket to the front sprocket. Maybe get a piece of square bar stock from Lowes or Home Depot hardware section.

I'm having a hard time understanding what you refer to as the 'inner stepped spacer'. Do your self a favor if you haven't and use http://www.motogrid.com/OEMpartfinder.htm?aribrand=HOM to plug in the different models on the left, get your part number then plug that in on the right side and see which models that actual part number fits. You may find that you already have the same 'inner stepped spacer'.

[jamesw]

Hey Jerry....tomorrow I'll take pics of the front sprocket and post them. Glenn (admin) told me the problem I had with posting pics was due to their size. I'll take some new ones and post them tomorrow.

As for the spacer, I posted a link to its ebay listing previously in this thread. I'll use the link you provided in the future. For comparing parts I've been using houseofhonda parts listings and comparing myself.

In this pic below it's piece #10 axle sleeve that is longer on the 78 vs the 72. And because it's not available, I bought it from ebay.

[Jerry Rxman Griffin aka MuthaF'er]

Quick message, I'll look at your stuff later. OPEN A PHOTOBUCKET ACCT! Get the app for your phone. Free and easy. Upload your pics from your phone to your new acct. Copy the IMG code of each pic then paste here! THAT EASY.  IT sizes the pics for the site. If I can do it ANYONE can.... 

[mystic_1]

10mm is a little more than 3/8", if your sprockets were offset that far you'd be able to see the slight "zig zag" in the chain as you sight down it, but a laser or a long straight rod laid on top of the chain  would be a good call to be sure of things.  I'd think you'd also be seeing one-sided sprocket wear if the bike had very many miles on it in this configuration.

mystic_1