Engine Build Advice for 78 GS1000 Roadracer

[cbxchris]

I would rather have a head done right on a serdi taking full advantage of your stock valves with some good blending at the seat area. For your application a full port job is a waste. Personally I would get the straight cut gear and a falicon billet hub. If you want heat to not be a issue larger sleeves will help that with the kit you intend to use. Under cutting the tranny is a good idea as others have recommended. I would probably spring for case and cylinder studs/nuts. In your application I am not sure I would spend a great deal of money in cams and titanium retainers with buckets. Your engine with the head work,kit and carbs would pull like a tractor out of the corners. Cams and lighter valve train naturally would increase high rpm HP but trust me for every thing you add up top on the head you lose a certain amount of dependability. I had a GS1000 in 78 and made it a 1055 with turbo.....I found every weakness that engine had to offer.

[rcp]

What has 81-100-81 carb spacing?

Sudco is so far unable to tell me what application uses 81-100-81 spacing on VM33s - they're going to check with the tech in the back and call me back.

The impediments to changing the spacing are the throttle shaft (which can be drilled and tapped if need be), the racking rails (which are easily drilled), and 2 or 3 o-ringed-pipe or tube connections between each pair. The pipes are the real sticking point, as they'd require machining (or a very lucky hardware or auto parts store find) to duplicate.

Anyone got a set of VM33 (good or bad) or parts?
I'm going to check the CVs on my GS1000G streetbike to see if any bits will fit.

- Richard

[rcp]

I got a note from another vintage racer from my club that carb spacing for HONDA CB750F, 900F, 1100F is 80-100-80. That must be what these are for.

[rcp]

I've got a swap arranged to get a set of GS-spacing VM33s (which should be clean and intact) for the Honda VM33s, and I've got backup set coming from ebay. So I should be covered for carbs. I'll take my time cleaning up the other set, and then pass them on if I don't need them.

I discovered a couple of broken bits in the clutch last night. A broken fibre plate,and a broken spring:



Haven't found the rest of the pieces of the plate yet, but imagine they're in the sump.

- Richard

[rcp]

Shopping List

Still have to find, or more likely, will order new from APE, Web/Megacycle:
- reinforced clutch, or reinforced clutch plate kit
- hardened clutch hub nut
- manual cam chain tensioner
- push-pull throttle
- heavy duty cylinder studs
- 54mm pod air filters
- 14mm T.D.C. tool and degree wheel
- not-too-lumpy cams (maybe just an intake cam).

Anyone got any of these parts lying around?

- Richard

[first timer]

I would save a few bucks and keep the oem studs. I am running oem, just bought some new ones. They were good enough for Pops. The HD studs are bigger in dia and I don't like the idea of reducing oil flow to the head.

[cbxchris]

I would save a few bucks and keep the oem studs. I am running oem, just bought some new ones. They were good enough for Pops. The HD studs are bigger in dia and I don't like the idea of reducing oil flow to the head.

Easily eliminated by drilling the cylinders and using GSXR o-rings to seal the head. Cylinder and head gasket must be properly bored to use the o-rings. Did it for years on a pro mod and never leaked a drop. I also used studs bigger than APE.(Elmer Trett made them especially for nitro/turbo applications.) No oil gear either.

[rcp]

What's the word on engine coatings for best engine heat transfer? Is Kalguard (aka KG, aka Gun-Kote) still the best stuff?

Would you mate that with ceramic treatment of headers or more Kalguard?

I can't figure out if the ceramic coating of headers insulates, and thus more heat stays in the exhaust gas and goes out the tailpipe, or if it's something else?

Better to get the hot gasses out the tailpipe, or from the headers into the breeze? (Into the breeze, I suppose, present your cylinder head with hotter air).

[first timer]

i am going to kal gaurd https://www.kgcoatings.com/index.php...d&productId=20 the engine and headers.

it was good enough for Pops, gives about a 15% cooling according the a old bike magazine artical.

[rapidray]

Richard, ceramic coatings on the header help keep the heat in the PIPE which keeps other parts around it cooler & helps get the heat out of the motor. As for coatings INSIDE the motor, the only thing I would do is have the piston skirts dry film lubricant coated. Ray.

[rcp]

i am going to kal gaurd https://www.kgcoatings.com/index.php...d&productId=20 the engine and headers.

it was good enough for Pops, gives about a 15% cooling according the a old bike magazine artical.

That's the stuff I'm thinking about - about $300 CDN to do an entire engine according to a Canadian distributor, so it gave me pause. Wanted to see if there's not a newer, better alternative. The Kal-Guard coating requires baking in the oven, so the engine has to be disassembled (which it is), and the wife and kids need to be out of the house :-).

Richard, ceramic coatings on the header help keep the heat in the PIPE which keeps other parts around it cooler & helps get the heat out of the motor. As for coatings INSIDE the motor, the only thing I would do is have the piston skirts dry film lubricant coated. Ray.

Thanks Ray, I thought the ceramic must be an insulator. Therefore the best header treatment would be one that does the inside of the pipes as well as the exterior, right?

I wonder why they're putting ceramic in rattle-can engine paints?

As clarification, I was only thinking external coatings. I would assume that the dry film lubricant on piston skirts falls into the category of "insurance". If this something you would generally recommend? Are you talking about a PTFE/Teflon coating or something else?

- Richard

[rcp]

I would save a few bucks and keep the oem studs. I am running oem, just bought some new ones. They were good enough for Pops. The HD studs are bigger in dia and I don't like the idea of reducing oil flow to the head.

Easily eliminated by drilling the cylinders and using GSXR o-rings to seal the head. Cylinder and head gasket must be properly bored to use the o-rings. Did it for years on a pro mod and never leaked a drop. I also used studs bigger than APE.(Elmer Trett made them especially for nitro/turbo applications.) No oil gear either.

I'll have to compare the GSXR against the GS - I hadn't considered the possibly tighter oil passages from H.D. studs. Are the H.D. studs actually greater in diameter or just of greater tensile strength?

My thinking was that greater compression might require the H.D. studs to avoid stretching them. I'm not going crazy with power from this engine - want to keep the broad torque curve to maintain rideability on our majority tight, twisty tracks - but I want to make sure I build in reliability as I increase the output.

- Richard

[reddirtrider]

I'll have to compare the GSXR against the GS - I hadn't considered the possibly tighter oil passages from H.D. studs. Are the H.D. studs actually greater in diameter or just of greater tensile strength?

My thinking was that greater compression might require the H.D. studs to avoid stretching them. I'm not going crazy with power from this engine - want to keep the broad torque curve to maintain rideability on our majority tight, twisty tracks - but I want to make sure I build in reliability as I increase the output.

- Richard

They're greater in diameter. If you use them you need external oil lines to feed the cams. The money starts to escalate rather quickly.

[renobruce]

They're greater in diameter. If you use them you need external oil lines to feed the cams.

which can't be done on an 8 valve. I wouldn't worry about the studs. Buy new stock ones and be done with it. I've never heard of the studs being a weak point.

[first timer]

about the studs, i have also heard it's hard to get hd studs for the gs8v ape doesn't stock them and would have to make some if ordered. They are bigger dia because of the rod they use is imperial sized (cheaper in price then metric), i have heard they just cut it down for the threads. Please correct me if i am wrong. You hear lots of thing over this interweb.

I'll let you know how much it is do an engine, I was going to have a powder coat place just do it (i ordered the coating). But if you are thrifty find a place to blast with the media KG recomends) and just get a cheap harbor freight gun and do it yourself, I have been told by kg it's not that bad in the over