16 valve top end on an 850?

[Smooth Operator]

I?m sure this sounds strange until you think about it. The engine designer in me has always drooled over the Twin Swirl combustion chamber. It has great theoretical potential for octane tolerant efficiency. The 850 has never been a gas miser. Also, since liter+ bikes almost always get better mileage than my 850, I?ve always pondered the relative difficulty of fitting a liter+ crank and 16 valve top end into my 79 850.

Now, you might ask: ?why not just get an 1100G?? Well, the old timer in me MUST have a kick starter and the 79 850 was the only Suzuki shaft drive I?m aware of with this feature. I?ve used the kick starter on many sub zero mornings and simply won?t do without one.

There are, naturally, questions?

Is the 16 valve head worth it? Have you guys experienced actual efficiency comparisons??

What about engine durability. Do the 16 valvers experience rocker bushing and/or valve guide wear? I KNOW the 8 valve head is bulletproof, with the buckets shielding the guides from thrust loading, but the adjustable tappets might be ?nice? ??? or??? Looking for opinions.

Converting an 850 to a 1000/1100???? Would the crank fit? Can I assume cylinder spacing is OK, since camshafts interchange? ????

Gearing is another issue?The bigger engine would require taller gearing than the 850, for my tastes. I?d always assumed the ?taller? bevel gears from a 1000G would interchange, but a thread on this site indicated they?re not interchangeable. That same thread did indicate there is a taller ratio final drive? ????

My old 100k 79 850 is due for a resurrection and I?d greatly appreciate ANY opinions, sanity checks, ideas, tech info?

Thanks

BTW just found this site. It sure is great to see the GS?s thriving.

[dpep]

That question has been asked in the past and the practical answer was no. The 16v head will not bolt up to the 8v block. Of course ANYTHING can be done with enough time and money and machine shop.

The 850 mechanically may be the most solid and reliable motorcylcle ever mass manufactured. Why would you wand to trash all of that for a 1-off curiousity?

Get yourself an 1100G or 1000G. Get the RR & Stator taken care of with soldered connections between them. Get a new gel battery. Get a Battery Tender. You will never need or miss your kickstarter. If you want to play it even safer, keep a spare battery on the Tender.

[Smooth Operator]

Thanks Don. That?s the type of advice I?m looking for.

The 16 valve concept might be more trouble than it?s worth? although? i DO have time, money AND a machine shop? so?

I know I?m nuts and most rational folks would just ??get a good battery and forget the kick starter?? Perfectly sane advice. Advice that?s truly appreciated. It?s just that, as a four season rider, I?ve NEEDED kick starters way too many times? Coast starting is not an option when you can barely stand on ice.

With the mercury at 20 below (Fahrenheit, that is), 10w40 is the consistency of petroleum jelly and must be squeezed from the bottle. That poor roller bearing crank must squeeze that stuff around the rollers to get started under those conditions and the poor Suzuki starter just doesn?t pack the HP to start an 850 at 20 below regardless of battery condition, cable/ground condition, or even size. That?s been my experience, at least. I?ve racked up 100k of 4 season experience on this machine and have tried a lot of things. My 250 lb of body weight handily kicks her to life every time.

Once experimented, with limited success, at feeding the starter with 18VDC, but the relaying complications and space limitations for the additional battery are difficult issues. Plugging her in overnight helps a lot. So does a pan heater. Neither are very useful during wintertime overnights at primitive sites. Just can?t find a ?current bush? to plug into.

The legitimate question, of course, is: ??why in God?s name are you trying to start a motorcycle at -20 degF ???? well? it?s a very loose knit and exclusive club of ?four season riders?. With proper equipment and precautions, wintertime touring can be an immensely satisfying experience. The wife enjoys it too!! (words of experience: NEVER let a woman get cold, EVER, even once!!!! Equipment is the key?) In the ten years since my poor old 79 850?s been parked, two of my friends have ridden to Alaska in WINTER months? and I ENVIED them. Sanity?s a relative aspiration?

Thanks again for the sane advice. The RR and soldered connections are must do?s.
Still deciding whether to use the Honda RR or build my own, or ???

So? I guess that if the 16 valve head/cylinder won?t bolt up, and if I can?t get the drive ratio down to accommodate a liter+ crank (even if it would fit), I should just appreciate my 850 as the toughest thing on wheels and resurrect her as she was created? More or less?

Or? ??????

[duaneage]

If you compare two almost identical engines ( like the 750) where 1 uses 8 valves and the other 16 you'll see only a slight increase in top end power and a little bit higher redline. You will also see that the 8 valve engine does a little better on the low end because the camshaft timing is not as aggressive. I think the 750 16v engine puts out 8 more HP according to specs. I don't think 10% more power is much to get excited about.

The sad truth is you only get serious gains in power with the big blocks. And you have to go all out to get the kind of HP newer fuel injected water cooled monsters are doing today. To get 175 HP you need big pistons and serious airflow through big carbs. Look for Racing Jake's posts to get an idea what a 200 HP Suzuki looks like.

I have never even considered "hopping up" my 650. It is what it is and does what it does well. I see the posts about pods and pipes all the time and at the end of the day success is declared by it's not running bad. I would like to see before and after tests to see if there is even a measurable difference after all that. Surely not worth three weeks in the garage and running up and down the street with spark plug sockets in your pocket.

[dpep]

In the ten years since my poor old 79 850?s been parked, two of my friends have ridden to Alaska in WINTER months? and I ENVIED them. Sanity?s a relative aspiration? ..............

So? I guess that if the 16 valve head/cylinder won?t bolt up, and if I can?t get the drive ratio down to accommodate a liter+ crank (even if it would fit), I should just appreciate my 850 as the toughest thing on wheels and resurrect her as she was created? More or less?

Or? ??????

It sounds like you have answered your own question, and sensibly. It strikes me that if your intent is to travel remote roads in harsh weather the last thing you would want is a motorcycle with a lot of mechanical customization.

I would want to fix the things that are known problems and leave stock the rest of a motorcycle that has over 25 years become a legend for reliability.

Check your rear wheel splines and keep them well lubed. That is the one mechanical thing most likely to leave you stranded somewhere. Your '79 has the points type ignition which requires more maintenance, but might be more suited to remote adventure riding. It is certainly makes it cheaper to carry a spare.

[duaneage]

I parted out an 850 that had almost 60000 miles on it. If there is anything these GS bikes are known for, it's longevity. I would do the Honda Regulator Mod on it and change the fork oil out. Touring stresses the rear shocks so a better pair of springs back there is a good investment. Engine crash bars with auxillary footpegs are a good idea and cheap.


Basically you already own a great bike. Look on this site for more great ideas to make it better.

[Steve]

Smooth Operator,

You state "The 850 has never been a gas miser." What might your definition be of a gas miser? This summer we rode from oHIo to Colorado for a Kawasaki rally, my wife was on her '82 GS850GLZ. I keep record of all expenses in a spreadsheet and analyze it when we get home. For the trip there, we had a low of 41.57 and a high of 49.98, with an overall average for 2240 miles of 45.98 mpg. I am sure that did not break any records, but that's pretty darn good in MY book.

[Smooth Operator]

I should?ve been more clear about my objectives. Power is really not an issue, for me. Mileage is. I?d even sacrifice 10 HP for a few mpg. Not for the economics of it, but for the range. I?ve always wanted more fuel capacity, but can?t bring myself to part with Suzy?s beautifully proportioned tank. Better mileage is always the best way to improve range.

I once rode with a friend on a 3000+ mile trip, in the late 80?s. He was on an 1100G (can?t remember the year) that was set up very similar to Suzy (Fairing, luggage, etc). He had his wife and I was solo and he ALWAYS got around 5mpg better than me. Same speeds, side by side. I was the one looking for stations first EVERY time. I would have ran out and bought an 1100 if they had a KICK STARTER. (don?t worry, I?d NEVER sell Suzy!! )

Now, in all honesty, my 850 might have gotten better mileage than the 1100 had we slowed down to something under 80mph? Also, Suzy had 80,000+ miles, at the time, and his 1100G had less than 20K. Suzy had points (usually run aftermarket electronic) and his 1100 was electronic, so?. Mileage is a VERY relative thing?

Because compression ratio is also EXPANSION ratio, it has direct impact on an engine?s thermal efficiency. My THEORY, is if Twin Swirl allows higher compression, there should be theoretical improvement in potential efficiency. The only way to prove this theory is to prove it (practical experience) which is why I?m looking to this great site for its valuable experience. I?ve known and met folks with 1150?s that claimed some impressive mpg, but none with a fairing, so? ????

What do I consider a ?gas miser?? Well? my 59 BMW R26 (250cc single, shaft drive!!) (15 hp ) got 104 mpg at Craig Vetter?s mileage contest? (I?m converting it to run ethanol for my daughter ) My 57 BSA Rocket Gold Star (an A10 engine in a Gold Star frame) always got 60+mpg. Had a 61 Sportster that always got 55+mpg? so ? NONE of those machines could hold a candle to Suzy when it comes to ?burning up the map?? So, like I said before, mileage is a VERY relative thing.

Don, I seem to remember a Suzuki ?recall? on the rear wheel (splines?) back in 79. It took less than an hour and they put a little punch mark by the engine serial number signifying that it had been updated? are these the rear wheel splines you?re referring to?? Are all models subject to this failure, or just the ?non-updated? 79?s??? I have always kept them lubed with a molly compound. Thanks for the heads up.

I?ve always wondered about the final drive splines. These take a beating with every bump in the road and are difficult to check? has anyone experienced problems with these??

Thanks to everyone for the valuable input.

[johnrregan]

other option

if you have a machine shop, the time and patience to do it, why not just try to fit a kickstart to a 16 valve bottom end, rather than a 16 valve top to an 850!!!!!!!

[flyingace]

I can't make much sense or your goals. You have a big heavy, motorcycle and you think a better breathing cylinder head is going to improve milage? I don't think so.

If range was my goal, I'd just get a different tank. Personally, my butt starts to hurt after 100 miles or so, and a fill up is usually welcomed.

[jimcor]

Why in the world are you using a 10W40 oil at -20F? That cold weather is what synthetic 0W series oils are for.

[dpep]

I should?ve been more clear about my objectives. Power is really not an issue, for me. Mileage is. I?d even sacrifice 10 HP for a few mpg. Not for the economics of it, but for the range. I?ve always wanted more fuel capacity, but can?t bring myself to part with Suzy?s beautifully proportioned tank. Better mileage is always the best way to improve range. ...................

Because compression ratio is also EXPANSION ratio, it has direct impact on an engine?s thermal efficiency. My THEORY, is if Twin Swirl allows higher compression, there should be theoretical improvement in potential efficiency. The only way to prove this theory is to prove it (practical experience) which is why I?m looking to this great site for its valuable experience. I?ve known and met folks with 1150?s that claimed some impressive mpg, but none with a fairing, so? ???? .............

Don, I seem to remember a Suzuki ?recall? on the rear wheel (splines?) back in 79. It took less than an hour and they put a little punch mark by the engine serial number signifying that it had been updated? are these the rear wheel splines you?re referring to?? Are all models subject to this failure, or just the ?non-updated? 79?s??? I have always kept them lubed with a molly compound. Thanks for the heads up.

I?ve always wondered about the final drive splines. These take a beating with every bump in the road and are difficult to check? has anyone experienced problems with these??

Yes, I can sympathize with your desire for greater range. When I ride it is usually for long distances and I like to stretch out the time between gas stops. You may want to consider an auxiliary tank. I saw one recently that was essentially a bladder designed as a tank bag. It looked pretty slick but was expensive. I cannot find that link. Here is a site that sells more conventional aux tanks; not that pretty, but functional. Hooking a t-connector into your fuel line is a lot less challenging than custom engine work.

http://www.tourtank.com/

I have taken the simplest way out and will simply carry an extra gallon of gas with me. I may next substitute a product called "Rescue" which is a fuel with less volatility that will only work in a hot engine. It is expensive, but the advantage is that it is easier and safer to transport; it remains good as long as the container stays sealed. I use these supplies as reserves to my reserve. They allow me to stretch my tank as far as I can without fear of being stranded roadside. I don't want to actually have to be pouring fuel into my tank on the side of the interstate on a regular basis.

You may want to check the accuracy of your odometer. You may for instance have a speedo gear off a bike with a different size front wheel. I discovered my odo was actually reporting fewer miles than I had traveled. Usually it is the other way around. So just using odo figures someone else's bike would report more miles and therefore better mileage for the same true distance and same gasoline amount.

Carb tuning can change your mileage figures considerably; the leaner you run, the better mileage you get. Of course the leaner you run the hotter you run, so it can be self-limiting. Also running hot consistently is not good for the longevity of the bike. I know I could get better mileage from leaning out my mixtures, but I would rather have it a little too rich rather than a little too lean...a form of liquid cooling. Of course I live in Florida. Overheating would be less of a problem riding to Alaska in the winter.

I hope to get an oil cooler installed this winter which will make me feel a little bit better about leaning out mixtures.

Keep in mind that somewhere between 50 and 60 mph the amount of energy used to overcome air resistance exceeds the amount needed to overcome friction and gravity. And it goes up exponentially from there. If you really want good gas mileage, locate one of those old dustbin fairings they had back in the 50's. Front only fairings can either increase or decrease wind resistance depending upon design, speed, etc. I don't think there has been a lot of wind tunnel testing on consumer motorcycle configurations. Motorcycles and their riders are inherently more "dirty" passing through the air than enclosed vehicles with smooth lines. Your best bet is probably no fairing or a small fairing and lying on the tank. The worst is probably sitting bolt upright with no fairing at all. But the only way you can really know is to try different setups until you find one that seems to consistently work best for you.

Click on the Search function at the top of this page. Enter the word "splines" and set the search for Posts rather than Topics (lower left corner of screen). Set it to return the first 1000 characters of the post. That should catch you up pretty well on the splines topic.

[jimcor]

BTW. Smoothie, give ya $50 bucks for the RGS. 8O :twisted:

[Smooth Operator]

Well? if I could make sense of my goals, I wouldn?t need to be asking dumb questions?

There are examples of engine designs where ?free-er breathing? configurations have improved efficiency? Cam profile and port configuration are as significant as the number of valves.

My interest in twin swirl is its detonation resistance. The ability to safely increase compression is one key to increased efficiency. This is one reason Diesels get better mileage than gassers.

One little detail often overlooked regarding seat comfort is ? britches! Cut out seams that cause pressure points or buy pants (and shorts) with minimal seams and you might be amazed at how many more miles you can go before needing a ?britches break??


I try to avoid 10w40 when things get anywhere near that cold, if I can plan? but I have been caught by surprise? One thing?s for sure, you?re not going to drain it at those temperatures?

Thanks for the link, Don. That?s a perfect answer. Hard to believe I?ve missed it for so long? I need to get out more? Keep in mind that you?ll eventually lean to the point where mileage suffers. Suzy?s had a Lockhart thermostatic valved cooler since day one. The thermostatic valve isn?t that important unless you?re in the really cold stuff.

You?ll have to do a little better than $50. I gave $75 for that RGS back in high school? It?s in a little better shape now than it was then.