T8's 750 Cafe Racer Project

[hjfisk]

I really don't know for sure what your plans are with this bike , but if you are planning on riding it on the track[or street] and those are race rain tires, you may want to reconsider. A race rain tire on dry pavement will actually tear it self apart. I have road raced for 5-6 years and have been on rains when the track went dry. It is not fun , you can feel the tires give up on you. They require water to keep them cool enough to not disintegrate. I had pics of some that I had on my bike , where the tread actually came off a lug at a time.

From the moto GP web sit;
WET RACES

For wet conditions, special wet tyres with full treads can be used, but they deteriorate quickly if the track dries out.

Here are a couple pics of Race rains that were run on a track with minimal water, this is 1 - 8 lap heat race , wet at the start and dried out 1/2 way through the race. Had 1 other heat race in full wet. I understand that they are not the exact model you have but , most all manufacturer's tire's do the same.

Just don't want to hear that you fell down because of bad tire choice.
Food for thought, just my .02 cents

Well, how does that slide vice work out as a milling machine? What do the bits look like for it? I got a huge floor standing drill press at an auction over the summer for $35, anxious to try this kind of setup out, as I didn't know it was even possible! I assume the hardest part is getting the object clamped into the vice perfectly level and parallel with the drill press deck, or rather perpendicular to the milling bit? This kind of setup could really come in handy!

You want to go buy some end mills in whatever size you want. I prefer around 5/16 or so. Big enough to get some material out of the way but small enough to get into somewhat tight spaces. A two or three flute end mill does well in aluminum because if you get more than that the soft metal will try to gum up in your end mill and screw up your work piece. Keep in mind that you never want to mill away too much material at a time. While a cnc miller could plow through aluminum it is made for the lateral loads it will encounter while a drill press is made only for vertical loads. So LIGHT milling is key. But yeah getting the part vised up is usually the tough part. I'm not using mine for super tight tolerance parts though so I usually just eyeball it. I'm not a professional machinist by any means so I'm only relaying info that I've found useful and learned the hard way.

The X-Y vise is basically just a vise that can move forward-backward and left-right. You control the Z-axis with the press. With an X-Y vise you definitely get what you pay for. I bought mine from a guy in the classifieds for $35 and it has quite a bit of play in it (more than I like anyways). I recommend spending at least $100-$300 on new or buy a good used brand-name vise. Non of that Harbor Freight crap. I'm back in the market for a better vise already. I've seen guys put stepper motors on them and make it CNC. Pretty sweet for a poor man who can't afford a CNC machine. Check this one out. He's doing wood with it but it's essentially the same thing. http://www.youtube.com/watch?v=kVHh_3sXzhk

[Chuck78]

Well, how does that slide vice work out as a milling machine? What do the bits look like for it? I got a huge floor standing drill press at an auction over the summer for $35, anxious to try this kind of setup out, as I didn't know it was even possible! I assume the hardest part is getting the object clamped into the vice perfectly level and parallel with the drill press deck, or rather perpendicular to the milling bit? This kind of setup could really come in handy!

New Drill Press

So I FINALLY got the drill press I ordered. Don't mind the mess in my little garage. The work continues! The body work is very dusty so as I'm sure you can see in the pics everything is covered in dust. I just set up the press last night and was able to use it today after I went ice fishing. We caught some bass through the ice! Anyways, I also bought an X-Y vise so I could do some light milling with it. I just so happened to have a little milling job to do and some solid carbide end mills that my boss gave to me because they were just laying around. I threw one in, fastened my vise, clamped the brake bracket in and away I went. It turned out really well for for a mill/press job.
I also received my heim joints and the new rear floating rotor. Needless to say I'm way pumped for the new stuff. The drill press gives me the ability to do some low tolerance work from home without having to schedule a day to go to the shop with Ben. Anyways, like I said in an earlier post, Ben and I should be getting some machine work done here in the next couple of weeks. The rear brake set-up is number one on my list and then the dampener bracket (as far as machine work goes). I'll keep you all updated

Uni filters

I too have run into problems running pod filters on some bikes because of the air restriction the rubber mount causes. I did however discover that most Uni filters worked better because the "stop" in the rubber inlet wasn't flat and didn't block the air passages. The Uni's I was using were tapered inside at about a 45 degree angle so it still allowed air to flow thru the carb properly.

[Chuck78]

Proper carb tuning

http://www.caferacer.net/forum/technical/19639-pod-filter-thread-geeto.html

Read that thread and at least shave some rubber out of the EMGO Pod base area so that it no longer restricts the VM carb's pilot jet and pilot air screw air intake passages. Those filters reduce performance from the stock airbox setup very drastically, sad but true. they restrict the funneled opening area, and block the pilot passages 35%!

Also, clean those carbs really thoroughly, raise the needle 1 spot from stock especially if the thicker 5F21 (u may have the skinny 5DL36 if you're lucky, shim 1/2 notch higher or try 1 notch higher). For the main I think you will find at higher altitude you will need a 115-120. Some people run up to 125 in a GS750, but I think they haven't done their plug chops with smaller jets to see how much more performance they can get out of a bike with the proper air/fuel ratios.

I started at 122.5 and now am at 110. may be able to squeeze a 107.5 in there, but on a cold day that may be too lean. the main jet size that gives you the perfect plug chop coloration at the BOTTOM of the insulator (where you can't see without cutting the plug apart) will give you way more fuel mileage AND way more power than too large of a main jet that someone with a bigger-is-better attitude recommended. a size or two too lean will also give you tremendous horsepower, but will will put you at the edge of detonation, bad bad thing.... that and even leaner mains will run so hot as to start vaporizing the aluminum on the tops of the pistons, and burning your valves/seats. Very important to do a $50-ish dyno run with an AFR meter and a chart of what the AFR's on an air cooled bike should be at the various throttle openings (much richer like 10:1 at idle and pilot circuit openings than at mid or WOT -12:1 or 13.5:1 if I remember, look it a chart), or do a few evenings worth of jet swaps and plug chop test rides on deserted roads before you ever really really run the bike. Oh, and I think you may have trouble getting the bike to idle consistently and smoothly if you have a #15 pilot jet still. I couldn't get mine rich enough with 2 turns out on the air screw and backing the fuel screw out past 2 turns, using a Gunson ColorTune tool to get the perfect mixture. 17.5 really helped.

PLEASE READ WHEN TUNING THE CARBS:

http://jetsrus.com/FAQs/FAQ_spark_plugs.htm

http://www.xs11.com/xs11-info/tech-tips/maintenance/carburators/68-tuning-carbs-by-reading-spark-plugsthrottle-chop.html

http://jetsrus.com/FAQs/FAQ_rejetting_101_how_to_rejet.htm

http://www.strappe.com/plugs.html

http://www.dragstuff.com/techarticle...ark-plugs.html

I would be afraid to take that thing to high speeds without the needle bearing conversion ($40-ish?) AND a good steering stabilizer. I would have gone to great lengths to get stock height forks, IMO. I'd be geared towards getting a proper geometry that does not require a steering stabilizer, and will drop a little weight (no stabilizer but a little more fork weight).

I AM afraid haha that's why I'm starting out at the race track. There's no safer place to put this thing through the paces. I NOW know that I should have tried to stay longer on the forks ha but the build goes on. If I do not like the handling and I don't die on the first ride another fork swap or fork mod is definitely not out of the question. I figured I did this much though and I may as well give her a go. As far as what I've calculated my geometry is pretty close to a modern sportbike. Most sportbikes come standard with a dampener nowadays. I'm sure the engineers are pushing to design something that will ride the fine line between a headshake maniac and a quick turning speed demon and throw the dampener on there for when the bike crosses that line. You'll be happy to know I did do a needle bearing swap when I put the GSXR fork in. The main reason I went with this fork is because the legs are 45mm and it is RSD. I wanted the RSD for looks (remain somewhat old school looking) and I wanted the biggest one I could find with the biggest axle. My current fork is awesome in that regard and it's also adjustable. We'll just have to see how it handles but I remain optimistic and think it will knock my socks off (in a good way) .

[Chuck78]

Oh wow, yeah I see what ya mean on that top photo! A modified ignition and stator cover wouldn't be too bad with some careful chopping and TIG welding. The cast aluminium is quite difficult to get a good weld on first pass, as I have experienced with my MillerMatic MIG Spool Gun. I'd try it as is, but wow, didn't realize your forks were sooooo short! You will definitely want to do the AllBalls needle bearing conversion for your steering head bearings if you have not already. ball bearings were phased out a year or so after your bike was built. Dropping my front just a mere 1/4" (went GS750 single disc 35mm forks to GS650 dual disc 35mm forks) gave me a real weird headshake at around 45mph that goes away after 55. I was told that needle bearings would get rid of that problem, haven't installed em yet though, but with yours being so drastically altered, jacking up the rear SUBSTANTIALLY and dropping the front SUBSTANTIALLY, I would be afraid to take that thing to high speeds without the needle bearing conversion ($40-ish?) AND a good steering stabilizer. I would have gone to great lengths to get stock height forks, IMO. I'd be geared towards getting a proper geometry that does not require a steering stabilizer, and will drop a little weight (no stabilizer weight but a little more fork weight).

My muffler can sits next to the swingarm just under the passenger footpeg, and I scrape that HARD and OFTEN in the hills of SouthEast Ohio's twisty heaven... I run it to the edge of the tread on the hardest leans, and have never scraped the engine cases even with soft shock springs and slightly stiffer chopped fork springs, which both compress easier than I'd prefer in turns until I can afford Sonic Springs and Hagon or YSS shocks. Not sure on your bike's geometry clearning in hard leans though. Just have two buddies lean the bike over at a mocked up cornering angle so that you are 1/4" or less from the edge of the tread, and lean down there and look at how much case clearance you have, leaving 1" for surface variation and suspension compression.

I am pretty certain the GS1000 case is narrower, and the engine weighs AT LEAST 10-12 lbs less (lighter crank and kickstarter delete mostly). It is taller though, much longer stroke on the GS1000. I would say do the 7-11 swap, but I think a Bandit GSF1200 or 1100?EFE motor would be the way to go, much more hp and more refined air&oil-cooled modern engine keeping in the same appearance as the original powerplant. The 1st gen GS1000's are awesome and reliable engines though. 2nd gen 4 valve heads are supposedly prone to cracking, but a wonderful advance in combustion chamber/piston dome/valve angle/intake runner technology (and very $ought after for drag racing). Honestly though, a Wiseco 844cc 10.25:1 GS750 (maybe eventually with cams and some mild porting), proper jetting and needles, K&N filters, and a good 4-1 exhaust is really PLENTY FAST, I can attest to that with a pods/pipe/GS850 piston'ed/rejetted/re-needled GS750 engine. It is amazing how fast I can pass people when I downshift into the high-hp powerband, and amazing how fast the bike does 0-60 (3.8 sec) and 0-90 (never timed it but maybe ~7.6 seconds?) or even 0-100. acceleration above 90 starts slowing down, and after 110-115, it isn't what I'd call "fast" acceleration, but it still goes.... All on a closed circuit, off-road course, of course!

If considering swapping to a narrower engine, measure the width of a Suzuki GSF1200 Bandit mill... The bottom end looks substantially smaller and narrower than our engines. A 530lb dry weight '01 Suzuki Bandit GSF1200 with a skilled rider and good environmental conditions and tune does a 10.98 1/4 mile and 0-60mph in 2.9 seconds in stock form (June '01 "Cycle World"), holy smokin' tires that's fast! It'll look similar to the original air cooled I-4 format and will be absolutely a blast and more streetable&useable powerband than other big modern engines that need to rev 8000-14000 rpm's to be competitive. It has a short stroke compared to the original GS1000 and I assume the GS1100 and other TSCC GSX engines, so it may be stuffed in the GS750 frame's height a little easier. Pods/pipe/jets on one will be an absolute screaming monster. Honestly though, that much power on tap is just insane, a stock GS1000 is more than fast enough for a street driven bike, and will give you more power than you ever should be using. as my sport bike friend says, "time to downgrade, 110+ rwhp is just too much, too easy to abuse on a street bike."

My buddy has a mildly modded H-D XL1200C, basically the fastest Harley-built HD (cus the big ones are monstrous cruisers that require the torque of an 1800cc twin to move them and their portly passengers). his 1200 has great pull at highway speeds, whereas an inline-4 you have to downshift into the 5000+rpm powerband to get great power, but when side by side, he gets me off the line for 10-15 feet, but then my bike just flies past him by leaps and bounds, and my buddy's 1132cc 10:1 KZ1000 just smokes the crap outta him and leaves me a slight bit behind, even with highway gears vs my one tooth up from stock rear sprocket! Anyway, DON'T LOSE THE JAPANESE I-4 engine format!!!! Sooooo superior for what we are doing with them

what are the roads like out in the mountains by you? I assume you live near mountains. I am picturing very long sweeping turns winding through the mountains with epic elevation changes a plenty. Here in the small foothills of the Appalachians beginning just south of the city I live in (Columbus, OH), you can find a large abundance of tight & twisty backroads winding through the hills. Lots of 15 to 35 mph turns to lean the bike over plenty while wearing an ear to ear grin! I seriously became addicted to finding the tightest twisty roads in Ohio and beyond into Kentucky and West Virginia where they get even more wild. All states surrounding West Virginia have at least some areas of AMAZING riding terrain in the hills and mountains. my friends go out to the bars and drop tons of money, while I am thinking, "hmmm less money to put in the gas tank and buy tires with!" Meanwhile I keep thinking of the best stretch of road I've ever ridden, US33 climbing and descending the mountain that the Ky/WVa border sits on the ridge of. Wow. Amazing. Best road in the eastern usa for sure!

We've got tons of mountain roads here. I live in a small valley east of SLC and the two canyons that bring you are are pretty fun. The only bad part is the traffic. There are a few good roads I've had my eye on that run up to a few of the ski resorts and the traffic is very very minimal in the summertime. I also live about an hour away from Miller Motorsports Park and plan to ride there for the first ride on an open track day. A full suit is required so I've been looking for a good one for a while now. I'll likely get an Alpinestars suit. They are good and under $1000. As far as my crank cases hitting the ground you have to remember my fork is 3" shorter and I went from 19" front and 18" rear wheels to 17" front to back. My ground clearance is considerably less even though I raised the rear. Look at some of the road racing pics of the old 750's They all have modified casings with the bottom wedged out. In most pics of them in a good lean they are less than an inch away from hitting and that's with a taller bike. We'll just have to see how it goes on track day in the spring.

[Chuck78]

what are the roads like out in the mountains by you? I assume you live near mountains. I am picturing very long sweeping turns winding through the mountains with epic elevation changes a plenty. Here in the small foothills of the Appalachians beginning just south of the city I live in (Columbus, OH), you can find a large abundance of tight & twisty backroads winding through the hills. Lots of 15 to 35 mph turns to lean the bike over plenty while wearing an ear to ear grin! I seriously became addicted to finding the tightest twisty roads in Ohio and beyond into Kentucky and West Virginia where they get even more wild. All states surrounding West Virginia have at least some areas of AMAZING riding terrain in the hills and mountains. my friends go out to the bars and drop tons of money, while I am thinking, "hmmm less money to put in the gas tank and buy tires with!" Meanwhile I keep thinking of the best stretch of road I've ever ridden, US33 climbing and descending the mountain that the Ky/WVa border sits on the ridge of. Wow. Amazing. Best road in the eastern usa for sure!

[Chuck78]

Cool, I think I've ruled out the Ikon's, as the Hagon 2810 is very similar for 80 bucks less (although not rebuildable), and have 6 adjustment positions for dampening instead of 4. so I think it will be betweenthe YSS like yours and the hagon 2810.

The EMGO pods are crap... If you end up having stock jets, do not ride that bike with stock jets (w/pods& free flowing exhaust) or else you may burn valves/seats or start melting your pistons! I am down to a 110 main jet now from 122.5. I think I even have a spare set of 125's. Good to start on the high side & do lots of plug chops. You need to nail WOT plug chop coloration within 2 sizes of a perfect mixture in my opinion. Don't just go with whatever size is in it or whatever the first size you swap in it. Gotta find an uphill stretch to do excessive speeds on (backroads or highway entrance ramp) & do several legit chops. Look up my thread info on reading plugs. Lots if useful links. I may've had 2 separate threads.

JetsRus.com has an oem equivalent very affordable jet for experimenting until you nail it down. I may be able to send you some of my spares if needed, although the smaller sizes I'd like to keep as I think I'll need 107.5-115 on the 920 build. More cc's = more air velocity thru 26mm carb venturi = more suction to siphon more fuel, so a 920cc with vm 26's will need smaller mains than a 750 or 844.

I don't think you will have to worry about scraping your wide engine on the ground during hard cornering, mine is never close and I lean the bike really really far with soft stock rear shocks compressing. I scraped my exhaust, the muffler in particular, very often when riding on the really twisted back roads and hills, and the engine never comes close to scraping. A 78-79 GS1000 or bandit 1200 engine or something similar would be an AWESOME drop-in if you decide to swap. 90-110 hp is easily possible from boring a 750, & is really all the engine (I.e. speed potential on-tap) that you could EVER need on tge strets or even remote backroads. My bike in just so-so tune with gs850 pistons was very fast, and the only big practical reasons for upgrading to 920 is because I found a rare old big bore piston set brand new, & I needed to replace my head gasket and cam chain tunnel o ring to fix an oil leak, so I figured, why not do it. A little better acceleration at highway speeds was a perk as well, from the extra torque gained from the big bore upgrade.

Thanks for the run down on the YSS socks. They will now be at the top of my list. Those rearsets of yours have been tempting me for over a year now as well... Hmmm.... Chop the passenger pegs or not??

Also I am really set on getting a decent pair of armored padded leathers and armored leatger riding jacket (Xelement Executioner!) and having a local shop stitch the pants attachment zipper to tge jacket for a stay-put-when-wrecking 1 piece black leather racing suit... Several close calls almost high siding or low siding turns really stood out in my mind after hitting a deer after powering out of a nice uphill corner 6 weeks ago on the GS. Kept it on the wheels thankfully, no frame/fork damage. Started a thread obmn mad max style armored jackets & leathers as well. LongLife Leather in Miami gwts my vote for pants, maybe on their custom jackets. My buddy also scraped his crash bars & spun out into a ditch following me in some remote twisties last June, twisted forks bent bats and only minor shredding on his jeans luckily (35mph tight twisties). Definitely, please, please gear up! I may add frame sliders to mine in lieu of crash bars, they sit higher and are much lighter.sorry, I didn't mean to dampen your spirits, but just trying to look out for my friends! We all are likely to put our bikes down at some point or another during our lives. Luckily a twisted lower triple, & handlebar & gauge damage was all that came of the kz1000 ditch-slide, and gauges/headlight/turn signals/spark plug& cap & stator cover oil leak are all that came of my deer collision. Lucky for both my buddy & I

Wow T8, your bike is looking GREAT! Wish I had the time and money to just geek out on my bike. My mods are so sporadic, but then again, I have had a bike to ride nonstop for a few years now.

Are you running the engine stock/rejetted for now? I remember you posting a while back about engine mods. I'm picking up almost 2 spare engines (one seized - parked since '86, good bottom though), so that I can keep a runner in the bike and build the 920cc 10:1 kickstart GS750 based beast! Hope to get it to that stage by summer. If you tear the engine apart for anything, DEFINITELY swap in some Wiseco 844cc pistons, it is WELL WORTH IT for the extra cc's and compression ratio. Are those EMGO pods??? I'm really digging the K&N RC-2222 filters. The EMGO's are a bit restrictive to the throat openings due to the thick rubber flange, partially blocks the little air passages to the sides.

What model YSS shocks are those, Z-302, Z-362, Z-366?? I was considering Ikon's for $380, Hagon's for $299, and thinking about others (YSS, Works). What made you end up with those versus the ones I mentioned? I think the Hagon and Ikon are oil dampened, and the YSS all look like gas shocks with 60 clicks of dampening adjustment. The YSS also look to use more aluminium and look pretty trick, but are definitely more money. I'm holding out to make the shocks the last big expense to the bike, since they are so easy to swap and I should really be saving up as much money as possible to get the best shocks I can afford for the bike that I will probably never sell.

Keep up the awesome work. The way it looks, both of us will be burning through corners on our 1st gen GS750's next season!

You're a stud Chuck. I've enjoyed getting to know you through our bikes. As far as I know the jets are stock but the guy who sold me the bike cut the pipes and cleaned the carbs so he may have re jetted it to make it run right with those pipes. He also installed the pods which are likely EMGO but for now they'll work. I want K&N in the future but for now I need to get the big stuff done. My focus has been all chassis and I'm excited to get it running and put a little more thought into the engine. I'll be following your engine build ups closely because I'll prob end up doing something similar. If my bike can't lean in corners far enough due to that massively wide crankcase and my lower bike I may just end up putting a newer motor in it because they are narrower. I've even thought about a HD 1200. We'll see where it goes.

I chose the YSS Z-362 TRL Twins because in my opinion they are the best balance of features/quality and price. You can't get a better shock at a better price. These shocks are cheap compared to others that offer the same quality and features. Fully adjustable ride height, compression damping, rebound damping, and preload. I wanted fully adjustable no matter what because this bike's geometry is so modified I can only make educated guesses on how it will handle and need to be able to make adjustments. Again, for a fully adjustable shock I highly recommend YSS. Better to spend a little more and only spend once than spend it on something else and always have that erk in the back of your mind wishing you'd have just spent the dough on the good stuff. Their guy who builds the shocks is hilarious. He is always super rude and ornery and acts like everything is a pain in the butt. Just be super rude right back to him haha. It seems that's just how he communicates. Bottom line is tell him what you want and he will make it, he's a champ. I was able to get a pretty hefty discount from him in the end so even though when we spoke there wasn't a hint of what you might call "customer service" he must have liked me and wanted my business again. You just need to snap back at him when he gets feisty. His name is Klaus if I remember right.

[Chuck78]

Wow T8, your bike is looking GREAT! Wish I had the time and money to just geek out on my bike. My mods are so sporadic, but then again, I have had a bike to ride nonstop for a few years now.

Are you running the engine stock/rejetted for now? I remember you posting a while back about engine mods. I'm picking up almost 2 spare engines (one seized - parked since '86, good bottom though), so that I can keep a runner in the bike and build the 920cc 10:1 kickstart GS750 based beast! Hope to get it to that stage by summer. If you tear the engine apart for anything, DEFINITELY swap in some Wiseco 844cc pistons, it is WELL WORTH IT for the extra cc's and compression ratio. Are those EMGO pods??? I'm really digging the K&N RC-2222 filters. The EMGO's are a bit restrictive to the throat openings due to the thick rubber flange, partially blocks the little air passages to the sides.

What model YSS shocks are those, Z-302, Z-362, Z-366?? I was considering Ikon's for $380, Hagon's for $299, and thinking about others (YSS, Works). What made you end up with those versus the ones I mentioned? I think the Hagon and Ikon are oil dampened, and the YSS all look like gas shocks with 60 clicks of dampening adjustment. The YSS also look to use more aluminium and look pretty trick, but are definitely more money. I'm holding out to make the shocks the last big expense to the bike, since they are so easy to swap and I should really be saving up as much money as possible to get the best shocks I can afford for the bike that I will probably never sell.

Keep up the awesome work. The way it looks, both of us will be burning through corners on our 1st gen GS750's next season!

Really seeing your craftsmanship and taste in this build.
Drooling over those YSS shocks and those wire wheels.....

If I ever quit being so cheap I will be working on a tasteful build like this.

Will be watching.

Oh, forgot about the kick :-P cool, I might look into this as opposed to the universal kits they sell online. Might be a cheaper option too :-)

It's definitely cheaper. Trust me. I checked. Online. Ha jk but yeah it really is the cheaper route and in my opinion it's the better option because you don't have to design and machine your own brackets. Plus I think the torzochi kits look good but they're just so bulky. With a stock gsxr rearset or any other sportbike for that matter they are a slimmer unit and you have the option to install aftermarket pegs, levers, and footpedals.