Building an ST1300 from the ground up.

Long story short, I haven't been able to find a bike in my price range that meets the requirements of what I'm looking for. In a nutshell, they are- fuel injected, not an inline, naked, more comfortable and less intense than my canyon bike, and good for an occasional two up. I've been thinking about building an ST1300 for about three years as I was inspired when I saw Butch Demerle's bike online and after speaking with him through email.

And so, I have a complete engine kit, headers, rear shock, swing arm, final drive, frame, rear axle and all the engine mount bolts on their way to me. I have an '05 CBR600RR front end laying around that I'm hoping will bolt up (stem bearing dimensions are the same), and just need a rear wheel to make it a roller. The parts will all be here by the end of the month, and I should have it roughed out in May. After that, it'll just be a matter of buying all the little stuff, overcoming any hurdles I run into, and updating this thread.

The plans are to go with superbike bars with bar end mirrors and a Vrod headlight, and since it's a two up machine, am thinking either a VFR800 or CBR600F4 tail because those bikes have nice looking tails and use banana seats. If I go with a VFR800 tail, I'd like to use the '02+ for the undertail exhaust, but am not sure if I'll be able to tastefully route the exhaust from the ST headers up to the VFR tail. I won't know that 'till I can see the bike sans tail in person. The color scheme I have in mind will be gloss black wheels with polished lips, black calipers, radiator, frame, swing arm, fork tubes, triples, handlebars, rear sets and engine, chrome the headers and various bits to tastefully accent, and am undecided what to do for the tank, tail, front fender, headlight bucket and valve covers. I may pay homage to The Big One and do a white/ red scheme that accents the lines and curves of the tank.

But, talk is cheap. I'll post some pictures as the parts start showing up and I have a chance to introduce them to each other.

Can't wait to see the progress. Sounds interesting.

Good luck on getting this project off the ground. Look forward to seeing it through the build.

Please post your progress. I've been thinking of doing such a project. Maybe not as big an engine, maybe more of a Caf?/Frankenstein build, but after the scooter rebuild I may get into something like that.

Georges

Wow, super cool idea!!!!

Engine mounts and hardware came today. Everything else should be here on Thursday, and the engine will be here next Monday. I'll post a picture when I get this stuff put together.

I figure, along with pictures of what I'm actually doing, I can maybe kind of make this a blog/ journal and include my thoughts as well. I also openly welcome discussion if anyone has ideas, questions or anything else they'd like to add.

The subframe and tail.
I spent some time last night looking at pictures of a 6th gen VFR800, a couple pictures I found of ST1300's without fairings, pictures of parts on eBay, Bike Bandit's microfische, and the service manual I have for the ST. I do strongly suspect that the VFR sub frame will work on the bike. On the ST frame, there's two tabs where the top of the subframe bolts to. The top stringer of the VFR subframe is actually a rectangular tube with a bolt hole through it at the end. If bolted to the ST frame between those two tabs I mentioned, I believe it would put the VFR seat in just about the same position as the ST subframe and seat. The bottom stringers of the VFR subframe would have to be modded and I would probably blend them down in to where the ST rearsets bolt to the frame. If there's an issue with the shock, then I'd probably just weld some bosses to the frame and bolt the bottom stringers to those. We'll see. Oh, and as an added bonus with the VFR tail: If I really want to do some long distance touring, I can get the hard bags for the VFR, no problem.

The exhaust.
Since I won't be using the under seat ST tank (more on that in a minute), and will be using the VFR subframe and tray to house electronics and battery, that opens up a whole lot of room under the seat. I believe that if I cut the ST headers just in front of the collectors and build new collectors out of 45? bends to bring the exhaust together in the area where the center stand would be, and then turn it up through the hole in the swing arm, I should be able to route it up to the two VFR cans under the tail. Since I'll essentially be building a 4-2-1-2 exhaust, I'll have to look into primary and secondary lengths and how they'll affect the power delivery. That's a bit down the road and a subject I'll come back to.

The tank.
I really like the lines of the ST tank, and I like how it helps create a nice arc with the frame that draws your attention to the engine. I also like how it, you know, bolts on. No fuss, no mess, done. I don't like the second under seat tank. Well, I do, because the thought of 7.7 gallons is pretty sweet. But, I don't see that second tank working with the VFR tail and exhaust that I want to do. And so, practicality succumbs to fashion. Since the top tank doesn't have a fuel pump, I had thought of buying a junk CBR tank and fuel pump and cutting the part of the CBR tank out where the fuel pump bolts on and then welding that to the bottom of the ST tank. I may still do this depending on how much room I have under that part of the tank, but at this point, I'm leaning towards just using the joint hose outlet and plumb an inline external pump to feed the fuel rails.

The early GSX1300R used an external fuel pump, filter that might work for you. Might fit behind the stock air box if the purge valve was moved or eliminated.

I did not know that. I just did some reading and looking at pictures and noticed that they have the fuel pressure regulator and fuel return integrated in the pump body. That's a pretty cool, tidy setup. Problem is, the ST needs to see 50 PSI at idle, and the Hayabusa FPR is set for 42 PSI. It wouldn't be hard to compensate for this by using a Bazzaz with AutoTune, but that's an additional expense. Then again... with the exhaust I may end up building for the VFR tail, having a tuner may not be a bad thing.

Cheapest Hayabusa pump I'm seeing is $280 + $300 for the Bazzaz (I already have the AutoTune), or... a Walbro 155 LPH pump is about $100.

I need a big favor from anyone reading this and able to fulfill my request!

The next time you have a minute, can you please measure the distance from the center of your front axle to the top of your bottom triple tree as well as to the top of the top triple tree? And if able, can you take these measurements both with and without the weight of the bike on the suspension? If you can only take one or two of these measurements, I would still greatly appreciate it! Thank you!

And the frame.



It'd still be super sweet if someone could take at least one of those measurements- preferably the one from the axle to the top of the top tree with the weight off the front wheel.

Thoughts on the front end...

The CBR600RR front end I have won't work; the stem is too short and I'm pretty sure the fork legs are too short as well. Never mind it being woefully undersprung.

After doing a bit of research, I'm looking at two options for the front end:
1) ST1300 stem pressed into a K0-K5 GSXR750 lower tree with an RC51 forks and top tree.
2) ST1300 stem pressed into a Hayabusa lower tree with Hayabusa forks and an RC51 top tree.

The ST has a lower stem diameter of 30mm, which is the same as the GSXR and the Hayabusa, so at this point, I'm assuming the part of their stems that are pressed into their triples is the same diameter as the ST stem. Likewise, the RC51 and the ST share the same 26mm top diameter, so I'm assuming the RC51 top tree will work on an ST stem.

The RC51 forks are about an inch longer than the Hayabusa forks, and it is generally said that the RC51 still to this day has one of the best stock front brake setups on any sport bike. However, the Hayabusa front end is much more common and would probably be a good bit cheaper.

I have lowers/ stems/ bearings for an ST, Hayabusa and GSXR on the way to me and depending on what I find when I start measuring, I'll make a decision then as to the direction I take.

Very interesting Peter.....

Don't know how sizes compare but there is a moderatly prices stem and lower tree made for the Wing that is very ridgid. It could just work. I think the top nut is not changed for many road bikes so the size may be workable.
PM me if you want info.

Mandrake said:

I need a big favor from anyone reading this and able to fulfill my request!

The next time you have a minute, can you please measure the distance from the center of your front axle to the top of your bottom triple tree as well as to the top of the top triple tree? And if able, can you take these measurements both with and without the weight of the bike on the suspension? If you can only take one or two of these measurements, I would still greatly appreciate it! Thank you!

Click to expand...

Hopefull someone else will confirm quick measurements it's raining LOL.
20 1/8"
28 5/16"
on the side stand.

Carl, thank you very much! That certainly helps quite a bit!

The GL stem, if long enough to work with the ST frame, would only work with the RC51 lower (again, assuming based on lower bearing dimensions). The reason I'm using the ST stem is because I know it's compatible with the frame. The reason for the GSXR lower is that if I decide to go with RC51 forks, the GSXR lower will fit the RC51 forks (54mm at lower) and will (I assume) work with the ST stem. The Hayabusa forks are 55mm at the lower, and since the Hayabusa has the same lower bearing dimension as the ST, I'm assuming the ST stem can be pressed in to the Hayabusa lower. Both the Hayabusa and the RC51 forks are 50mm at the top tree, but the top of the Hayabusa stem is 30mm whereas the ST and RC51 stems are both 26mm, so the RC51 top tree will work with the ST stem and either forks. Plus, it's flat so I can put risers on for the bars I want to use.

Oh, and the swing arm came today...



But they forgot to include the pivot bearings and hardware that were shown in the auction, so I don't have any shots of it bolted to the frame. Plus, there's a possibility that the engine may be here tomorrow instead of Monday. Happy days, happy days.

Well, thanks to Bob (SupraSabre) with the unloaded front end measurement that I was looking for (29.75"), I have been able to determine what front end I'll use. As much as I'd love to run an RC51 front end as it's only 5mm shorter than the ST front end, plus has awesome brakes and keeps things Honda, I've decided to go with an '06 GSXR600 front end due to cost (about $600 cheaper). The GSXR forks are only 17mm shorter than the ST forks, and between that and the 17" front wheel, I'll only lose 1.17" of height. I think I can live with this and if not, a steering damper should take care of things. If that doesn't work, I'll just pony up for some drop trees.

Interestingly, according to RaceTech's website, the ideal spring rate for my weight is .901 kg/mm, which is exactly what the stock springs in the GSXR are.

Barring any unforseen circumstances, I should have a roller in about three weeks. After that, it's tank, fuel pump, wiring, lights, tail and exhaust, in that order.

Engine showed up today.

Motorvation!

opcorn

Will be fun to watch your progress Mandrake.

Thanks, guys!

While I have the engine out, is there anything I should look at specific to these bikes beyond the usual stuff like valve clearance, plugs, air filter? The fellow I got the engine from said it has 45K on it, so I was just going to perform the 24K mile service on it. I did some reading about the turbo city thermostat, but when I tried to find where to buy it, I came up empty handed.

MD-
What year is the engine? What does the oil / coolant staining look like at the waterpump weep hole? (There are two holes, one round, one square. I mean the round one that is slightly above and rearward of the square one.) Here's mine:


Turbo City sold all their 'TurboTom' thermostats to NewEnough.com a few years ago, and NewEnough.com has sold them out. Issues in the early-year OEM thermostats (2003 to about 2005 or 2006) have gone away--no reason not to use a Honda thermostat.

I'd replace all the coolant hoses and hose clamps (use Breeze clamps) if that were mine.

Oh, I'd also replace the vacuum lines and clean the 5-way tee under the throttle bodies.