'80 GS1100E rebuild

[cavehamster]

Cave,
This is a general discussion about front sprockets and not meant to suggest your doing anything wrong.

Next time you have your front sprocket off measure the depth of the spline engagement. I measured a stock 14 tooth 630 Sunstar sprocket and the amount of engagemet was about .65". I measured a 17 tooth PBI 3/8" offset sprocket and it has about .35" to .37" engagement depth. I measured a Kosman 5/8" offset and it has about .55" engagement.

I realize we can compensate by adding and subtracting washers so the nut is tight but I'm starting to worry that less than .5 puts too much stress on the output shaft splines. It would seem the more the better so long as actual sprocket gear is where you want it. There is about 3/4" to 1" inch of exposed output shaft spline to engage with.

I welcome discussion, no worries.

I'm sure you are right about the limited amount of engagement not being a good thing. However, I felt that as long as my sprocket engagement width was the same or better than a 520 sprocket, things should be mostly alright.

My (perhaps poor) reasoning behind this is due to a) I have put about 50 launches at the drag strip on a 520 front sprocket (I didn't have the right tooth count 530 handy at the time), and b) my V-Strom, a 95ish hp large motorcycle, uses a 520 chain and etc and seems to do just fine with it, so, these things combined, I made the assumption that I could get away with it on my GS, at least until I crank up the HP past 110 or so.

So far, there has been no noticeable change to the splines, ie, they have not been twisted at the point of engagement, and sprockets slide up and down them without catching. However, I'm not a huge fan of doing it this way for long

At this point, I will probably go with a standard offset sprocket in the next couple of months once I get the front end swapped out and have time to concentrate on the engine.

I've spent the last week or so concentrating on getting a better handle on datalogging my track performance so I can identify what needs to be fixed up. I already have an Innovate wideband installed on the bike, but the LC-1 does not get RPM data, and I have found the graph to almost be useless without that. Being a tinkering sort of fellow, I have reverse engineered their serial protocol using the little bit of documentation they provide plus a lot of serial port captures and have emulated their SSI-4 box on a microcontroller. I've also got an embedded computer in a small enclosure that will get strapped to the seat and collect data that I can view later. I'll post pictures and further information about this stuff as I get it cleaned up and off the protoboard I also dug up a accelerometer chip in my parts bin that I have working, which might give me some interesting data.

[cavehamster]

So, it turns out I was wrong, my dished sprocket does not have the same bite as a 520 on the shaft, it's the same as a 525, as I forgot my 'template' sprocket was a 525, hah.

Headed off to the strip tonight. I built a small board that hooks to the low voltage side of the coil and uses a low pass filter and optocouple to give me a tach input, built a clone of Innovate's SSI-4 module to get RPM data, and wired it in with the LC-1 for AFR data. I hooked up an old single board computer I had on hand into a small box to interface with this stuff (with an isolated battery to keep it going), and I'm going to strap it to the seat and datalog my launches.

Put one step richer jets in the carbs, as the prelim AFR data I had looked a little leaner than I wanted, but I should get the real story tonight. I'll post pictures/schematics later as I get a chance.

EFI is still coming, though right now I am aiming for it to be a late season/winter project. I'm currently concentrating on getting stuff together to get the front end swapped to go with the updated rear suspension, and getting the seat redone before the next person asks, 'hey, you gonna fix that?' It's become so bad that a friend of mine made a huge stink about it and 'fixed' it trackside with a roll of black duct tape one day, haha.

[cavehamster]

Well, this season of drag racing is over, so I'll have some time to make some further progress on the bike update. I ended up the season running an 11.93 at the local track, and a 11.41 at a track further away that I frequent. Not too bad for 4500 foot altitude on a pretty much stock machine.

Here's a summary of videos from last Sunday, in HD no less.

http://www.youtube.com/watch?v=t1dyztDSGfs&hd=1

I've got mostly everything together for the fuel injection, I just need to get a fuel pump going. I think I am gonna go with a surge tank so I can use a much cheaper fuel pump.

[midnightcafe]

very interesting camera POV, it really demonstrates the ****ty track quality you were running on!