Mike R's GS550/650 bare bones street racer

[boontonmike]

No photos on this update. Good news! I had my knee arthroscopic surgery today and everything went smooth. I can take the bandages off on sunday and i should be back to 100% in 6 weeks. I'm allowed to start bearing weight on it in a day or two and slowly work it back to normal use. I just started a new job this year so this is really good news because I have no sick or vacation time so any time out is lost money.

On another good note, my exhaust system came in today and looks pretty sweet. I ordered a used motion pro 1/4 turn throttle with cable off ebay for 30 shipped thats on the way. Also ordered another rear caliper for $25 shipped to either replace, or mix and match with the one on my bike. The one i have one piston was siezed into.

On my "to order while I sit with a bum knee weekend" list is a stator, reg/rectifier, and battery to complete my entire updated electrical system to go with the dyna 2000 going on the bike. I will also most likely pick up an AEM Wideband 02 to make carb tuning alot easier( also with wideband and dyna2000 when I decide to turbo her down the road I'll be set up for it).

I have some cool tings planned for my battery and will share all of that information when I get to that point. After all this stuff comes in and I'm able to wrench on the bike again I'll be just about ready to fire her up after a rewire.

Thats it for this update. Hoping to be back wrenching and updating by mid next week with the help of my friends doing the any lifting.

(Sedatives and Percosets probably made by grammer all messed up)

 

[brslk]

Good to read the Knee surgery went as expected. Been there... got the shirt.
Take it easy the first few days but be aggressive with the physio!

I'm enjoying your build and getting curious about the battery.

Bruce.

 

[boontonmike]

Thanks Bruce! I'm sittin on my couch with my leg up on a bunch of pillows and i heard big brown roll up. Hobbled to get this:

quarter turn throttle. It's so nice, I wish I had one on every bike I've owned since day one. I can tell this won't be the last one I buy. Also, the cable appears like the length is going to work out great. I'm going to try and have my friend Bill help (aka do most while I watch) install the throttle and exhaust. I jsut can't wait to get the stuff on there.

 

[boontonmike]

So my friend Bill picked me up and we put on the BUB exhaust from Jim. Fits like a glove and works with all the modifications on my bike. Oil cooler and lines, rearsets, rear brake arm all have great clearance. Pipe looks great. I may or may not cut it down a bit. I will probably get it running and see how it sounds before I go messing with it. Looks pretty good too.

You can also see that I removed the black spring shrouds off my rear shocks. I used the string and rod twist method to compress the springs. it worked great.

 

[Charlie G]

It's looking pretty nice.

cg

 

[brslk]

That throttle looks pretty cool and simple. Might I ask where you bought it from?
The rest of the bike is looking pretty good also.

And stop hobbling around. Give the knee at least a day or two.
(not that I did)

Bruce.

 

[Suzuki_Don]

I Finally got my new front sprockets in. Ended up going with a 13/48 setup to start with. I figured I will start out most radical and tone it down from there if I don't like it. I love the way my DRZ revs up so fast so I am trying to mimic that powerband.

Mike, you will find that gearing way too low.

I have the same setup as you, minus 34mm carbs and head porting. And I have found that with the 50 tooth rear sprocket and a 16 tooth front sprocket I never had any use for first gear. It was like riding a 5 speed bike.

My ratio with the 16/50 sprockets was 3.125 and you are going with a 3.7 ratio with the 13/48 combination.

With a minimum of 80hp as opposed to 49hp originally you need to gear up, not down. Standard gearing on the 550 was 3.33 and you are even lower than that.

My gearing was OK with brilliant acceleration on the old tires that I had on the bike, but I couldn't believe the difference when the new rear tire was fitted. It must have been a much lower profile than the tire that came off the rim. It lowered the gearing soooo much that I just didn't use 1st any more. 2nd gear became like first and acceleration away from lights, etc. was still very brisk.

I am in the process presently of fitting a 45 tooth rear sprocket to go with my 16 tooth front sprocket which will give me a ratio of 2.82 - the GS750 has a 15/41 sprocket setup (2.73 ratio) and our bikes put out more hp than the 750. The only hiccup is that one of the sprocket bolts stripped it's threaded when I was tightening things up after fitting the new sprocket. It's the weekend here so will have to wait till Monday to order new bolts and nuts (rated at 9).

You will see what I mean when you get the bike on the road and this does not take into account the fact that your rear wheel/tire might be a smaller combination than the original setup.

 

[boontonmike]

I'm actually at 14/48 now which is pretty close to stock at 3.4 to 1 . I went up in the front to accomodate the chain clearing thr swing arm. I am aware of the more power/gearing issues and I made the decision to start out most drastic and dial it back. I have 2 other fronts and 2 other rear sprockets to dial in gearing.
I could go to a 15/45 or 3 to 1 if needed prividing I can clear my chain. Thanks for the heads up though as I wasn't sure what to run and did alot of searches coming up with nothing really.

You're engine build was exremely helpful in my build process. Thanks alot

 

[boontonmike]

That throttle looks pretty cool and simple. Might I ask where you bought it from?
The rest of the bike is looking pretty good also.

And stop hobbling around. Give the knee at least a day or two.
(not that I did)

Bruce.

Throttle I got off ebay. It's a Motion Pro 1/4 turn made for dirstbikes. They go for 65-80 new for the full setup. Used I got it for 30 shipped. Its very nice and simple and will look even ebetter when I pull off the rubber protector piece.

The knee is killin me today so I've been restin and moving as little as possible. It sucks.

 

[Guest]

Mike that exhaust is great, it hugs the lines of the frame very well and tucks up nicely. Personally I don't see a need to shorten it and think it looks great as is, so good call to try it first and see.

Hope that knee heals up soon!

 

[boontonmike]

Mike that exhaust is great, it hugs the lines of the frame very well and tucks up nicely. Personally I don't see a need to shorten it and think it looks great as is, so good call to try it first and see.

Hope that knee heals up soon!

Thanks alot. I am trying to figure out if I'm going to run the baffle with or without packing. I haven't heard or read much to convince me to go one way or the other. Ultimately it's going to come down to running the bike and playing around.

 

[Guest]

Thanks alot. I am trying to figure out if I'm going to run the baffle with or without packing. I haven't heard or read much to convince me to go one way or the other. Ultimately it's going to come down to running the bike and playing around.

Cool, I guess the big difference (aside from noise) will be the effect on jetting... one of those things that are definitely suck-and-see right?

 

[boontonmike]

Cool, I guess the big difference (aside from noise) will be the effect on jetting... one of those things that are definitely suck-and-see right?

Well my goal is max performance. So I really don't want to be doing all that intake carb work and then choke the exaust back down with an overkill baffle. I also don't want it to be ungodly loud to where I'll be pulled over everytime its on the road. That's why I'm leaning towards baffle with no packing from a theoretical standpoint. I won't be able to tell until it's running.

 

[Guest]

Yep that makes a lot of sense to me... noise for noise sake is just noise... no point unless it does something right?

 

[boontonmike]

Took the wrap off my knee. They weren't lieing about it being minimal scarring. Its\'s about twice the size of my other knee at the moment and the small incisions don't really do the pain justice. On the plus, I tend to heal pretty fast. This next week of work is going to be a bit brutal but it should become more tolerable by next weekend. It's so tender right now that if I walk on crutches and my knee moves at all it's pretty painful.

 

[Suzuki_Don]

You're engine build was exremely helpful in my build process. Thanks alot

Mike, No probs at all. Glad someone could get some use out of all the stuff i put up.

BTW which camshafts did you use in your motor; 550 or 650.

On the gearing issue; I have not got my bike back on the road yet for a test because of the stripped sprocket bolt, but if I find it is geared a bit high then i can go from the 16T front sprocket to the 15T that came off it originally. It's still in good condition. And that will lower the gearing a bit, but I think 16/45 should be about right. Coming down 1T on the front is about equivalent of 3T on the rear.

 

[boontonmike]

I went with the 550 cams after reading about the differences it seemed like the high duration would better suit what I'm after.

 

[Suzuki_Don]

I went with the 550 cams after reading about the differences it seemed like the high duration would better suit what I'm after.

It will be interesting when you get the bike on the road to see what you have to say about the power band. When my bike was a 550 there were three different surge points over the rev range. One at about 3000rpm, a second at about5500rpm and it really took off at 7000rpm. Whereas the 650 cams seem to have an even spread of power across the range with a surge around 7000rpm - but vivid acceleration all the same.

Did you degree the cams, or were you able to time the cams without doing that? How many links did you use between ↑2 and ↑3 on the cam sprockets.

 

[boontonmike]

It will be interesting when you get the bike on the road to see what you have to say about the power band. When my bike was a 550 there were three different surge points over the rev range. One at about 3000rpm, a second at about5500rpm and it really took off at 7000rpm. Whereas the 650 cams seem to have an even spread of power across the range with a surge around 7000rpm - but vivid acceleration all the same.

Did you degree the cams, or were you able to time the cams without doing that? How many links did you use between ↑2 and ↑3 on the cam sprockets.

I followed the 550 service manual to time the cams to stock with 20 pins from arrow to arrow. I didn't have to degree the cams because everything from the cam setup was off the original 550. Everything lined up perectly. I am also interested in the final result and will keep this thread updated through the whole tuning process until it's dialed along with some videos when complete.

 

[Suzuki_Don]

I followed the 550 service manual to time the cams to stock with 20 pins from arrow to arrow. I didn't have to degree the cams because everything from the cam setup was off the original 550. Everything lined up perectly. I am also interested in the final result and will keep this thread updated through the whole tuning process until it's dialed along with some videos when complete.

As I said I used the 650 cams, slotted the sprockets and degreed them in. I ended up with 19 pins between arrows to get everything correct. Better wind the motor over a few times by hand just to make sure there are no clunking sounds when you hit that starter button for the first time.