'80 GS750 Brat build

dilbone said:
I know it's no more than 20, if I remember correctly it's closer to 15

Appreciate it. Keep an eye out for my thread when i start gettin stuff done.
Im doing a 77 gs750

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Pilgrim9283 said:
Appreciate it. Keep an eye out for my thread when i start gettin stuff done.
Im doing a 77 gs750

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Cool, I will for sure.

I don't have much to show right now. We were a week on vacation and now I'm working on the side covers and getting some painting prep done.
 
I've been putting off paint for a few days because I'm just dreading it. Before I can paint though I needed to get the tail light holes marked and drilled in the fender. It was a pain to get it lined up right and I'm still not convinced that it is, but the holes have enough play in them that I can get it where I need it when it's done and I throw this thing together finally.

I also took the tank and side covers and knocked down the gloss with some 220 grit along with a razor blade to scrap off the pin striping.




After finishing that I went ahead and hit everything with some self etching primer then mixed up some 2k filler primer I had left from my last project and got 3 nice coats on everything. Tomorrow I'll have to get the bondo out and fill the sides of the tank where the badges attach then hit some of the small imperfections and chips with some glaze putty. Hopefully I'll be painting early next week. I decided I'm going black with the burnt copper accent stripe. The black I have is single stage semi gloss and the burnt copper is lacquer. I think I'm going without clear on this...I don't want to cut, buff and polish. I hope it looks ok.
 
Man you got some skills!!


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I did quite a bit of bondo work getting the tank badge mounts concealed and all sorts of chips and dings in the original paint filled.

Today I was finally ready to start slinging some single stage black semi-gloss on the tins and the frame mods. I've been thinking about how to paint this for a while now and I just don't have the desire to do a cut and polish and with the semi-gloss single stage I thought I'd be in a good place for that. However, after seeing the amount of orange peel I see so far I'm thinking I'm gonna have to cut and polish this single stage and go for a more glossy finish...not happy.

We'll see how it looks tomorrow in the light and go from there. I have a burnt orange to add to the design, but if a wet sanding session is in order that will definitely put the brakes on this paint job.

Here's a few pics. The tank and fender in the pic hadn't flashed yet and were still pretty glossy wet...they've definitely gone more semi-gloss as they flashed and gassed out.



 
A closer look at a side cover was a long sag off of the top edge...ugh

I ended up having to use 1500 then 2000 grit to wet sand it out then did a quick rub with Meguiar's swirl remover 2.0
It glossed up so much it sticks out like a sore thumb and makes the orange peel, which is worse on the side panels than anything else, look just terrible. My choices are to use the semi-gloss engine enamel with ceramic on this shiny area after I knock down the gloss, or cut and polish the whole thing like I didn't want to in the first place. Oh well...it looks like there's a ton of wetsanding in my future. For being a quick and easy paint job this is really turning into a drag. I know it will look good in the end, but I'm just not looking forward to all this work.

Nice sag


Wet sanded


Rubbed out
 
I decided to wet sand the side cover all the way down and polish it knowing I'd have to do the same to the same to all the tins. I was just about finished and I had a couple spots of just barely sand throughs on a curved edge...at this point I threw in the towel and got out the duplicolor semi-gloss engine paint and hit that side cover with 2 quick coats. The more I look at everything, it's gonna have to be good enough the way it is. I brought it all out in the sun to expedite the process so I could start masking off for the burnt orange stripes.

Rear fender has a long scratch which I'm not sure how it happened most of which will be under the tail light.


Side cover on the right is the one that was wet sanded and hit with the duplicolor semi-gloss engine paint...looks pretty close to the single stage black semi-gloss to me.


The longer it dries the better the tank looks, I think it's gonna be just fine. It looks ok up close, but looks really good from 10ft away haha
 
Once I decided to keep the black as is I started to get masked for the stripes I was thinking about.

I used some 1" masking pieces to space my 2 quarter inch tape lines...what a pain


That's a lot of masking...then fender was by far the worst with no straight lines...but all of it was a pain...not as big of a pain as wet sanding and buffing though


I just did a couple of really dry coats to keep it from wanting to bleed under the tape followed by one decent wet coat. I didn't want too big of a buildup at the tape edges. Looks like I have decent coverage.


It's growing on me...I'm still not 100% sold on it but it'll work I think.


I couldn't resist a quick mock up for some pics





Now on to the wiring of the signals and brake/tail light, then hopefully a fire up soon to follow...and it needs cleaned up terribly.
 
Looks great. Like how you tied in everything !!


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Pilgrim9283 said:
Looks great. Like how you tied in everything !!


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Thanks, Pilgrim9283

I'm not sure what happened to the links for the pics...the last three were all the same so I fixed it.

Also, instead of working on the wiring tonight I decided to dump gas in it with a funnel and see if it would start. It fired up pretty easily with some choke and I let it run for a little while and it seemed to settle a bit and run a little smoother. I shut it down and started cleaning up what I could with #0000 steel wool when I noticed that one cylinder was cold and obviously hadn't been running. I checked the plug cap and it was in terrible shape all cracked and dried out. None of the others looked quite that bad. I fired it up again and went to just touch the cap and got a nice poke through the cap. I'll pick up plugs and wires for this and hopefully by the weekend it will be on the road and ready to roll.
 
JustinLonghorn said:
I think I see some Barred Rock, hens. Nice.
Yep...we still have a few left that the fox and coyotes haven't gotten yet along with one partridge rock. Funny little critters
 
So yesterday I picked up a new plug cap to replace the number three cap that gave me a jolt the other day. I installed it and gave it some more gas and still no heat in the 3rd exhaust pipe...

As I let it run for a minute or so I noticed what sounded like a vacuum leak...I felt around at the carb on #3 the rubber boot clamp was completely loose and air was rushing in like nobody's business.

I tightened up the clamps and check the rest then fired it up and voila...I had fire in #3...

Its been 3 days since I sprayed the single stage black, so I think I'm going to go ahead and start assembly so I can wire this thing up. The front signals I can obviously do now, but the rear signals and tail the fender needs to be mounted to know how long the wires need to be.

First ride will be SOON!!!
 
Today I got to wiring it and finishing cleaning it up. I got all the lights and rear fender done and installed then went and picked up a UNI filter to put on in place of the old filter air box since my seat tabs wouldn't allow that to fit into place.

Upon closer inspection the carbs had some issues. Some of the intake side boots weren't even tight and the carbs weren't fully seated in them. Then I noticed the back end where the plenum attaches to the carbs that a couple carbs weren't fully in the boots and the clamps were half off. It took a while but I finally got that sorted out after having to take off the gas tank since I hadn't noticed all of this until I installed it and hooked up the lines. I know I should have taken the carbs off and gone through them, but knowing the PO and knowing it was a decent runner and even had fuel stabilizer in it when he parked it, I just wanted to get this going and deal with any issues if/when they arise.

Once I got all of that buttoned up I was able to fire it right up take it up and down my road a few times...I'm digging it for sure. For not having run in a year it started out a bit rough, but that got better just in the couple of miles I went. The rear caliper might need some attention, we'll see once I get tags and insurance on it.

I still need to get the bar end mirror on it, so hopefully I can do that and get some miles in on this tomorrow. Here it is after its maiden voyage as a brat.





 
I've ridden the bike about 70 miles and I am impressed. It is comfy, smooth, and has some punch to it. I went out last Saturday night to hop on it and take a cruise with a buddy and it was not running right at all. It stalled twice on the way to my buddies house and would not idle at all. I couldn't figure out what was going on as it had never acted like this before.

I ended up bringing it back home and hopping on my electra glide...

I was totally bummed, but figured it was one of 2 things. I had replaced one plug cap that was arcing through to the head already, but didn't notice that cylinder 2 had a very similarly looking plug cap bottom rubber. Also, the carbs have been leaking some gas...only while running though and the air box boots don't fit the greatest on the mouths of the carbs. I can't tell if there's leaking there or not and I'm out of brake parts cleaner to spray at it and check.

In my mind it had to be an intermittent missfire from the plug boots, or a vacuum leak at the carbs. I went ahead and ordered the plug caps and o-ring kit/bowl gaskets/rubber plugs for the carbs. I haven't taken the carbs off yet and was hoping that because it was running so well at first I could just ride it for a couple of months then tear the carbs off and go through them with a fine tooth comb over the winter.

I just put the new plug caps on and it does seem better now. Not perfect, the idle still seems a little weird, but not wild like it was before. The choke is so loose it won't stay on when pulled...probably leaking air in all kinds of places right now. I'm thinking the leak might be the o-rings on the fuel T bar. We'll see once the o-ring kit comes in.

Other than that it really reminds me of the honda cb550 I had. RPM and bike feel are very similar...just a bit more power. I was planning on flipping this bike for a decent profit, but I think I'm gonna have to hang onto it for a while. It makes the xs650 bobber feel like I'm riding a jackhammer...
 
I only took it up the road and back after changing plug caps, so I just went out and put a few miles on it. It's definitely better and running like it was before. The humidity was also terrible when it was acting up before which makes sense because humid air is a poorer dielectric and allowed the spark to jump the gap through the cracked boots and air to the head.

I still have a bad gas leak to figure out. I'm gonna pull the carbs when the o-rings come in and see what things look like. I just filled up the tank while I was out and got a whopping 29mpg. I hope after figuring out this leak that improves...

What is normal mileage for the GS750?
 
The o-rings came in so I took off the carbs to take a look. These should be the BS32 carbs.

First thing I noticed when looking at them before any disassembly is that Carb #3 had no bowl gasket. Not a dry, cracked, worthless one....literally not a gasket at all. At this point I assumed I had found my leak and decided not to completely disassemble them and save that for this winter. I did pull a couple of needle valves just to make sure they didn't have any crud in them and they looked very clean.

I also checked the float level. Stock level says 22.4mm and all of these were 21mm at the most even 20.4mm a full 2mm higher. I was unsure if that was also contributing to a leak so I set them at the stock level with my calipers.

I put the carbs back on and buttoned it back up. I took it for a brief spin and saw I had no leak...sweet...however when getting on the throttle I have a hesitation in the midrange as I roll the throttle on. I'd say it's probably between 1/4-1/2 throttle. WOT it pulls like a train.

I hadn't had any hesitation in the throttle that I've noticed yet. I am running stock pipes and have a UNI filter on the air plenum but no stock filter box. Could lowering the float height to stock level have exposed the lean condition??

Any thoughts on that?

On the plus side...I'm not leaking fuel any more.
 
Well before I rip the carbs off again and raise the float height back close to where it was I decided I would check the air mixture screws and see if that might take care of it.

They were only 2 turns out so I took them 3 and a 1/2 and it definitely improved but still not anywhere close to where it should be. Looks like float height is next...
 
pulled the carbs and re-set the floats to 21.4mm which is the low end of the accepted range, took it on a short jaunt and I'm still getting a complete bog down at more than 1/3 throttle under 4,000RPM

Mains and needles are good...once I get above 5,000RPM everything is fine, but low end full throttle is just not happening now. I supposed I could take them off again and raise the fuel level 1 more mm. I'm going to actually fill up the tank here in the next day or two and run it for a while and see what happens once it's really warm.

Literally the only things I changed was putting a gasket on #3 bowl and changing float height and things started bogging in the low end. If it doesn't clear up once fully warm I'm gonna have to take these damn carbs off again and try another float adjustment. I'll cross my fingers and hope for the best...I'm definitely getting faster at taking them off and on.

One other thing I'm going to try is to cover up part of the UNI filter I have on in place of the stock air box. I want to see if it's just too lean and the increased fuel level in the bowls is just compensating for that. It's hard to believe the only air inlet in the air box are those 2 small holes...
 
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