Took it for its first ride! but...

[midnightcafe]

I finally got my gs750 registered and took it for a 25 mile ride. I pulled in after 12 and noticed a very small oil leak from the clutch cover. There was a small puddle underneath after letting it sit for an hour. After the ride, I let it sit again and found no trace of oil leaking. I guess the gasket is seated now? Should be fine unless it leaks again.

There is a noticeable engine noise at idle. The bike has 8500 miles, should I check valve clearance/cam chain tension? (I'm at work and don't have the manual on me to check the maintenance period). Nothing too ominous, maybe I'm not used to the sound of an aircooled motor. How loud should the top end be? Should it be louder than the air pods' vacuum, louder than the exhaust?

I let the tank go down to near reserve and there was a loud metal clunk, but it was coming from the tank. I'm pretty sure it was the gas meter, but it could have been a cable vibrating against the tank. Anyone experience this with their gas gauge? I may have bent the fuel meter float off center when reassembling it. Next time it tape I'll check inside the gas tank.


I bought an aftermarket oil pressure gauge from RenoBruce. I pm'd him this question but he hasn't responded yet, maybe someone else knows the answer. After warming up, the oil pressure stops reading at idle. It does work when it's up to speed at roughly 3psi at 3500rpm. This is normal? Yes.

I rejetted the VM26ss carbs to 125 mains and raised the needles two notches. Running APE pod filters and a MAC exhaust, which I believe was repacked because it isn't too much louder than stock. I performed a carb sync using a Motion Pro carb sync tool (not recommended, the damn vacuum fluid gets bubbly no matter what). It ran excellent, much better than I anticipated. I have pod filters on my XS850 but haven't rejetted those carbs yet, and that bike runs very weak midrange and up and backfires like a bastard child. The GS750 never burbles or backfires running up the rev range, except when engine braking it burbles (excuse the lack of a better term than 'burble' ) and in enthusiastic downshifting it backfires a bit. I don't want this! I'm pretty sure I have to readjust the pilot fuel and air screws; anyone know where I can find information on doing this? Does this running condition sound normal for a bike running aftermarket intake and exhaust?

Sorry for the barrage of questions, I just want to make sure everything is alright and taken care of before I ride it home to Boston next week. I was pumped to take it out for its first ride after restoration. Kids were giving me the thumbs up and people were staring at me wondering what I was riding. Not to sound narcissistic, but it felt gratifying that my bike caught people's attention. I rode past my professor and he was like 'woah! that looks great!'

I'll post pictures soon to show you what I'm talking about.

 

[Steve]

Several issues, let's take them one at a time:

After the ride, I let it sit again and found no trace of oil leaking. I guess the gasket is seated now?

That's a good possibility.

There is a noticeable engine noise at idle. The bike has 8500 miles, should I check valve clearance/cam chain tension? (I'm at work and don't have the manual on me to check the maintenance period). Nothing too ominous, maybe I'm not used to the sound of an aircooled motor. How loud should the top end be? Should it be louder than the air pods' vacuum, louder than the exhaust?

The engines are noisy, but there is a reasonable limit to how much.
Unless you have another bike to compare it to, it's hard to tell you what's "normal".

I let the tank go down to near reserve and there was a loud metal clunk, but it was coming from the tank. I'm pretty sure it was the gas meter, but it could have been a cable vibrating against the tank. Anyone experience this with their gas gauge?

Check the throttle and clutch cables under the tank.

Another possibility is that the float inside the tank is bent sideways a bit and hitting the tank. When the fuel level is higher, the float is away from the narrow tunnels on the sides, so it does not matter. When the fuel is down to that level again, use a flashlight to look in the tank to see if the float is off-center.

I bought an aftermarket oil pressure gauge from RenoBruce. I pm'd him this question but he hasn't responded yet, maybe someone else knows the answer. After warming up, the oil pressure stops reading at idle. It does work when it's up to speed at roughly 3psi at 3500rpm. This is normal?

I know that pressure is very low, but that sounds a little too low. I have never run with a gauge for reference, though.

I rejetted the VM26ss carbs to 125 mains and raised the needles two notches. Running APE pod filters and a MAC exhaust, which I believe was repacked because it isn't too much louder than stock. I performed a carb sync using a Motion Pro carb sync tool (not recommended, the damn vacuum fluid gets bubbly no matter what). It ran excellent, much better than I anticipated. I have pod filters on my XS850 but haven't rejetted those carbs yet, and that bike runs very weak midrange and up and backfires like a bastard child. The GS750 never burbles or backfires running up the rev range, except when engine braking it burbles (excuse the lack of a better term than 'burble' ) and in enthusiastic downshifting it backfires a bit. I don't want this! I'm pretty sure I have to readjust the pilot fuel and air screws; anyone know where I can find information on doing this? Does this running condition sound normal for a bike running aftermarket intake and exhaust?

I have not bothered to look up to see if the 125s are a good choice, but for your backfiring, you will want to adjust your pilot jets, not the main. Start with the pilot fuel screws (the ones on the bottom of the carbs), turn them out 7/8 to one full turn out from lightly seated. Turn the pilot air screws (the ones on the sides of the carbs) double that, or 1 3/4 to 2 turns out. Use that as a starting point. When the bike is warm, slowly turn the air screws, listening for highest engine idle speed.

I'll post pictures soon to show you what I'm talking about.

You are right:

.

 

[midnightcafe]

I bought an aftermarket oil pressure gauge from RenoBruce. I pm'd him this question but he hasn't responded yet, maybe someone else knows the answer. After warming up, the oil pressure stops reading at idle. It does work when it's up to speed at roughly 3psi at 3500rpm. This is normal?

This is more in regards to the operation of the oil pressure gauge. A little search did the trick:

http://www.thegsresources.com/_forum/showthread.php?t=154475&highlight=oil+pressure+gauge

So this question is crossed out, no longer a problem. It's fine that the bike doesn't read any oil pressure at the gauge when it idles after warming up.

 

[midnightcafe]

I've also noticed that it accelerates much quicker than before, even without the intake/exhaust mods. I regeared the front/rear sprockets from 15/41 OEM to 17/47. If I recall correctly that's an added 300rpm cruising at 60mph in 5th gear. Not much speed near the top end, but then again I don't plan on going over 110 any time soon on this oldie.

 

[posplayr]

It's fine that the bike doesn't read any oil pressure at the gauge when it idles after warming up.

As long as the oil light is not on

 

[TheCafeKid]

On an 8v 750, 3psi would be normal at idle when the oil is warm. On a 16v 750, it uses a HIGH pressure system. 3psi at idle sounds low to me. I'd be looking into that soon, along with your top end noise, those motors are semi-notorious for oiling problems... Usually involving lack of oil flow to the top end, usually number one cylinder side cam journals. If you keep running it like that, and there is a problem, the top end will be smoked pretty quick. It's very important that you keep the oil topped off and clean, even if there is no problem, with that motor.

 

[Larry D]

Oiling problems ? Did someone say oiling problems ?

This what my '81 750 16V cams looked like after the dreaded top-end oiling problem. It's all fixed up now and running like a scalded dog with about +-2,000 miles on the re-build.

 

[midnightcafe]

Alright, second night riding and it started right up this time. Took a bit longer than I expected to warm up (5 minutes?) but after that she was good to go. went to a neighboring town's high school parking lot to practice some low speed maneuvers (man I need to read my MSF book again ). It was dark out tonight and I realized that I can't see SH1T with my headlight. The light scatters on the front fender and way above the road horizon. I'm gonna adjust the angle later and bolt it down tight, but I was also wondering if the headlamp housing has the ID number located on the bottom or the top of the headlamp?

Oil gauge still read zero at idle after warming up, gonna check the oil level soon. Learned that I need to tighten down the throttle casing as well.

Should there be noise coming from the clutch when idling? I can hear a distinct noise coming from it at idle, nothing too precarious, it goes away with engine speed.

Gonna install my ammo box saddlebag for my morning commute, go help my friend work on his RF600, and finally end the night with a few beers.

 

[midnightcafe]

tightened down the headlight and throttle. Also the engine case bolts I torqued down more for peace of mind. Threw on the ammo box but it's WAY too low to the ground, I'll have to remount it higher.

Now for some pictures:

 

[cbbjoemama]

what was your paint process, flat or satin black...how logn did it take to polish too?

your color scheme charms me!

 

[midnightcafe]

what was your paint process, flat or satin black...how logn did it take to polish too?

your color scheme charms me!

Flat Black all around, minus the satin black motor top end. Polishing took probably at most 60 hours total (including learning curve), although I found that obtaining a satin polish finish (read: hazy, grain intact) like I have on my front forks was the best bang for you buck.

Satin Polish:
Sanded 180, 220, 400, 600, wd40 on #00 steel wool, wd40 on #0000 steel wool, and finally (a little trick I found useful) end with Mother's aluminum polish on #0000 steel wool. All sanding in a single direction. You won't see your reflection but it a much easier shine to obtain

Mirror Polish:
180, 220, 400, 600, sanding across the previous grain direction. Jump on a buffing wheel and do a three stage polish, cutting direction on the first two compounds (pulling against the buffing wheel), feed on the last (with the buffing wheel) also all buffing in the same direction.

So I was riding home for lunch break and the ammo box started dragging... I knew I had a bad feeling about it gonna have to weld some brackets in for a more permanent, higher position.

 

[Flaming Chainsaws]

Correct me if I'm wrong... Is that an "L" model?

The bike looks great! That tail piece looks very nice. More pictures!

EDIT: NVM. Took a look at your album.

 

[midnightcafe]

Yes, it is/was an L model. I fabricated the footpegs and seat to alter the riding geometry so it's much more aggressive with superbike bars.

Not done yet. Going through the fine details. Front brakes squeal below 5mph (brake dust?), timing cover STILL leaking, even with a new gasket I cutout (could be the rubber piece holding the timing wire), may use a wire mesh from overhead lighting to cover what the sidecovers don't (maybe the taillight as well), adapt foot controls to shift levers I fabricated (right now I have to stick my feet out to shift/brake, definitely temporary for now)

 

[midnightcafe]

So I put the new timing cover gasket on (which didn't solve anything), tried tightenting down the cover bolts, and I felt the bottom one free up after tightening it a bit too much

Thankfully, I broke the screw and didn't strip the threads on the bolt hole. It broke near the bolt head so I just took the cover off and unthreaded the broken part out.

Here's a look at the gasket:

You can see the oil collected at the bottom of the gasket. It seeps through and has been leaking more steadily with the new gasket I cut out. What could I do to the next gasket I make that would prevent this leak? I don't even know WHY there is oil in the timing cover

Besides that, I replaced the broken screw and found a nice scenic byway to ride on. I didn't have any fancy directions holder so I just stuck some magnets on the tank:

That and I went shopping at WalMart:

So you can say I'm enjoying my new freedom to the fullest extent